Bioactive phytochemicals from the tubers of Bletilla striata Rchb.f

Thirty-four phytochemicals were isolated from dry tubers of Bletilla striata Rchb.f. The compounds were classified as bibenzyls 1-14, dihydrophenanthrenes 15, 17, 20, 21, phenanthrenes 16, 18, 19, simple benzoids 22-24, a fatty acid 25, glucosyloxybenzyl 2-isobutylmalates 26-32, and glucosyloxybenzyl cinnamates 33, 34. Compounds 1-4, 7, 8, 11, 12, and 16 inhibited melanogenesis (17.96-55.27%) induced by α-MSH in B16F10 cells at 10-40 μM. However, compounds 9, 10, 17, 18, and 21 exhibited significant cytotoxicity against melanomas, with IC₅₀ values of 12-34 μM. Additionally, compounds 15, 17, 19, 20, 23, 31, and 33 reduced the ROS generation induced by H₂O₂ in HaCaT cells at 6.25-100 μM. In particular, compounds 15, 19, and 20 strongly inhibited ROS generation, with IC₅₀ values of 2.15-9.48 μM. Consequently, compounds 1-4, 7-12, and 15-21 may be the strongest leads to follow in B. striata extract for further research on the skin disorders, hyperpigmentation, melanoma, and ageing.