Limonoids from the Leaves and Twigs of Walsura yunnanensis

Nine new cedrelone limonoids, namely, walsuranolide B (1), 11 beta-hydroxy-23-O-methylwalsuranolide (2), yunnanolide A (3), yunnanol A (4), 11 beta-hydroxyisowalsuranolide (5), 11 beta-hydroxy-1,2-dihydroisowalsuranolide (6), 1 alpha,11 beta-dihydroxy-1,2-dihydroisowalsuranolide (7), 11 beta-hydroxy-1 alpha-methoxy-1,2-dihydroisowalsuranolide (8), and yunnanolide B (9), together with a new cycloartane triterpenoid, (245*,25R*)-cycloartane-3,6,24,25,26-tetrol (10), were isolated from the leaves and twigs of Walsura yunnanensis. Their structures were elucidated on the basis of spectroscopic analysis and by comparison with literature data. Compounds 3 and 5 exhibited potent cytotoxicity against five human tumor cell lines with IC50 values in the range 2.2-4.2 mu M.