title: Dimerization, ROS formation, and biological activity of o-methoxyphenols.
abstract: o-Methoxyphenols are antioxidants widely used in the cosmetic and food industries. Dimers from 1, 2, or 3 were synthesized and their radical-scavenging and biological activities were compared with those of the original or other phenols. Radical-scavenging was evaluated from a kinetic induction period method (IPM). To simulate biomimetic thiolcooxidation with antioxidants, the behavior of mixtures of 1, 2, 3, 4, or catechin with mercaptomethylimidazole (MMI), a thiol was investigated using IPM. Polyphenols 4 and catechin was accompanied by extensive oxygen uptake, suggesting the formation of thiyl radicals from MMI and their reaction with molecular oxygen. In contrast,1 markedly enhanced radical-scavenging without oxygen uptake, probably because of the formation of EUGQM/MMI-conjugates. 2 showed relatively small oxygen uptake, probably resulting from the predominant formation of benzyl radicals. Intracellular reactive oxygen species (ROS) in cancer cells by 4 ,but not by compounds 1, 2, 6, 7, 8, 9, and 10 was found, suggesting a possible link between physicochemical oxygen-uptake and intracellular ROS. The induction of apoptosis by 4 in HL-60 cells was accompanied by intracellular ROS. Dimers 6 and 7 inhibited nuclear factor (NF)-kappaB, activation stimulated by lipopolysaccharide (LPS) in RAW 264.7 cells. Also,6 ,7,and 9 inhibited LPS-induced cyclooxygenase-2 expression in RAW 264.7 cells in a dose-dependent manner, whereas 1, 2, and 3 did not. Dimerization of o-methoxyphenols may be a useful tool for the design of drugs to act as potent chemopreventive and anticancer agents.
authors.affiliation: Department of Oral Diagnosis Meikai University School of Dentistry, Keyakidai, Sakado, Saitama 350-0283, Japan. fujisawa@dent.meikai.ac.jp
authors.forename: Seiichiro
authors.initials: S
authors.lastname: Fujisawa
authors.forename: Toshiko
authors.initials: T
authors.lastname: Atsumi
authors.forename: Yukio
authors.initials: Y
authors.lastname: Murakami
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Kadoma
mesh_terms: D000840:Anisoles / Q000737:chemistry* / Q000494:pharmacology*; D000975:Antioxidants / Q000737:chemistry* / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D002460:Cell Line; D019281:Dimerization; D015195:Drug Design; D016166:Free Radical Scavengers / Q000737:chemistry / Q000494:pharmacology; D006801:Humans; D015394:Molecular Structure; D016328:NF-kappa B / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*
chemical_list: D000840:Anisoles; D000975:Antioxidants; D016166:Free Radical Scavengers; D016328:NF-kappa B; D017382:Reactive Oxygen Species; D009569:Nitric Oxide