Aims

Sinomenine (SIN) is clinically used as an anti-rheumatic drug. However, the metabolic and pharmacological mechanisms of SIN combined with its metabolites are unclear. This study aims to explore the cyclic metabolic mechanism of SIN, the anti-inflammation effects of SIN and its major metabolites (N-demethylsinomenine (DS) and sinomenine-N-oxide (SNO)), and the oxidation property of SNO.

Materials and methods

SIN was administrated to rats via gavage. Qishe pills (a SIN-containing drug) were orally administrated to humans. The bio-samples were collected to identify SIN's metabolites. Enzymatic and non-enzymatic incubations were used to reveal SIN's metabolic mechanism. Impacts of SIN, SNO and DS on the inflammation-related cytokine's levels and nuclear translocation of NF-κB were evaluated in LPS-induced Raw264.7 cells. ROS induced by SNO (10 μM) was also assessed.

Key findings

CYP3A4 and ROS predominantly mediated the formation of SNO, and CYP3A4 and CYP2C19 primarily mediated the formation of DS. Noteworthily, SNO underwent N-oxide reduction both enzymatically, by xanthine oxidase (XOD), and non-enzymatically, by ferrous ion and heme moiety. The levels of IL-6 and TNF-α and nuclear translocation of NF-κB were ameliorated after pretreatment of SIN in LPS-induced Raw264.7 cells, while limited attenuations were observed after pretreatment of DS (SNO) even at 200 μM. In contrast, SNO induced ROS production.

Significance

This study elucidated that SIN underwent both enzymatic and non-enzymatic cyclic metabolism and worked as the predominant anti-inflammation compound, while SNO induced ROS production, suggesting more studies of SIN combined with SNO and DS are necessary in case of DDI and potential toxicities.

中文翻译：

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青藤碱及其主要代谢产物N-去甲基青藤碱和青藤碱-N-氧化物的代谢机理和抗炎作用。

目的

青藤碱（SIN）在临床上用作抗风湿药。但是，尚不清楚SIN及其代谢物的代谢和药理机制。本研究旨在探讨SIN的循环代谢机制，SIN及其主要代谢物（N-去甲基青藤碱（DS）和青藤碱-N-氧化物（SNO））的抗炎作用以及SNO的氧化性质。

材料和方法

通过管饲法向大鼠施用SIN。将奇舍丸（一种含SIN的药物）口服给人类。收集生物样品以鉴定SIN的代谢产物。酶促和非酶促孵育用于揭示SIN的代谢机制。在LPS诱导的Raw264.7细胞中评估了SIN，SNO和DS对炎症相关细胞因子水平和NF-κB核易位的影响。还评估了SNO（10μM）诱导的ROS。

主要发现

CYP3A4和ROS主要介导SNO的形成，而CYP3A4和CYP2C19主要介导DS的形成。值得注意的是，SNO在酶促作用下通过黄嘌呤氧化酶（XOD）进行了N-氧化物还原，在非酶促作用下通过亚铁离子和血红素部分进行了N-氧化物还原。在LPS诱导的Raw264.7细胞中SIN预处理后，IL-6和TNF-α的水平以及NF-κB的核易位得到改善，而DS（SNO）预处理后甚至在200μM下也观察到有限的衰减。相反，SNO诱导了ROS的产生。

意义

这项研究阐明了SIN可以同时进行酶促和非酶促循环代谢，并且是主要的抗炎化合物，而SNO可以诱导ROS的产生，这表明在DDI和潜在毒性的情况下，需要对SIN与SNO和DS联合进行更多的研究。