Phytochemicals and biological activities of Macaranga hosei and Macaranga constricta (Euphorbiaceae)

Abstract

Phytochemicals and biological activities of the leaves of Macaranga hosei and Macaranga constricta have been studied. Fractionation and purification of the extracts of M. hosei afforded two triterpenoids, lupenone (1) and β-sitostenone (2) and two flavonoids, 5-hydroxy-7,4’-dimethoxyflavone (3) and 5-hydroxy-6,7,4’-trimethoxyflavone (4). Three triterpenoids characterized as taraxerone (5), taraxerol (6) and β-amyrin (7) were isolated from M. constricta. The structures of these compounds were established by analysis of their spectroscopic data, as compared to that of reported compounds. Biological activities which include antibacterial, α-glucosidase inhibition and antioxidant were also carried out. The antibacterial activities have demonstrated that all extracts and isolated compounds exhibited weak inhibition against the tested bacterial strains with MIC value exceeded 500 μg/mL. Evaluation of α-glucosidase inhibition activity using ρ-nitrophenyl-ρ-D-glucopyranosidase on extracts exhibited α-glucosidase inhibitory potential. The most potent α-glucosidase activity was exhibited by the petroleum ether extract of M. hosei with inhibitory concentration at 50% (IC50) of 25.3 ppm compared with quercetin (4.5 ppm) and acarbose (12.6 ppm). The antioxidant activity was conducted through DPPH radical scavenging activity and total phenolic content. All the extracts displayed positive results and the methanol extract of M. hosei displayed the highest scavenging activity with scavenging concentration at 50% (SC50) value of 25.8 ppm. The methanol extract of M. hosei also gave the highest total phenol content with 347.7 mg GAE/g.