Classification and antioxidant assays of polyphenols:a review

Polyphenols are widely recognized as the effective antioxidants,which are divided into flavonoids,phenolic acids,stilbenes,lignans,tannins and so on.They could regulate internal functions and protect the body from diseases related to oxidative damage.Due to the fact that their antioxidant capacity is influenced by the structure,stability and bioavailability,the detection of their bioactivity should be considered comprehensively.Currently,the methods for measuring the antioxidant capacity of phenolic compounds are divided into chemical,cell-based and in vivo assays.The chemical assays include 2,2-diphenyl-l-picrylhydrazyl(DPPHI),2,2"-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid)(ABTS),ferric reducing/antioxidant power(FRAP),oxygen radical absorbance capacity(ORAC),peroxyI radical scavenging capacity(PSC),which are rapid identification method,but their reaction mechanism has a great gap with the internal body response.The cell-based assays are more consistent with biological reaction,but still do not take the bioavailability into consideration.The in vivo assays,which commonly utilized Caenorhabditis elegans or rats as models,are more representative,but these methods are more complex and spend longer.This review summarizes the antioxidant evaluation methods of phenolic compounds and discusses their advantages and limitations comparatively,which could help discriminate and select the appropriate assay in the actual operation,and facilitate the development of comprehensive approaches as well.

Comparative and quantitative analysis of antioxidant and scavenging potential of Indigofera tinctoria Linn. extracts

OBJECTIVE：To compare and elucidate the antioxidant effi cacy of ethanolic and hydroethanolic extracts of Indigofera tinctoria Linn.（Fabaceae family）.METHODS：Various in-vitro antioxidant assays and free radical-scavenging assays were done.Quantitative measurements of various phytoconstituents,reductive abilities and chelating potential were carried out along with standard compounds.Half inhibitory concentration（IC50）values for ethanol and hydroethanol extracts were analyzed and compared with respective standards.RESULTS：Hydroethanolic extracts showed considerably more potent antioxidant activity in comparison to ethanol extracts.Hydroethanolic extracts had lower IC50values than ethanol extracts in the case of DPPH,metal chelation and hydroxyl radical-scavenging capacity（829,659 and 26.7μg/m L）but had slightly higher values than ethanol in case of SO2-and NO2-scavenging activity（P〈0.001 vs standard）.Quantitative measurements also showed that the abundance of phenolic and fl avonoid bioactive phytoconstituents were signifi cantly（P〈0.001）greater in hydroethanol extracts（212.920 and 149.770 mg GAE and rutin/g of plant extract respectively）than in ethanol extracts（211.691 and 132.603 mg GAE and rutin/g of plant extract respectively）.K arl Pearson’s co rrelation analysis（r2）between various antioxidant parameters and bioactive components also associated the antioxidant potential of I.tinctoria with various phytoconstituents,especially phenolics,fl avonoids,saponins and tannins.CONCLUSION：This study may be helpful to draw the attention of researchers towards the hydroethanol extracts of I.tinctoria,which has a high yield,and great prospects in herbal industries to produce inexpensive and powerful herbal products.

Antibacterial and antioxidant effects from seaweed,Sargassum wightii(Greville,1848)against marine ornamental fish pathogens

Objective:To screen seaweed Sargassum wightii(S.wightii)for bioactive natural substance against marine ornamental fish bacterial pathogens,and also study the antioxidant properties,brine shrimp toxicity effect.Methods:Crude extract was made using three solvents(acetone,ethanol and methanol)and screened for antibacterial activity and purified by column chromatography,purified fractions obtained were tested for the activity.The 1st fraction of acetone extract showed maximum activity,this was again subjected for purification and obtained three sub-fractions also tested for the activity.Total phenols and flavonoid contents,reducing power,free radical scavenging activities(DPPH and H_(2)O_(2))and brine shrimp toxicity were also studied using purified acetone extract followed by standard methods.Results:The purified acetone extract showed maximum activity against eight pathogens among ten.GC-MS results revealed two major compounds such as 24-methylene cholesterol(79.9%)and methyl oleate(30.3%)which presented in higher percentage in purified extract and had highest phenols and flavonoid contents,reducing power,free radical scavenging activities,and also showed less toxicity effect.In he present study,the purified extract of S.wightii had potential antibacterial activity against Aeromonas hydrophila[(22.25±0.35)mm]and minimum activity against Streptococcus sp.[(10.00±0.00)mm].The purified extract of S.wightii also had potential total antioxidant activity of(3.87±0.04)μg at 100μg/mL concentration and the lowest activity was exhibited(1.52±0.01)μg at 25μg/mL.Conclusions:The present study concluded that the brown seaweed,S.wightii has potential antimicrobial and antioxidant activities,which can be used in aquaculture industry for treated bacterial diseases in infected fishes.