Two new lignans, zanthoxyloside C (1) and zanthoxyloside D (2), together with nine known compounds comprising lignans (3-5), flavonoids (6-8), and phenolics (9-11), were isolated from the methanol extract of the stems of Zanthoxylum piperitum. All isolates were evaluated for their antioxidant and anti-osteoporotic activities using oxygen radical absorbance capacity (ORAC), cupric reducing antioxidant capacity (CUPRAC), and tartrate-resistant acid phosphatase (TRAP) assays. Compounds 7-10 showed peroxyl radical-scavenging capacities and 4, 6-7, and 9 showed reducing capacities. Moreover, compounds 3, 6-9, and 11 significantly suppressed TRAP activities. These results indicated that the stems of Z. piperitum could be an excellent source for natural antioxidant and anti-osteoporosis.
Keywords: Anti-osteoporosis; Antioxidant; CUPRAC; ORAC; TRAP; Zanthoxylum piperitum.