Research On Extraction And Separation Of Bacteriostatic Active Compositions From Bitter Melon And Antimicrobial Activities

Bitter melon is rich in protein, sugar, vitamins and all kinds of essential amino acids, etc., and is called"medicinal vegetables". Some antibacterial active ingredients were extracted by ultrasonic assisted extraction, and the bacteriostatic action was evaluated by antibacterial effect(inhibition zone diameter).At the same time, the best optimal extraction and separation parameters were selected by the antibacterial effect. Finally, the main antibacterial components were separated and the correlated bactriostasis were studied in this paper.Firstly, on the basis of the single factor test results and according to the response surface method with 4 factors and 3 leve1s was adopted in this paper.The result shows: the best condition is 300w of ultrasonic power, 60min of processing time, 1:20 of bitter melon powder to ethanol, 70% of ethanol, the best inhibition zone diameter is 12.8mm. Secondly, different polar positions of bitter melon were extracted by dichloromethane, ethyl acetate, butanol, ethanol and water. Escherichia coli andStaphylococcus aureus were selectd as the indicator bacteriaes and the antibacterial effect(inhibition zone diameter) was selectd as the evaluating indicator.The results show: the best inhibitory position is dichloromethane extraction, and thebest inhibition zone diameter are 16.0mm and 12.0mm. The medium and weak polarities are the main compositions.Thirdly, the antibacterial activity components of bitter melon were separated by the preparative high performance liquid chromatography (Pre-HPLC).Theresult shows: the best antibacterial activity components were separated under the conditions of the petroleum ether (60-90℃): ethyl acetate is 7:3, 50μL of injection volume, 5mL/min of velocity, the detection wavelength is 280nm.The escherichia coli was inhibited well and the ihibition zone diameter is 12.0mm.Fourthly, qualitative and quantitative analysises were used to detect the anti-bacterial active ingredients.The results show:flavonoid glycosides, alkaloids,organic-acids and saponins are contained in it. The contents of flavonoid glycosides and saponins are 31.61% and 6.25%, which were detected by UV-visiblespectrophoto-meter. And the antibacterial active ingredients were tested by GC-MS. The con-dition are quartz capillary column of Rtx-5ms(0.25mm×30m×0.25μm);60℃of column temperature in 2mins,then up to 280℃with 10℃/min and keep 11mins; He of carrier gas, 1.5mL/min of carrier gas flow rate; 250℃of injection port- temperature; 1uL of sample volume; 25:1 of split ratio. The result show: 10 com-ponents were tested in it.erucylamide and dodecamethylcyclohexane are the maincomponents and the contents are 38.83% and 8.53%.Fifthly, antibacterial spectrum and stability of extracting solution from bitter melon were studied in this paper. The results show: bacterias like escherichia coli and bacillus subtilis are inhibited by the extracting solution well, and the MIC are 18.75mg/mL and 9.38mg/mL . However, mold and yeast aren't controlled obviously. The inhibiting effect of the extracting solution is better than potassium sorbate under the same concentration. Meanwhile, the stability of the extracting solution is well under certain temperature, pH, UV exposure time and concentration of inorganic salts.Sixthly, the inhibition effects of antimicrobial activity ingredients and potassium sorbate by single and mixing action to escherichia coli, bacillus subtilis,enterobacter aerogenes,staphylococcus aureus, saccharomyces cerevisiae, aspergillus niger and aspergillus oryzae. The results show: escherichia coli, bacillus subtilis and enterobacter aerogenes were inhibited well under lower concentration, but staphylococcus aureus, saccharomyces cerevisiae , aspergillus niger and aspergillus oryzae were not inhibited. The best proportion(antimicrobial activityingredients: potassium sorbate) are 7:3 and 3:7.Finally, antimicrobial activity ingredients was detected by microbial detection and the total number of bacteria is 32 CFU/mL; the E.coli and mold number are 0CFU/mL. At the same time, the preservation of fresh pork, fruits and vegetables juice were studied in this paper. The results show: the total number of bacteria are 2.2×105CFU/g, 1.9×104CFU/g, 2.2×104CFU/g)in the three tested samples,and allof them are in the national standard range.