Human Intestinal Bacteria Mediate Reduction of the N-Oxides of Isoline and Monocrotaline to the Corresponding Parent Alkaloids
作者:Jun Tang、Zhengtao Wang、Teruaki Akao、Masao Hattori
DOI:10.14233/ajchem.2013.13283
日期:——
The role of human intestinal bacteria in the biotransformation of pyrrolizidine alkaloid N-oxides was investigated. Two naturally-occurring hepatotoxic pyrrolizidine alkaloids, isoline and monocrotaline and their N-oxides were incubated with a human fecal suspension in an in vitro model, respectively. The metabolites were isolated and purified by chromatographic techniques and identified by the spectral analyses and the metabolic profiles were further analyzed by a specific TLC method. Human intestinal bacteria showed high reduction effects on the pyrrolizidine alkaloid N-oxides but not on the resultant tertiary alkaloids, suggesting that IB may play a partial role in the cyclic conversion between each pyrrolizidine alkaloid and its N-oxide in vivo. This evidence implied the potential risk of the pyrrolizidine alkaloid-containing Chinese medicinal herbs to human health when used in decoctions.
研究了人类肠道细菌在吡咯里西啶生物碱 N-氧化物生物转化中的作用。在体外模型中,两种天然存在的具有肝毒性的吡咯里西啶生物碱--伊利西林和单克洛林及其 N-氧化物分别与人类粪便悬浮液进行了培养。这些代谢物通过色谱技术进行分离和纯化,并通过光谱分析进行鉴定,代谢轮廓则通过特定的 TLC 方法进一步分析。人体肠道细菌对吡咯里西啶生物碱的 N-氧化物有很高的还原作用,但对由此产生的三级生物碱却没有,这表明 IB 可能在体内每种吡咯里西啶生物碱与其 N-氧化物之间的循环转换中发挥了部分作用。这些证据表明,含有吡咯里西啶生物碱的中草药在煎煮使用时对人体健康有潜在风险。