Further flavonol and iridoid glycosides from Ajuga remota aerial parts

Abstract

Five new iridoid glycosides characterised as 6-keto-8-acetylharpagide (1), 6,7-dehydro-8-acetylharpagide (2), 7,8-dehydroharpagide (3), 8-acetylharpagide-6-O-β-glucoside (4), harpagide-6-O-β-glucoside (5) together with three flavonol glycosides, myricetin 3-O-rutinoside-4′-O-rutinoside (6), myricetin 3-O-rutinoside-3′-O-rutinoside (7) and isorhamnetin 3-O-rutinoside-7-O-rutinoside-4′-O-β-glucoside (8) have been isolated from the aerial parts of Ajuga remota. Also isolated were two known compounds ajugarin IV and ajugarin V. Their structures were established using spectroscopic methods including UV, IR, FAB-MS, HR-MS, 1D and 2D NMR techniques.

Keywords:

• Ajuga remota
• Labiatae
• Iridoid glycosides
• Flavonol glycosides

Acknowledgements

The authors are grateful to Alexander von Humboldt Stiftung for awarding L.M. a fellowship. Maseno University, Institute for Postgraduate Research Studies is acknowledged for providing a research fund that partially financed the work. Mr. Mathenge of the Botany Department, University of Nairobi is acknowledged for plant material identification.