Antioxidant Iridoid Glucosides From Wendlandia Formosana

Abstract

Two new iridoid glucosides of 10-O-caffeoyl scandoside methyl ester (3), and 6-methoxy scandoside methyl ester (4) besides the known compounds of scandoside methyl ester (1), methyl deacetyl asperulosidate (2), 10-O-caffeoyl daphylloside (5), phytol (6), and ursolic acid (7) were isolated from the leaves of Wendlandia formosana. Structure elucidation of the new iridoid glucosides was based on interpretation of high-resolution 1D and 2D NMR spectral data and chemical conversions. Antioxidant activity of Compounds (1–5) against diphenylpicrylhydrazyl (DPPH) and hydroxyl radical, and peroxynitrite was reported.

Keywords:

• Wendlandia formosana
• Rubiaceae
• Iridoid glucosides
• Antioxidant activity
• Scavenging activity

Acknowledgements

This work was supported by a grant from the National Science Council of the Republic of China (NSC 89-2323-B-038-001). We thank Ms. Shwu-Hui Wang, Center for Instrumentation, Taipei Medical University, for recording the NMR data and Ms. Shu-Yun Sun (Taipei Regional Analytical Instrumentation Center, NSC) for measurement of the low- and high-resolution FABMS.