Antioxidant Activity Related to Phenolic and Flavonoid Compounds from Seeds of Melastoma saigonense

Abstract

This research focuses on the assessment of total phenolic and flavonoid contents, antioxidant activity, as well as phenolics and flavonoids characterization of crude extracts from seeds of Melastoma saigonense (Kuntze) Merr.Fresh seeds of M. saigonense were extracted successively with methanol, followed by sequential fractionation based on solvent polarity to afford four crude extracts, including n-hexane, ethyl acetate, n-butanol and aqueous extracts, respectively. The results revealed that the ethyl acetate extract showed the highest total phenolic (967.22 ± 38.13 mg GAE/g DE) and flavonoid (850.84 ± 14.42 mg GAE/g DE) contents. Moreover, it also showed the highest antioxidant activity when determined by the DPPH (IC₅₀ = 35.91 ± 0.16 µg/mL), ABTS (IC₅₀ = 21.14 ± 0.56 µg/mL) and FRAP (30.20 ± 0.52 mmol Fe(II)/g DE) methods. The total phenolic and flavonoid contents of the extracts were positively correlated with the antioxidant activity. RP-HPLC analysis suggested that sinapic acid is the predominant phenolic acid found in the ethyl acetate extract, while the predominant flavonoid is myricetin. Thus, the seed extracts of M. saigonense might be considered as a good candidate to use as a dietary supplement and natural medicinal products.