Non-enzymatic Reduction of Sennidins and Sennosides by Reduced Flavin(Biological)

概要

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Reduced flavin-adenine dinucleotide (FADH_2), which was produced by fiavin-adenine dinucleotide (FAD)-dependent sennidin reductase, reduced methyl orange non-enzymatically in a molar ratio of 2:1 under anaerobic conditions. Similarly, sennidins and sennosides were reduced non-enzymatically to rheinanthrone and 8-glucosylrheinanthrone, respectively, by the reduced forms of cofactors such as FAD, flavin mononucleotide (FMN), riboflavin and benzyl viologen. The reaction was inhibited by oxygen. FADH_2 reduced sennidins equimolarly, but sennosides were reduced much less effectively than sennidins (about one-tenth). The polarographic half-wave potentials of sennidins A and B, and sennosides A and B were -115, -133, -184 and -201 mV, respectively. Therefore, it was confirmed that the reduction of sennidins and sennosides by FAD-dependent sennidin reductase consists of the following two reactions; (1) the reductase reduces cofactors such as FAD and (2) sennidins and sennosides are reduced non-enzymatically by the reduced forms of cofactors. On the other hand, oxidation of rheinanthrone to sennidins in a neutral solution occurred with oxygen but not with FAD.
公益社団法人日本薬学会の論文
1987-05-25