Hydroxyl Radical Scavenging Assay Research Articles

Antioxidant, anti-quorum sensing and anti-biofilm potential of ethanolic leaf extract of Phrynium capitatum and Dryptes indica

Objective: To investigate the antioxidant and anti-infective potential of Phrynium capitatum and Dryptes indica extract. Methods: The antioxidant potentials were determined by DPPH radical scavenging, reducing power, hydroxyl radical scavenging and total antioxidant assays. We further examined anti-quorum sensing activity and inhibition of synthesis of pathogenic factor of Chromobacterium violaceum and Pseudomonas aeruginosa PAO1. Bioactive compounds were determined using gas chromatography–mass spectrometry analysis. In silico analysis was conducted to determine the binding affinity of bioactive compounds of plant extracts for the quorum sensing regulatory receptor LasR. Results: DPPH assay showed that the ethanolic extract of Phrynium capitatum and Dryptes indica at 500 μg/mL showed (86.96 ± 4.07)% and (74.83 ± 3.47)% inhibition, respectively. Hydroxyl radical scavenging assay showed (73.17 ± 3.03)% and (62.63 ± 4.59)% activity, respectively. The ethanolic extract of Phrynium capitatum and Dryptes indica showed high level of attenuation of quorum sensing regulated pyocyanin production. Confocal laser scanning microscopic analysis revealed that the extracts had the potential to effectively inhibit biofilm formation of Pseudomonas aeruginosa. Molecular docking analysis showed a better binding affinity of bioactive compounds from the extracts for the structure of LasR protein of Pseudomonas aeruginosa. Conclusions: The ethanolic extracts of Phrynium capitatum and Dryptes indica possess antioxidant activity and the potential to inhibit the quorum sensing system and its regulatory irulence traits in Pseudomonas aeruginosa PAO1.

Evaluation of antioxidant capacity of polysaccharide in Jerusalem artichoke (Helianthus tuberosus L.) during overwintering

To determine the effect of different harvesting time on antioxidant capacity in Jerusalem artichoke polysaccharides (inulin), the Jerusalem artichoke before and after overwintering were collected from the same region, and then evaluate their antioxidant capacity in vitro by reducing power assay, DPPH radical-scavenging assay and hydroxyl radical-scavenging assay. Ascorbic acid at similar mass concentration was served as positive control. The results showed no significant difference were observed in reducing power when the absorbance values were about 0.3. When the mass concentrations before and after overwintering were 0.9 mg/mL and 1.7 mg/mL, the DPPH radical-scavenging rate both reached at 50%. And when the mass concentrations were both 10 mg/mL, the hydroxyl radical-scavengings were 35.8% and 27.9%, respectively. Thus, it could be concluded that the antioxidant capacity in Jerusalem artichoke polysaccharides before overwintering was higher than that after overwintering, and showed a good dose-dependent manner with its mass concentration.

Phytochemical evaluation and in vitro antioxidant studies of selected species of Gomphostemma Wall. ex Benth. from Western Ghats

Plants are a rich source of bioactive compounds and have played a vital role in traditional medicine. Plant derived compounds are proved to have less side effects as compared to synthetic compounds. However, a truncated history on the contribution of plants to medicine together with lack of validation of plant derived components have led to massive research in phytochemistry and allied fields. Present study was intended to identify as well as to assess and compare different phytochemicals and antioxidant potential of selected taxa of Gomphostemma endemic to Western Ghats. Methanolic extracts of aerial parts of Gomphostemma heyneanum var. heyneanum, Gomphostemma heyneanum var. rottleri and Gomphostemma eriocarpum were subjected to preliminary phytochemical screening. Quantitative estimation of phenols and flavonoids was done with Folin-Ciocalteu method and modified Aluminium chloride method respectively. Antioxidant potential was examined by DPPH assay, Hydroxyl radical scavenging assay and Reducing power activity. Preliminary screening indicated the presence of many secondary metabolites like phenols, flavonoids, alkaloids, terpenoids and steroids. Results of quantitative estimation revealed that G. heyneanum var. heyneanum has the highest concentration of phenols and flavonoids. Antioxidant potential determined in terms of inhibition percentage also displayed that Gomphostemma species have significant radical scavenging activity. The antioxidant potential exhibited by the plant species may be attributed to their phenol and flavonoid content.
 Keywords: Phytochemical constituents, Gomphostemma, Quantitative estimation, Total phenolics, Flavonoids, Antioxidant activity, DPPH assay, Hydroxyl radical scavenging assay, Reducing power activity.

Free radical-mediated conjugation of chitosan with tannic acid: Characterization and antioxidant capacity

Chitosan (CS) is a natural biopolymer with versatile applications. In this work, CS was functionalized with tannic acid (TA) by a free radical grafting procedure to improve its antioxidant capacity. The resulting TA-conjugated CS (TA-CS) showed a high TA equivalent content of 267.1 ± 5.4 mg TAE/g. The formation of TA-CS was verified by UV–vis, FTIR, and 1H NMR analyses. Moreover, TA-CS showed a lower thermal stability and crystallinity than CS and exhibited a good water-solubility of 15.0 ± 0.3 mg/mL. The DPPH radical scavenging activity of TA-CS reached a maximum of 91.6%, which was 6.4-fold higher than that of CS. Similar results were also observed in ABTS and hydroxyl radical scavenging assays. Moreover, TA-CS showed a higher superoxide radical scavenging activity and ferrous ion chelating activity than both TA and CS. These results suggest that conjugating with TA is an available way to enhance the antioxidant capacity of CS.

Phytochemical Screening and in vitro Antioxidant Properties of Methanol and Aqueous Leaf Extracts of Geophila obvallata

Aim: This study investigated the phytochemical constituents and in vitro antioxidant properties of methanol and aqueous leaf extracts of Geophila obvallata using standard methods.
 Materials and Methods: The in vitro antioxidant assays carried out were 1, 1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical scavenging ability, Nitric oxide (NO•) radical scavenging activity assay, 2, 2'-azino-bis (3-ethylbenzthiazoline-6-sulphonic acid) (ABTS•+) radical cation scavenging assay, ferric reducing properties and hydroxyl radical scavenging assays.
 Results: Phytochemical analysis revealed the presence of alkaloids, flavonoids, phenolic compounds, steroids, saponins, terpernoids and cardiac glycosides in both extracts. Relative to the aqueous extract, the methanol extract contained a higher amount of the secondary metabolites. However, both extracts exhibited appreciable and dose-dependent capacities for quenching DPPH, ABTS•+ and NO• free radicals, and potent ferric reducing ability to levels comparable to those of ascorbic acid. The crude methanol extract showed significantly increased (P<0.05) antioxidant activity than the aqueous extract.
 Conclusion: It was concluded that the extract possesses strong antioxidant properties due to its content of phytochemicals, and provides scientific basis for its ethno medicinal applications.

In vitro antihypertensive and antioxidative properties of trypsin-derived Moringa oleifera seed globulin hydrolyzate and its membrane fractions.

Moringa oleifera seed globulin was hydrolyzed with trypsin and fractionated to produce <1, 1–3, and 3–5 kDa peptide sizes. These were evaluated for antioxidant properties: DPPH, hydroxyl radical scavenging assays, FRAP, and metal chelation tests; and in vitro antihypertensive properties: ACE and renin inhibition. Membrane fractionation led to improved antioxidative properties of 29.13% (<1 kDa), 180% (<1 kDa), and 30.58% (1–3 kDa) for DPPH, FRAP, and metal iron chelation, respectively. There was however 48.77% reduction (1–3 kDa) in hydroxyl radical scavenging activity. There was also improvement in ACE inhibitory potentials of the peptides with the 1–3 kDa peptide showing significantly highest ACE inhibition (72.48%)but very low (17.64%, 1–3 kDa) inhibition against the renin. It was concluded that hydrolysis of M oleifera seed globulin with trypsin produced peptides and peptide fractions with potential antioxidant and antihypertensive properties.

Evaluation of Antioxidant Activities of Alpinia galanga (L.) Willd

Present research was designed to evaluate the free radical scavenging capacities and antioxidant activities of rhizome extracts of Alpinia galanga prepared in different solvent systems (60% aqueous methanol, 60% aqueous ethanol and distilled water) using different in vitro chemical assays. Antioxidant components such as total phenolic content (TPC), total flavonoid content (TFC) and ascorbic acid contents of the ginger species were screened. Antioxidant assays employed included sulphur free radical reactivity assay, ferric ion reducing power assay, DPPH free radical scavenging capacity assay, hydroxyl radical scavenging assay, nitric oxide scavenging activity assay and hydrogen peroxide scavenging assay. The obtained data reveal that the plant extracts contained significant amount of the observed antioxidant components and also exhibited significant free radical scavenging capacities. Methanol (60%) extract exhibited highest antioxidant activity than other solvents. The polyphenolic constituents of the plant extracts appear to be largely responsible for the radical scavenging capacity. The plant extracts act as promising source of antioxidants, and may be useful for development of nutraceuticals and pharmaceutical drugs.

PHARMACOGNOSTICAL AND PHARMACOLOGICAL EVALUATION OF CRINUM LATIFOLIUM L.

Objective: Pharmacognostical study along with the development of a quantitative HPTLC method for Crinum latifolium and evaluation of its traditional claims.Methods: Quantification of three marker compounds oleanolic acid, linoleic acid, and lupeol was done through HPTLC. In vitro antioxidant activity was determined by six different models, namely total phenolic and total flavonoid content, DPPH radical scavenging assay, ferric reducing power, antioxidant capacity and hydroxyl radical scavenging assay. In vitro antidiabetic activity was evaluated by α-amylase inhibition assay based on starch iodine and DNS method.Results: The content of oleanolic acid, linoleic acid, and lupeol were found to be higher in aerial parts like 0.015%, 0.048%, and 0.028% respectively, while in root extract 0.006%, 0.027% and 0.025% respectively on a dry weight basis. Free radical scavenging activity was done by DPPH assay, showing the IC50 value of 410±1.105 µg/ml in roots and 441.95±1.788 in aerial parts. In vitro antidiabetic potential of both the parts were assessed by starch iodine color assay and DNS method of alpha-amylase inhibition model. In 3,5 DNS assay, IC50 of extract from aerial parts was 282.21±2.151µg/ml whereas in root extract it was 193.33±2.45µg/ml. Iodine-starch assay of C. latifolium (aerial part) shown the IC50 value of 340.81±0.49 µg/ml and C. latifolium (root) of 74.64±1.28 µg/ml.Conclusion: The results indicate that the aerial parts of the plant possess more antidiabetic potential in comparison to the root. Thus, the aerial part can be used to get better results as a drug and roots can be used as an alternative.

Amino acid composition and antioxidant properties of Moringa oleifera seed protein isolate and enzymatic hydrolysates

The aim of this work was to compare the antioxidant and angiotensin converting enzyme (ACE) inhibitory properties of Moringa oleifera seed protein isolate (ISO) and its enzymatic protein hydrolysates. ISO was subjected to enzymatic (alcalase, pepsin and trypsin) hydrolysis to obtain alcalase isolate, pepsin isolate and trypsin isolate hydrolysates (AIH, PIH, TIH). Amino acid composition was similar for the samples except that TIH had lower Sulphur-containing amino acids while PIH was lower in tryptophan. All the samples were tested for antioxidant properties through free radical scavenging abilities such as 2,2 diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl radical scavenging assays as well as ferric reducing antioxidant power (FRAP) and metal ion chelation assays. The maximum percentage inhibition obtained for the samples from the different assays are: DPPH, 36% (PIH); FRAP, 0.04% (PIH); hydroxyl radical scavenging activity, 42.98% (ISO); and inhibition of metal ion chelation, 29.46% (AIH). AIH (79.3%) had the highest ACE-inhibitory activity followed by TIH (75.1%) while PIH (43.0%) had the least. Generally, the hydrolysis process produced hydrolysates with improved antioxidant and ACE-inhibitory properties when compared to the isolate. We conclude that enzymatic hydrolysis with alcalase, pepsin and trypsin may be used to produce M. oleifera seed protein hydrolysates with potential to be used as ingredients for the formulation of functional foods and nutraceuticals.

EVALUATION OF THE ANTIOXIDANT ACTIVITY OF FRUIT EXTRACTS OF INDIGENOUS MEDICINAL PLANT, ZIZYPHUS XYLOPYRUS (RETZ.) WILLD

Aim: This study aims to investigate the antioxidant activity of fruit extracts of an indigenous medicinal plant, Zizyphus xylopyrus (Retz.) Willd. Materials and Methods: The coarsely powdered fruit of Z. xylopyrus Willd. was successfully extracted first with petroleum ether and chloroform, followed by ethyl acetate and at last ethanol. The total flavonoids content (TFC), total phenolic content (TPC), and total tannin content (TTC) were estimated using quercetin and tannic acid equivalents as standard. The antioxidant activity of different extracts was determined by different standard in vitro methods including. Results: Among all extracts, ethyl acetate extract (ZXEAE) possessed potent antioxidant activity, namely hydroxyl radical (OH°) scavenging assay (IC50 128.1 ± 0.63 μg/mL), 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical (DPPH°) scavenging assay (IC50 101.2 ± 1.75 μg/mL), nitric oxide radical (NOo) scavenging assay (IC50 122.5 ± 2.04 μg/mL), superoxide radical (O2¯) scavenging activity assay (IC50 64.1 ± 1.24 μg/mL), and inhibition of lipid peroxidation (98.6 ± 2.05 μg/mL). Study results suggested that antioxidant activity of ZXEAE might be due to presence of polyphenols, namely TFC (31.23 ± 0.39 quercetin equivalent [QE] mg/g extract), TPC (198.14 ± 0.69 gallic acid equivalent [GAE] mg/g extract), and TTC (18.38 ± 1.79 GAE mg/g extract). Conclusion: The present study demonstrated the presence of flavonoids in Z. xylopyrus fruits showing marked antioxidant activity, which can be used for establishing the hepatoprotective potential of Z. xylopyrus

Assessing and comparing antioxidant activities of lactobacilli strains by using different chemical and cellular antioxidant methods

Some lactobacilli strains had beneficial effects on human beings due to their antioxidant activities. In this study lactobacilli strains stored in our laboratory were screened for potential antioxidant activities by investigating their 1,1-diphenyl-2-picrylhydrazyl free radical scavenging activity, oxygen radical absorbance capacity, resistance to H2O2, and hydroxyl free radical scavenging activity; then the antioxidant activities of the screened strains were evaluated by cellular antioxidant assay and protection for HT-29 cells against H2O2 injury assay. The results showed that Lactobacillus plantarum Y44 could scavenge oxygen free radicals, inhibit the production of intracellular reactive oxygen species without creating obvious cytotoxic effects, and protect HT-29 cells against H2O2 injury evidenced by the significant decrease of the Bcl-2-associated X protein (Bax)/B-cell lymphoma 2 (Bcl-2) ratio and heat shock protein 70 expression, increase of superoxide dismutase and glutathione peroxidase activities, and decrease of malondialdehyde level of HT-29 cells damaged by H2O2. It was speculated that L. plantarum Y44 protect HT-29 cells against oxygen radical injury through scavenging reactive oxygen species and activating intracellular antioxidant enzymes. A significant correlation was observed among the results of the hydroxyl radical scavenging assay, protection assay for HT-29 cells against H2O2 injury, and the cellular antioxidant assay. The findings indicated that L. plantarum Y44 could be a probiotic candidate with antioxidant properties and combining several chemical antioxidant methods and antioxidant cellular models could be an effective procedure to screen lactobacilli strains with antioxidant activity.

Effect of Lactobacillus plantarum NCU116 Fermentation on Asparagus officinalis Polysaccharide: Characterization, Antioxidative, and Immunoregulatory Activities.

Lactic acid fermentation represents a novel method to produce bioactive functional ingredients, including polysaccharides. In this work, a selected lactic acid bacteria strain NCU116 was used to ferment Asparagus officinalis (asparagus) pulps. Two polysaccharides were subsequently separated from both unprocessed and fermented asparagus pulps, namely, asparagus polysaccharide (AOP) and fermented-AOP (F-AOP). The physicochemical and bioactive properties of AOP and F-AOP were characterized and investigated. High-performance anion-exchange chromatography showed that fermentation increased the proportions of rhamnose, galacturonic acid, and glucuronic acid in polysaccharides by 46.70, 114.09, and 12.75‰, respectively. High-performance size-exclusion chromatography revealed that fermentation decreased the average molecular weight from 181.3 kDa (AOP) to 152.8 kDa (F-AOP). Moreover, the fermentation reduced the particle size and changed the rheology property. In vitro, F-AOP displayed superior free radical scavenging properties compared to AOP, using 2,2-diphenyl-1-picryhydrazyl, hydroxyl, and superoxide anion radical scavenging assays. In vivo, F-AOP administration dose-dependently promoted a gradual shift from Th17-dominant acute inflammatory response (IL-17 and RORγt) to Th1-dominant defensive immune response (IFN-γ and T-bet). These results indicated that the Lactobacillus plantarum NCU116 fermentation was practical and useful to obtain promising bioactive polysaccharides.

Effects of in vitro saliva, gastric and intestinal digestion on the chemical properties, antioxidant activity of polysaccharide from Artocarpus heterophyllus Lam. (Jackfruit) Pulp

Polysaccharides are one of the most widely distributed and abundant compounds in plants, animals and microorganisms. In this study, we investigated the effects of in vitro saliva, gastric and intestinal digestion on the reducing sugar contents, molecular weight and structure change of polysaccharide from Artocarpus heterophyllus Lam. Pulp (JFP-Ps). Digested samples of JFP-Ps were also subject to antioxidant assays including DPPH scavenging assay, hydroxyl radical scavenging assay, superoxide radical scavenging assay and ferric reducing power assay. Results revealed that in vitro digestion could significantly increase the reducing sugar contents and decrease the molecular weight of JFP-Ps. FT-IR results showed that structure and conformation of JFP-Ps were remarkably altered after simulated digestion. The intestinal digested samples of JFP-Ps exhibited obvious DPPH, hydroxyl radical, and superoxide radical scavenging activities in a time-dependent manner during digestion, but with a relatively low reducing power. These results indicated that digestion remarkably affected the chemical properties, structure and antioxidant activity of JFP-Ps during gastrointestinal digestion, and might help maximize the potential applications of JFP-Ps as a dietary source of antioxidant phytochemicals that survive the gastrointestinal digestion process.

Assessment of free radical scavenging activity and polyphenolic content in leaves of Neurocalyx calycinus (R. Br. ex Benn.) Rob. - a medicinal plant used by Cholanaickan tribe

Neurocalyx calycinus (R. Br. ex Benn.) Rob. is an endemic species of the family Rubiaceae, found in Western Ghats of India and Sri Lanka. The leaf paste of N. calycinus has been used by Cholanaickan tribe as medicine to heal wounds, burns, inflammation and pain. Many of the human diseases are manifested due to the accumulation of free radicals. Plant derived antioxidants have the power to scavenge these free radicals without any internal complications. Aqueous, n-hexane, chloroform, ethyl acetate and ethanol extracts of the leaves of N. calycinus were selected for qualitative phytochemical screening. DPPH, nitric oxide, superoxide and hydroxyl radical scavenging assays were carried out. Total phenolic, flavonoid and antioxidant content of all the extract was measured. Phytochemical screening showed that alkaloids, steroids, phenolic compounds, glycosides and saponins were found in the ethanolic extract. Ethanol extract showed better antioxidant activity than the other solvent extracts. The reducing power of all the extracts was increased dose dependently. Highest amount of phenolic (56.27 mg of gallic acid equivalent /gm of dried extract), flavonoid (36.92 mg of quercetin equivalent/gm of dried extract) and antioxidant (85.68 mg of ascorbic acid equivalent/gm of dried extract) content was found in the ethanolic extract. A positive correlation (R2) was found between the total phenolic content and free radical scavenging activity of the leaf extract of N. calycinus. The results confirmed that the phenolic compounds in the ethanolic extract of the leaves of N. calycinus are potent source of natural antioxidants.

Evaluation of antioxidant properties of different extracts of Chaetomium cupreum SS02

To evaluate the antioxidant properties of different extracts (chloroform, ethyl acetate, n-butanol and methanol extracts) of fungus C. cupreum SS02. The antioxidant properties were evaluated by using five antioxidant methods, metal chelating assay, 2,2-azino-bis (3-ethylbenzthiazoline-6-sulphonic acid (ABTS), hydroxyl radical (HO) scavenging assay, superoxide anion (O2) radical scavenging assay, and nitric oxide (NO) scavenging assay. Methanol extract of C. cupreum showed highest metal chelating activity (63.61 ± 0.07 mg EDTAE/g DW), followed by chloroform extract (57.25 ± 0.12 mg E DTAE/g DW) and n-butanol extract (27.33 ± 0.07 mg E DTAE/g DW) whereas ethyl acetate extract showed least metal chelating activity (18.35 ± 0.07 mg E DTAE/g DW) at 50 µg/ml. In ABTS assay, n-butanol extract showed highest ABTS inhibition activity (19.91 ± 0.14 μmol RE/g DW), followed by ethyl acetate extract (13.07 ± 0.59 μmol RE/g DW) and chloroform extract (13.07 ± 0.82 μmol RE/g DW) whereas methanol extract showed the lowest activity (11.65 ± 0.16 μmol RE/g DW at 50 µg/ml). In hydroxyl radical scavenging assay, n-butanol extract showed highest scavenging activity (31.95 ± 0.21 mg RE/g DW), followed by ethyl acetate extract (28.19 ± 0.21 mg RE/g DW), methanol extract (22.93 ± 0.37 mg RE/g DW) and chloroform extract (18.04 ± 0.21 mg RE/g DW) at 50 µg/ml. In superoxide anion scavenging assay, chloroform extract showed highest scavenging activity (56.44 ± 0.03 mg RE/g DW) followed by ethyl acetate extract (49.88 ± 0.09 mg RE/g DW), n-butanol extract (19.49 ± 0.09 mg RE/g DW) and methanol extract (7.75 ± 0.06 mg RE/g DW) at 50 µg/ml. The highest inhibition of nitric oxide radical was observed in chloroform extract of C. cupreum (11.23 ± 0.11%) followed by ethyl acetate extract (7.62 ± 0.06%), n-butanol extract (4.72 ± 0.90%) and methanol extract (3.20 ± 0.06%) at 50 µg/ml. The results showed that different extracts of C. cupreum have significant antioxidant activity due to the presence of different phytochemicals. Thus, it is suggested that C. cupreum extracts should be further studied for their antioxidant properties for food and pharmaceutical applications.

Antioxidant, Anti-Inflammatory and Anti-diabetic Efficiency of Indian Medicinal Plants against Streptozotocin Induced Diabetes in Male Wistar Rats

Objective: The study was aimed to assess the anti-oxidative and anti-diabetic efficacy of few dietary supplements such as Artocarpus heterophyllus (Raw Jackfruit), Zea mays (Corn Silk), Syzygium cumini (Black plum), and Shilajit (Black asphaltum) in in vitro and in vivo models. The phytoextracts were compared with the known commercial diabetic drugs (Aminoguanidine, Glibenclamide and Insulin) in controlling Streptozotocin induced hyperglycemia, advanced glycation end-products (AGEs), hyperlipidemia and activation of inflammatory mediators (iNOS) in in vivo. Methods: Collection and preparation of phytoextracts, superoxide anion scavenging assay, phosphomolybdate assay (total anti-oxidant capacity), Hydroxyl radical scavenging assay, quantification of hemoglobin glycation, body weights, lipid profile, Pro-inflammatory gene expression, agarose gel electrophoresis and histopathology. Results: We found that natural extracts of A. heterophyllus, S. cumini, Z. mays, and Shilajit exhibited considerable antioxidant capacity and inhibited hemoglobin glycosylation in a dose-dependent manner in in vitro. In STZtreated diabetic rats, the extracts showed clear effects on blood glucose and lipid levels, body weight and pro-inflammatory gene expression (iNOS). Histopathology of treated rat pancreas further supported our in vivo findings. Overall, our study indicates that the natural extracts we tested could be a useful source of antioxidant agents, functional foods and nutraceuticals, particularly in diabetes and related complications. Conclusion: The findings from our study showed reversal of the effects induced by Streptozotocin administration on phytoextracts supplementation in experimental diabetic rats and the therapeutic capacity was similar to that of commercial diabetic drugs, hence these extracts could serve as an alternate in management of diabetes and allied complications.

Total Phenolic, Flavonoid and Alkaloid Contents, Oxidative DNA Damage Protective and Antioxidant Properties of Methanol and Aqueous Extracts of Dissotis rotundifolia Whole Plant

Background: Antioxidants present in natural sources helps to scavenge free radicals and thus, provide health benefits. The main objective for this research is to determine phenolic, flavonoid, and alkaloid contents, nitric oxide scavenging activity, hydroxyl radical scavenging activity, and DPPH-scavenging activity, ferric reducing power of the extracts and DNA damage protecting activity to evaluate the antioxidant potential of various extracts. Materials and Methods: In vitro antioxidant potential of the D. rotundifolia extract was evaluated using 1, 1‑diphenyl‑2‑picrylhydrazyl (DPPH), nitric oxide (NO), and hydroxyl (OH) radical scavenging assays. Ferric reducing power ability of the extract was also examined using tannic acid, and ascorbic acid as standard. Concentrations of plant extracts ranging from 0.02 to 0.10 mg/ml were prepared and mixed with appropriate volumes of reagents. Results: Methanol extract of D. rotundifolia exhibited higher content of phytochemical compounds (alkaloid = 12.4 mg QE/g; flavonoids = 19.3 mg QE/g; and phenols = 18 mg QE/g) at concentration 0.1 mg/ml compare to the aqueous extract (alkaloid = 9.1 mg QE/g; flavonoids = 10.5 mg QE/g; and phenols = 16.5 mg QE/g). An over-all trend found in the present study highlights the fact that the methanol extract have better antioxidant capacities (DPPH, NO, OH and FRAP) than the aqueous extract. D. rotundifolia extracts exhibited considerable protection to the damage of native supercoiled circular at concentrations, 0.1 mg/ml and 10 mg/ml. Conclusion: The study showed that the extracts can competently protect the body against oxidative stress, therefore can be used as a source of potent natural antioxidant compounds.

ENHANCEMENT OF IN VITRO ANTIOXIDANT POTENTIAL OF TERMINALIA CHEBULA BY VARIOUS FRUIT EXTRACTS AND OPTIMIZATION OF CONCENTRATION BY RESPONSE SURFACE METHODOLOGY

Objective: The main objective of this study was to determine the enhancement of in vitro antioxidant potential of fruits of Terminalia chebula (TC) when used in combination with fruit extracts of Phyllanthus emblica, Ananas comosus, and Punica granatum. Hydroxyl (OH) radical scavenging and 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assays were used to analyze the antioxidant potential.Method: Formulations of different combinatorial concentrations of fruits to prepare a mixture were achieved with central composite design through response surface methodology. Screening of 300 different combinations of various concentrations was done through hydroxyl radical scavenging assay followed by statistical analysis of data. Further validation of results was done by measuring the antioxidant potential of most bioactive extracts by DPPH method.Results: Screening of 300 samples of different combinations for antioxidant potential revealed the samples with highest percentage inhibition in aqueous (85.2%), ethanolic (92.9%), and aqueous-ethanolic (84.21%) extracts. Data were subjected to analysis of variance and generated a three-dimensional response surface plot for highest activity. Further subjecting these extracts to DPPH assay revealed a significant enhancement in the antioxidant potential of ethanolic extract of TC when used in mixture with other plants.Conclusion: Antioxidant activity of TC was enhanced when used in combination with other fruits extracts. These synergistic studies generating valuable interactions between various phytochemicals could lead to a momentous increase in other associated activities to fight against diseases such as cancer and cardiovascular disorders. Further research on isolation of bioactive compounds in the mixture and their potential to fight various types of cancer could lead to a significant augmentation in the activity of natural compounds.

Qualitative Phytochemical Analysis and In-Vitro Antioxidant Evaluation of Alternanthera philoxeroides (Mart.) Griseb from Mizoram, Northeast, India

The current study was aimed to identify the phytochemicals and determine the in vitro antioxidant activity of the methanolic leaves extract of Alternanthera philoxeroides (Mart.) Griseb (MEAP) from Mizoram, India. A. philoxeroides (Amaranthaceae) is an aquatic plant commonly called Alligator weed. Reported pharmacological activities of the plant include antiviral, antinociceptive and antihyperglycaemic activities. Successive extraction was carried out using Soxhlet apparatus with solvents of increasing polarities (Petroleum ether, Chloroform, Methanol). Phytochemical screening of the methanolic leaves extract and in vitro antioxidant activity was determined by DPPH assay, reducing power and hydroxyl radical scavenging assay. The extract revealed the presence of glycosides, carbohydrates, flavonoids, steroids, triterpenoids, inulin and saponins. The extract exhibited Ic50 values of 87.06 µg/mL and 89.75 µg/mL for DPPH and hydroxyl radical scavenging respectively. The plant extract also exhibited concentration-dependent reducing activity. The results from the experiment suggest that the plant under study, possess antioxidant activity and can be opted as a promising source of natural antioxidant compound.

Preparation, identification, and activity evaluation of ten antioxidant peptides from protein hydrolysate of swim bladders of miiuy croaker (Miichthys miiuy)

Alcalase was screened out for hydrolyzing the swim bladder proteins of miiuy croaker (Miichthys miiuy) from five proteases using hydroxyl radical scavenging assay, and its optimal hydrolysis conditions were be determined as time 3.5 h, temperature 55 °C, pH 9.5, solid-liquid ratio 1:5, and enzyme dose 2.5%. Ten new antioxidant peptides were isolated from SMAH using ultrafiltration and consecutive chromatography, and their sequences were identified as FYKWP, FTGMD, GFEPY, YLPYA, FPPYERRQ, GFYAA, FSGLR, FPYLRH, VPDDD, and GIEWA. FPYLRH and GIEWA exhibited strong scavenging activities on hydroxyl radical (EC50 0.68 mg/mL and 0.71 mg/mL for FPYLRH and GIEWA, respectively), DPPH radical (EC50 0.51 mg/mL and 0.78 mg/mL for FPYLRH and GIEWA, respectively), and superoxide anion radical (EC50 0.34 mg/mL and 0.30 mg/mL for FPYLRH and GIEWA, respectively). In addition, FPYLRH and GIEWA could be effectively against lipid peroxidation in the β-carotene linoleic acid and in the linoleic acid emulsion system.