Resin Glycosides from the Seeds of Calonyction muricatum

Abstract

Resin glycosides represent an important chemotaxonomic marker of the Convolvulaceae family and are responsible for the purgative properties of some medicinal convolvulaceous plants. The genus Calonyction comprising of seven species grows in the tropical and subtropical regions of America and Asia. Previous chemical investigations on this genus have led to the isolation of a number of structurally diverse Gibberellins [1,2], indolizidine alkaloids [3], and two resin glycosides, Calonyctin A1 and A2, which have been found to be plant growth regulators [4]. In our recent study, sixteen new resin glycosides, Calonyctins B-Q (1-16), were isolated from the seeds of Calonyction muricatum. Their structures with the absolute configuration were established on the basis of comprehensive spectroscopic analysis and chemical methods. Among these, calonyctins K-Q (10-16) possessed an unprecedented skeleton in the family of resin glycosides, that the aglycone moiety, 11S-hydroxyhexadecanoic acid (jalapinolic acid) or 11S-hydroxytetradecanoic acid (convolvulinolic acid) and the oligosaccharide core were linked by a 3-hydroxy-2-methylbutanoic acid moiety to form a macrocyclic ester structure.