MRSA是全球医院感染的重要革兰氏阳性菌，而抗生素的滥用导致MRSA多药耐药现象日益严重。因此寻找有效的抗MRSA新药已经迫在眉睫。我国丰富的药用植物资源为抗MRSA天然药效物质的筛选和开发提供了重要来源。但是现有药用植物药效成分的抗MRSA考察多集中于体外活性考察，缺少体内活性评价和深入的作用机制研究。申请人前期以抗菌活性为导向，对多种药用植物进行筛选，发现豨莶草具有一定的抗MRSA活性。因此，本研究在前期研究工作基础上，首先对豨莶草中具有直接抗MRSA作用的活性物质进行定向分离，然后对该活性物质进行体内、外生物学活性研究，最后对其抗MRSA作用机制进行研究。该课题将从体外—体内—细胞—分子层面，阐明豨莶草中贝壳杉烷型二萜化合物抗MRSA的作用及分子机制，为发现新的药物靶点和治疗MRSA感染的药物提供依据。

MRSA is one of the most important gram-positive bacteria for nosocomial infection in the world. The abuse of antibiotics has led to the increasingly serious phenomenon of MRSA multi-drug resistance. Therefore, it is urgent to find effective anti-MRSA drugs. Abundant resources of medicinal plants in China provide an important source for the screening and development of natural pharmacodynamic substances resistant to MRSA. However, the anti-MRSA studies of the active ingredients of medicinal plants mostly focus on activities in vitro, lacking in activities in vivo evaluation and in-depth study on the mechanism of action. In the early stage, we screened a variety of medicinal plants and found that Siegesbeckia orientalis L. showed significant anti-MRSA activity. Therefore, on the basis of previous studies, this study firstly conduct directional separation of the active compounds from Siegesbeckia orientalis L. which show anti-MRSA effect, then study the in vivo and in vitro biological activities of the active compounds, and finally study its anti-MRSA mechanism. This study will elucidate the anti-MRSA effect and molecular mechanism of ent-kuaran diterpenoids from Siegesbeckia orientalis L. and lay a foundation for the discovery of new drug targets and the treatment of MRSA infection.