黄芩素抑菌活性及其机制的初步研究

Antibacterial activity and mechanism of baicalein

以金黄色葡萄球菌为供试菌,探讨黄芩素的抑菌活性及其作用机制。通过测定黄芩素对其细胞膜的通透性、呼吸代谢途径、可溶性蛋白质和DNA拓扑异构酶的影响,阐述黄芩素的抑菌作用机制。实验结果显示,黄芩素可抑制金黄色葡萄球菌的生长,其最低抑菌浓度为0.04 mmol.L-1;黄芩素作用菌体6 h后,电导率比对照组增加了2.48%,DNA和RNA大分子增加了1.8%;黄芩素能抑制三羧酸循环(TCA)中的琥珀酸脱氢酶和苹果酸脱氢酶的活性,其抑制率分别为56.2%和57.4%;黄芩素作用20 h后,菌体可溶性蛋白总量比对照组减少了42.83%;此外,黄芩素能抑制DNA拓扑异构酶I和II的活性,当黄芩素的浓度为0.2 mmol.L-1时,上述两种酶的活性完全被抑制。综上所述,黄芩素对金黄色葡萄球菌有显著抑制作用,其抑菌作用是通过影响细胞膜的通透性,抑制菌体内蛋白质合成,抑制细菌代谢和DNA拓扑异构酶等多靶点来实现的。

Baicalein （BAI） is an effective bactericide. The antibacterial activity and mechanism experiments were carried out by determining conductivity and content of macromolecules of membrane penetrability, the oxidative respiratory metabolism and protein synthesis changes and the inhibition of DNA topoisomerase activities. Electrical conductivity and the number of large molecules of BAI increased 2.48% and 1.8%, respectively, than that of the control. However, the membrane integrity did not destroyed by BAI directly. With BAI treatment, inhibition rates of activities for SDH and MDH were 56.2% and 57.4%, respectively, demonstrating that BAI could inhibit cell respiratory. After treated with BAI for 20 h, the total soluble content of proteins decreased by 42.83%. Moreover, the activities of DNA topoisomerase Ⅰ and Ⅱ were inhibited completely by 0.2 mmol·L-1 BAI. These results indicated that BAI had obvious antibacterial activity on Staphylococcus aureus. The mechanism is that it could affect bacterial membrane penetrability, inhibit protein synthesis and influence SDH, MDH and DNA topoisomerase Ⅰ and Ⅱ activities to exert its antibacterial functions.