Supercritical carbon dioxide hops extracts with antimicrobial properties

Abstract

Extracts obtained from hops (Humulus lupulus L., Cannabaceae) by supercritical fluid extraction (SFE), SFE followed by isomerization, as well as by conventional technique, were investigated for their chemical composition and antibacterial activity against selected foodborne pathogens and microorganisms capable to cause the food spoilage. The antibacterial activity of the extracts was compared with the antibacterial activity of xanthohumol, compound known for its broad pharmacological properties, isolated from the raw material remained after the SFE. Xanthohumol (XH, 96%) proved to posses the most prominent activity against all the tested strains, with the MIC values ranged between 2.5 and 20 μg mL -1 . Supercritical hops extract and potassium isomerized supercritical hops extract showed strong antibacterial activity against the tested strains as well. Escherichia coli was not affected by the extracts, meaning that their oral admission would not cause the same problem as antibiotic application in intestinal flora. The chemical composition of the investigated hops extracts was analysed by GC-MS. Contents of α-acids, β-acids, iso-α-acids and xanthohumol in the samples were determined by HPLC.

Effect of the Concentration of Hop Cone Extract on the Antibacterial, Physico-Chemical and Functional Properties of Adhesive Toilet Cleaners

“…The effect is manifested as growth inhibition zones and increases in proportion to an increase in the percentage content of the extract in the formulation. The obtained results are consistent with the literature data [18]. The probable mechanism of antimicrobial activity of the extract involves a change in the properties and permeability of microbial cell membranes which causes a leakage of intracellular substances in bacteria.…”

“…Similar results for a pure hops extract obtained under supercritical CO 2 conditions were reported by Rój et al [18].…”

Characterization of bioactive compounds in the biomass of black locust, poplar and willow

“…For this reason, studies on bioactive compounds of poplars focus on the raw material of buds. The supercritical fluid extraction has been widely used in the separation of phenolic compounds from different plant materials (Kosmala et al 2017;Michalak et al 2016;Rój et al 2017). This is evidenced by a number of applications provided by the researchers so far.…”

Exploration of isoxanthohumol bioconversion from spent hops into 8-prenylnaringenin using resting cells of Eubacterium limosum

“…An interesting 8-PN bioproduction process could thus consist of alkaline pretreatment of X in spent hops (spent hop-X), yielding the isomerized spent hop-IX, and subsequent bioconversion of the latter into 8-PN. Traces of particular compounds have been quantified in spent hops (Krishna et al 1986;Anioł et al 2007;Aniol and Zolnierczyk 2008;Rój et al 2015), yet, while the amount of X was almost not affected by sCO 2 extraction, extensive characterization of the main other residuals in different batches of spent hops is not available. It is however clear that spent hops may still contain traces of a complex mixture of different compounds.…”