Planta Med 2015; 81 - PC17
DOI: 10.1055/s-0035-1545204

Anti-vancomycin-resistant Enterococcus faecium and E. faecalis activities of (-)-gossypol and derivatives from Thespesia garckeana

VM Masila 1, JO Midiwo 1, J Zhang 2, BM Gisacho 1, R Munayi 1, LK Omosa 1, FT Wiggers 2, MR Jacob 2, MA Ibrahim 2, LA Walker 2, 3, I Muhammad 2
  • 1Department of Chemistry, School of Physical Sciences, University of Nairobi, P. O. Box 30197 – 00100, Nairobi, Kenya
  • 2National Center for Natural Products Research
  • 3Department of BioMolecular Sciences, Research Institute of Pharmaceutical Sciences, School of Pharmacy, University of Mississippi, University, MS 38677, USA

The roots extract of Thespesia garckeana yielded three sesquiterpenoids, (-)-gossypol (1), (-)-6-methoxygossypol (2) and (+)-6, 6′-dimethoxygossypol (3), and the stem bark afforded E-docosyl 3-(3, 4-dihydroxyphenyl) acrylate, stigmasterol and betulinic acid. Their structures were determined by full spectral analysis. Compound 1 showed potent antibacterial activity against vancomycin-resistant Enterococcus faecium (VRE) with IC50/MIC/MBC values of 0.89/2.50/10.00 µg/mL, whereas vancomycin was found to be inactive. The mono and di-methoxylated derivatives of 1 (i.e., 2 and 3) were less active with respective IC50/MIC/MBC values of 1.45/2.50/5.00 µg/mL and 3.35/10.00/10.00 µg/mL, respectively, against this microbe. Compound 2 was more potent than the standard drug against low level VRE strain with IC50/MIC/MBC values of 2.31/5.00/5.00 µg/mL (vs 2.45/10.00/> 20 µg/mL for vancomycin). Both 1 and 2 also showed good inhibition of C. glabrata (IC50 0.38 and 1.58 µg/mL) but were weakly active against methicillin-resistant S. aureus (IC50 4.66 µg/mL, 9.22 µg/mL).