The Antimicrobial Effect Of Mulberry Leaves And The Extract And Isolate For Its Antimicrobial Activities

In this paper, extract of Mulberry leaves was tested for its antimicrobial activities, including investigation of its antimicrobial spectrum, MIC value. The processing conditions of leaching active substances from Mulberry leaves were optimized with the orthogonal design test. The sensitivity to universal factors of the extract was studied. At the same time, the isolation and purification of the antimicrobial components of Mulberry leaves were also studied .The antimicrobial effect by water system extracting and alcohol- water system extracting in different concentrations were studied. We use D-value method to fast determine the efficacy. The results showed that both the extract by water system and alcohol- water system can effectively inhibit the growth of bacteria thus kill large amounts of the bacteria. The MIC of extraction from Mulberry leaves by alcohol- water system was 0.43% against Staphylococcus aureus,which was 0.055% against Escherichia coli. As to the extract by water system, the data was 0.86% against Staphylococcus aureus and 1.54% against Escherichia coli. Apparently, the effect by alcohol- water system was better.The optimum extraction conditions of leaching active substances determined by the single factor experiment method were as follows: the concentration of ethanol was 70%; temperature for extracting was 70°C with 4h, the ratio of material and solvent was l:30. with the orthogonal design test, the results showed that the optimum extracting condition was the concentration of ethanol was 70%; temperature for extracting was 70°C with 6h, the ratio of material and solvent was l:40. Under this condition, the diameter of antibacterial of the extract was up to 8.81mm.The stability to temperature, acid, alkali and ultraviolet of the extract of Mulberry leaves were also studied. The result showed the extract was very stable to temperature and ultraviolet. Antibacterial activities were better when pH< 7.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 normal butyl alcohol took second place. To track antimicrobial components in the extracts of ethyl acetate in which many different antibacterial points appeared after diffusion. The qualitative analysis of extracting sample is conducted by the specific reaction of total flavonoids with AlCl3 and so on, It is confirmed that the extraction material is flavonoids.the extracts of ethyl acetate of mulberry leaves by polyamide columnchromatography and silica gel columnchromatography had three antibacterial components at least. The Rf value were 0.20, 0.27, 0.72. Antibacterial component was determined by HPLC. The results showed that one of antibacterial components was morin.The extract of Mulberry leaves was applied in cosmetics. All the results confirmed that extract of Mulberry leaves has the antimicrobial effect, the skin-lightening effect and the moisturizing effect. So it can be widely used in cosmetics.