Symplocos polyandra, locally known as balakbakan, is distributed throughout Southeast Asia, especially in the Philippines. The lack of available literature regarding the phytochemistry of this plant species prompted the conduct of testing of its potential antioxidant activity and quantification of its total flavonoid content and phenolic content. Balakbakan leaves were collected, exhaustively extracted with methanol, and fractionated on a silica gel column. 2,2-diphenyl-1-picrylhydrazyI (DPPH) assay showed that the acetone fraction has the highest percent DPPH radical inhibition with 86.41% at 500 ppm compared to 0.5 mM ascorbic acid at 87.61%. The acetone - methanol fraction has the highest ferric reducing capacity with a value of 208.24 μM ascorbic acid equivalents at 500 ppm. The total phenolic content of the different fractions ranged from 21.88 to 29.99 pg/mL catechin equivalents, with hexane - acetone fractions having the highest value. The flavonoid content ranged from 14.28 to 16.64 pg/mL catechin equivalents, with the methanol fraction having the highest value. The compounds responsible for the high antioxidant activity may not be a phenolic or flavonoid. Fractions from Symplocos polyandra are a promising source of bioactive compounds with antioxidant activity. Cytotoxicity test and analyses of alkaloid and chlorophyll content of the leaves is recommended for the leaves to be developed into tea products....

The purpose of this study is to investigate the antioxidant activity of fractions from epicarpium of Citrofortunella microcarpa (Philippine Lime) peels extract. Dried epicarpium of peels were extracted with methanol and fractionated with silica column and subjected to DPPH and FRAP assays as well as determination of total phenolic and flavonoid content. Three fractions were obtained after silica gel fractionation. The acetone-methanol fraction had the highest antioxidant activity with 81.06% DPPH radical inhibition and ferric reducing capacity of 1420.33 pM Fe²⁺ released, in comparison with ascorbic acid standard of 88.26% DPPH inhibition and ferric reducing activity of 502.038 ascorbic acid equivalents, respectively. The acetone-methanol fraction also contained the highest total phenolic and flavonoid content at 73.26 and to 55.11 μg/mL catechin equivalents, respectively. This demonstrates that the high antioxidant activity of the acetone-methanol fraction can be attributed to its high total phenolic and flavonoid content. Value could be added to calamansi waste peels by developing the peels extracts into products such as high antioxidant functional foods, or antioxidant dermal cream or ointments....

Calamansi is a condiment used in a vast variety of Filipino dishes, as well as an ingredient in various beverages, such as calamansi juice. Calamansi peels are discarded as waste. Thus, this research study was conducted ...