A new cytotoxic and larvicidal himachalenoid, rosanoids and other constituents of Hugonia busseana

Abstract

A new cytotoxic himachalene sesquiterpenoid 4α-methoxy-5,9-oxahimachal-9-ene (hugonianene A) which exhibited moderate activity against Anopheles gambiae mosquito larvae after 24 h at a concentration of 0.237 mg mL⁻¹, and at 48 h and 72 h contact time causing complete larval mortality up to a concentration as low as 0.01369 mg mL⁻¹, was isolated as the major constituent of the cytotoxic root bark extract of Hugonia busseana. Hugonianene A was obtained together with the hitherto unreported rosane diterpenoid 18-hydroxyrosane, the known rosane diterpenoid hugorosediol, an inseparable mixture of 12-methoxy-13-methylpodocarpa-8,11,13-trien-3,7-dione and 12-methoxy-13-methylpodocarpa-1,8,11,13-tetraen-3,7-dione, and the di-podocarpanoid hugonone B that was previously obtained from H. castaneifolia.

Keywords:

• Hugonia busseana
• Linaceae
• Himachalenoid
• Rosanoids
• Cytotoxicity
• Larvicide

Acknowledgements

Financial support through a Sida/SAREC grant to the Faculty of Science at the University of Dar es Salaam is gratefully acknowledged. LDB thanks the Germany Academic Exchange Services (DAAD) and NAPRECA for a PhD fellowship under the DAAD-NAPRECA Fellowship Scheme. We thank Mr Leonard B. Mwasumbi, a retired curator of the Herbarium of the Department of Botany at the University of Dar es Salaam, for locating and identifying the investigated plant species. We wish to gratefully acknowledge the support of Professor Berhanu M. Abegaz from the University of Botswana for availing NMR analyses, and Mr G.M. Mahanga and Ms E. Innocent from the Department of Chemistry at the University of Dar es Salaam for recording mass spectra and carrying out larvicidal assays.