Title: Humulon
CAS Registry Number: 26472-41-3
CAS Name: (6R)-3,5,6-Trihydroxy-4,6-bis(3-methyl-2-butenyl)-2-(3-methyl-1-oxobutyl)-2,4-cyclohexadien-1-one
Additional Names: a-bitter acid; a-lupulic acid; humulone
Molecular Formula: C21H30O5
Molecular Weight: 362.46
Percent Composition: C 69.59%, H 8.34%, O 22.07%
Literature References: Antibiotic constituent of hops (Humulus lupulus L., Moraceae). See also Lupulon. Isoln from commercial hops: Bungener, Bull. Soc. Chim. [2] 45, 487 (1886); Barth, Lintner, Ber. 31, 2022 (1898); Wollmer, Ber. 49, 780 (1916); Lewis et al., J. Clin. Invest. 28, 916 (1949). Structure: Riedl, Ber. 85, 692 (1952); Carson, J. Am. Chem. Soc. 73, 4652 (1951). Absolute configuration and structure of preferred isomer: DeKeukeleire, Verzele, Tetrahedron 26, 385 (1970).
Properties: Crystals from ether, mp 65-66.5°. Bitter taste, esp in alcoholic soln. More stable to air than lupulon. Monobasic acid. [a]D20 -212° (1.0 g in 15.5 g 96% alc). uv max (ethanol): 237, 282 nm (e 13,760; 8330). Soluble in the usual organic solvents. Slightly sol in boiling water from which it separates as a milky precipitate on cooling. Forms a sodium salt which is readily sol in water. Suffers no loss of bacteriostatic potency against Staphylococcus aureus upon autoclaving 40 ppm in phosphate buffer at pH 6.5 or 8.5. The presence of ascorbic acid in low concns extends the duration of bacteriostatic action.
Melting point: mp 65-66.5°
Optical Rotation: [a]D20 -212° (1.0 g in 15.5 g 96% alc)
Absorption maximum: uv max (ethanol): 237, 282 nm (e 13,760; 8330) |