Drop Blood Pressure Of Probiotics Screening And Safety Evaluation

Angiotensin-converting enzyme (ACE) plays an important role in conquering the blood pressure in the Rennin-Angiotensin System(RAS) and Kinin-Kallikrein System(KKS) of human. Inhibition of ACE activity and the function of antagonism angiotensin has become the key of the development of antihypertensive drug. Among them, the ACE inhibitory peptides deriving from food are safe and less side effect, and it has become a hot research. The protease produced by probiotics can cut down the ACE inhibitory peptides in fermented dairy products, which include ACE inhibitory peptides. So it plays an important role in protection and conquering the blood pressure safely. The purpose of this study was to get good candidate strains by selection and evaluation in vitro, and determine their physiological and biochemical, metabolic and genetic characteristics. Moreover, in order to get the safe and good character strains, we also performed functional experiments and safety evaluation in vitro. The study demonstrates that:1. Of 72 strains which used for their acid and bile tolerance test,36 strains have strong acid and bile resistance. Five of which with strong ACE inhibitory activity (the strains No. are DM9028, DM9007, DM9057, DM9073, and DM9053 and inhibition rates of ACE are 80.69%,77.55%,73.91%,72.19%, and 67.39%) were selected.2. DM9057 was selected as candidate strains for further study for the capabilities of enzyme-resistant of the gastrointestinal tract, inhibition and resistance, and the adhesion of human colon cancer cell HT-29.3. Further microbiology, physiology and biochemistry, and 16S rDNA sequence analysis demonstrated that DM9057 has the obvious characteristics of lactic acid bacteria.4. Acute toxicity and translocation experiments showed that strains DM9057 has little influence on the habitus of rat, physiological function and organs, and there isn't translocation phenomenon either. Therefore, it can determine the security of the strain preliminarily. 5. The functional experiments of Spontaneously Hypertensive rats(SHR) in vivo indicated that the candidate strain DM9057 has obvious effect for conquering blood pressure, but litter effect for body weight, serum total cholesterol, triglycerides, and high density lipoprotein.6. The characteristics of the growth and fermentation of strain DM9057 demonstrated that it is feasible using tyrosine as an indicator of proteolytic activity and ACE inhibition index. The fermented milk was stored at 4℃, and the results demonstrated that the function and sensory index were greatly influenced by storage time. As a result, it should be less than 11 days.This topic is an important part of National High Technology Research and Development Program of China (863 project)-the probiotic directional screening key technology and product research and development (grant no.2007AA10Z356). The research results have established a set of research and development of innovative mode and scientific thinking system for functional screening of probiotics, genetic characteristics and biological function evaluation. And this lays a foundation to develop the probiotics with the function of antihypertensive and study their mechanism intensively.