Study On Antimicrobial Action Of 10-HDA

10-Hydroxy-2-Decenoic acid (10-HDA), the chemical property of it is stable. It is an important unsaturated fatty acid of royal jelly and it's content is 50% of total fatty acid and 1.4%-2.0% of royal jelly. It exists only in royal jelly in the nature, so it is called queen acid or royal jelly acid. It has many physical activities: it can tone up our body and can strongly inhibit lymphoma, breast cancer and other cancer cells; it can enhance the immune function and can cure acute radiation injury and the damage caused by chemical substances. In this paper, we discussed the technical flow of extraction of 10-HDA from royal jelly. Then, we determined the antimicrobial effect of 10-HDA by drug sensitivity test and flow cytometry test with extracted materials. At last, we made a preliminary deduction about antibacterial mechanism of 10-HDA.In this paper, we used two kinds of organic solvents and adjusted twice pH to extract 10-HDA from royal jelly. The best conditions about the extraction of 10-HDA from the Royal Jelly was: first adjusted the pH of the solution to 10, then added 50mL aether to pick-out the fat-soluble impurity which can dissolve in aether, and then adjusted the pH to 2 and added 50mL aether to extract 10-HDA from the solution, and then recovered aether from the liquid with rotary evaporator, added 10mL ethanol to dissolve the extraction, and filtrated the extraction, then recovered ethanol with rotary evaporator under low-pressure, finally we can obtain the crude products of 10-HDA.Then we we determined the antimicrobial effect of 10-HDA to three bacterias and two yeasts by bacteriostatic circle method and oxford-cup test with extracted products, and we also determined the MIC of 10-HDA by double dilution method. The results showed that the antimicrobial effect of 10-HDA varied with the pathogenetic microbes. The antimicrobial minimum dosage of 10-HDA were as follows: Escherichia coli 1.25 mg?mL-1, the biggest diameter of filter paper-inhibition zone was 27.3mm; Bacillus subtilis 2.5mg?mL-1, the biggest diameter of filter paper-inhibition zone was 24.4mm; Staphylococcus aureus 5 mg?mL-1, the biggest diameter of filter paper-inhibition zone was 22.5mm; but it was noneffective to the yeasts. The antimicrobial effects of 10-HDA were as follows: Escherichia coli>Bacillus subtilis >Staphylococcus aureus>yeast. The results showed that the 10-HDA could effectively inhibit the growth of bacterium.Finally we used flow cytometry method which used the non-permeable membrane fluorescence dye PI as a probe and E.coli as a template to further explore the inhibitory mechanism of 10-HDA in this paper. The result was as follow: after 10-HDA reacted on E.coli cells two hours, the fluorescence intensity of PI in the cells was increased with 10-HDA concentration increasing, and there was a certain linear relationship between them. So according this, we could infer that: when 10-HDA reacted on E.coli cells, the cell membrane integrity had been damaged and it's permeability had been enhanced, which lead to the important intracellular materials flow out from cell and finally caused cell to die.Flow cytometry is an advanced high-tech precision instrument, it has lots of advantages: simple, rapid, sensitive and the result is objective, accurate and so on. If we form a mature scientific method and apply it to conventional microbiological experiments, it will lead to a revolutionary change of the traditional microbial experiments.