Study On The Method For Screening Angiotensin Converting Enzyme Inhibitor From Chinese Herbal Medicine

Angiotensin converting enzyme (ACE) is one of the key kinds of enzyme in resin-angiotensin system, which has an important effect on regulating people's blood pressure. Angiotensin converting enzyme inhibitor (ACEI) is capable of reducing blood pressure by inhibiting the activity of ACE, which makes it a wide-used clinical antihypertensive drug. ACEI was also found in natural drugs in the research of recent years. Compared with synthesized, it has fewer side effects, higher security, and it is more up to hypertensive patients' expectation. However, its wide species and complex composition make it difficult to screen ACEI from natural products for researching and developing new types of antihypertensive drugs. Therefore, the aim of this dissertation is to exploit new approach to screen ACEI.Our chief research work is as follows:1. A new HPLC method was developed to monitor biological activity ofACEI in vitro, and it was applied to test 23 kinds of the extracts ofChinese herbs. Among these, there were 14 kinds of extracts found tohave inhibiting effect.2. A new affinity chromatography method was provided to purify ACE inhog lung. In this method, Lisinopril was used as ligand; 1,4-butanediol-2-glycidyl ether was used as joint arm; and Sepharose CL-4B was used as stationary phase carrier, to synthesize affinity chromatography gel, which was then packed into column. The column was applied to separate and purify ACE from the crude extracts from hog lung. In view of the simplicity and satisfactory purification effect on ACE, the present method is recommendable for self making ACE in laboratory.3. Chitosan microsphere was prepared, and used as carrier, with the aid of glutaraldehyde as cross-linking agent to immobilize ACE. The concentration of glutaraldehyde and the amount of ACE were optimized to determine their influence on the activity of immobilized enzyme. It was demonstrated that compared with solution enzyme, the pH range of enzyme activity and the thermostability of immobilized enzyme were both increased, and of which the repeating utilization ratio and the storage stability were satisfactory.4. A valid method for high throughput screening ACE from natural drugs was introduced for the first time. In this approach, the ACEI was rapidly screened from complicated matrixes samples by comparing each analyte' peaks before and after affinity , with using the immobilized ACE as affinity matrices, and with the aid of affinity between ACEI and ACE, associated with HPLC to investigate the systems before and after affinity.