Based On The Plant Extracts 1 - Dna - D - Xylulose 5 - Phosphoric Acid Synthase Inhibitor Screening

Terpenoids are the most widely distributed compounds in nature with the most members. They possess a number of biological activities and also plenty of pharmaceutical usefulness. There are two biosynthetic pathways for this class of compounds, namely classical mevalonate (MVA) pathway and2-methyl-D-erythritol4-phosphate (MEP) pathway. The majority of human pathogenic bacteria and protozoa only use the MEP pathway to synthesize the terpenoids which they required, but animals and humans rely on the MVA pathway to prepare the desired terpenes. Therefore, every enzyme of the MEP pathway can be used as an important target for antibiotic screening.1-Deoxy-D-xylulose5-phosphate synthase (DXS) is the first enzyme in the MEP pathway, also the first regulatory site of the pathway. Thus, looking for the effective inhibitors of DXS enzyme and developing them into new antibiotics seem particularly important, especially under current situation of increasing tolerance of pathogenic bacteria to existing antibiotics. Studies have shown that numerous chinese herbal medicines display very good anti-bacterial and anti-inflammatory activities. In this thesis, some chinese herbal medicines which have exhibited good antibacterial activity were investigated in order to find inhibitor(s) of DXS.Firstly, the crude extracts were obtained from more than20Chinese traditional medicinal plants with good antibacterial activity and used to detect inhibitory activity against DXS prepared from two bacteria. Isomerization of D-GAP and DHAP were catalyzed by pure enzymes, the substrate consumption or product formation were detected by pre-column derivatization HPLC. Also we optimized DXS enzyme activity system. This method does not require large, expensive instruments, and the procedure is simple, fast, and highly sensitive. Furthermore, also the substrate does not require sotope labeling.During this study we found that the petroleum ether extract of the fresh peel of Juglans regia, the butanol extract of Schisandra chinensis (Turcz.) Baill., the ethyl acetate extract of Isatis tinctoria L. and Artemisia argyi Levl. Vant, the aqueous phase of the fruit of Cercis chinensis Bunge, volatile oil of Hippophae rhamnoides Linn. all showed weak inhibitory activity against DXS, The in-depth research is still being carried out.