云实属植物降血脂活性化合物发现及构效关系研究

Hypercholesterolemia is a leading contributor to cardiovascular-related morbidity around the world. The first-line pharmacologic treatment for hypercholesterolemia is hydroxyl-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitor (statin) therapy, based on the class’s efficacy. Although statin therapy has been hailed for its efficacy in approximately 20 million users, nearly 20% of individuals experience side effects that hinder the drug’s ability to achieve target LDL levels. These statin-induced side effects include myopathy, myalgia, hepatic dysfunction, renal dysfunction, diabetes mellitus, and psychiatric changes including irritability and aggression. As a result of these goal-limiting factors, there has been an ongoing search for nonstatin cholesterol-lowering agents..Our previous research work revealed that some cassane diterpenes isolated from Caesalpinia decapetala showed good antihyperlipemia activities in vitro. Therefore, we are planning a systematical investigation of this type of compounds from three species of the Caesalpinia genus. A total of 100 to 150 compounds are expected to be separated from these species, and then evaluated on cellular assay models, such as HepG2 DiI-LDL uptake cell model, and animal models, such as ApoE gene knockout mouse and LDL-R gene knockout mouse. The structure-activity relationship of these compounds will be also studied. This project will lead to a discovery of five to ten compounds with good antihyperlipemia activities, valuable information about the mode of action of these compounds, and a summary of their structure-activity relationship. The results are expected to present more chemical structure information of cassane diterpenes, and provide scientific evidences to develop this type of compounds as a new class of leads for the treatment of hypercholesterolemia.

高血脂是引起人类动脉粥样硬化性疾病如脑卒中、心肌梗死等独立而重要的危险因素。羟甲基戊二酸单酰辅酶A（HMG-CoA）还原酶抑制剂---他汀类药物为目前降低LDL-C的首选临床药物。尽管他汀类药物使得约2000万患者受益，但约有20%患者出现副作用，如肌肉病变、肝肾功能异常、糖尿病、精神异常包括易怒以及攻击性增强等。因而开发非他汀类降血脂药物成为全球关注的热点。本课题组拟在前期研究工作基础上，从3种云实属植物中分到100~150个卡山烷型二萜类化合物，利用HepG2 DiI-LDL uptake细胞模型结合包括ApoE 基因和LDL-R基因敲除小鼠在内的动物模型对这些化合物降低LDL-C活性进行测试，希望得到5~10个具有良好降低LDL-C活性的化合物，并在此基础上阐明该类化合物降血脂构效关系，为将卡山烷型二萜发展成为一类新的用于治疗高脂血症药物开发的先导化合物提供科学依据

PCSK9是当前降血脂热门研究靶点，小檗碱（Berberine）是目前已报道的首个调节PCSK9 的天然小分子化合物，其通过作用于PCKS9 基因转录因子的HNF1α位点而降低PCSK9 表达水平，增加肝细胞表面LDLR 的表达水平，从而实现降低血脂的目的。本课题组前期在天然产物降脂活性筛选过程中，发现从云实科云实属苏木（Caesalpinia sappan）中分到的数个卡山烷型二萜类化合物在HepG2细胞LDL吞噬模型上表现出良好的增加肝细胞对LDL的摄取的活性，其中化合物18 的促肝细胞摄取LDL 活性接近小檗碱。基于这一活性线索，本课题拟在前期工作基础上，选择3 种云实属植物开展深入的化学成分研究，预期从中分到100~150 个化合物；利用HepG2 DiI-LDL uptake 细胞模型活性进行测试，发现5-10个活性化合物，总结构效关系；并在动物模型上对活性化合物的体内药效进行验证，最终为用于高脂血症治疗的先导化合物发现提供有价值的科学依据。.本课题选择苏木属三种植物苏木、刺果苏木和洋金凤的果实开展系统的分离纯化和结构鉴定工作，利用多种分离技术手段从中共分离得到121个化合物，其中55个新化合物（均为卡山烷型二萜类化合物）。在HepG2 DiI-LDL uptake模型上，我们对苏木属所分离得到的部分化合物进行了活性评价，已发现13个化合物可以明显促进肝细胞对LDL的摄取，包括10个卡山烷型二萜和3个苯并呋喃型木脂素。.初步的构效关系总结发现，对于卡山烷型二萜，D环为内酯环时的活性略优于内线酰胺环；A、B环氧化程度越高，促肝细胞摄取LDL活性反而越弱。对于苯并呋喃型木脂素，当R为羧基时活性最强，羧基还原成醛基或羟基，活性减弱。.在上述活性化合物中，化合物149的活性明显优于阳性对照。在高脂喂养的金黄地鼠模型上，该化合物在30 mg/kg的剂量下，无论是口服给药，还是腹腔注射给药，均能明显降低高脂金黄地鼠血浆中TG、TC、LDL的水平。苯并呋喃型木脂素的降血脂活性此前从未有报道，且口服和腹腔给药效果差异小，是一类值得深入研究的降血脂先导化合物。