The transformation of quinoline, isoquinoline and 3-, 4-, 6- and 8-methylquinoline by Desulfobacterium indolicum was compared with that of the N-containing analogues indole and 1-, 2-, 3- and 7-methylindole. The metabolites were identified using high-performance liquid chromatography with UV detection, thin-layer chromatography, combined gas chromatography/mass spectrometry and proton NMR spectroscopy. All degraded compounds were initially hydroxylated at position 2 by D. indolicum . A new degradation product of quinoline was observed in the second transformation step, where 3,4-dihydro-2-quinolinone accumulated. This ring-reduced compound was further transformed into unidentified products. The transformation pathway of indole was characterized by well-known steps through oxindole, isatin, and anthranilic acid. No further transformation of the hydroxylated methyl analogues: 3- and 7-methyloxindole and 3- and 4-methyl-2-quinolinone, was observed within 162 days of incubation. These degradation products accumulated in stoichiometric amounts, while 6- and 8-methyl-2-quinolinone were further degraded to 6- and 8-methyl-3,4-dihydro-2-quinolinone in stoichiometric amounts. Isoquinoline, 2-methylquinoline and 1- and 2-methylindole were not degraded by D. indolicum . These observations indicate that a methyl group at or close to position 2 results in blockage of the microbial attack, and that transformation of hydroxyquinolines methylated at the heterocyclic ring also was blocked or sterically inhibited. An incomplete transformation of some methylated compounds was observed, e.g. for 3- and 6-methylquinoline and 3- and 7-methylindole, with residual concentrations of 0.5–4 mg/l in relation to initial concentrations of 10–15 mg/l.

中文翻译：

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吲哚 脱硫杆菌 （DSM 3383）的喹啉，吲哚及其甲基化类似物的代谢途径

比较了 靛蓝脱硫杆菌对喹啉，异喹啉和3-，4-，6-和8-甲基喹啉的 转化 与含N的类似物吲哚和1-，2-，3-和7-甲基吲哚的转化。使用具有紫外检测功能的高效液相色谱，薄层色谱，气相色谱/质谱联用和质子NMR光谱对代谢产物进行鉴定。最初，所有降解的化合物都被 D. indolicum 羟基化 。在第二个转化步骤中观察到新的喹啉降解产物，其中积累了3,4-二氢-2-喹啉酮。该环还原的化合物进一步转化为未鉴定的产物。吲哚的转化途径的特征在于通过吲哚，靛红和邻氨基苯甲酸的众所周知的步骤。在孵育的162天内未观察到羟基化的甲基类似物：3-和7-甲基羟吲哚以及3-和4-甲基-2-喹啉酮的进一步转化。这些降解产物以化学计量量积累，而6-和8-甲基-2-喹啉酮进一步以化学计量量降解为6-和8-甲基-3,4-二氢-2-喹啉酮。 D. indolicum 不会降解异喹啉，2-甲基喹啉以及1-和2-甲基吲哚 。这些观察结果表明，在位置2处或附近的甲基导致了微生物侵袭的阻断，并且在杂环上甲基化的羟基喹啉的转化也被阻断或在空间上被抑制。观察到一些甲基化化合物的不完全转化，例如3-和6-甲基喹啉和3-和7-甲基吲哚，相对于初始浓度10-15 mg / l，残留浓度为0.5-4 mg / l。