Six new triterpenoids and other triterpenoids and steroids from three Quercus species of Hong Kong

Six new triterpenoids have been isolated from three local Quercus species, and identified as taraxera-1,14-dien-3-one (1) and taraxer-14-ene-3β,16α-diol (7)(from Q. bambusaefolia), 21αH-hopane-3β,22-diol (14)(from Q. championi), and 24,25-dimethyl-lanosta-9(11),23-dien-3β-ol (30), its acetate (29), and the corresponding ketone (31)(from Q. myrsinaefolia). The isolation of two steroids and seventeen other triterpenoids, including olean-12-ene-3,16-dione (3), taraxer-14-ene-3,16-dione (6), hop-17(21)-en-3-one (13), 3β-hydroxylup-20(29)-en-30-al (23), and lup-20(29)-ene-3β,30-diol (24), is also reported.