Rauvolfianine, a new antimycobacterial glyceroglycolipid and other constituents from Rauvolfia caffra. Sond (Apocynaceae)

Abstract

The chemical investigation of the extract of the dried leaves of Rauvolfia caffra (Sond) (synonym Rauvolfia macrophylla) (Apocynaceae) led to isolation of a new glycoside derivative, rauvolfianine (1) as well as six known compounds: oleanolic acid (2), sitosterol-3-O-β-D-glucopyranoside (3), betulinic acid (4), vellosimine (5), sarpagine (6) and D-fructofuranosyl-β-(2→1)-α-D-glucopyranoside (7). Compounds 1, 2, 3, 4 and 7 were evaluated for antitubercular activity. Compounds 1 and 2 were the most active (MIC = 7.8125 and 31.25 μg/mL) towards the Isoniazid resistant strain of Mycobacterium tuberculosis AC45. Their structures and relative stereochemistry were elucidated by spectroscopic methods.

Keywords:

• Rauvolfia caffra
• Apocynaceae
• Rauvolfianine
• glycerol ester
• 1D and 2D NMR
• antitubercular activity

Acknowledgements

We also thank the DAAD / STIBET Doktoranden Scholarship for financial support and travel grants for Mr. Mbabi to Germany. We thank Mr. V. Nana for the collection and identification of plant material. We thank Mr. Felix Fehr of Department of Chemistry of University of Fribourg and Koert’s team of Philipps-Universität Marburg for spectral analysis.