185. Chemistry of hop constituents. Part XVIII. Hulupinic acid

Quantitative Sensomics Profiling of Hop-Derived Bitter Compounds Throughout a Full-Scale Beer Manufacturing Process

“…Interestingly, the decreasing concentrations of hulupones during beer processing were not accompanied by an accelerated formation of hulupinic acid (36). These findings give first evidence that in contradiction to literature data (13), the degradation of hulupones does not lead exclusively to the formation of hulupinic acid (36), and further unknown pathways contribute to the decrease of hulupones (18)(19)(20) in beer.…”

“…An amount of 77.2, 51.8, and 82.5% of the starting dosage of R-acids (3)(4)(5) were isomerized to the corresponding iso-R-acids (6)(7)(8)(9)(10)(11) in the final beer VII (Table 3), which is in the range to be expected for a Pilsner-type beer (32,33). In addition, 6.6-7.4% of the parent R-acids were found to be transformed into humulinones (12)(13)(14) and humulinic acids (40-45). Interestingly, the formation of these oxidation products from the a Chemical structures of the individual compounds are given in Figure 1 and 2. b Sample numbering refers to Figure 4.…”

“…Reaction routes for the transformation of the hop-derived bitter compounds xanthohumol (1), R-acids(3)(4)(5), and β-acids (15-17) upon beer manufacturing leading to the formation of isoxanthohumol (2), trans-and cis-iso-R-acids (6-11), humulinones(12)(13)(14), hulupones(18)(19)(20), tricyclic β-acid cyclization products (21-35), hulupinic acid (36), tricyclohumols (37-39), cis-and trans-humulinic acids (40-45), cis-and trans-alloisohumulonehydroxides (46-51), and the corresponding -hydroperoxides (52-57).…”

CHEMISTRY OF HOP CONSTITUENTS: XXII. PROTON MAGNETIC RESONANCE SPECTROSCOPY OFISOHUMULONE A

“…It was separated from the mother liquors of the isomerization of humulinic acid A by a lengthy countercurrent distribution proce dure,1 and more recently we have prepared it in good yield by a chemical procedure. [3][4] In this, humulinic acid A is oxidized to dehydrohumulinic acid (V) and this is reduced with sodium borohydride to give the humulinic acid B. In a similar manner two isomers, each of dihydrohumulinic acid, acid we determined their proton magnetic resonance spectra (see Figs.…”

“…These spectra establish that the compounds are stereoisomers, differing in the relative con figuration of the Cg-tsopentenyl side chain and the C4-hydroxyl. 3 Humulinic acid A has the trans configuration. The B isomer has the cis configuration which, in presence of base, reverts to the more stable trans form A.…”