title: Evaluation of properties of apigenin and [G-3H]apigenin and analytic method development.
abstract: This study provides baseline data and analytical methods to assist in the evaluation of apigenin, a plant flavonoid with promising chemopreventive activity against skin cancer. Apigenin was freely soluble in dimethylsulfoxide (> 100 mg/mL), but it had low solubility (0.00135-1.63 mg/mL) in all the other solvents and surfactants tested, especially in highly hydrophilic or nonpolar solvents. The partition coefficient (log K) calculated from the solubility ratio of apigenin in n-octanol and water was 2.87. Apigenin strongly absorbed UV light, with three maximum absorption wavelengths at 212, 269, and 337 nm (epsilon = 29,800, 19,020, and 18,930 M-1 cm-1, respectively). Using quercetin as the internal standard, a reversed-phase HPLC method was developed to quantitatively analyze apigenin in epidermal cells obtained from SENCAR mice. Apigenin was labeled at position 6, 8, 3', and 5' with tritium by a platinum-catalyzed proton-tritium exchange as confirmed indirectly by 1H NMR analysis of the deuterated apigenin. The tritium label was stable in aqueous environments, especially under acidic and neutral conditions, so [G-3H]apigenin was considered suitable for subsequent absorption and metabolic studies.
authors.affiliation: Department of Pharmaceutical Sciences, University of Nebraska Medical Center, Omaha 68198, USA.
authors.forename: B
authors.initials: B
authors.lastname: Li
authors.forename: D H
authors.initials: DH
authors.lastname: Robinson
authors.forename: D F
authors.initials: DF
authors.lastname: Birt
mesh_terms: D000818:Animals; D016588:Anticarcinogenic Agents / Q000032:analysis / Q000494:pharmacology*; D002478:Cells, Cultured; D020843:Chamomile; D002851:Chromatography, High Pressure Liquid; D005069:Evaluation Studies as Topic; D005419:Flavonoids / Q000032:analysis / Q000494:pharmacology*; D009682:Magnetic Resonance Spectroscopy; D051379:Mice; D009822:Oils, Volatile / Q000032:analysis / Q000494:pharmacology*; D010946:Plants, Medicinal; D012867:Skin / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet; D014316:Tritium
chemical_list: D016588:Anticarcinogenic Agents; D005419:Flavonoids; D009822:Oils, Volatile; D014316:Tritium