Planta Med 2010; 76 - P68
DOI: 10.1055/s-0030-1251830

Antimicrobial Abietane Diterpenoids from Clerodendrum eriophyllum

F Machumi 1, V Samoylenko 2, MR Jacob 2, FT Wiggers 2, JP Hester 2, JO Midiwo 1, LA Walker 2, I Muhammad 2
  • 1Department of Chemistry, University of Nairobi, P.O. Box 30197, Nairobi, Kenya
  • 2National Center for Natural Products Research, School of Pharmacy, The University of Mississippi, University, Mississippi 38677, USA

Clerodendrum eriophyllum Gürke (Verbenaceae) is a shrub or small tree distributed in the dry bushlands of Eastern Kenya. The plant has no record of previous phytochemical analysis. A bioassay guided isolation of the methanol extract of C. eriophyllum afforded one new abietane diterpenoid, namely 12-hydroxy-8,12-abietadiene-3,11,14-trione (1) and nine known abietane analogs (2–10). The structures of the compounds 1–10 were determined by 1D and 2D NMR spectra, including COSY, HMQC and HMBC experiments, and ESI-HRMS. The isolated compounds 3, 6–8 exhibited in vitro antimicrobial activity against a panel of microorganisms, including potent activities against C. neoformans by 3 and 7 with IC50 0.58 and 0.96µg/mL respectively. Circular Dichroism (CD) spectra of isolated compounds 1, 3, 6–8 were registered to evaluate the stereochemistry.

Acknowledgment: The authors sincerely thank Ms. Marsha Wright and Dr. Bharathi Avula, NCNPR, for assistance in biological work and recording mass spectra, respectively. This work was supported in part by the United States Department of Agriculture, Agricultural Research Service Specific Cooperative Agreement No. 58–6408–2-0009 and NIH, NIAID, Division of AIDS, Grant No. AI 27094.

P68, Fig.1