Syntheses of all stereoisomers of aptosimon (9-oxosesamin) and their effects on plant growth regulation and diacylglycerol acyltransferase inhibition

Abstract

All eight stereoisomers of aptosimon (9-oxosesamin) were synthesized by employing Evans’ anti- and syn-aldol condensations. Among them, the (7S,7′R,8R,8′S)-aptosimon was more active than (+)- and (−)-sesamin at 1×10⁻⁵ M in promoting lettuce root growth under illumination conditions (44 µmol·m⁻²·s⁻¹). The effect of the 9-oxo group on the promotion of lettuce root growth was not observed from the results of activity experiments of stereoisomers carrying the same stereochemistry as those of (+)- and (−)-sesamin (1). However, the importance of 7S-configurations of aptosimon (9-oxosesamin) stereoisomers for the higher promotion of lettuce root growth was suggested. Based on optical rotation data and NMR analysis of the synthesized stereoisomers, the diacylglycerol acyltransferase inhibitory aptosimon was determined to be (7S,7′S,8S,8′R)-aptosimon and its enantiomer.