Trichiconlides C-F, four new limonoids with 1,2-seco phragmalin-type carbon skeleton from the fruits of Trichilia connaroides

Phytochemical investigation of the fruits from Trichilia connaroides led to the isolation of four rare 1,2-seco phragmalin-type limonoids (1-4) with C-7/28 delta-lactone ring along with two known triterpenoids (5-6). An oxygen bridge between C-1 and C-2 formed an rare 9-oxa-tricyclo[3.3.2.1(7,10)]undecane-2-ene moiety in structure of 1 and 2, and 3-4 possessed a bicyclo[5.2.1(4,10)]decane skeleton. Their structures were established based on extensive spectroscopic methods and their absolute configurations of 1 were confirmed by TDDFT/ECD calculation and comparative analysis. Compounds 5-6 showed moderate inhibitory effects on Hela tumor cell lines with inhibition ratio values of 83.8% and 87.1% at concentration 40 mu M, respectively.