基于靶向代谢组学探究广藿香活性成分治疗炎症性肠病的作用和机理

Pogostemon cablin has been used for thousands of years to treat diarrhea, abdominal pain and vomiting in China, but its effective components and uderlying mechanism remains obscure. Our previous metabonomic profiling find a total number of 11 metabolite markers in plasma and urine of rats with 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced inflammatory bowel disease (IBD). These markers indicate intestinal barrier damage, microbiosis and inflammatory response in TNBS rats. Whereas, patchouli alcohol, the major volatile effective component of Pogostemon cablin with established anti-inflammatory and antimicrobial effects, attenuated the disease activity index and alleviated inflammtion in TNBS rats. This result revealed that patchouli alcohol has a significant anti-IBD activity. Pogostone, another major volatile ingredient, has potent anti-microbial activity. Apigenin, a major flavonoid constituent, is well known for its anti-inflammatory, anti-oxidative and anti-microbial activities. Based on these facts, it can be speculated that patchouli alcohol, pogostone, and apigenin are possible effective components, by which Pogostemon cablin exert a protective effect against IBD, and these components can modulate IBD-related metabolite markers. In this study, we will examine the anti-IBD activity of the three patchouli ingredients in TNBS rat model, and investigate whether the three patchouli ingredients exerted their anti-IBD effects by protecting intestinal barrier, restoring host-microbiota homeostasis and inhibiting inflammation. To further clarify the protective mechanism of the three patchouli ingredients, a metabolomic analysis targeting on the previously discovered 11 IBD-related metabolite markers and critical upstream or downstream metabolites will be conducted. This study aims to identify the effective anti-IBD components in Pogostemon cablin, and explore the underlying mechanism using a targeted metabolomic approach.

广藿香是历代医家治疗脘痞呕吐、腹痛吐泻的要药，但其治疗腹泻腹痛的物质基础和作用机理尚不清楚。前期代谢轮廓分析发现，在TNBS诱导的IBD大鼠血液和尿液中检测到11个代谢标志物，分别与肠道菌群失衡、免疫炎性反应和肠屏障损伤等IBD病理机制密切相关；而广藿香的主要成分广藿香醇可显著减轻IBD模型动物的疾病指数、改善炎性症状，具有明确的抗IBD作用；广藿香酮和芹菜素分别具有抗病原微生物和抗炎、抗氧化等生物活性，可能是广藿香抗IBD活性成分。本课题提出"广藿香醇等广藿香有效成分群通过保护肠屏障功能、调节菌群和免疫炎性反应而发挥抗IBD的作用；可以影响IBD相关的内源性代谢物水平"。拟采用TNBS大鼠对上述主要活性组分进行抗IBD作用考察，结合靶向代谢分析，明确其对IBD相关代谢标志物的调节作用，探讨其可能的作用机制。本研究将进一步阐明广藿香的物质作用基础，为应用代谢组学进行中药研究提供新思路。

广藿香是历代医家治疗脘痞呕吐、腹痛吐泻的要药，可能是通过保护肠屏障功能、调节免疫炎性反应、调节肠道菌群而发挥抗 IBD的作用。研究首先通过TNBS和DSS诱导的炎症性肠病（IBD）动物模型，筛选了广藿香主要活性成分的抗IBD活性。结果发现，广藿香醇（PA）、广藿香油（PO）和广藿香酮具有抗IBD作用，其中PA和PO的作用更为显著。具体发现如下：⑴PO对TNBS诱导的IBD模型大鼠，可显著降低结肠宏观和DAI评分，明显降低结肠组织MPO水平，减轻局部组织的炎性浸润和损伤；对尿液的靶向代谢分析发现，4种代谢标志物（分别属于肠道菌群代谢物及色氨酸代谢物）的水平在TNBS造模后升高，而PO治疗后显著降低；⑵ PA对TNBS诱导的IBD模型大鼠，表现出跟PO相同的治疗作用，提示可能是其主要活性成分；⑶对于DSS诱导的IBD模型小鼠，PA可显著改善结肠宏观评分和DAI评分，降低MPO水平，减轻结肠炎性浸润和损伤；升高结肠粘蛋白和紧密连接蛋白表达，但降低凋亡及程序性坏死蛋白表达；靶向代谢分析发现，PA可减慢色氨酸向犬尿氨酸及5-羟色氨酸的代谢，这一作用与其抑制色氨酸代谢的关键限速酶有关；肠道菌群分析结果表明PA能有效抑制致病菌的生长，并促进优势菌的繁殖。上述结果表明，PA可能是广藿香抗IBD的主要活性成分，通过保护肠粘膜屏障、抑制免疫炎性反应、调节肠道菌群、调控色氨酸代谢等作用而发挥抗IBD作用。研究应用药理学和系统生物学的方法，从多角度阐述了广藿香活性成分治疗IBD的物质基础和作用机制，为临床应用广藿香治疗IBD提供了实验依据；且在研究中发现了模型动物尿液和血浆中IBD代谢标志物，为进一步采用非侵入性手段诊断和监控IBD提供了初步数据，值得深入研究。