Antioxidant constituents from the leaves of Piper crassipes Korth ex Miq. growing in Malaysia

The genus Piper, belonging to the Piperaceae family, includes over 2,000 species, many of which are widely recognized for their significant economic and medicinal value. This study aimed to investigate the phytochemicals isolated from the leaf extract of Piper crassipes. Soxhlet extraction of the dried powdered leaves was employed to extract the phytochemicals using a polarity gradient of hexane, dichloromethane, and methanol. The phytochemicals were obtained using chromatography techniques and their structures were confirmed by spectroscopic analysis (IR, NMR, and MS) and comparison with the literature. Furthermore, the isolated phytochemicals were evaluated for their DPPH free radical scavenging activity. The isolation successfully led to the identification of ten phytochemicals: asaricin (1), chavibetol (2), dillapiole (3), β-sitosterol (4), 5,7-dimethoxyflavone (5), 4',5,7-trimethoxyflavone (6), N-(3-phenylpropanoyl)pyrrole (7), chavicol (8), N-isobutyl-(2E,4E,14Z)-eicosatrienamide (9), and 4-allyl resorcinol (10). Among the isolated phytochemicals, compounds (8) and (10) showed the highest DPPH radical scavenging activity, with IC50 values of 189.3 and 195.8 µmol/L, respectively. This study offers important insights into the antioxidant potential of P. crassipes constituents, highlighting further opportunities to explore their nutraceutical and pharmaceutical applications. KEY WORDS: Piperaceae, Piper crassipes, Constituent, Phenylpropanoid, Antioxidant. Bull. Chem. Soc. Ethiop. 2025, 39(3), 561-570. DOI: https://dx.doi.org/10.4314/bcse.v39i3.13