Lignans and Triterpenes from the Bark of Durio carinatus and Durio oxleyanus.

Investigation of chemical constituents from the bark of Durio carinatus has led to the isolation of three lignans, boehmenan X (1), threo-carolignan X (2), and erythro-carolignan X (3), together with the three known lignans boehmenan, threo-carolignan E, and erythro-carolignan E. The bark of D. oxleyanus yielded two new lignan ethers, threo-carolignan Y (4) and erythro-carolignan Y (5), together with compounds 1, 3, and boehmenan. J-Based configurational analysis and NOE measurements were used to explore conformational issues for the lignan diastereomers, while CD measurements supported an 8'S configuration for the various lignans. The triterpenes 3β-O-cis-caffeoylbetulinic acid and 3β-O-trans-caffeoylbetulinic acid were also characterized from D. carinatus.