In miso, due to the substantial presence of genistein, flazin is often overlapped and masked by genistein in HPLC analysis. Flazin in the miso extracts could be resolved with genistein through medium-pressure liquid chromatography run under a nonacidified methanol–water system and subsequently fractionated by semipreparative HPLC and identified by NMR spectroscopic analysis. As referenced, flazin was detected in all 11 locally marketed miso products, with contents ranging from 3.5 to 124.8 μg/g. In lab-made miso fermented at 28 and 37 °C for 8 weeks, flazin formed faster at 37 °C than at 28 °C. Based on the time-dependent HPLC chromatographic changes of the miso extracts during fermentation, the presence of tryptophan-derived ß-carboline intermediates was deduced. Tryptophan was then supplemented for miso fermentation, and four peak substances were targeted for isolation by sophisticated approaches. Four ß-carbolines were purified and instrumentally identified, i.e., P1: 1-(1,3,4,5-tetrahydroxypentyl)-9H- pyrido[3,4-b]indole, P2 (diastereomer of P1): 1-(1*,3,4,5-tetrahydroxypentyl)- 9H-pyrido[3,4-b]indole, and Miso 101: 1-(1,3,4,5-tetrahydroxypentyl)-9H- pyrido[3,4-b]indole 3-carboxylic acid, and Miso 111 (diastereomer of Miso 101): 1-(1*,3,4,5-tetrahydroxypentyl)-9H-pyrido[3,4-b]indole 3-carboxylic acid. Each of the purified β-carbolines along with tryptophan and flazin exhibited varied ABTS^·+ scavenging and xanthine oxidase inhibitory activities.

中文翻译：

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味噌中 Flazin 的存在以及发酵过程中形成的四种色氨酸衍生的 β-咔啉的鉴定


在味噌中，由于大量存在染料木黄酮，在 HPLC 分析中，黄素经常被染料木黄酮重叠和掩盖。味噌提取物中的黄素可以通过在非酸化甲醇-水系统下运行的中压液相色谱法与金雀异黄素进行解析，随后通过半制备型高效液相色谱法进行分级，并通过核磁共振波谱分析进行鉴定。据参考，本地市售的11款味噌产品均检出黄素，含量介乎3.5至124.8微克/克。实验室制作的味噌在 28 和 37°C 下发酵 8 周，37°C 下的黄素形成速度比 28°C 下更快。根据发酵过程中味噌提取物随时间变化的 HPLC 色谱变化，推断出存在色氨酸衍生的 β-咔啉中间体。然后补充色氨酸进行味噌发酵，并通过复杂的方法分离出四种峰值物质。纯化并仪器鉴定了四种β-咔啉，即P1：1-(1,3,4,5-四羟基戊基)-9 H-吡啶并[3,4- b ]吲哚，P2（P1的非对映异构体）：1- (1*,3,4,5-四羟基戊基)- 9 H-吡啶并[3,4- b ]吲哚，和Miso 101：1-(1,3,4,5-四羟基戊基)-9 H-吡啶并[3 ,4- b ]吲哚 3- 羧酸和 Miso 111（Miso 101 的非对映异构体）：1-(1*,3,4,5-四羟基戊基)-9 H-吡啶并[3,4- b ]吲哚 3-羧酸。每种纯化的β-咔啉以及色氨酸和flazin 均表现出不同的ABTS ^·+清除和黄嘌呤氧化酶抑制活性。