Study On The Antibacterial Activity And Antioxidant Activity Of Mulberry Leaf Extract

In this paper, extract of Mulberry leaves was tested for its antimicrobial activities and antioxidant activities.The main conclusion was as follows:1.The antimicrobial effect by water system extracting, alcohol-water system extracting and Potassium sorbate in different concentrations were studied. The results showed that both the extract by water system and alcohol-water system can effectively inhibit the growth of bacteria, but had weak inhibition of Mildew. Potassium sorbate had a good inhibitory effect on the Mildew, but a weak inhibition of bacteria.The extraction was optimized by response surface analysis based on one-facter-at-a-time experiments. The results showed that the optimal conditions for improved extraction of antimicrobial substances from Mulberry Leaves were as follows:ethanol concentration60%, solid-to-liquid ratio lg:30ml and extraction temperature70℃for a reflux extraction duration of2h. 2. Fourthly, qualitative and quantitative analysises were used to detect the anti-bacterial active ingredients. The results show:flavonoid glycosides, alkaloids and polyphenols are contained in it. The contents of flavonoid is31.9%, which were detected by UV-visiblespectrophot-meter. All extracts obtained in different fractions by using different polarities of solvents such as petroleum ether, chloroform, ethyl acetate, normal butyl alcohol and water were compared through the testing of their antibacterial activities. The results showed the antibacterial activities of ethyl acetate were strongest. And the antibacterial active ingredients were tested by GC-MS. The result show:9components were tested in it, Ketones, acids and Esters are the main components3. The stability of the extract of Mulberry leaves were also studied.The extracting solution is well under certain temperature, pH, UV exposure time and concentration of inorganic salts. The inhibition effects of antimicrobial activity ingredients and potassium sorbate by mixing action to escherichiacoli, staphylococcus, aspergillus niger and aspergillus oryzae. The results show:escherichiacoli and staphylococcus were inhibited well under lower concentration of potassium sorbate; when the proportion of potassium sorbate was high, aspergillus niger and aspergillus oryzae were well inhibited.4. Antioxidant activity research of mulberry leaf extracts.The research discovered that the three extracts of mulberry leaf have strong antioxidant activity. DPPH radical-scavenging:water extract>ethanol extract>60%ethanol extract, the hydroxyl radical scavenging ability:ethanol extract> water extract>60%ethanol extract, reducing capacity:ethanol extract> water extract>60%ethanol extract, anti-linoleic acid oxidation:60%ethanol extract> ethanol extract> water extract.