Relationship Between The Antibacterial & Immunologic Activity Of Houttuyfonate Homologues And Their Surface Activities

Based on the molecular structure of sodium houttuyfonate(decanoyl acetal sodium sulfite, HOU-C10), five homologues of sodium huttuyfonate(HOU-Cn) including butanoyl (HOU-C4), caproyl acetal sodium suIfite(HOU-C6), octanoyl acetal sodium sulfite ( HOU-C8), decanoyl acetal sodium sulfite (HOU-C10), lauroyl acetal sodium sulfit(HOU-C12), had been synthesized successfully in our laboratory by modification the alkyloyl carbochain of HOU-C10 .The surface activity and it's innate regulation of HOU-Cn had been studied systematically by using surface tension theory. To evaluation the antibacterial properties of HOU-Cn, bacteria such as Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Saccharomyces cerevisiae were used as target microbes in antibacterial test of paper disc and tube-dilution method (turbidimetry). The little white mice were used as the animal model to investigate the effect of carbon chain length variation on immunologic function, specifically tested the carbon granular expurgation index (K), immunorgans, NK cell activity and activity level of lysozyme in serum of animals.The synthesis method was summarized as follows. Firstly, the intermediate product of HOU-Cn was realized in laboratory by fatty acid reaction under specific condition. Then, the intermediate product was purified by rectification. After that, the purified intermediate product mixed with Na, sodium sulfite and ethyl formiate in a flask which immersed in cool water with temperature lower than 4癈, agitated the mixture constantly for 24h. Finally, crude HOU-Cn was precipitated in solution of the mixture. More than 97%purity of HOU-Cn was achieved by crystallization three times in 20% alcohol. The results of quality and quantity test, melting point test, ultrared and violet spectrogram showed that the HOU-Cn synthesized was conformed to literatures.The study on surface activity indicated that HOU-Cn with longer carbochain were typical surfactants with exception of HOU-C4. From HOU-C6 to HOU-C12, their critical micelle concentration(CMC) in turn are: 5.32 X 103 mol/L,1.41 X 10-3mol/L,3.88 X10 -4mol/L and 1.06X 10-4T'rnol/L. The logarithm of their CMC of HOU-Cn versus carbon number of alkyloyl carbochain is a negative linear relationship. It means that the larger of carbon number, the less the logCMC will be. According to the free energy formula of micelle formation(G=2.303 X RT X log(CMC)), The longer the carbon chain, the easier the micelle would be formed and the stronger the hydrophobic interaction with other hydrophobic groups would be. It may conclude that the hydrophobic ability of HGU-Cn increased along with elongation of the carbon chain.The target microbes involved in the experiment showed a quite different sensitivity to each homotogues tested by paper disc method in vitro. Staphylococcus aureus and Bacillus subtilis weremostly sensible to all the homologues applied. Escherichia coli only was susceptible to HOU-C4 and HOU-C6. Saccharomyces cerevisiae was not susceptible to HOU-C4 and HOU-C12.Further test with Staphylococcus aurens and Bacillus subtilis by tuber dilution method indicated that the minimum bactericidal concentration (MBC) of HOU-C4, HOU-C6 ,HOU-C8 HOU-C10 ,HOU-CI2 for Staphylococcus aureus were: 436mg/L,363mg/L,154mg/L,78mg/L and 55mg/L.MBC for Bacillus subtilis were: 360 mg/L,240 mg/L, 126 mg/L,68 mg/L and 50 mg/L.MIC for Staphylococcus aureus were: 80mg/L,78mg/L,39mg/L,39mg/L and 39mg/L, and for Bacillus subtilis were: 36 mg/L,36mg/L,36mg/L,15mg/L and 15 mg/L. Statistics from both MBC and MIC to the two microbes showed a trend to decline with the increase of alkyloyl carbochain. Taking the previous result of surface activity study on those homologues, bacterostatic effect linearly related to logCMC negatively, and decreased with the increases of CMC. It may conclude that the susceptibility of Staphylococcus aureus and Bacillus subtilis sharpened with the augment of homologues' hydrophobic ability as well as the elongation of the alkyloyl carbochain of HOU-Cn.About one percent of Staphylococcus aureus survived...