Biochemistry and transcriptome analysis reveal condensed tannins alleviate liver injury induced by regulating cholesterol metabolism pathway

Free cholesterol has been considered to be a critical risk factor of nonalcoholic fatty liver disease(NAFLD).It remains unknown whether dietary intake of condensed tannins(CTs)have distinguishable effects to alleviate liver damage caused by a high cholesterol diet.Male C57BL/6 mice were fed a high cholesterol diet for 6 weeks,and given CTs treatment at a dosage of 200 mg/(kg·day)at the same time.The results indicated that compared with mice fed a normal diet,a high cholesterol diet group resulted in significant weight loss,dysregulation of lipid metabolism in blood and liver,and oxidative stress in the liver,but CTs treatment dramatically reversed these negative effects.Hematoxylin and eosin(H&E)staining and frozen section observation manifested that CTs treatment could effectively reduce the deposition of liver cholesterol and tissue necrosis caused by high cholesterol intake.CTs alleviated liver injury mainly by regulating the expression of related genes in cholesterol metabolism pathway and AMPK phosphorylation.Our results confirmed that CTs have remarkable cholesterol lowering and anti-liver injury effects in vivo.

Structural Elucidation of the Polymeric Condensed Tannins of Acacia nilotica Subspecies by ^(13)C NMR, MALDI-TOF and TMA as Sources of Bioadhesives

Tannin was extracted from different subspecies of Acacia nilotica,Acacia nilotica nilotica(Ann),Acacia nilotica tomentosa(Ant)and Acacia nilotica adansonii(Ana).The aim was to elucidate their structure and evaluate their reactivity as bioadhesives in the wood industry.The extracts were prepared by hot water extraction(90°C tem-perature).Their gel time with paraformaldehyde was used atfirst to compare their reactivity.The tannin contents and the percentage of total polyphenolic materials in different solutions of the extracts spray dried powder were determined by the hide powder method.Concentrated solutions(47%)were tested by both MALDI ToF,13CNMR.The thermomechanical analysis(TMA)was performed to evaluate their modulus of elasticity(MOE)at different pHs.The gel times of all the three tannin extracts showed that their reactivity and it was com-parable to other known procyanidin/prodelphinidin tannin extract types.Ana,Ann and Ant showed highest per-cent of total polyphenolic materials at 70%,64%,and 57%,respectively.The 13CNMR spectra showed that the three subspecies of condensed tannins were mainly constituted of procyanidins(PC)and prodelphinidins(PD)in slightly different ratios.Ann(56.5%PC and 43.4%PD),Ant(57%PC and 43%PD)and Ana(58%PC and 42%PD).MALDI–TOF spectra showed the presence offlavonoid monomers,and oligomers some of which linked to short carbohydrates monomers or dimers.TMA revealed that the three types of tannins had high MOE at their initial pH(5).

Antioxidant, antimicrobial and cytotoxic potential of condensed tannins from Leucaena leucocephala hybrid-Rendang

Condensed tannins(CTs)are one of the promising compounds due to their potentially health-promoting qualities.In this study,CTs were extracted from a Leucaena leucocephala hybrid-Rendang and subjected to various biological studies including antioxidant(using Ferric reducing antioxidant power(FRAP),DPPH and ABTS radical scavenging assay),anti-microbial(against different pathogens)and cytotoxic activities(toward human breast adenocarcinoma(MCF-7),human colon carcinoma(HT29),human cervical carcinoma(HeLa)and human liver carcinoma(HepG2)cell lines)in cancer cells through in vitro experiments.The structural characteristics and purity of CTs extract were determined using 13C NMR.The results showed that CTs exhibited higher in vitro antioxidant activities(2257.12±80.55 mg TEAC/g extract,605.3±1.82 mg TEAC/g extract and 1014.03±1.20 mg TEAC/g extract in FRAP,ABTS and DPPH assay,respectively)and demonstrated anti-microbial activities toward selected Gram’s positive and Gram’s negative bacteria tested with MIC and MBC value at 6.25–50 mg/mL.Furthermore,among other selected cancer cells,CTs also demonstrated cytotoxic activity toward human breast cancer cells(MCF-7)(IC50=38.33±2.08mg/mL).Characteristic of apoptosis such as cell shrinkage,nuclear condensation and apoptotic bodies were shown in MCF-7.These preliminary investigations have provided scientific rationale to use CTs as an alternative therapy for various oxidative and inflammatory associated diseases.©2016 Beijing Academy of Food Sciences.Production and hosting by Elsevier B.V.All rights reserved.

Lead Removal from Aqueous Solutions Using Novel Gel Adsorbent Synthesized from Natural Condensed Tannin

Lead has caused serious environmental pollution due to its toxicity, accumulation in food chains and persistence in nature. In this paper, removal of lead from aqueous solutions is investigated using a novel gel adsorbent synthesized from natural condensed tannin. The novel adsorbent performs in aqueous solutions as a weak base with valid basic groups of 1.2mmol·g-1 tannin gel particles and therefore results in the elevation of pH value of aqueous solutions. Even when initial pH is 3.6, final pH at equilibrium can climb up to 6.5 that is above the pH value for Pb(OH)2 precipitation formation and then lead can be removed from wastewater by this so-called surface precipitation. The adsorption isotherm can be expressed by the Langmuir equation and the maximum capacity for adsorption of Pb is up to 92 mg·g-1 (based on dry adsorbent) when initial pH value is 3.6. Hence, the adsorbent does offer favorable properties in lead removal with respect to its high adsorption capacity at low initial pH value, which is advantageous to lead removal from acidic wastewater. A model is put forward to describe the individual adsorption phenomenon of the tannin gel adsorbent.

Effects of Condensed Tannins from Quebracho Extract on the Kinetic of in vitro Gas Production on Trifofium repens, Lotus corniculatus and Lofium perenne

The aim of this work was to study the effect of condensed tannins （CT） on the kinetic of gas production in vitro, on the three main species of Azorean pasture： Trifolium repens, Lotus corniculatus and Lolium perenne, using Quebracho extract as the source of CT, and also to calculate total tannins and condensed tannins on the species studied. Lotus corniculatus, Lolium perenne and Trifolium repens were tested in vitro with the inclusion of Quebracho extract in doses of 0%, 2.5% and 5% DM. The total content in tannins was determined in the 3 species. We have found, in comparison with standard tannic acid, that tannins exist in the flower of T. repens （0.81 equivalents of tannic acid） and in L .corniculatus （1.07 equivalents of tannic acid） but not in L .perenne （0 equivalents of tannic acid）. The concentration of condensed tannins in the 3 species was： 0.34 mg/mL for T. repens; 0.83 mg/mL for L. corniculatus and 0 mg/ml for L. perenne. We verified that a significant reduction （P 〈 0.05） of gas production happened for doses of 5% of CT in comparison with the other two concentrations： 0% and 2.5% of CT. The results of this study express a reduction of the fermentation rate, which implies a reduction of gas production, so, a reduction of methane emission to the atmosphere and an increase of exploitation of the protein by ruminants.

Seasonal variation and ecological importance of tannin and nutrient concentrations in Casuarina equisetifolia branchlets and fine roots

In this study,we investigated the effects of environmental factors on plant phenolic variability,seasonal dynamics of total phenolic content(TP),extractable condensed tannins(ECT),protein-bound condensed tannins(PBCT),fiber-bound condensed tannins(FBCT),total condensed tannins(TCT),protein precipitation capacity(PPC)and nutrient content in the branchlets and fine roots of Casuarina equisetifolia.TP and TCT concentrations in branchlets were lowest in the spring,then increased in summer and autumn,similar to the seasonal dynamics in air temperature.TP and TCT concentrations in fine roots were highest in summer,coinciding with heavy precipitation.In general,TP and TCT concentrations were higher in branchlets than in fine roots.No significant difference was found in C concentration among various seasons for either branchlets or fine roots.Branchlets had significantly higher N and P concentrations than fine roots in most seasons.The C/N and N/P ratios in branchlets were significantly lower than in fine roots in all seasons,except summer.The relationship between branchlets and fine roots was significant for C,P and FBCT,but no significant relationships were found for N,TP,ECT,PBCT and TCT.Additionally,TP and TCT content were each significantly correlated with PPC in branchlets and in fine roots.Both TP/N and TCT/N ratios were highest in the autumn for the branchlets and in the summer for fine roots.The results indicate that high temperatures lead to increased tannin production in branchlets,but that the tannin content in fine roots is mainly affected by precipitation.Tannin content was greater in branchlets than in fine roots,which may indicate that selective pressure is greater on branchlets than on fine roots.

Tannin Nanoparticles(NP99)Enhances the Anticancer Effect of Tamoxifen on ER+Breast Cancer Cells

Recently,natural substances in the form of nanoparticles are increasingly being used in different field,particularly in medicines to enhance their beneficial effects in treatment and prevention.Cancer cells of the breast(MCF-7)have been chosen to be examined and treated in vitro with conventional drug Tamoxifen(Tam)and tannin nanoparticles extract(NP99)individually or in combination.MTT reagent has been applied to assess the cell viability and propagation percentage,DNA fragmentation and mRNA relative expression of apoptotic genes to study the cell death pathway.The results showed that Tam and tannin NP99 triggered cytotoxic activity towards the MCF7 cell.They reduce the viability and induced high potent repressive activity on cell proliferation percentage and induced apoptosis as indicated by rising the percentage in DNA fragmentation.Effect of NP99 extract exhibited its effect in a dose and time-varying.The combined treatment of Tam and NP99 were much more efficient than individual drugs.It could be concluded that NP99 is considered a promising natural anticancer agent as a new tool in therapeutic strategies.

Chemistry and ecological significance of tannins

This paper summarized of the chemistry characteristics of tannins and their various adverse effects onmammalian herbivore, including the chemical nature of hydrolyzable and condensed tannins, their analysis mathods, and the tannins antifeedant mechanisms.

Carcass Characteristics and Meat Quality of Kiko Crossbred Male Goats as Influenced by Feeding Phytochemical Tanning Containing Supplementations

This research assessed the effect of incorporating condensed tannin-rich pine bark (PB) and sericea lespedeza (SL) into meat goats’ diets on carcass traits, chemical composition, and meat quality of goat meat (chevon). Meat goats were supplemented with bermudagrass hay (BG-diet, control), SL, PB, or 1:1 mixture of SL and PB (SL + PB-diet), with the remainder of each diet made uCIE ap of 70% alfalfa pellets mixed with a commercial corn-based sweet feed. Furthermore, four experimental diets provided a total of 4.9, 40.1, 49.0, or 45.0 g of condensed tannins, CT/kg DM, respectively. Carcass traits were assessed after the slaughter at the end of 50 d feeding period. After 24 h cooler storage (2˚C), edible tissues were collected from each carcass for analyzing meat quality parameters. No significant differences were found in carcass traits and primal cuts among goats fed the experimental diets. Supplementing goats with wood-derived condensed tannins (pine bark) produced redder (higher CIE a* values; P < 0.003), tenderer (lower Warner-Bratzler shear force values;P < 0.002), and healthier (higher linoleic and α-linolenic acids;P < 0.03) chevon than that from goats fed either forage-derived (sericea lespedeza) or combined condensed tannins (1:1 mixture of sericea lespedeza and pine bark). Our findings indicate that either forage-, wood-derived condensed tannins, or their combined one can be used as a dietary supplement since they do not have any detrimental effect on meat goats’ performances and meat quality characteristics of chevon. Furthermore, feeding meat goats with wood-derived condensed tannins probably produced tenderer and healthier chevon than that from meat goats fed either forage-derived only or combined with forage and wood derived-condensed tannins.

Effects of Quebracho Tannins on Growth Performance and Blood Routine of Simmental Fattening Cattle

[Objectives]The effects of condensed quebracho tannins on the production performance and blood routine indices of Simmental fattening cattle were investigated experimentally.[Methods]Twenty four Simmental fattening cattle were selected and randomly divided into two treatment groups according to their body weight,with 12 animals in each group.The diet of the control group consisted of beef cattle concentrate supplement+silage+hay,and the diet of the experimental group consisted of beef cattle concentrate supplement+silage+hay+tannins,and the experimental period was 30 d.[Results]Compared with the control group,the addition of tannins[30 g/(cattle·d)]to the diet of beef cattle increased the daily weight gain of Simmental beef cattle by 24.68%(P<0.01),while the feed conversion ratio decreased by 2.57%(P>0.05).The gross profit per cattle increased by 973.63 yuan,and the economic benefit increased by 114.78%.Platelets were higher in the experimental group than in the control group(P<0.01);hemoglobin was lower in the experimental group than in the control group(P<0.01);leukocytes,neutrophils,monocytes and lymphocytes were lower in the experimental group than in the control group(P<0.01);and erythrocytes were lower in the experimental group than in the control group(P<0.05).[Conclusions]This study provides a theoretical basis for the rational utilization of quebracho tannins.

Dynamic changes of phenolic compound contents in leaf and bark of poplar during autumn temperature drop

We investigated seasonal dynamics of phenolics substance in leaf and bark of two cultivars of poplar, Populus alba×berolinensis and P. בZhonglin Sanbei 1’, during autumn temperature drop for analyzing the roles of phenolic secondary metabolites in cold resistance. Results show that the contents of condensed tannin and flavonoid in poplar leaf and the flavonoid contents in bark of P. בZhonglin Sanbei 1’ were increased with the decrease of autumn minimum temperature, showing a significantly negative correlation between the contents of soluble phenolic substance in the leaves and changeable temperature. In contrast, lignin content in the poplar leaves is decreased in the process of temperature drop, showing a significantly positive correlation. These results indicate that the variation in phenolic substance has a close correlation with its cold-resistance during the autumn temperature drop.

Effects of inclusion of purple prairie clover (Dalea purpurea Vent.)with native coolseason grasses on in vitro fermentation and in situ digestibility of mixed forages

Background:Incorporation of legume species into native North American pastures is considered an effective method to increase native pasture productivity and improve the nutritive value of forage.This study evaluated the effects of inclusion of purple prairie clover(PPC,Dalea purpurea Vent.),a native legume forage,with native coolseason grasses on the in vitro fermentation and in situ digestibility of mixed forages.Methods:Whole plant PPC and mixtures of cool-season grasses were harvested when the PPC reached the vegetative(VEG),full flower(FL)and seedpod(SP)stages,and were combined in ratios(DM basis)of 0:100,25:75,50:50,75:25 and 100:0 at each maturity.In vitro ruminal incubations using these mixtures were conducted for 48 h to determine gas production(GP),in vitro DM disappearance(IVDMD),total volatile fatty acids(VFA)and ammonia-N production.Mixtures of forages harvested when the PPC reached the FL stage and 50:50 mixture of forages harvested at VEG,FL and SP stages were incubated in the rumen of three heifers for 0,2,6,12,24,48,72 and 96 h to determine in situ degradabilities of DM,neutral detergent fibre(aNDF)and crude protein(CP).Results:Contents of aNDF and ADF increased(P<0.01),while CP decreased(P<0.001)as PPC matured.Concentrations of extractable condensed tannins in PPC ranked as FL>VEG>SP(P<0.05).Regardless of PPC proportions in the mixture,GP decreased(P<0.05)with increasing PPC maturity.Increasing PPC proportions linearly increased(P<0.001)GP,IVDMD and total VFA at VEG,but linearly decreased(P<0.001)them at SP.Irrespective of PPC maturity,ammonia-N production linearly increased(P<0.01)with increasing proportions of PPC and the concentration was higher(P<0.05)at VEG than at FL and SP stages.Increasing proportion of PPC at either maturity linearly increased(P<0.001)molar percentage of acetate(A)and branched-chain VFA,but linearly decreased(P<0.001)molar percentage of propionate(P),resulting in a linearly increase(P<0.001)in the A:P ratio.Increasing FL PPC in the mixture linearly and quadratically(P<0.01)increased a(soluble fraction),but linearly and quadratically decreased(P<0.01)b(potentially degradable fraction)for DM and aNDF,resulting in linear(P<0.05)and quadratic(P<0.01)increases in DM and aNDF maximum potential degradabilities(a+b).Effective degradabilities of DM and aNDF were also linearly and quadratically increased(P<0.05),and CP was quadratically increased(P<0.05)with increasing FL PPC,with the greatest effective degradability being observed with ratios between 50:50 and 75:25.Ruminal maximum potential degradabilities of DM and aNDF decreased(P<0.001)as the forage matured.Effective degradability of DM ranked as VEG>FL>SP(P<0.001),whereas the effective degradability of aNDF was similar between VEG and FL and both were greater(P<0.01)than SP.Conclusions:Inclusion of vegetative PPC in a mixed forage diet resulted in the greatest digestibility and incorporation of PPC before seedpod stage with native grasses had a positive effect on ruminal fermentation.Effects of PPC on ruminal digestion depend on both the stage of maturity and its proportion in mixed legume-grass pastures.Pastures containing 50%of PPC in full flower stage would likely provide the greatest quality diet to grazing ruminants subject to potential animal selectivity.

Introduction, Collection and Characterization of Lotus spp. Germplasm in Chile

The information related with results of a project on germplasm characterization of three Lotus species, important as forage plants, curried out in five environments of the central-southern zone of Chile, was reviewed. An evaluation was made of 12 L. corniculatus cultivars introduced from different parts of the world, as well as germplasm naturalized in Chile, being 11 accessions of L. tenuis and 21 accessions ofL. uliginosus collected from 33°S to 38°S and 38°S to 45°S, respectively. Phenological, morphological, and agronomical characters were evaluated. Nitrogen fixation in field conditions and concentrations of condensed tannins in herbage were also included. It is concluded that there are cultivars of high value in L. corniculatus introduced germplasm which can be recommended for different environments of the central zone of Chile, as well as for local species breeding programmes. Information obtained from L. tenuis and L. uliginosus accessions shows genetic variability within both species. L. tenuis germplasm is adapted to clay, medium-textured, or sandy soils with water restrictions and phosphorous deficiency. Therefore, characterized accessions could be used to breed cultivars for low input production systems in constrained environments. L. uliginosus accessions include genotypes collected in sites with acid soils and variable tannin content in plant tissues that may be promissory genetic materials for breeding programmes with the objective of producing cultivars for animal production systems for the wet and acid soils in the southern zone of the country.

Antioxidant Activity and Phenolic Compounds Content of Extracts from Ceratotheca sesamoides Endl and Striga hermonthica (Delille) Benth Used as Antheminthic in Burkina Faso

The revaluation of medicinal plants in the veterinary pharmacopoeia is essential for the development of livestock in Burkina Faso. In order to justify the use of C. sesamoides and S. hermonthica in the treatment of gastrointestinal parasitosis of small ruminants, a quantification of phenolic compounds as well as antioxidant activity and acute toxicité evaluation of both plants were performed. Acute toxicity was evaluated by administering a single dose of 2000 mg/kg body weight of aqueous extract of both plants to mice. The highest total polyphenol content for C. sesamo?des was obtained in the ethyl acetate fraction with 47.236 ± 2.57 mgEAG/100mg while that of S. hermonthica was 74.871 ± 2.57 mgEAG/100mg obtained with the n-butanol Fraction. The dichloromethane extract of S. hermonthica obtained the highest total flavonoid content with 7.31 ± 0.48 mgEQ/100 while the highest total flavonoid content of C. sesamo?des was obtained with ethyl acetate fraction with 5.4273 ± 0.35 mgEQ/100mg. The aqueous extract of C. sesamo?des obtained the highest content of condensed tannins with 3.028 ± 0.13 mgEAT/100mg. Both plant’s extracts did not show any signs of toxicity in NMRI mice after administration of the dose of 2000 mg/kg. The antioxidant activity by DPPH, FRAP and ABTS methods was good compared to those of Quercetin and Trolox taken as standard.

Effect of Ensiling on Nutritional Properties of Sericea Lespedeza Alone or in Mixtures with Alfalfa

In this investigation,fresh sericea lespedeza(SL;Lespedeza cuneata)and alfalfa(Medicago sativa)were cut in the field,frozen,chopped and mixed into ratios of 100:0,75:25,50:50,25:75 and 0:100,respectively,with each treatment combination packed into 12 mini-silos and sealed to be air-tight.Three mini-silos per treatment were opened after 1,7,21 and 84 d of ensiling and analyzed for pH,neutral detergent fiber(NDF),acid detergent fiber(ADF),and acid detergent lignin(ADL),unbound and bound condensed tannins(CT),nitrogen(N),nitrate N(NO3-N),and ammonia N(NH4+N)content.All of the forage combinations ensiled well,with a rapid drop in pH(below 5.0 by Day 7).Fiber concentrations(NDF,ADF,ADL)were greater in 75% and 100% SL silages than in 0%,25% and 50% SL samples by Day 84 of the study,possibly due to interference of CT in the detergent analysis system.Concentrations of N,NO3-N and NH4+N were decreased in silages as percentage SL in the mixture increased,while unbound,bound and total CT increased as percentage SL increased.In this study,there was reduced proteolysis during ensiling of combinations of SL and alfalfa,as indicated by reduced NO3-N and NH4+N production as percentage SL in the silage mixtures increased.

Microcosm study on fate and dynamics of mangrove tannins during leaf litter leaching

Background Mangrove tannins can participate in wetland biogeochemical cycling.However,their fate and dynamics during leaf litter leaching have yet to be elucidated in coastal aquatic environments.Methods By using a simulated microcosm experiment,changes in leaf litter mass and tannin compounds,including total phenolics(TP),extractable condensed tannins(ECT),and bound condensed tannins(BCT),were examined in the litters and leachates of four common mangrove species:Kandelia obovata(Ko),Aegiceras corniculatum(Ac),Sonneratia apetala(Sa),and Avicennia marina(Am).Results Leaching caused a notable decline in litter mass,TP,and ECT in the leaf litter of Ko,Ac,Sa,and Am,while BCT increased significantly in Ko and Ac.Loss in foliar TP was higher than in leaf litter mass,and loss in foliar ECT was higher than in TP of Ko and Ac,but Sa showed the opposite result.The temporal changes of TP and ECT concentrations in leachates followed a similar trend,with an initial increase followed by a decrease.ECT dynamics in Ko and Ac leachates correlated with their TP concentrations,while in Sa leachate,the peak ECT occurred 72 h later than its TP peak.The leachate ECT concentrations were highest in Ac,followed by Ko,and significantly lower in Sa.The peak TP and ECT proportions in leachates accounted for 9.2-23.9%and 7.7-9.4%of the total decreases in foliar TP and ECT,respectively.Conclusion During the leaching process,tannins’fate was species-specific,while the dynamics were almost similar.

Seasonal changes in tannin and nitrogen contents of Casuarina equisetifolia branchlets

Seasonal dynamics of total phenolics (TP), extractable condensed tannins (ECT), protein-bound condensed tannins (PBCT), fiber-bound condensed tannins (FBCT), total condensed tannins (TCT), and protein precipitation capacity (PPC) in young, mature and senescent branchlets of Casuarina equisetifolia were studied at Chishan Forestry Center of Dongshan County, Fujian Province, China. In addition, nitrogen contents of branchlets at the different developmental stages were also determined. The contents of TP and ECT, and PPC in young branchlets were significantly higher than those in mature and senescent branchlets through the season. However, PBCT contents were significantly higher in senescent branchlets than those in young and mature branchlets; FBCT fluctuated with season. Young branchlets had the highest N content, which decreased during branch maturity and senescence. The highest contents of TP and the lowest contents of TCT and N in young and mature branchlets were observed in summer. There was a significant negative correlation between TP and N contents. In contrast, TCT contents were positively correlated to N contents. Nutrient resorption during senescence and high TCT:N ratios in senescent branchlets are the important nutrient conservation strategies for C. equisetifolia.

Carbon aerogels prepared by autocondensation of flavonoid tannin

The first carbon aerogels prepared by autocondensation of condensed(flavonoid)tannin,a cheap renewable resource extracted from Mimosa barks,are presented.Mixing aqueous solutions of tannin and sodium silicate indeed produced the very fast gelation of tannins,thus leading to organic hydrogels which were first converted into organic aerogels by supercritical drying,and then into carbon aerogels after pyrolysis at 900℃.Subsequent dissolution of the silica nanoparticles thus formed within the carbon structure further increased significantly the porosity of the materials.Silica thus appeared to be both the gelation catalyst and a pore-directing agent.In this work,the influence on the porosity of the silica/tannin ratio and of the nature of the etching agent used for removing the silica was thoroughly investigated by combining several techniques.The conditions for producing either the most porous materials or those with the highest surface areas were identified and discussed.

The complexities of proanthocyanidin biosynthesis and its regulation in plants

Proanthocyanidins(PAs)are natural flavan-3-ol polymers that contribute protection to plants under biotic and abiotic stress,benefits to human health,and bitterness and astringency to food products.They are also potential targets for carbon sequestration for climate mitigation.In recent years,from model species to commercial crops,research has moved closer to elucidating the flux control and channeling,subunit biosynthesis and polymerization,transport mechanisms,and regulatory networks involved in plant PA metabolism.This review extends the conventional understanding with recent findings that provide new insights to address lingering questions and focus strategies for manipulating PA traits in plants.

Influences of elevated CO2 and pest damage on the allocation of plant defense compounds in Bt-transgenic cotton and enzymatic activity of cotton aphid

Plant allocation to defensive compounds by elevated CO2-grown nontransgenic and transgenic Bt cotton in response to infestation by cotton aphid, Aphis gossypii （Glover） in open-top chambers under elevated CO2 were studied. The results showed that significantly lower foliar nitrogen concentration and Bt toxin protein occurred in transgenic Bt cotton with and without cotton aphid infestation under elevated CO2. However, significantly higher carbon/nitrogen ratio, condensed tannin and gossypol were observed in transgenic Bt cotton ＂GK-12＂ and non-transgenic Bt cotton ＇Simian-3＇ under elevated CO2. The CO2 level and cotton variety significantly influenced the foliar nitrogen, condensed tannin and gossypol concentrations in the plant leaves after feeding by A. gossypii. The interaction between CO2 level x infestation time （24 h, 48 h and 72 h） showed a significant increase in cotton condensed tannin concentrations, while the interaction between CO2 level x cotton variety significantly decreased the true choline esterase （TChE） concentration in the body ofA. gossypi. This study exemplified the complexities of predicting how transgenic and non-transgenic plants will allocate defensive compounds in response to herbivorous insects under differing climatic conditions. Plant defensive compound allocation patterns and aphid enzyme changes observed in this study appear to be broadly applicable across a range of plant and herbivorous insect interactions as CO2 atmosphere rises.