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.