Novel Sesquiterpenoids from Siegesbeckia orientalis

Abstract Five new sesquiterpenoids, namely, 8 β ‐(angeloyloxy)‐4 β ,6 α ,15‐trihydroxy‐14‐oxoguaia‐9,11(13)‐dien‐12‐oic acid 12,6‐lactone ( 1 ), 4 β ,6 α ,15‐trihydroxy‐8 β ‐(isobutyryloxy)‐14‐oxoguaia‐9,11(13)‐dien‐12‐oic acid 12,6‐lactone ( 2 ), 11,12,13 ‐ trinorguai‐6‐ene‐4 β ,10 β ‐diol ( 3 ), (1(10) E ,4 E ,8 Z )‐8‐(angeloyloxy)‐6 α ,15‐dihydroxy‐14‐oxogermacra‐(1(10),4,8,11(13)‐tetraen‐12‐oic acid 12,6‐lactone ( 9 ), and (1(10) E ,4 β )‐8 β ‐(angeloyloxy)‐6 α ,14,15‐trihydroxygermacra‐1(10),11(13)‐dien‐12‐oic acid 12,6‐lactone ( 11 ), and three new artifacts, (1(10) E ,4 Z )‐8 β ‐(angeloyloxy)‐9 α ‐ethoxy‐6 α ,15‐dihydroxy‐14‐oxogermacra‐1(10),4,11(13)‐trien‐12‐oic acid 12,6‐lactone ( 6 ), (1(10) E ,4 Z )‐8 β ‐(angeloyloxy)‐9 α ,13‐diethoxy‐6 α ,15‐dihydroxy‐14‐oxogermacra‐1(10),4‐dien‐12‐oic acid 12,6‐lactone ( 7 ), and (1(10) E ,4 Z )‐8 β ‐(angeloyloxy)‐9 α ‐ethoxy‐6 α ,15‐dihydroxy‐13‐methoxy‐14‐oxogermacra‐1(10),4‐dien‐12‐oic acid 12,6‐lactone ( 8 ), together with the three known sesquiterpenoids 4, 5 , and 10 , were isolated from the aerial parts of Siegesbeckia orientalis L. Their structures were established by spectral methods, especially 1D‐ and 2D‐NMR spectral methods.