New methods for extraction of phenolic, flavonoids and catechin compounds from natural sources

Abstract

The extraction of phenolic compounds from natural sources is crucial for their utilization in various applications, including food, pharmaceuticals, and cosmetics. However, current extraction methods often suffer from drawbacks such as low yield, long extraction times, and the use of harsh chemicals. The present study aimed to assess in vitro the antioxidant activities of solvent extracts from different wild plants (green tea, al sidr, and sage), in addition to introducing a novel, environmentally friendly method for extracting phenolic compounds from different wild plants and finding the best solvent system for extraction of different phenolic compounds. In the present work, 15 solvent extracts from 3 plant samples were evaluated against 2, 2-diphenyl-1-picrylhydrazyl (DPPH) and potassium permanganate (KMnO₄) as non-radical reagents and compared with ascorbic acid as a natural standard antioxidant, in addition to the analysis of the chemical constituents of promising extracts from wild plants using HPLC. The obtained results revealed that both methods go in parallel, showing that the concentration of extract and incubation time are dependent and proportional to the concentration of phenolic compounds. Buffer-ethanol extract from green tea plant recorded the highest antioxidant activity when compared with other solvent extracts, with more than 95% against the DPPH radical method, but the activities decreased in the case of the KMnO₄ method. Thus, the HPLC analysis of aqueous extracts of promising buffer and buffer-ethanol solvent systems for the 3 plants showed a highly complex profile, containing approximately 14 and 18 different components. From these compounds, gallic acid recorded the highest concentration for green tea in both extracts at 982.06 and 275.06 µg/ml, respectively. While rosmarinic acid recorded the highest concentration for sage in buffer-ethanol extract at 395.93 µg/ml. From the obtained results, it could be concluded that the solvent extracts of plant samples are rich in different active ingredients, especially phenolic compounds and their derivatives. The extracts from green tea, especially with buffer solution, are more acceptable when compared with other extracts. Buffer, ethanol, and ethanol-buffer extracts (from al sidr, sage, and green tea) recorded high concentrations of phenolic compounds and their derivatives and exhibited antioxidant activity, respectively.