Structural Identification on the Saponification Products of Raw Cajanolactone A

Abstract:

The aim of this work was to obtain a natural hypoglycemic and hypolipidemic drug lead cajanonic acid A (CAA) by saponification of a natural product cajanolactone A (CLA). A mixture containing about both 50% amount of CAA and pinostrobin was treated with 0.65% KOH in aqueous ethanol for 3.5 h under reflux, the mixed products were isolated through column chromatography and identified by physico-chemical and spectroscopic analysis. Besides the expected product CAA, four minor saponificative products were obtained, and identified as 1-(2,6-dihydroxy-4-methoxyphenyl)-ethanone (2), pinostrobin chalcone (3), cajanotone (4), and compound 1. Compound 1, a structural isomer of CAA, was found to be a new compound and named as cajanonic acid B. These would provide a new experimental basis for the further research and development bioactive component of Cajanus cajan leaves.