The antimycobacterial components of hops (Humulus lupulus) and their dereplication.
Bioassay-guided fractionation of a hexane extract of strobile hops (Humulus lupulus) was undertaken to isolate and characterize the antimycobacterial constituents using the fast-growing mycobacterial species Mycobacterium fortuitum. Activity was associated with a low polarity fraction and 1H NMR spectra indicated the presence of a fatty acid mixture with unsaturated components. GC-MS of the derivatives indicated the presence of palmitic, stearic and oleic acids with small quantities of lignoceric, arachidic, behenic and linoleic acids. These compounds were assessed against M. fortuitum and all saturated fatty acids were inactive at concentrations greater than 256 microg/ml, whereas the unsaturated fats oleic and linoleic acids displayed minimum inhibitory concentrations of between 4 and 16 microg/ml against the fast-growing species tested. The widespread occurrence of these components could render screening for antimycobacterials from natural sources highly problematic without adequate dereplication. We propose that GC-MS of derivatised components of lipophilic extracts be a first step before any antimycobacterial bioassay-guided study, as this technique is the method of choice for dereplication of fatty acids.
Stavri
Michael
M
Centre for Pharmacognosy and Phytotherapy, The School of Pharmacy, University of London, UK.
Schneider
Ruth
R
O'Donnell
Gemma
G
Lechner
Doris
D
Bucar
Franz
F
Gibbons
Simon
S
D000995:Antitubercular Agents / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D027582:Humulus; D008826:Microbial Sensitivity Tests; D009161:Mycobacterium / Q000145:classification / Q000187:drug effects*; D008517:Phytotherapy; D010936:Plant Extracts / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use
D000995:Antitubercular Agents; D010936:Plant Extracts