关键词: 干漆, 有机酸类化合物, 金黄色葡萄球菌, 抑菌活性

Abstract:

The optimal extraction method of organic acids from Toxicodendron vernicifluum and the main antibacterial components against Staphylococcus aureus were investigated， in order to elucidate the antibacterial activity and mechanism of action， and provide a theoretical basis for the development of new clinical drugs to prevent and control Staphylococcus aureus infections. In this study， the organic acid components of Toxicodendron vernicifluum were extracted by heating and refluxing with anhydrous ethanol at 30， 45 and 60 ℃ for 6 h， a solid-liquid ratio of 1∶5， and extracted once as the process. The types and relative contents of organic acids were determined by gas chromatography mass spectrometry （GC-MS）， and the parameters of extraction process were optimized with the help of paper diffusion as the index of bacterial inhibition， and the leakage of bacterial proteins and biological analysis by scanning electron microscopy （SEM） were conducted. The results showed that the diameters of the circles of inhibition of 30， 45， 60 ℃ alcohol extraction group and anhydrous ethanol control group were 8.78±0.97， 9.45±0.98， 11.80±0.39 and 6.94±1.16 mm， respectively. Compared with the control group， only the 45 ℃ and 60 ℃ alcohol extraction groups showed significant differences （P<0.05）， with the 60 ℃ alcohol extraction group being the most significant. The GC-MS determination of organic acids showed that there were 4 kinds of organic acids in 30 ℃ alcohol extraction group as hexanoic acid （1.95%）， acetic acid （0.36%）， 2-hexyl-cyclopropaneacetic acid （0.33%）， and n-hexadecanoic acid （0.27%）， 2 kinds of organic acids in 45 ℃ alcohol extraction group as hexanoic acid （0.38%） and acetic acid （0.22%）， 5 kinds of organic acids in 60 ℃ alcohol extraction group as isoleic acid （55.16%）， n-hexadecanoic acid （37.25%）， octadecanoic acid （3.17%）， valeric acid （0.86%）， and oleic acid （0.82%）. SEM and protein leakage analysis showed that 60 ℃ alcohol extraction group could affect the morphological changes of Staphylococcus aureus， leading to intracellular protein extravasation and leakage from 4 h after administration， resulting in the decrease of the integrity of the cell membrane and the increase of the permeability of the cell membrane， and ultimately leading to the damage and death of the bacteria. The five organic acids obtained from Toxicodendron vernicifluum extracted by anhydrous ethanol at 60 ℃ for the first time， mainly isoleic acid， supplemented by n-hexadecanoic acid， octadecanoic acid， valeric acid and oleic acid， and could exert antibacterial activity by changing the morphology and structure of Staphylococcus aureus and affecting the function of the biofilm， disrupting the intracellular homeostasis. The results could provide a reference for the development of new natural product antimicrobial agents for the application against Staphylococcus aureus infections.

Key words: dried lacquer, organic acid compounds, Staphylococcus aureus, antibacterial activity