Note: Novel acylkaempferol glycoside from the endemic species, Vernonia travancorica Hook. f.

Abstract

Vernonia travancorica Hook. f. is a taxon, endemic to the evergreen forests of Western Ghats (above 1000 m), India. From the aqueous EtOH extract of the air-dried corymbose inflorescence a novel secondary metabolite, 3-O-β-[β-(6‴-acetyl)-d-glucopyranosyl(1→2)]-d-glucopyranosyl kaempferol (1), has been isolated, together with three other compounds, viz., 4′-methoxykaempferol (2), its 3-O-β-d-glucopyranoside (3) and kaempferol (4). The structure of the new natural product has been established based on chemical analysis, including characteristic colour reactions, rigorous hydrolytic procedures involving acid, alkali and enzyme, as well as spectral (UV, ¹H and ¹³C NMR and FABMS) evidences.

Keywords:

• Vernonia travancorica
• Asteraceae
• Flavonoids
• 3-O-β-[β-(6‴-Acetyl)-d-glucopyranosyl(1→2)]-d-glucopyranosyl kaempferol

Acknowledgements

The authors are grateful to Dr A.G. Ramachandran Nair, Department of Chemistry, Cochin University of Science and Technology, Cochin for generously sparing the authentic compounds and offering valuable suggestions. We also thank the SIF, Indian Institute of Science, Bangalore, the Central Drug Research Institute, Lucknow, and the SPIC Science Foundation, Chennai for the spectral data.