A new abietane-type diterpenoid from roots of Burkea africana Hook (Fabaceae) with α-amylase inhibitory potential

Abstract

A new abietane-type diterpenoid, rubesanolidic acid (1), alongside six known compounds including β-sitosterol (2), lupeol (3), betulinic acid (4) ursolic acid (5), β-sitosterol 3-O-β-D-glucopyranoside (6) and stigmasterol 3-O-β-D-glucopyranoside (7) were isolated from the roots of Burkea africana through column chromatography. Their structures were elucidated from spectroscopic analyses (UV, IR, MS, 1D and 2D NMR) data and by comparison with data from previous studies. The extract and compounds were tested for their α-amylase inhibition. The extract was more active than the isolated compounds with a percentage inhibition of 51.0 ± 2.5% at 400 µg/mL and was the only sample showing above 50% inhibition at this dose. Amongst the isolated compounds and at the dose of 400 µg/mL, the new diterpenoid Rubesanolidic acid exibited the highest percentage inhibition of α-amylase of 38.2 ± 2.0% while β-sitosterol showed the lowest inhibition of 9.6 ± 0.5%. The results indicate that B. africana is a potential source of antidiabetic compounds.

Graphical Abstract

Keywords:

• Burkea africana
• chemical composition
• rubesanolidic acid
• antidiabetic potential

Acknowledgements

The authors are grateful to the Laboratory of NMR and Molecular Imaging, University of Mons for carrying out NMR analysis of the compounds. Equally, material support from the Department of Chemistry, Physics and Environment, “Dunarea de Jos” University of Galati is greatly acknowledged.

Disclosure statement

No potential conflict of interest was reported by the authors.