Flavonoids from Artocarpus hirsutus Lam: Synthesis of new prenyl ethers, acetates and their anti-acne activity

Artocarpus hirsutus Lam., one of the species of Artocarpus, is not well studied. The present study is intended to isolate the chemical constituents present in stem wood extract of A. hirsutus, to synthesize their new derivatives and to evaluate their activity against Propionibacterium acnes. Three major flavonoids, cudraflavone A, cycloartocarpin and artocarpin were isolated from the stem wood extract and cudraflavone A was isolated for the first time from this plant. New prenyl ether and acetate derivatives of isolated flavonoids have been synthesized. This is the first to report on the evaluation of in vitro anti-acne potential of crude extracts, isolated flavonoids and their new synthetic derivatives. The crude extracts (MIC values 2, 4 and 15.6 μg/mL) and the isolated constituents (MIC values 2, 0.5 and 0.25 μg/mL) showed significant in vitro anti-acne activity against P. acnes which was comparable with commercially available anti-acne agent, tea tree, oil and a standard antibiotic, Clindamycin (MIC 0.03 μg/mL) indicating their potential as anti-acne agents.