ABSTRACT
@#Literature has consistently reported that horticultural wastes including leaves, skin, stones and seeds contain substantial amounts of bioactive compounds. Therefore, this study aims to evaluate antioxidant activity, Total Phenolic Content (TPC) and colour parameters in avocado, banana, and papaya leaves. Antioxidant activity of the leaves was determined using Trolox Equivalent Antioxidant Capacity (TEAC) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assays, TPC was evaluated using Folin-Ciocalteu assay whereas the colour parameters were analysed with a colour picker software. Data analysis was carried out using SPSS version 25.0 of triplicate determinations. Mean differences among the fruit leaves extracts were determined using One-way ANOVA, while the correlations between the studied components were by the Pearson’s Correlation Coefficient test. The TEAC values were in the range of 332.30 ± 18.04 µg Trolox/g D.W. (avocado leaves) to 12217.71 ± 18.04 µg Trolox/g D.W. (banana leaves) while the DPPH radical scavenging activity was from 10.07 ± 3.89% (banana leaves) to 86.70 ± 0.26 % (avocado leaves). Besides, TPC was from 871.33 ± 38.35 µg GAE/g D.W. (papaya leaves) to 1199.08 ± 6.00 µg GAE/g D.W. (avocado leaves). The hue values were from 19º in avocado leaves extract to 37º in banana leaves extract. Results from Pearson’s Correlation Coefficient test revealed that there were no significant correlations between the studied assays. Avocado leaves had the highest DPPH radical scavenging activity and TPC among the three extracts. Findings derived from the present study could be exploited in nutraceuticals formulation.
ABSTRACT
Quantitative Structure-Activity Relationships (QSAR) are useful in understanding how chemical structure relates to the biological activity of natural or synthetic compounds and for designing newer and better compounds. In the present study, 22 N-arylmethyl substituted anilines were treated with ABTS (2,2'-azinobis- (3-ethylbenzothiazoline-6-sulfonic-acid)) and DPPH (2,2-diphenyl-1-picrylhy-dracyl) radicals in order to evaluate their TEAC (mmol trolox/mmol antioxidant, Trolox Equivalent Antioxidant Capacity) and EC50 (mmol antioxidant/mmol initial DPPH, Antioxidant Equivalent Concentration to decrease the initial DPPH concentration by 50 %) values, respectively. Different QSARs were developed based on these data, using theoretical descriptors derived from geometry-optimized molecular structures. A model with electronic energy (EE), total charge weighted partial positively charged surface area (PPSA-2), and exact polarizability (αzz) as descriptors showed satisfactory predictive TEAC performance according to internal and external validation procedures. It can be useful in predicting data and setting a testing priority for those compounds not yet synthesized or for which experimental data are not available.
Las relaciones cuantitativas actividad-estructura (QSAR) son útiles para entender la forma en que la estructura química de sustancias sintéticas y naturales se relaciona con la actividad biológica, y para el diseño de nuevos y mejores compuestos. En el presente estudio fueron evaluadas las capacidades de 22 anilinas N-arylmetil sustituidas para la captura de los radicales ABTS (ácido 2,2'-azino-bis(3-etilbenzo-tiazolino-6-sulfónico) y DPPH (2,2-difenil-1-picrilhidracilo), relacionadas con los valores de TEAC (mmol trolox/mmol antioxidante, capacidad antioxidante equivalente al Trolox) y EC50 (concentración equivalente de antioxidante para disminui r la concentración inicial de DPPH enun 50%), respectivamente. Las TEAC, las EC50 y los descriptores teóricos derivados de las estructuras moleculares optimizadas fueron utilizados para elaborar las diferentes QSAR. Los modelos TEAC con descriptores como EE (energía electrónica), PPSA-2 (carga total pesada con el área superficial cargada positivamente) y αzz (polarizabilidad exacta) mostraron una capacidad de predicción satisfactoria por procedimientos de validación interna y externa, por lo que pueden ser útiles para la predicción de actividades de compuestos que aún no han sido sintetizados o con datos experimentales no disponibles.
Relaçãos quantitativa atividade - estrutura tem sido empregado para estabelecer se a estrutura química está relacionada com a atividade biológica dos químicos naturais e sintéticos e para o desenho de novos e melhores compostos. No presente estudo foram avaliadas as capacidades de 22 anilinas N-arylmetil sustituidas para a captura dos radicais de ABTS (ácido-2,2'-azino-bis(3-etilo-benzo-tiazolino-6-sulfônic o) e DPPH (2,2-difenilo-1-picrilhidracilo), relacionadas com os valores de TEAC (mmol trolox/mmol antioxidante, capacidade antioxidante equivalente ao Trolox) yEC50 (concentração equivalente de antioxidante para a diminuição da concentração inicial de DPPH para um 50 %) respectivamente. As TEAC, as EC50 eos descritores teóricos derivados das estruturas moleculares otimizadas foram empregados para elaborar as diferentes QSARs. Os modelos TEAC com descritores como EE (Energia Eletrônica), PPSA-2 (carga total pesada com a área superficial carregada positivamente) y αzz (polarizabilidade exata) mostraram uma satisfatória capacidade de predição pelos procedimentos de validação interna e externa, e por tanto podem ser úteis para a predição da capacidade antioxidante de compostos que ainda no tem sido sintetizados com dados experimentais não disponíveis.
ABSTRACT
This study was aimed at assessing the antioxidant capacity and phenolic (free, bound, and total) contents in selected commercial beverages. Three different types of beverages commonly available in Malaysian supermarkets namely, cocoa, coffee and tea were selected. Phenolic contents were determined using a Folin-Ciocalteu assay. Antioxidant capacity (ferric reducing power and scavenging activity) was determined using FRAP and TEAC assays. Based on analysis of variance, coffee showed the highest amount of free phenolic compounds and antioxidant capacity compared to cocoa and tea (p < 0.05). The major phenolic compound detected in coffee was chlorogenic acid. Cocoa showed higher phenolic content than tea. However, cocoa and tea have similar catechin content and possessed comparable antioxidant capacity. The free phenolic content in the three beverages was found to be highly correlated with antioxidant capacity. In addition, moderate correlation was observed between total phenolic content and antioxidant capacity. On the other hand, there was no significant contribution of bound phenolic compounds towards antioxidant capacity. The contribution of antioxidant capacity in these beverages could be due to phenolic compounds in the free form. The study indicated that the beverages studied possessed varying degrees of antioxidant capacity and phenolic contents.
Subject(s)
Antioxidants , Tea , CoffeeABSTRACT
Leiothrix (Eriocaulaceae) é um gênero exclusivo da América do Sul, com 37 espécies restritas ao Brasil. Leiothrix flavescens (Bong.) Ruhland e Leiothrix curvifolia (Bong.) Ruhland, são espécies endêmicas em áreas dos Estados de Minas Gerais e Bahia. Existem na literatura poucos estudos químicos e biológicos realizados com espécies desse gênero. Neste trabalho, foi estudada a atividade antioxidante pelo ensaio TEAC (Trolox Equivalent Antioxidant Capacity) e de autoxidação, utilizando ácido linoléico, de xantonas isoladas dos extratos etanólicos de L. curvifolia e L. flavescens. As substâncias apresentaram moderada atividade antioxidante, quando comparadas com padrões de quercetina e de BHT (2, 6 - ditercbutil - 4 - metóxifenil).
Leiothrix (Eriocaulaceae) is an exclusively South American genus of which 37 species are restricted to Brazil. Leiothrix flavescens (Bong.) Ruhland and Leiothrix curvifolia (Bong.) Ruhland, are species endemic to areas of Minas Gerais and Bahia States. Chemical and biological investigations of this genus are scarse. The objective of this work was to investigate the antioxidant effect using TEAC and linoleic acid assays of the xanthones isolated from the ethanolic extract of these species. These substances showed a moderate antioxidant activity when compared to quercetin and to BHT.