New Constituents of Sweet Capsicum annuum L. Fruits and Evaluation of Their Biological Activity

Four new acyclic diterpene glycosides named capsianosides (1−4), together with 12 known compounds, were isolated from the fresh sweet pepper fruits of Capsicum annuum L., a plant used as a vegetable food, spice, and external medicine. The chemical structures of new natural compounds, as well as their absolute configurations, were established by means of spectroscopic data including infrared, high-resolution mass spectrometry, and one- and two-dimensional nuclear magnetic resonance and by chemical derivatization. The known capsidiol (11) showed bacteriostatic properties in vitro against Helicobacter pylori with a minimum inhibitory concentration (MIC) of 200 μg/mL when compared with the commercial drug metronidazole (MIC, 250 μg/mL). Some purified components were also tested for their antioxidant activities. Keywords: Capsicum annuum L.; Solanaceae; capsianosides; 2D-NMR; Helicobacter pylori; antioxidant activity; liquid chromatography