Abstract
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.
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Claims 8
Claim · model-written summary
Activity of the hexane extract of hop strobiles against Mycobacterium fortuitum was associated with a low polarity fraction.
Verbatim
t0“hops (Humulus lupulus)”
e0“Activity was associated with a low polarity fraction”
Claim · model-written summary
1H NMR spectra indicated a fatty acid mixture with unsaturated components in the active hop fraction.
Verbatim
t0“hops (Humulus lupulus)”
e0“1H NMR spectra indicated the presence of a fatty acid mixture with unsaturated components”
Claim · model-written summary
GC-MS of the derivatives indicated palmitic, stearic and oleic acids in the active hop fraction.
Verbatim
t0“hops (Humulus lupulus)”
e0“GC-MS of the derivatives indicated the presence of palmitic, stearic and oleic acids”
Claim · model-written summary
The active hop fraction contained small quantities of lignoceric, arachidic and behenic acids.
Verbatim
t0“hops (Humulus lupulus)”
e0“with small quantities of lignoceric, arachidic, behenic and linoleic acids”
Claim · model-written summary
The active hop fraction contained a small quantity of linoleic acid.
Verbatim
t0“hops (Humulus lupulus)”
e0“with small quantities of lignoceric, arachidic, behenic and linoleic acids”
Claim · model-written summary
All saturated fatty acids were inactive against M. fortuitum at concentrations above 256 microg/ml.
- Taxon
- hopst0
- Interactor
- M. fortuitum
Mycolicibacterium fortuitume0pathogen - Outcome
- inactivee0
- Value
- 256 microg/mle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“hops (Humulus lupulus)”
e0“These compounds were assessed against M. fortuitum and all saturated fatty acids were inactive at concentrations greater than 256 microg/ml”
Claim · model-written summary
The unsaturated fatty acids oleic and linoleic acid had minimum inhibitory concentrations of 4 to 16 microg/ml against the fast-growing mycobacteria tested.
Verbatim
t0“hops (Humulus lupulus)”
e0“the unsaturated fats oleic and linoleic acids displayed minimum inhibitory concentrations of between 4 and 16 microg/ml against the fast-growing species tested”
Claim · model-written summary
The authors propose GC-MS of derivatised lipophilic extract components as a first dereplication step before antimycobacterial bioassay-guided studies.
Verbatim
t0“hops (Humulus lupulus)”
e0“We propose that GC-MS of derivatised components of lipophilic extracts be a first step before any antimycobacterial bioassay-guided study”