The antimycobacterial components of hops (Humulus lupulus) and their dereplication

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.

Antimycobacterial Activity of the Red AlgaPolysiphonia virgata.

“…(Santalaceae) (Suksamrarn et al, 2005). Stavri et al (2004) investigated the hexane extract of hops, namely Humulus lupulus L. (Cannabaceae), for antimycobacterial compounds, and found a fatty acid mixture to be the bioactive principle. Among the fatty acids were palmitic, stearic, and oleic acid with small quantities of lignoceric, arachidic, behenic, and linoleic acids.…”

Inhibitory effects of xanthohumol from hops (Humulus lupulus L.) on human hepatocellular carcinoma cell lines

“…Flavonoids in hops, including xanthohumol, isoxanthohumol, dehydrocycloxanthohumol, tetrahydroxy-3′-prenylchalcone and 8-prenylnaringenin, have been reported to have anticancer functions, antioxidant activities, antidental caries functions and phytoestrogenic activities (Gerhauser et al, 2002;Stavri et al, 2004;Milligan et al, 2000;Ososki and Kennelly, 2003). Xanthohumol is one of the main flavonoids in hop extracts and, therefore, in beer .…”

Antimicrobial testings, gas chromatographic analysis and olfactory evaluation of an essential oil of hop cones (Humulus lupulus L.) from Bavaria and some of its main compounds

“…Despite the importance of hop and its essential oil for the aroma and bitterness of beer production, few data of biological activities such as sedative effects caused by prenylflavonoids [21], as well as antimycobacterial [22] and antibacterial [23] effects were published, but no detailed information about the influence of some main and minor compounds of the essential oil on their antimicrobial activities are available until now.…”