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

Abstract

SummaryThe essential oil of hop cones ( Humulus lupulus L.) was analyzed by GC and GC-MS to assess the composition of volatiles and to evaluate olfactorially the principle aroma compounds. Myrcene (45.3%), -humulene (31.2%) and -caryophyllene (9.8%) were found to be the main constituents of this H. lupulus sample.The essential hop oil, the 3 main compounds and three minor concentrated constituents, isobutyl isobutyrate, geraniol and -pinene, were tested for their antimicrobial activities against some different strains of Gram-positive and Gramnegativebacteria as well as the yeast Candida albicans by using agar diffusion and agar dilution method, respectively. The same was done using the phenolic aroma compound eugenol and the synthetic antibiotics Ciproxin The obtained data were discussed to get more insight into the influence of pure aroma compounds on the antimicrobial activities of essential oils.

Season's Variation Impact on Citrus aurantium Leaves Essential Oil: Chemical Composition and Biological Activities

“…According to Delaquis and others (2002), linalool is a determinant component in antilisterial activity. Moreover, it was widely reported that β‐caryophyllene was active in vegetable defense (Jirovetz and others 2006). Furthermore, some components revealed strong activities toward various strains of microbial even when they were present in few amounts such as α‐pinene, limonene, caryophyllene oxide, and myrcene (Skomen and others 2004; Jirovetz and others 2006).…”

“…Moreover, it was widely reported that β‐caryophyllene was active in vegetable defense (Jirovetz and others 2006). Furthermore, some components revealed strong activities toward various strains of microbial even when they were present in few amounts such as α‐pinene, limonene, caryophyllene oxide, and myrcene (Skomen and others 2004; Jirovetz and others 2006). These results highlighted the impact of minor components on the global antimicrobial activity; they may contribute by their hydroxyl groups or by synergisms with major components (Ultee and others 2002; Skomen and others 2004; Edris 2007).…”

In vitro inhibition of foodborne pathogens by volatile oil and organic extracts of Poncirus trifoliata Rafin. seeds

“…18 -20 The antibacterial activity of individual components of essential oils such as spathulenol or α-humulene has been reported previously. 21,22 On the other hand, components in lower amounts, such as isocaryophyllene, pentadecanoic acid, β-selinene, elemicin, trans-β-farnesene, β-bisabolene and γ -muurolene, also contributed to antibacterial activity of the oil. 23,24 It is also possible that the minor components might be involved in some type of synergism with the other active compounds.…”

Italian hop germplasm: Characterization of wild Humulus lupulus L. genotypes from Northern Italy by means of phytochemical, morphological traits and multivariate data analysis

“…The presence of bitter secondary metabolites, and of course of essential oils, have been evaluated in wild populations of H. lupulus growing in the United States, in Chile and in countries of Central and Northern Europe (del Valle et al, 2003;Bernotienë et al, 2004;Jirovetz et al, 2006;Patzak et al, 2010a). On this regard, it must be noticed that some geographical areas have not been properly scrutinized and the genetic pool at present screened do not include mediterranean accessions, despite the fact that H. lupulus can be easily found in the wild also in subalpine areas (Murakami et al, 2006;Patzak et al, 2010b).…”