Humulene Diepoxides from the Australian Arid Zone Herb Dysphania: Assignment of Aged Hops Constituents.

Dysphania is an abundant genus of plants, many of which are endemic to the Australian continent, occurring primarily in arid and temperate zones. Despite their prevalence, very few investigations into the phytochemistry of native Dysphania have been undertaken. Described herein, is the isolation and elucidation of two enantiomeric diastereomers of humulene diepoxide C from D. kalpari and D. rhadinostachya, of which unassigned diastereomers of humulene diepoxide C have been previously reported as components in beer brewed from aged hops. In addition, two (+)-humulene diepoxiols (humulene diepoxiol C-I and C-II) were isolated from D. rhadinostachya. Analysis of Chinook hops oil confirmed the presence of both humulene diepoxide C-I and C-II as trace components, and in turn enabled GC-MS peak assignment to the relative stereochemistry. Anticancer assays did not reveal any significant activity for the (+)-humulene diepoxides. Antifungal assays showed good activity against a drug-resistant strain of C. auris, with MIC50 values of 8.53 and 4.91 µm obtained for (+)-humulene diepoxide C-I and C-II, respectively.

Evaluation of Nonvolatile Chemistry Affecting Sensory Bitterness Intensity of Highly Hopped Beers.

The range of different nonvolatile constituents extracted from hops in highly hopped beers suggests that isohumulones may not be the sole contributor to beers' bitterness. Among brewers producing hop-forward beer styles, there is concern that the bitterness unit (BU) is no longer an accurate predictor of beer bitterness. This study examined factors within the beer matrix that influence sensory bitterness perception in highly hopped beers. Over 120 commercial beers were evaluated using sensory and instrumental techniques. Chemical analysis consisted of the BU via spectrophotometry, hop acids via high-performance liquid chromatography, total polyphenols via spectrophotometry, and alcohol content plus real extract via an Alcolyzer. Sensory analysis was conducted over two studies, and the beers' overall bitterness intensities were rated using a 0-20 scale. This study identified that the BU measurement predicts sensory bitterness with a nonlinear response, and it proposed an alternative approach to predicting bitterness based on isohumulones, humulinones, and ethanol concentrations. The study also revealed the importance of oxidized hop acids, humulinones, as a significant contributor to beer bitterness intensity.