Study On Inhibitory Effect Of Dihydromyricetin

Dihydromyricetin（DMY）belongs to flavonoids, which was also known as doublehydrogen arbutus element, ampelopsin, Fujian theine, or the snake bark, In recentyears, some pharmacological and bacteriostatic experiments demonstrated that DMYhad multiple functions, including antibacterial, protecting liver, relieving cough andphlegm, heat clearing and detoxifying, reducing blood sugar, antioxidant, anti-tumor,enhancing immunity, promoting blood circulation and removing blood stasis andother effects, with applications in medicine, food processing, cosmetics industry andbroad prospects. This paper investigated the bacteriostasis of DMY and its influencefactors.In this paper, the extraction of DMY was used90%ethanol from ampelopsisgrossedentata dry bud leaf, optimized by orthogonal test. The optimum process wasas follows: the ratio of sample to solvent of1:12, extraction temperature of70℃,extraction time of90min. In accordance with the optimization conditions of the test,the result of verification test was18.51%; DMY extraction was dissolved in acetoneto separate and purify. After recrystallization for5times, the purification of DMYwas94.50%.In this paper, disc diffusion method and dilution method were used to determinethe inhibition activity of DMY and the minimal inhibitory concentration againstEscherichia coli, Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginsa,Klebsiella pneumoniae, Shigella flexneri, S.Paratyphi B. DMY had obviousinhibitory effect on Escherichia coli, Staphylococcus aureus, Bacillus subtilis,Pseudomonas aeruginsa, Klebsiella pneumoniae, Shigella flexneri, S.Paratyphi B,and the inhibitory effect had the positive correlation with the concentration of DMY.The MIC of DMY repressing Staphylococcus aureus was0.06mg/mL, repressingShigella flexneri, Proteus and Pseudomonas aeruginosa was0.12mg/mL, repressingEscherichia coli, S. Paratyphi B and Klebsiella pneumoniae was0.24mg/mL, andrepressing Bacillus subtilis was0.95mg/mL. Result showed that the DMY has broad-spectrum antibacterial effect, and the minimum inhibitory concentration is low.DMY have differences on the antibacterial activity of different bacteria, but ingeneral, Its bacteriostatic activity becomes stronger when it is in the acidic andneutral environment. DMY will become very unstable, with increasing time andtemperature, it will be easily oxidized so that its inhibitory effect be reduced. itsantibacterial activity will be receded with the presence of Na+, Ca2+, related to Ca2+,the influence of DMY antibacterial activity decreased more obviously. Therefore, toensure the best efficacy of DMY, it should avoid high temperature and contact Na+,Ca2+when processing and preservation process, its most appropriate pH is acidic andneutral conditions (pH<7).The results of this study showed that with the food preservatives (potassiumsorbate and sodium benzoate) and food antioxidants (TBHQ and BHT) were used toincrease the antibacterial activity, the antibacterial activity of DMY was enhanced,but when compound with food preservatives and food antioxidants, the antibacterialactivity was different. When the mass ratio of potassium sorbate and sodium benzoatewas1:1, the antibacterial activity of DMY was worse than the single. Whilecompound with TBHQ and BHT(quality ratio1:1), the antibacterial activity was wasbetter than the single.The research of this thesis was DMY prevention as a traditional Chinesemedicine preparation used in clinical common pathogenic diseases and natural foodadditive used in food processing industry, as well as to ensure matters DMY effectshould pay attention to provide the theoretical basis.