Extraction yield, antioxidant activity andphenolics from grape, mango and peanut agro-industrial by-products / Rendimento de extração, atividade antioxidante e compostos fenólicos dos subprodutos agro industriais de uva, manga e amendoim

ABSTRACT: The objective of this study was to determine and correlate the extraction yields, antioxidant activity, total phenolics and total flavonoids from grape, mango and peanut agro-industrial by-products. The β-carotene/linoleic acid autoxidation system and scavenging capacity for DPPH and ABTS free radicals assays were used. The results were expressed in terms of lyophilized sample or dry extract. Mango bagasse exhibited the highest extraction yield (37.07%) followed by peanut skin (15.17%) and grape marc (7.92%). In terms of lyophilized sample, total phenolics did not vary significantly among the residues evaluated (average of 60.33mg EAG g-1); however, when they were expressed as dry extract grape marc exhibited the highest total phenolic (768.56±116.35mg GAE g-1), followed by peanut skin (404.40±13.22mg GAE g-1) and mango bagasse (160.25±4.52mg GAE g-1), Peanut skin exhibited the highest content of total flavonoids (2.44mg QE g-1), while grape marc (1.76mg QE g-1) and mango bagasse (1.70 mg QE g-1) showed no significant differences. The extraction yield showed strong negative linear correlation with total phenolic and total flavonoid. This study showed that peanut skin was the sample with the highest antioxidant activity and it was strongly influenced by total flavonoids. All extracts of byproducts showed antioxidant activity comparable to α-tocopherol, and they can be a source of natural compounds with potential to replace synthetic antioxidants such as BHT.

RESUMO: O objetivo deste estudo foi determinar e correlacionar os rendimentos de extração, atividade antioxidante, compostos fenólicos totais e flavonoides de subprodutos agroindustriais de uva, manga e amendoim. A autoxidação do sistema β-caroteno/ácido linoleico e a capacidade de sequestro dos radicais DPPH e ABTS foram os ensaios antioxidantes utilizados. Os resultados foram expressos com base na amostra liofilizada ou no extrato seco. O bagaço de manga apresentou o maior rendimento de extração (37,07%) seguido da película de amendoim (15,17%) e bagaço de uva (7,92%). Em termos de amostra liofilizada, o teor de fenólicos totais não variou significativamente entre os resíduos avaliados (média de 60,33mg EAG g-1), entretanto, quando foi expresso com base no extrato seco, o bagaço de uva exibiu o maior teor de fenólicos totais (768,56±116,35mg EAG g-1), seguido da película de amendoim (404,40±13,22mg EAG g-1) e bagaço de manga (160,25±4,52 mg EAG g-1). Apelícula de amendoim apresentou o maior conteúdo de flavonoides totais (2,44mg EQ g-1), enquanto os bagaços de uva (1,76mg EQ g-1) e de manga (1,70mg EQ g-1) não mostraram diferenças significativas. O rendimento de extração mostrou fortes correlações lineares negativas como teor de fenólicos totais e flavonoides totais. Este estudo mostrou que a películade amendoim foi o material que apresentou a maior atividade antioxidante e isso foi fortemente influenciado por flavonoides totais. Os extratos avaliados mostraram atividade antioxidante comparável à do α-tocoferol, com potencial para substituir antioxidantes sintéticos, tais como o BHT.

In vitro antioxidant capacity and free radical scavenging evaluation of active metabolite constituents of Newbouldia laevis ethanolic leaf extract

BACKGROUND: The aim of the present study was to evaluate the in vitro antioxidant and free radical scavenging capacity of bioactive metabolites present in Newbouldia laevis leaf extract. RESULTS: Chromatographic and spectrophotometric methods were used in the study and modified where necessary in the study. Bioactivity of the extract was determined at 10 µg/ml, 50 µg/ml, 100 µg/ml, 200 µg/ml and 400 µg/ml concentrations expressed in % inhibition. The yield of the ethanolic leaf extract of N.laevis was 30.3 g (9.93%). Evaluation of bioactive metabolic constituents gave high levels of ascorbic acid (515.53 ± 12 IU/100 g [25.7 mg/100 g]), vitamin E (26.46 ± 1.08 IU/100 g), saponins (6.2 ± 0.10), alkaloids (2.20 ± 0.03), cardiac glycosides(1.48 ± 0.22), amino acids and steroids (8.01 ± 0.04) measured in mg/100 g dry weight; moderate levels of vitamin A (188.28 ± 6.19 IU/100 g), tannins (0.09 ± 0.30), terpenoids (3.42 ± 0.67); low level of flavonoids (1.01 ± 0.34 mg/100 g) and absence of cyanogenic glycosides, carboxylic acids and aldehydes/ketones. The extracts percentage inhibition of DPPH, hydroxyl radical (OH.), superoxide anion (O2 .-), iron chelating, nitric oxide radical (NO), peroxynitrite (ONOO-), singlet oxygen (1O2), hypochlorous acid (HOCl), lipid peroxidation (LPO) and FRAP showed a concentration-dependent antioxidant activity with no significant difference with the controls. Though, IC50 of the extract showed significant difference only in singlet oxygen (1O2) and iron chelating activity when compared with the controls. CONCLUSIONS: The extract is a potential source of antioxidants/free radical scavengers having important metabolites which maybe linked to its ethno-medicinal use.

Evaluation of hypoglycemic effect of mangifera leaf.

From the time of immemorial people have used various plant extracts in their own ethnic therapeutic system. Mango (Mangifera indica) is adorned all over the world as a fruit. But these plants have some medicinal utility also. The present research work is done to evaluate the antidiabetic effect of mango leaf on albino rat. Phytochemical tests are made with ethanolic extract of mango leaf. Albino rats were treated with ethanolic plant extract at the dose of 100,200 and 400 mg/kg body weight respectively. Another group of diabetic rats are given standard insulin dose as hypoglycemic agent. The blood sugar levels are monitored separately for different groups at different time periods. A significant reduction in blood glucose level is observed at 200mg/kg level after four hours of leaf extract application. It shows that Mangifera leaf is almost equipotent to insulin in its ability to reduce blood sugar.