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Spatial variation in acid and some heavy metal composition of rainwater harvesting

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Nat Hazards(2010)55:307–319DOI10.1007/s11069-010-9529-2O R I G I N A L P A P E RSpatial variation in acid and some heavy metal composition of rainwater harvesting in the oil-producing region of NigeriaS.I.EfeReceived:2January2008/Accepted:24March2010/Published online:5May2010ÓSpringer Science+Business Media B.V.2010Abstract The study adopted the experimental research design andfield survey of the oil-producing region of Nigeria for the past10years.A total of100sterilized rain gauges were randomly distributed on the basis of50each to the eastern and western division of the oil company operating in the region.The rainwater samples harvested through this process were transferred into sterilized plastic containers and kept in coolers and taken immediately to the laboratory for analysis soon after every rain event.The rainwater samples were analysed in the laboratory with the most appropriate techniques.The physicochemical characteristics of rainwater harvested were subjected to paired t test and3-year moving average statistical analysis.The following are the results:There is widespread acid rain in the region,this is evident from pH values that span4.98–5.15and5.06mean values.The result also revealed that acid rain(pH)varied significantly(P[0.05),and it decreases with increasing distance from gasflare sites throughout the period of study.Other physico-chemical characteristics of rainwater resources conform to safe limit with the exception of turbidity,TSS,Pb and NO3,which is also significant at P[0.05with increasing distance from the gasflare sites,as such they decreases with increasing distance.This certainly has serious environmental effects on the human and other species,soil,water and vegetation resources and calls for the extinction of gasflaring,in this region.Sources of water that are acidified should be periodically limed to reduce the acid concentration in such water. Keywords Acid rainÁHeavy metalÁGasflareÁNiger Delta1IntroductionAcid rain is one of the major environmental problems that have characterized the oil-producing region of Nigeria in recent times.There are a series of widespread allegations that gasflaring in the Niger Delta region of Nigeria was contributing greatly to acid rain in this region(Shell Petroleum Development Company SPDC1995).The consequences of S.I.Efe(&)Geography and Regional Planning,Delta State University Abraka,Abraka,Nigeriae-mail:efesunday@this according to the host communities are not only limited to the corrosion of metals,but also lowers the quality of rainwater harvesting,acidifies other water sources and depletes soil fertility leading to the extinction of vegetation species in the area(Akporido et al. 2000;Okecha2000).Shell Petroleum Development Company(1995)asserted that although the occurrence of acid rain is restricted to the foci or vicinity of the gasflares,there is no evidence that gas flaring is the major factor.However,Alakpodia(2000)and Okecha(2000)suggested that gasflaring is the major cause of acid rain in the Niger Delta region of Nigeria and called for more studies to regularly assess the issue of acid rain and its causes in this region. More recently,the occurrence of acid rain has also been confirmed in18rural coastal communities of Delta State(2006).A mean pH value of6.4was observed in the open atmosphere,whereas lower pH values of5.0–5.3were seen in roof catchments of buildings in some coastal communities of Delta State,which was attributed to the proximity of these buildings to gasflare sites and the nature of the roofing materials(Efe2006).Acidification of surface and ground water by acid rain in the Western Niger Delta has also been reported (Olobaniyi and Owoyemi2004;Omo-Irabor et al.2008).In addition to impacts on rain pH, it has been suggested that routineflaring in the Niger Delta is linked to thermal pollution, climatic anomalies,extinction of vegetation and animal species and an increase in roof leakages due to a lower rain quality(Ogbe1999;Alakpodia2000;Efe2002;Onianwa et al. 2002).Despite these results,the operatingfirms still hold the view point that gasflaring has no negative impact on the region.Thus,the issue of acid rain in the oil-producing region of Nigeria is still a subject of controversy.It is therefore imperative to empirically assess the precise nature and mag-nitude of the occurrence of acid rain in the region.This study examines the level of acid and heavy metals in rainwater,with the specific aim of ascertaining the spatial distribution of acid rain(if any),its trend and possible environmental implications in the oil-producing region of Nigeria.The concept of acid rain wasfirst referred to by Robert Augus in1872during the industrial revolution to mean any acidic precipitation(such as rain,fog)or depositions that occur downwind of areas where major emission of SO2,CO2,NO x etc.from human activities take place(Oden1976;Botkin and Keller1998;Efe2005).Using this concept,Fig.1shows the various atmospheric pollutants from gasflaring, which react with water in the atmosphere to produce acid rain.It is evident that gaseous emissions of SO2,CO2,NO x,NH3,etc.from burning fossil fuels,form the major source of acid deposition in the region.Once airborne,these pollutants can travel for several thou-sand kilometres,and this long atmospheric lifetime enables their oxidation into acidic species(Wright et al.1976;Berret et al.1983;Pickering and Owen1994;Tripathy and Panda1999).Subsequent deposition of these acids onto land,leads to widespread soil and surface water acidification.Through infiltration processes acid rain also leaches various heavy metals from the soil into subsurface water,which impacts aquatic life.Acid rain also affects theflora and fauna on land as well as causing damage to sculptures and buildings (Pickering and Owen1994;Tripathy and Panda1999).2Study areaThe oil-producing region of Nigeria otherwise referred as Niger Delta region falls within the central coastlands of southern Nigeria.It lies at the intersection of latitude5°31N and5°33Nand longitude 5°30E and 5°32E,one-third of the region is made up of wetlands and house the third largest mangrove forest in the world (Efe 2002).Alakpodia (2000)found oil spillages and gas flaring in the region have resulted in the extinction of many species of vegetation.The region is characterized with subequatorial climate,but this climate has been influenced by the gas flaring in this region with higher temperatures observed closed to gas flare sites.Rainfall is over 3,000mm per year with no dry season,as rain in all months is over 2.5cm.Relative humidity is normally over 90%in the mornings,but drops to 80%in the afternoons (Efe 2002).Although there are other industries in the region like Delta Steel Company Aladja,Warri,Beta Glass Factory Ughelli,Coca Cola Bottling Company Benin and many other oil servicing company these have little influence on the observed climate anomalies (Efe 2003,2005).The region is also characterized with high traffic clogged areas in the cities of Benin,Warri,Yenagoa,Port Harcourt,etc.The pollution from the traffic area in Warri has resulted in mildly acidic rainwater in the city and its environs (Efe 2005).Over 75%of the gas in the Niger Delta gas province has been flared (Oyekunle 1999;Efe 2003),and the year 2010has been pegged by the Nigerian government for the extinction of gas flaring.3Methodology and data collectionThis study adopted the experimental research design,which utilizes data from direct field survey that last from January to December for 10years (1997–2006).A total of 100sterilized plastic rain gauges were randomly distributed on the basis of 50gauges to the western and eastern division each of the SPDC area of operation.The base map of the region,where the oil fields and gas flare sites are located,was obtained and used as basis for the choice of the gauge stations (Fig.2).The rain gauges were positioned at the designated study sites (at distances of 500m,4,8,12km from the flare sites)at 1.5m above the ground.To avoid deposition of dry precipitation on the gauges,they were removed immediately after the rain and returned to the sites when rain bearing cloud was observed.The rainwater samples were collected from the first rain events for every month,Black BoxWater acidificationAquatic biological effect OUTPUTSSoil acidification Terrestrial, biological effectlinking emissions of SO 2,NO x etc.to soil and water acidification modifiedand for time lapse experiment samples were taken at 5,10,15and 20min from the start of the rain event with a final sample for any subsequent rain.All the rain events studied were collected as time lapse samples.The volume of rain in each time interval was recorded,and the samples were analysed for their physicochemical parameters,the average values of the time lapse samples for each rain event were utilized for this study.This technique has been used by Somboon (1997)and Efe (2005,2006).A sub sample of the rain was used to measure pH and temperature immediately upon collection using a Teledo MC236pH meter and digital mercury thermometer.The remaining rainwater collected was poured into sterilized plastic containers with and kept in a cooler containing ice to reduce the degradation of samples before analysis.Upon arrival at the laboratory,turbidity was estimated with a turbidity meter (APHA 214A).NO 3-was determined by colorimetric spectrophotometry,and SO 42-was determined with spectrometry via precipitation with BalCl 2.A digital MC 226conductivity meter was used to determine the electrical con-ductivity and total dissolved solid (TDS)of the water sample.Na ?and K ?were deter-mined with a flame Emission Analyser.Lead,cadmium,magnesium and iron were analysed with an Atomic Absorption Spectrophotometer (AAS)3200Metler model.The details of the analytical methods are listed in Table 1.The paired t test statistical technique was used to test the level of significance difference of elemental concentrations with increasing distance and over the years.The 3-years moving average was employed to describe the trend over the years.Multiple regression and cluster analysis were also adopted to ascertain the causer factors of acid concentration in rain water.4Results and discussionThe data collected for the study are presented in Table 2,Fig.2and discussed later.Bonny platformKALAEKULEOPOBO SOUTHBONNY TERMINALBONNYUTAPATE SOUTHAKASOKRAKAMACAWTHORNE CHBODO WYORLABOMUKOROKORO TAI OBEAKPU AFAM ONNEALAKIRI UBAAJOKPORIEBUBUASARITORUORURIRI PORTHARCOURTISIMIRI APARAELELENWA BUGUMA CR.OBIGBO N.UMUECHEMAGBADANKALIIMO RIVERAWOBAOTAMINI EKULAMASOKUENWHEEBELERUMUEKPE MINI NTAAHIAUBIEMAMBE CR.ODEAMA CR.BELEMAKOLO CR.DIEBU CR.NUN RIVERBENI SEDEPOUKUSHI NOPUKUSHIGBARETELEBOUADIBAWAADIBAWA N.E.AVWERNIORONIOSIOKAUZERE E.UZERE W.UTOROGUURHUREOWEHISOKOOLOMOROUGHELLI E.UGHELLI W.AFIESEREOGINIERIEMUKOKORIWARRI R.WARRI ASSAUGADAEGBEMA W.OGUTAEGBEMARAPELEEGWA E.AJUJURATANEGWA W.FORC. YORKIODIDI ESCRAVOSBEACHJONES CR.UBEFANSAGHARAOTUMARAFORCADOS TERMINALForcados platformAFREMOOPUAMASAPELEOBENWESTERN DIVISION EASTERN DIVISION0250Km NOVHORAMUKPEKEY TERMINALSCITIES OIL PIPELINES OIL FIELDS/flare sites 4.89-4.974.98-5.055.06-5.15Fig.2Spatial distribution of acid rain in Niger DeltaThe mean pH values of rainwater samples collected for the 10-year period (1997–2006)were generally lower than the WHO (1993)threshold of 6.5for potable water and 5.6for normal rainwater.The pH values range from 4.98to 5.15with 5.07mean values (Table 2),Table 1Standards and methods of analysisTest parameter Units Standard test method Description of methods pH pH ASTM D1293B pH meter Temperature °C Thermometer Turbidity NTU APHA 214A Turbidity meter TSS mg/l Gravimetric Gravimetric TDS mg/l APHA 2080TDS meter Conductivity l s/cm -1APHA 145Conductivity meter DO mg/l APHA4500C Iodometric Cl 2mg/l Titration Titration Nitrate (NO 3-)mg/l APHA 419C Diazotization Sulphate (SO 42-)mg/l APHA 427C Colorimetric Ca 2?mg/l ASTM93-77AAS K?mg/l ASTM D93-77AAS Na ?mg/l ASTM D93-77AAS Pb 2?mg/l ASTM D3559FAAS Cd2?mg/l ASTM D511AAS Fe2?mg/l ASTM D106C FAAS Mg2?mg/lASTM D 511AASTable 2Statistical summary of physicochemical characteristics of rainwater resources in the Niger Delta RegionSource FieldworkaSignificant difference exists with increasing distance(P \0.05),but no significant difference over the years (P [0.05)Parameters Mean ±range pH 5.06±4.98–5.15a H ?12.3±0.5–39.9Temperature (°C)27.4±26–28.2a Turbidity (NTU) 6.56±5.18–6.80a TSS (mg/l)408±400–415a TDS (mg/l)29.65±28.5–31.5a Conductivity (Scm -1)70.2±65.9–69.3a DO (mg/l) 5.7±5.44–5.70a Cl 2(mg/l)26.3±25–27.3a Nitrate (mg/l NO 3)13.5±10.5–16a Sulphate (mg/l SO 42-)30.7±28–34a Ca 2?11.4±0–28K ?7±2–18Na?13±1–35Pb 2?(mg/l)0.99±0.88–1.04a Cd 2?(mg/l)0.001±0.00–0.001a Fe 2?(mg/l)0.03±0.02–0.03a Mg 2?(mg/l)0.7±0.6–0.8aindicating the occurrence of acid rain in the oil-producing region of Nigeria.Acid rain was widespread over the entire region where rainwater samples were harvested for this study as illustrated by Fig.2,which shows the spatial distribution of acid rain in the Niger Delta.Low pH values of 4.89–4.97were observed in rains in number oil fields in both western and eastern regions.The mean rain pH was slightly lower in the eastern region but no significant difference was observed between the western (pH 5.14±0.25and eastern regions (pH 5.14±0.25).Acid rain in the region varies with distance from gas flare sites,with lowest pH at sites closest to the gas flares (Table 3;Fig.3).The occurrence of acid rain is not limited to the communities where gas is flared,but it is spread to other non-gas flared communities in the region where pH values of 5.15to 5.30were generally observed (see Fig.2).For instance,a pH of 5.15,5.18,5.27,5.29and 5.30was observed in rains from Patani,Benin–city,Ibagba,Abraka and Agbor in western Niger Delta areas,and rain pH values of 5.1,5.16,5.28and 5.29were observed at Nkarahia,Calabar,Uyo and Umuahia in the eastern Niger Delta.The acidic concentration in rainwater harvested varied with the duration of rainfall.Higher acidic concentrations were generally recorded in the first 5min of rainfall and lowest at the end of the rain (see Table 4;Fig 4).This increase in rain pH throughout a rain event has been reported previously in rains in Bangkok,Thailand and in Warri and rural areas of the Delta State Nigeria (Somboon 1997;Efe 2005,2006).This decrease in acidity is attributed to acidic species being washed out of the atmosphere during rain events.Table 3Variation of mean pH in rainwater with distance from gas flare over the years Distance 1997199819992000200120022003200420052006Mean Range 500m 5.05 5.00 5.01 5.09 4.99 4.98 4.89 4.99 5.00 5.03 5.010.204km 5.09 5.12 5.08 5.10 5.01 4.99 4.98 5.00 5.08 5.07 5.050.148km 5.11 5.14 5.09 5.18 5.03 5.03 5.00 5.02 5.08 5.05 5.080.1812km 5.12 5.15 5.09 5.19 5.03 5.03 5.08 5.03 5.08 5.08 5.090.16Mean5.105.105.065.145.025.014.995.015.065.075.050.17Source Fieldwork4k 8k 12k 12k mDistancesSulphate NitrateThe low pH values in rainwater during this period correlated significantly with SO 42-and NO 3-(r =0.86and 0.51,respectively),with sites where the rain pH was lowest (for example Egwa,Sapele,Kokori,Uzere,Adibawe,Ahia,Soku,Bonny,Afam,Ogula)having the highest SO 42-and NO 3-concentration.Figure 4illustrates that in addition to an increase in pH,sulphate and nitrate rain concentrations increase with increasing distance from gas flare sites.The high concentration of SO 42-and NO 3-reflected in rainfall acidity has been linked to emission of SO 2and NO 2gases that subsequently dissolve in rainwater (Efe 2005;Olobaniyi and Efe 2007).The natural gas flared in the region at an average rate of 42.5million m 3day -1is rich in oxides of sulphur and nitrogen is likely to be a source of such species (Olobaniyi and Efe 2007).Cluster analysis revealed that study sites close to gas flaring had contributed 94%to acidity recorded in the region.Most of the sites had coefficient [11.45,which is significant at P [0.05.The concentrations of SO 42-,Ca 2?,Cl -and NO 3-ions correlatedTable 4Temporal variation in pH and estimated gas flares rate (BCM)Years 5min 10min 15min 20min [20min Mean Gas flare rates (a BCM)1997 4.89 4.9 4.98 5.06 5.12 4.9929.411998 4.995 5.05 5.16 5.2 5.0826.181999 4.89 4.93 5.06 5.12 5.11 5.02224.612000 4.92 4.985 5.03 5.17 5.0226.762001 4.89 4.935 5.08 5.11 5.00227.012002 4.9 4.99 5.06 5.14 5.19 5.05621.052003 4.9 4.98 5.08 5.1 5.16 5.04424.262004 4.93 4.99 5.03 5.12 5.17 5.04822.92005 4.95 5.06 5.1 5.18 5.04821.562006 4.98 5.03 5.1 5.16 5.19 5.09218.94Mean 4.919 4.973 5.042 5.107 5.16 5.040224.27Min 4.99 5.03 5.1 5.16 5.2Maxa4.894.94.985.035.11Source Authors’Fieldwork and Estimated gas flares (National geophysical data center (NGDC)NOAA Satellite and Information Service 2009)aThe lower the pH,the higher the acidity;BCM ,billion cubicmeterssignificantly to moderately(r=0.86,0.72,0.58and0.51,respectively)with low pH values in the sites that are close toflare sites and had combined cluster[10.34in the region.However,while a significant relationship exists between SO42-,Ca2?and Cl-(r=0.78),poor correlation exists between H?and SO42-(r=0.12).The high rela-tionship among SO42-,Ca2?,K?and Cl-,NO3-suggest an excess acidic anion,and the poor relationship between SO42-and H?shows that the inorganic acid anion present in rain water was not only associated with free acidity.This is consistent with a previous study of rain in Warri region,which found SO42-and NO3-contributed74and26%, respectively,to free acidity when they were at their highest(Ogunkoya and Efi2003).The lowest pH in rain was recorded in2000,when sulphate and nitrate concentrations were also at their highest with mean values of pH values of4.90,SO42-28.9mg/l and NO3-10.3mg/l,respectively(see Fig.5).Throughout the study,pH values span4.93in2006to 5.20in1998.Sulphate rain concentration ranged from30mg/l in2007to31.5mg/l in 2005and NO3-ranged from10.7mg/l in1997to16.9mg/l in2005(see Fig.5).These variation in the pH,sulphate and nitrate concentration of rainwater are not significant (P[0.05)over the years of study.On the other hand,paired t test analysis shows a significant difference in pH with increasing distances from gasflare sites(P\0.05).The most acidic rain was collected in the region in1997(see Table4;Fig.7,this coincided with a reported increase in gas flaring from18.94BCM in2006to29.41BCM in1997(see Figs.6,7).Thefluctuating pattern of acid rain in the region is a reflection of thefluctuating gasflaring rate,the higher theflaring rates the more the occurrence of acid in the region(See Table4).Rain in the non-oil producing region was less acidic than those in the oil-producing belts of Nigeria, but still showed some acidity.Gas released throughflaring into the atmosphere can be carried several thousand of kilometre,degrading the atmospheric environment over vast areas(Somboon1997;Efe2005,2006)Thus,this mildly acid rain observed in the non-oil-producing area could be attributed to the influence of gasflaring.The seasonal variation of pH showed that December generally had the highest acid concentration in rainwater(4.7mean pH value),while July had lowest acidity(5.3mean pH value),indicating lowest acid concentration over the months.It was generally observed that the dryer months of December,January and February had more acidic rain(pH4.7to4.8)than the wetter months (May–September)(pH5.2–5.3)(see Fig.7).An improvement in water quality during the wet season has also been reported in a previous study of the region (Efe 2006).Rainwater in the region is colourless and tasteless but often shows high levels of turbidity and total suspended solids (TSS).For instance,turbidity values ranges from 5.18to 5.80NTU with a mean of 6.56NTU which is [5NTU threshold of WHO (1993),while TSS span 400–415mg/l with a mean of 408mg/l which is far beyond [5mg/l maximum acceptable of WHO (1993)limit for potable water.Conductivity and total dissolved solids (TDS)and temperature were generally low,lower than WHO thresholds during the period of observation.These physical parameters showed significant variation (P [0.05)with distance and no significant difference (P \0.05)over the years.The concentrations of anions (NO 3-,SO 42-and Cl -)and metals (Pb,Cd,Mg and Fe)investigated in the rain also changed significantly with distance (P [0.05)from gas flaring site but not from year to year (P \0.05).It should be noted that NO 3was generally higher than the 10mg/l WHO (1993)thresholds;this could be partly responsible for the occurrence of acid rain in the entire region.Lead concentrations were higher than WHO drinking water guidelines (0.01mg 1-1)in the rain samples (0.88–1.04mg 1-l).Elevated Pb concentrations in rain from this region has been observed in a number of studies (Ogunkoya and Efi2003;Efe 2005,2006;Olobaniyi et al.2007;Olobaniyi and Efe 2007).Increased Pb concentrations have also been reported in groundwater and soil of the Niger Delta region (Olobaniyi and Efe 2007;4.44.64.855.25.45.6JFMAMJJASONDp HMonthsFig.7Seasonal variation in acid rainOrigho2009).The increased Pb may be linked to an increase in the rate of gas faring and high level of pollution from anthropogenic activities in the region(Efe2005,2006).5Environmental implications of acid rain in Niger Delta RegionThis study has revealed that there is widespread occurrence of acid rain in the oil-pro-ducing region of Nigeria.This varied significantly in space and has strong environmental implications on terrestrial aquatic lives as well as the soil components.It was observed and gathered from the inhabitants during the time of data generation that acid rain in the area has precipitated the following:At the leaf surface,chlorosis and yellowing of leaves,wilting of the leaf tips,abscission of leaves and accelerated senescence was observed and,over the past13years,more than 40%of tree and other plant species have been lost.These effects were most pronounced closest to the gasflaring sites where rain pH was lowest(pH3.39)in most of theflares sites.Deleterious effects of acid rain on plants have been reported previously(Jacobson 1984;Neufeld et al.1985).Acid also damages roots and stems in addition to the leaves of plant.Such damage to plants is also an indirect threat to the microorganisms which decompose them,and subsequently the rest of the ecosystem.Jeffrey et al.(1981)found application of simulated sulphuric acid to a number of crops resulted in decreased yield and growth and foliar injury.A decrease in the growth and yield of crops like cassava,sweet potatoes,maize,melon plantain,rubber among others has also been reported in the area potentially due to such effects from acid rain.This has invariably affected the socio economic life of the inhabitants of the oil-producing communities in these agrarian communities.Acid rain has also affected soils by removal of essential nutrients leading to soil infertility in the region.The quality of other sources of water in the area is also affected by acid rain as most of the rivers and streams are acidified and as a result contain high concentrations of anions and cations(Okecha2000;Ogunkoya and Efi2003;Olobaniyi and Efe2007).According the inhabitants acidification in the region has also led to productive failure in aquatic life. The eggs of somefish species such as goldfish,salamonide,roach and tilapia have reportedly been killed by high acidity.In addition,amphibians that spawn in streams in the early wet season have been unable to reproduce.Similarly,reduced Ca and increased Cd and Pb concentration in surface water as a result of acidification,result in deformed bone structures and poor growth infish(Olobaniyi and Efe2007;Efe and Mogborukor2008). Consequently,birds such as loons and osprey that predominate in the area and feed onfish are no longer found.The cornea and mucous layer of the respiratory tracts are very sensitive to acid rain. Rates of acidosis,irritation of eye,conjunctivitis,bronchitis and prolonged coughing and lung disease have been found around the gasflare sites are higher than in non-oil-producing regions of Nigeria(Asonye and Bello2004;Efe and Mogborukor2008).Health problems have been linked to exposure to airborne acidity previously(Lippmann1985) and Keratoconjunctivitis has been reported in a previous study among children in oil-producing industrial areas of Delta State,Nigeria where it was attributed to pollution in the area(Asonye and Bello2004).The high level of toxic heavy metals in fresh waters can also impact human health via consumption of birds andfish contaminated by exposure to these polluted waters.Buildings and structures in the area according to the residents have been decoloured and disfigured.Most landlords in the region asserted that they have to carry out routinerepainting of their houses every2years because of decolouration by acid rain.Similarly, because of corrosion of their roofs most buildings in most of the area suffer leakages. Recent surveys found over40%of houses in the region(especially those at the foci of the flare sites)were leaking and roof repairs or replacement was carried out every3years (Alakpodia2000;Efe2005),however,in the non-oil-producing region such repairs were required much less frequently.In addition most car owners in the region reported that their cars were regularly decoloured that they had to carry out re-spraying once every three to 4years.The bottom plate and body of the car were also affected by corrosion,leading to rust age,requiring annual body work on the car.Based on these environmental consequences,there is the need for legislation to put an immediate end to gasflaring;alternatively it should be converted to industrial raw material for the production of domestic gases.There should be reduction in emission of acid gases. Acidified well,rivers and other water bodies should be treated with lime to restore the pH to a level at whichfish and other organism can survive and rainwater harvested for domestic uses should be purified.All environmental laws for the protection of the envi-ronment should be implemented,mass education for the inhabitants of the area;should be available and periodic environmental impact assessment of the region by both the oil company and the federal government of Nigeria should be carried out.The gasflaring operators should plough back part of their profits for the provision of social infrastructures in the region and employment should be given to the inhabitants of the host communities that have the requisites qualifications.6ConclusionThe study has revealed that there is the occurrence of acid rain in the oil-producing region of Nigeria,which is not limited to the foci of gasflaring communities alone but it is widespread in the region.This is evident in5.06mean pH recorded in the region.Lower pH values of3.97–4.98were reported in area that are close to the gasflare sites.Over the years,acid rain in the region showed afluctuating pattern,reflecting variation in the gas flaring rate,with more acidic rain at higher gasflaring rates.Rain in the non-oil-producing region was less acidic than the oil-producing belts of Nigeria.Physicochemical charac-teristics of rain water resources were within WHO guidelines for drinking water,with the exception of turbidity,pH,TSS,NO3and Pb.However,these physicochemical parameters (pH,SO42-,NO3and Pb etc.)varied significantly in rainwater with distance from the gas flare sites(P[0.05),but showed no significant difference from year to years(P\0.05). The occurrence of acid rain in the region has far reaching environmental implications on the soil,vegetation and crops,aquatic life,water resources.It is therefore recommended that there should be an immediate extinction of gasflaring in the region,and there should be strict adherence to all environmental laws in the country by the oil companies operating the region.ReferencesAkporido SO,Emuobonoviel IJ,Akporideo CE(2000)A study of the quality characteristics of surface and underground water in Sapele and Ogharefe oil producing areas of Delta State.Niger J Sci Environ 2:75–86123。

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生物化学期末总复习资料(双语)

生物化学期末总复习资料(双语)

生物化学复习资料Amino acid（氨基酸）: All proteins are made up from the same set of 20 standard amino acids. A typical amino acid has a primary amino group, a carboxyl group, a hydrogen atom and a side-chain(R group) attached to a central α-group atom(Cα). Proline（脯氨酸）is the exception to the rule in that it has a secondary amino group.Primary structure（一级结构）: The linear（线状的）sequence of amino acids joined together by peptide bonds is termed（被称为）the primary structure of the protein. The position of covalent disulfide bonds between cysteine（半胱氨酸）residues is also included in the primary structure.Secondary structure（二级结构）: Secondary structure is a protein refers to the regular folding of regions of the polypeptide chain. The two most common types of secondary structure are the αhelix and βpleated sheet（β折叠）.Tertiary structure（三级结构）: Tertiary structure in a protein refers to the three-dimensional（三维的）arrangement of all the amino acids in the polypeptide chain. This biologically active, native conformation（构造；形态）is maintained by multiple（多重的；多样的）noncovalent （非共价的）bonds.Quaternary structure（四级结构）: if a protein is made up of more than one polypeptide chain it is said to have quaternary structure. This refers to the spatial（空间的）arrangement of the polypeptide subunits（亚基；亚单位）and the nature of the interactions between them.Protein stability（蛋白质稳定性）: In addition to the peptide bonds between individual amino acid residues, the three-dimensional structure of a protein is maintained by a combination of noncovalent interactions(electrostatic forces（静电力）, van derWaals forces（范德华力）,hydrogen bonds（氢键）, hydrophobic forces（疏水作用力）) and covalent interactions(disulfide bonds（二硫键）).The Bohr effect(波尔效应): H+, CO2and 2,3-bisphosphoglycerate（2,3-二磷酸甘油酸）are allosteric effectors（变构效应剂）, promoting the release of O2 from hemoglobin（血红蛋白）. H+ and CO2 bind to different parts of the polypeptide chains, while 2,3-bisphosphoglycerate binds in the central cavity（凹穴）between the four subunits.Dialysis（透析）: Proteins can be separated from small molecules by dialysis through asemi-permeable membrane（半透膜）which has pores that allow small molecules to pass through but not proteins.Function and diversity of collagen（胶原蛋白）: Collagen is the name given to a family of structurally related proteins that form strong insoluble（不可溶的）fibers. Collagens consist of three polypeptide chains, the identity and distribution of which vary between collagen types.Gel filtration chromatography(凝胶过滤层析)Ion exchange chromatography(离子交换层析)Affinity chromatography(亲和层析)Enzymes as catalysts（作为催化剂的酶）: Enzymes are catalysts（催化剂）that change the rate of a reaction without being changed themselves. Enzymes are highly specific and their activity can be regulated. Virtually all enzymes are proteins, although some catalytically active RNAs have been identified.Active site（活性位点）: The active site is the region of the enzyme that binds the substrate, to form an enzyme-substrate complex, and transforms it into product. The active site is a three-dimensional entity（实体）, often a cleft（裂口）of crevice（缺口）on the surface of the protein, in which the substrate is bound by multiple weak interactions. Two models have been proposed to explain how an enzyme binds its substrate: the lock-and-key model and the induced-fit model（诱导契合模型）.Enzyme classification（酶的分类）: Enzymes are classified into six major groups on the basis of the type of reaction that they catalyze. Each enzyme has a unique four-digit classification number.Enzyme assays（酶的测定）: An enzyme assay measures the conversion of substrate to product, under conditions of cofactors, pH and temperature at which the enzyme is optimally active（最佳活性的）.Coenzymes（辅酶）and prosthetic group（辅基）: Some enzymes require the presence of cofactors, small nonprotein units, to function. Cofactors may be inorganic ions or complex organic molecules called coenzymes. A cofactor that is covalently attached to the enzyme is called a prosthetic group. A holoenzyme is the catalytically active form of the enzyme with its cofactor, whereas an apoenzyme（脱辅基酶蛋白）is the protein part on its own.Isoenzymes（同工酶）: Isoenzymes are different forms of an enzyme which catalyze the same reaction, but which exhibit different physical of kinetic（动力学的）properties（性质）.Activation energy and transition state: For a biochemical reaction to proceed, the energy barrierneeded to transform the substrate molecules into the transition state has to be overcome. The transition state has the highest free energy in the reaction pathway. The different in free energy between the substrate and the transition state is termed the Gibbs free energy of activation. An enzyme stabilizes the transition state and lowers Gibbs free energy（吉布斯自由能）, thus increasing the rate at which the reaction occurs.Michaelis-Menten equation（米氏方程）: v＝Vmax[S]/ (Km+[S])It describe these observations and predicts a hyperbolic curve（双曲线）of V0 against [S]. The Michaelis constant, Km, is equal to the sum of the rates of breakdown of the enzyme-substrate complex over its rate of formation, and is a measure of the affinity（亲和性）of an enzyme for its substrate.Enzyme inhibition（酶的抑制）: The catalytic rate of an enzyme can be lowered by inhibitor molecules. Many inhibitors exist, including normal body metabolites, foreign drugs and toxins. Enzyme inhibition can be of two main types: irreversible or reversible. Reversible inhibition can be subdivided into competitive and noncompetitive.Irreversible inhibition（不可逆抑制）: An irreversible inhibition binds tightly, often covalently, to amino acid residues at the active site of the enzyme, permanently inactivating the enzyme.Reversible competitive inhibition（可逆竞争抑制）: A competitive inhibitor competes with the substrate molecules for binding to the active site of the enzyme. At high substrate concentration, the effect of a competitive inhibitor can be overcome. the type of the inhibition can increase the Km ,but leave the Vmax unchanged.（Km变大，Vmax不变）Reversible noncompetitive inhibition（可逆非竞争性抑制）: A noncompetitive inhibitor binds at a site other than the active site of the enzyme and decreases its catalytic rate by causing a conformational change in the three-dimensional shape of the enzyme. The effect of a noncompetitive inhibitor cannot be overcome at high substrate concentrations. This type of the inhibition can decrease Vmax ,but leave the Km unchanged.（Km不变，Vmax变小）Reversible uncompetitive inhibition（可逆反竞争性抑制）: A uncompetitive inhibition binds at a site located in the substrate-enzyme complex. Thus, the type of the inhibition can decrease both the Vmax and the Km.（Km和Vmax都变小）Allosteric enzymes: A plot（绘制成的坐标图）of V0 against [S] for an allosteric enzyme gives a sigmoidal-shaped curve（S形的曲线）. Allosteric enzymes usually have more than one active site which cooperatively bind substrate molecules, such that the binding of substrate at one active site induces a conformational change in the enzyme which alters the affinity of the other active sites for substrate. Allosteric enzymes are often multisubunit proteins(多亚基蛋白质), with an active site on each subunit. Two models have been proposed to explain the allosteric behavior of enzyme, the concerted or the symmetry model（齐变模型）and the sequential model（序变模型）.Reversible covalent modification: The activity of many enzymes is altered by the reversiblemaking and breaking of a covalent bond between the enzyme and a small nonprotein group. The most common such modification is the addition and removal of a phosphate group（磷酸基）; phosphorylation（磷酸化）and dephosphorylation（去磷酸化）, respectively. Phosphorylation is catalyzed by protein kinases（蛋白激酶）, often using A TP as the phosphate donor, whereas dephosphorylation is catalyzed by protein phosphatases.（蛋白磷酸酯酶或蛋白磷酸化酶）Proteolytic activation（酶原激活）: Some enzymes are synthesized as larger inactive precursors （前体）called proenzymes or zymogens（酶原）. These are activated by the irreversible hydrolysis（水解）of one or more peptide bonds.DNA double helix（DNA双螺旋结构）: In a DNA double helix, the two strands（串；条）of DNA are wound round each other with the bases（碱基）on the inside and the sugar-phosphate backbones（磷酸糖主干）on the outside. The two DNA chains are held together by hydrogen bonds between pairs of bases; adenine（A）always pairs with thymine（T）and guanine（G）always pairs with cytosine（C）. In the double helix, the two strands are organized in an antiparallel arrangement（反平行的排布）(one is oriented in the 5’→3’ , the other is in the 3’→5’).Between the sugar-phosphate strand is the gap which could be divided into two types, that is, the wide named major groove（大沟）and the narrow named minor groove（小沟）.Glycogen（糖原）: glycogen is a branched-chained polysaccharide containing glucose residues linked by α-1-4 bonds（α-1,4糖苷键）with α1-6 branchpoints（α-1,6糖苷键分支点）. The branched nature of glycogen makes it more accessible to glycogen phosphorylase（糖原磷酸化酶）during degradation（降解）, since this enzyme degrades the molecule by sequential removal of glucose residues from the nonreducing ends.Starch（淀粉）: Starch is a mixture of unbranched amylase(glucose residues joined by α1-4 bonds) and branched amylopectin(glucose residues joined α1-4 but with some α1-6 branchpoints).Overview of pentose phosphate pathway（磷酸戊糖途径综述）: The two major products of the pathway are nicotinamide adenine dinucleotide and ribose 5-phosphate（核糖-5-磷酸酯）. Ribose 5-phosphate and its derivatives are components of important cellular molecules such as RNA, DNA, NAD+，flavine adenine dinucleotide(FAD), A TP and coenzyme A(CoA). NADPH is required for many biosynthetic pathways and particularly for synthesis of fatty acids and steroids （类固醇）.Four Biological roles of fatty acids（脂肪酸的四个生理功能）:1.They are components of membranes(sphingolipids and glycerophospholipids)2.Several proteins are covalently modified by fatty acids;3.They act as energy stores(triacylglycerols) and fuel molecules;4.Fatty acid derivatives serve as hormones and intracellular second messengers.Role of Citric acid cycle(柠檬酸循环，又名tricarboxylic acid cycle（三羧酸循环），简称TAC): The cycle oxidizes pyruvate(formed during the glycolytic breakdown of glucose) to CO2andH2O,with the concomitant production of energy. Acetyl CoA from fatty acid breakdown and amino acid degradation products are also oxidaized. In addition, the cycle has a role in producing precursors for biosynthetic pathways.Energy yield of Citric acid cycle（柠檬酸循环的能量产出）: For each turn of the cycle,10 ATP molecules are produced, one directly from the cycle and 9 from the re-oxidation of the three NADH and one FADH2 molecules produced by the cycle by oxidative phosphorylation（氧化磷酸化）.20种常见氨基酸的名称和结构式名称英文缩写结构式甘氨酸(α-氨基乙酸)Glycine Gly GCH2COONH3丙氨酸(α-氨基丙酸)Alanine Ala ACH COONH3CH3亮氨酸(γ-甲基-α-氨基戊酸)*Leucine Leu LCHCOONH3(CH3)2CHCH2异亮氨酸(β-甲基-α-氨基戊酸)* Isoleucine Ile ICHCOONH3CH3CH2CHCH3缬氨酸(β-甲基-α-氨基丁酸)*Valine Val VCHCOONH3(CH3)2CH脯氨酸(α-四氢吡咯甲酸)Proline Pro P COONH H苯丙氨酸(β-苯基-α-氨基丙酸)* Phenylalanine Phe FCHCOONH3CH2蛋(甲硫)氨酸(α-氨基-γ-甲硫基戊酸) * Methionine Met MCHCOONH3CH3SCH2CH2色氨酸[α-氨基-β-(3-吲哚基)丙酸]* Tryptophan Trp WNCH2CH COONH3H丝氨酸(α-氨基-β-羟基丙酸)Serine Ser SCHCOONH3HOCH2谷氨酰胺(α-氨基戊酰胺酸)Glutamine Gln Q CH2CH2CHCOONH3H2N CO苏氨酸(α-氨基-β-羟基丁酸)*Threonine Thr TCHCOONH3CH3CHOH半胱氨酸(α-氨基-β-巯基丙酸)Cysteine Cys CCHCOONH3HSCH2天冬酰胺(α-氨基丁酰胺酸)Asparagine Asn N CH2CHCOONH3H2N CO酪氨酸(α-氨基-β-对羟苯基丙酸) Tyrosine Tyr YCHCOONH3CH2HO天冬氨酸(α-氨基丁二酸) Aspartic acid Asp DNH3HOOCCH2CHCOO谷氨酸(α-氨基戊二酸) Glutamic acid Glu ECHCOONH3HOOCCH2CH2赖氨酸(α,ω-二氨基己酸)*Lysine Lys KCHCOONH2CH2CH2CH2CH2NH3精氨酸(α-氨基-δ-胍基戊酸)Arginine Arg RH2N C CHCOONH2NHCH2CH2CH2NH2组氨酸[α-氨基-β-(4-咪唑基)丙酸] Histidine His H NCH2CH COONH3HN* 为必需氨基酸中性脂肪族氨基酸：Gly (Gly也是二十种中唯一不含手性碳原子的氨基酸，不具有旋光性)Ala Val Lue Ile含羟基或者巯基：Ser Thr Cys Met酸性氨基酸及其酰胺：Asp Asn Glu Gln碱性氨基酸和杂环氨基酸：Lys Arg His Pro芳香族氨基酸：Phe Tyr Trp非极性R基氨基酸：Ala V al Leu Ile Pro Phe Trp Met带正电荷(碱性)R基氨基酸：Lys Arg His不带电荷的极性R基氨基酸：Gly Ser Thr Cys Tyr Asn Gln带负电（酸性）的R基氨基酸：Asp Glu在280nm附近有吸收峰的氨基酸是：Phe Tyr Trp ，其中Trp的吸收峰在280nm处最强等电点：在某一pH的溶液中，氨基酸解离成阳离子和阴离子的趋势及程度相等，所带净电荷为零，呈电中性，此时溶液的pH称为该氨基酸的等电点。

写作业吃核桃补脑吗英语

写作业吃核桃补脑吗英语

Eating walnuts while doing homework may indeed help with brain function due to their nutritional content.Heres a detailed explanation in English:1.NutrientRich:Walnuts are packed with a variety of nutrients that are beneficial for brain health.They contain a high amount of omega3fatty acids,which are essential for cognitive function.2.Omega3Fatty Acids:These acids,particularly alphalinolenic acid ALA,are known to support brain health by helping to maintain cell membrane integrity and contributing to the production of neurotransmitters.3.Antioxidants:Walnuts are also a good source of antioxidants like polyphenols,which can help protect the brain from oxidative stress that can lead to cognitive decline.4.Vitamin E:This vitamin is an important antioxidant that can help to prevent cell damage in the brain.5.Enhancing Memory:Some studies suggest that consuming walnuts can improve memory and cognitive performance,especially in older adults.6.Boosting Brain Blood Flow:The omega3fatty acids in walnuts can help improve blood flow to the brain,which is crucial for maintaining cognitive health.7.Mood Regulation:Walnuts may also have a positive effect on mood regulation due to their content of serotonin precursors,which can help reduce stress and anxiety levels.8.Ease of Incorporation:Walnuts are easy to incorporate into a study snack.They can be eaten alone,mixed into yogurt,added to salads,or used as a topping for oatmeal or cereal.9.Moderation:While walnuts are beneficial,its important to consume them in moderation due to their high calorie content.A handful or a small portion is usually sufficient.10.Overall Brain Health:Incorporating walnuts into your diet as part of a balanced approach to brain health can contribute to overall cognitive wellbeing. Remember,while walnuts can be a part of a brainhealthy diet,they are not a substitute for a wellrounded approach that includes regular physical activity,adequate sleep,and a diet rich in a variety of fruits,vegetables,whole grains,and lean proteins.。

Acid-Base Balance and Disturbances(7)

Acid-Base Balance and Disturbances(7)


6. Anion Gap (AG) 阴离子间隙 )
AG 指血浆中未测定的 阴离子 (UA) 与未测定的阳 之间的差值. 离子 (UC) 之间的差值
4. Effect of Cells 细胞的调节作用 Ion exchange between intracellular and extracellular fluids H＋-Na＋ exchange H＋-K＋→hypokalemia/ hyperkalemia Na＋-K＋ exchange Cl--HCO3- exchange
4. Buffer Base (BB) 缓冲碱 )
血液中一切具有缓冲作用的负离子的总 和 。 包括HCO3- 、 Hb- 、 HPO42- 和 Pr- 等 ， 正 包括 常值为45～ 常值为 ～52mmol/L（平均 mmol/L）。 （平均48 ） BB是反映代谢性因素指标 是反映代谢性因素指标 BB↓：代酸； BB↑：代碱。 ↓ 代酸； ↑ 代碱。
Respiratory acidosis
[HCO3-]
Respiratory factor
Respiratory alkalosis
[H2CO3]=α×PaCO2
代谢性因素
代谢性酸中毒 代谢性碱中毒
24 pH = pKa + log =6.1+lg 1.2 [H2CO3] =7.4
呼吸性因素
呼吸性酸中毒 呼吸性碱中毒
3. Respiratory regulation of acid-base balance 呼吸的调节
Regulation through central / peripheral chemoreceptors
通过中枢和外周化学感受器作用 PaCO2 ↑ /↓, pH ↓ /↑ ↓ ↑ ↓ Chemorecertor (+)/(-) )() ↓ Pulmonary ventilation ↑/ ↓ 肺泡通气量 ↓ PaCO2 ↓/ ↑
Chemical constituents and biological activities of Azadirachta indica A. Juss

Chemical constituents and biological activities of Azadirachta indica A. Juss

ReviewChemical constituents and biological activities ofAzadirachta indica A. JussXuegui Liu, Yuqiu Sun, Jun Bian, Mengchao Lv, Ting Han, Danqi Li*, Pinyi Gao*College of Pharmaceutical and Biological Engineering, Shenyang University of ChemicalTechnology, Shenyang, Liaoning 110142, P. R. China––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––AbstractAzadirachta indica A. Juss is a tropical evergreen plant, belonging to the Meliaceae family. The plant is used as folk medicines for the treatment of fever, neuromuscular pains, skin infections, diabetes and heart disease. Previous researches show that the plant possesses several types of chemical constituents and diverse biological activities. The paper concludes chemical constituents, biological activities and pesticide products of A. indica.Key words:Azadirachta indica A. Juss; chemical constituents; pharmacological activities; pesticide products; review––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––––1 IntroductionAzadirachta indica A. Juss, known as neem, belonging to the Meliaceae family, is mainly distributed in the tropical and subtropical areas [1].A. indica has been used in the Indian Ayurvedic and Unani medicine along with Sanskrit medicine for thousands of years due to prevention and control of diseases, such as fever and neuromuscular pains, skin infections, diabetes and heart disease [2]. Neem twigs and oil are used for brushing teeth and skin care, respectively. Many parts of the neem tree (seeds, leaves, flowers and bark) are used for preparing many different medical preparations [3].Previous researches have shown that the plant possesses an array of biological activities, including antibacterial, antifungal and anticancer activities, especially the insecticidal activity [4]. More attention has been paid to the chemical constituents of this tree because of its medicinal and pesticidal properties. The chemical investigations have identified numerous diterpenoids and triterpenoids in A. indica, and some flavonoids, sulphurous compounds, carbohydrates and amino acids have been reported [5-7].By comparison with chemical insecticides, botanical insecticides have low toxicity, good safety, no residue and other characteristics. More interestingly, neem extracts have been confirmed as botanical insecticides [8]. The review is undertaken to conclude chemical constituents, biological activities and pesticide products, which will build the foundations for further exploring and utilizing neem products.* Author to whom correspondence should be addressed. Address: College of Pharmaceutical and Biological Engineering, Shenyang University of Chemical Technology, Shenyang 110142, People’s Republic of China; E-mail: lidanqi@, gpy1981@; Tel.: +86-24-89385213, +86-24-89381811.Received: 2018-07-27 Accepted: 2018-10-272 Chemical components of Azadirachta indica2.1 DiterpenoidsDiterpenes existing in A. indica belong to tricyclic diterpene type that generally has an aromatic ring with carbonyl groups at C-3 or C-7. Sixteen compounds from the root bark, seed and stem bark of the plant have been reported viz. nimolinin (1) [9], nimbidiol (2) [10], nimbonone (3), nimbonolone (4) [11], margolone (5), margolonone (6), isomargolonone (7) [12], nimosone (8), nimbosone (9), methyl nimbiol (10), methyl nimbionone (11), sugiol (12) [13], nimbisonol (13), nimbione (14), nimbionone (15) [14], and 7α-acetoxy-3-oxoisocopala-1,13-dien-15-oic acidarbutin (16) [15].14), nimbionone (15) [14], and 7α-acetoxy-3-oxoisocopala-1,13-dien-15-oic acidarbutin (16) [15].Fig. 1 Diterpenoids in Azadirachta indica2.2 TriterpenoidsTriterpenoids and their derivatives are the major constituents isolated and identified from A.indica. Derivatives of triterpenes are referred to as limonoids which are originated from theprecursor compound of a 4,4,8-trimethyl-17-furanylsteroid skeleton, containing A, B, C, D ringsFig. 1 Diterpenoids in Azadirachta indica2.2 TriterpenoidsTriterpenoids and their derivatives are themajor constituents isolated and identified fromA.indica. Derivatives of triterpenes are referredto as limonoids which are originated from theprecursor compound of a 4,4,8-trimethyl-17-furanylsteroid skeleton, containing A, B, C, D ringsand a furan ring. The structures of the limonoids are complex and various, which is attributed from many patterns of oxidation as well as rearrangement. Out of limonoids in A.indica, it has been reported that azadirachtin is the most representative compound, and salannin, meliantriol, and nimbin are also extensively investigated [16].Azadirachtin, a highly oxidative ring opening of limonoids, contains nine secondary carbons, seven quaternary carbons and 16 chiral carbons [17]. Eight compounds (azadirachtins B, D, F, H, I, K, M and N) of closely related structures with azadirachtin have been isolated from A.indica. Apart from azadirachtin type compounds, a series of gedunin, vilasin, nimbin and salannin derivatives from A.indica have been observed. Triterpenoids and their derivatives from A. indica reported to dates are given in Table 1.Compound Origin References Compound Origin References Azadirachtin (17)Seed kernels, Seed oil[18-20]Azadirachtin B (18)Neem oil[20] Azadirachtin D (19)Seed oil, seeds[21,22]Azadirachtin F (20)Seeds[23] Azadirachtin H (21)Seeds, Kernel[24,22]Azadirachtin I (22)Kernel[22] Azadirachtin K (23)seed kernels[25]Azadirachtin M (24)Seed kernels[26] Azadirachtin N (25)Seed kernels[26]Gedunin (26)Seed oil, Seed[14,27]6β-hydroxygedunin (27)Seed oil[27]7-deacetyl-7-benzoylgedunin(28)Seed, Fruit coat[14,28]7-deacetyl-gedunin (29)Fruit coats[28]Azadiraindin G (30)Fruit coats[28] Nimolicinol (31)Seed[15]Salannin (32)Seed oil, Bark[14,27] 3-deacetylsalannin (33)Root, Kernels[14,29]Salannol (34)Root[14]Salannol 3-acetate (35)Root[14]1-benzoyl-1-decinnamoylohchininacetate(36)Root[14]1-benzoyl-3-deacetyl-1-detigloyl salannin (37)Kernels[29]1-detigloyl-1-isovaleloylsalanninolide (38)Root[14]2,3-dihydro-3α-methoxy-nimbolide (39)Root[14]Nimbolide (40)Bark, Leaf[14,30]3-acetyl-11-methoxy-1-tigloylazadirachtinin (41) Bark[14]Nimbandiol (42)Bark[14]Root6-acetylnimbandiol (43)Root[14]Nimbin (44)Bark, Kernels[14,29] 6-deacetylnimbin (45)Bark, Seed, Kernels[14,31,29]6-deacetylnim-binolide (46)Leaf[15]6-deacetylnimbinolactone (47)Leaf[14]Isonimbinolide (48)Bark[14] Leaf6-deacetylisonimbinolide (49)Bark[14]deacetyl-20,21-epoxy-20,22-dihydro-21-deoxyisonimbi-nolide (50)Leaf[14] LeafNimbinene (51)Seed oil[27]Nimonol (52)Seed, Leaf[14,32] 23-deoxyazadironolide (53)Seed[14]Azadiradione (54)Seed, Fruit coats[14,28]7-benzoylnimbocinol (55)Seed[14]7-benzoyl-17-epinimbocinol(56)Seed[14]Isoazadironolide (57)Fruit coat[31]7-O-acetyl-7-O-debenzoyl-22-hy-droxy-21-methoxylimocinin (58)Flower [31]Table 1 Triterpenoids and their derivatives from A.indica(to be continued)Continued table 1Compound Origin References Compound Origin References Azadirachtol (59) Fruits[33]Azadiraindin F (60)Fruit coats[28]15-hydroxyazadiradione (61)Seed[15]17-hydroxyazadiradione (62)Seed[15]7-benzoyl-17-hydroxynimbocinol(63)Seed[15]17-epiazadiradione (64)Seed[15]17-epi-17-hydroxyazadiradione(65)Seed[15]7-acetyl-16,17-dehydro-16-hydroxyneotrichilenone (66)Seed[15] Azadiradionolide (67)Seed[15]23-deoxyazadironolide (68)Seed[15] 20,21,22,23-tetrahydro-23-oxoazadirone (69)Seed[15]Limocin E (70)Seed[15]23-epilimocin E (71)Seed[15]Epoxyazadiradione (72)Seed, Fruit coats[14, 27]7-deacetyl-7-benzoylepoxyazadiradione (73)Seed, Fruit coats[14, 28]Azadiraindin E (74)Fruit coats[28]3-acetyl-7-tigloylnimbidinin (75)Bark[14]7-tigloyl-12-oxo vilasini (76)Kernels[29]3-acetyl-7-tigloylvilasinin lactone(77)Bark[14]Isomeldenin (78)Leaves[32] Meliantriol (79) Oil, Fruits, Leaves[33]Azadirahemiacetal (80)Kernels[29] Azadiralactone (81)Kernels[29]α-nimolactone (82)Seeds[15]β-nimolactone (83)Seeds[15]Desfuranoazadiradione (84)Seeds[15] desfurano-6R-hydroxyazadiradione (85)Leaves[34]Zafaral (86)Leaves[35]2,3,4-trihydroxypregnan-16-one(87)Seed kernels[36]s2.3 FlavonoidsFlavonoids have been found in the flowers, leaves and bark of A. indica on basis of the studies. These compounds are identified as nimbaflavone (88(90), ((3′-(3-hydroxy-3-methylbutyl)naringenin 97), 4′-O -methyllespedezaflavanone C (98), 4′-O -methyl-8-prenylnaringenin (99), 3′-prenylnaringenin (100(102105106 3 Biological activities of Azadirachta indica3.1 Pesticidal propertyOne of the major biological activities of the by the well-on antifeedant, and for their feeding deterrents against the third instar larvae ofContinued fig. 2Fig. 3 Flavonoids inAzadirachta indicaand epoxyazadiradione were strong antifeedants against P . xylostella . Chandel and Sengar [41] tested anthelmintic activities of neem and their derivatives against third instar larvae of Athalia lugens proxima (Klug.) via dry-film technique. The result showed the neem seed kernel extracts, leaf extracts, deoiled neem seed kernel powder suspension and neem based insecticide were effective to some degree of repellency reducing the feeding and destruction rates.Growth evaluation and combination evaluation of neonate larvae of H. armigera and S. litura were investigated as reported by Koul [27] et al. In dietary experiments, growth inhibitory concentrations of 6β-hydroxygedunin for H. armigera and S. litura were 24.2 and 21.5 ppm (EC50), respectively. This efficacy was higher than gedunin (50.8 and 40.4 ppm), salannin (74.5 and 72.0 ppm), and nimbinene (391.4 and 404.5 ppm) and lower than azadirachtin (0.26 and 0.21 ppm). In feeding assays, it was found that EC50values of combinations with azadirachtin resembled that of azadirachtin alone. But EC50 values of combinations without azadirachtin displayed an enhancement effect based on the feeding deterrence and the physiological toxicity.3.2 Antifungal activityJabeen [42] et al. applied different organic layer of leaf extracts of A. indica to explore antifungal activities against Alternaria Solani that leaded to early blight in potato, showing ethyl acetate layer effectively inhibited fungal growth with MIC of 0.19 mg. Moreover, MIC value of the reference fungicide (Metalaxyl+Mancozeb) was 0.78 mg, which was lower than that of ethyl acetate layer.Salazar [43] et al. implicated that antifungal activities of leaves and seed oil extracts in A. indica were probably attributed to the presence of terpenoids. Various bioassays were performed on 14 extracts of the dermatophytes Trichophyton mentagrophytes, Trichophyton rubrum, Microsporum canis and Epidermophyton floccosum. It was observed that the MIC of leaves extract, seed oil extract, and positive control (Terbinafine) were 50 μg/mL-200 μg/mL, 625 μg/mL-2500 μg/mL and 0.0019 μg/mL-0.0313 μg/mL, respectively. Likewise, HPLC method was established for determining their content of terpenoids, explaining the differences of antifungal activities.Angèle [44] et al. discussed the effects of aqueous extracts of neem seeds (Azadirachta indica) on the development of Phakopsora pachyrhizi in vitro and tested the minimum inhibitory concentrations. It was found that the highest concentration of the tested extract (100 μg/mL) inhibited all fungi growth. Thus, the extracts could be used as fungicide for all tested P. pachyrhizi strains.3.3 Antibacterial activityYerima [45] et al. revealed antibacterial activities of stem, leaves, seeds and fruits extracts from A. indica against Pseudomonas aeruginosa, Corynebacterium diphtheriae and Bacillus spp. The stem extracts had stronger antibacterial properties at different concentrations (10 mg/mL, 30 mg/mL, 60 mg/mL and 90 mg/mL) against the above bacteria species. The seed and leaves extracts had antibacterial properties apart from 10 mg/mL concentrations against C. diphtheria, while the fruit extracts only at higher concentrations against P. aeruginosa. Obviously, this study indicated stem extracts could be used for curing cough, fever and wounds.The study by Maleki [46] et al. demonstrated that neem might be a promising therapeutic agent to combat antibiotic resistant bacteria. The antimicrobial activities of ethanol, methanol and ethyl acetate extracts of Azadirachta indica A. juss leaves were tested against some pathogenic bacterial strains including S. aureus ATCC6538, E. faecalis ATCC1394, P. aeroginosa ATCC 9027, E.coli ATCC25922 and their clinical isolates. The result showed that methanol extract has the strongest growth inhibitory effect on both standard and clinical isolated strains of P. aeroginosa. And ethyl acetate and ethanol extracts also showed a growth inhibitory effects on both standard and hospital isolated strains of S. aureus.3.4 Anti-cancer activityNumerous studies show that the isolates from A. indica have strong anticancer activities. Kikuchi [47] et al. isolated thirty-five limonoids and evaluated for their cytotoxicities against HL60, AZ521, A549, CRL1579 and SK-BR-3 cells. The results revealed that 7-deacetyl-7-benzoylepoxyazadiradione, 7-deacetyl-7-benzoylgeduin and 28-deoxonimbolide exhibited potent cytotoxic activities against HL60 cells with IC50 values in the range 2.7-3.1 μM.Nanduri [48] et al. displayed that azadirone had potent cytotoxic activities against breast, melanoma and prostate cell lines having GI50 values in sub micro molar concentrations. And in vivo hollow fiber assays, azadirone was found to possess good antitumor activity.4 Pesticide products of Azadirachta indicaSo far, there are a variety of constituents of botanical insecticides used in agriculture, such as nicotine, pyrethrin, rotenone, cevadine, asimicin, and azadirachtin [49]. Among these botanical products, azadirachtin-based insecticides are attracting great attentions. The commercial neem insecticides viz. Margosan-O, Green Gold R, Align TM, Azatin R and Turplex TM have been registered [50]. Commercial formulations also contain Neemol, Super Neemol, Neem Azal, Potenised Neem Systemic Oil [51], Neemix 90EC, Neemmzid, Trilogy 90EC, Bio-neem, Turplex, Bollwship, Fortune Aza, Fortune biotech, Neem Surakasha, Proneem, Neem wave, Aza technical, Neem Azal, Kayneem, Neemolin, Surfire, Neemachtin, Nimbecidine [52].5 ConclusionThe present study summarized chemical components and biological activities of A. indica, showing that insecticides originated from A. indica were significant for pest control. Nevertheless, investigations on the mode of action of neem formulation were limited. Therefore, the study wished to offer the foundations for further research on its mechanism of action and application of active insecticides in A. indica.References[1] Forim MR, Silva MF das GF da, Cass QB, et al.Simultaneous quantification of azadirachtin and 3-tigloylazadirachtol in Brazilian seeds and oil of Azadirachta indica: application to quality control and marketing. 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