Resin glycosides from Merremia hederacea with multidrug-resistant reversal activities

To expand the resin glycoside composition of Merremia hederacea, aerial parts of M. hederacea were collected and investigated. Two previously undescribed resin glycosides, named merremins H-I were isolated from M. hederacea, and their structures were determined based on spectroscopic data and chemical evidence. The results suggested that merremins H-I had macrolactone structures, forming 18-membered rings. Merremins H-I were evaluated for their MDR reversal activities in KB/VCR cells by the SRB method. Merremin I showed moderate MDR reversal activity and increased the cytotoxicity of vincristine by 2.8-fold when incorporated at 25 μM.