New glycosides from Capsicum annuum L. var. acuminatum. Isolation, structure determination, and biological activity

Investigation of polar extracts from ripe fruits of Capsicum annuum L. var. acuminatum yielded three new glycosides, capsosides A (1) and B (2) and ca psianoside VII (3), along with seven known compounds (4-10). The chemical s tructures were elucidated mainly by extensive nuclear magnetic resonance me thods and mass spectrometry, and the biological activities of icariside E-5 (4) were tested by different assays. Icariside E-5, in contrast to capsaic in, neither induces an increase in the intracellular levels of reactive oxy gen species nor affects the mitochondria permeability transition, and it do es not signal through the vanilloid receptor type 1. Interestingly, this co mpound protects Jurkat cells from apoptosis induced by the oxidative stress mediated by serum withdrawal. These results suggest that icariside E-5 may have antioxidant properties that strengthen the importance of peppers in t he Mediterranean diet.