香薷挥发油纳米乳喷雾的制备及其抗菌活性的研究

Preparation of nanoemulsion spray from Moslae Herba volatile oil and its antibacterial activity

香薷是常用芳香中药,挥发油类成分是其主要药效成分,具有广谱抗菌抗病毒作用,但香薷挥发油具有一定刺激性和不稳定性,需要制备为特定剂型以供使用。该文采用水蒸气蒸馏法提取香薷挥发油,采用HPLC测定其中麝香草酚和香荆芥酚的质量浓度分别为(0.111 9±0.001 0)、(0.235 4±0.004 7) mg·mL^(-1);采用伪三元相图法和表面活性剂复配法,筛选最适辅料(表面活性剂与助表面活性剂),制备得到香薷挥发油纳米乳,继而载入压力容器得到喷雾剂,并对其稳定性和抗菌活性进行评价。以澄明度、黏度、气味、体感等为综合指标,最终确定纳米乳的优选处方为香薷挥发油-薄荷油-cremophor EL-无水乙醇-蒸馏水7.78∶1.58∶19.26∶6.15∶65.23,制得的香薷挥发油纳米乳为淡黄色透明液体,经平行光照射能产生丁达尔现象,测得其pH为5.50,电导率为125.9μS·cm^(-1),平均粒径为15.45 nm,多分散系数(PDI)为0.156,Zeta电位为-17.9 mV;在透射电镜下纳米粒子呈规则球形,相互之间并无粘黏团聚现象。稳定性考察结果表明,香薷挥发油纳米乳在4~55℃稳定性良好,且30 d内并未出现破乳分层的现象;将香薷挥发油纳米乳以12 000 r·min^(-1)离心30 min,无分层现象。制得香薷挥发油纳米乳对金黄色葡萄球菌标准菌株、金黄色葡萄球菌耐药菌株及大肠杆菌标准菌株均有良好的抑制作用,最低抑菌质量浓度分别为0.39、3.12、1.56 mg·mL^(-1)。以上结果表明所制得的香薷挥发油纳米乳工艺可行、理化性质稳定、具有良好的抗菌作用,为香薷挥发油的防疫防感产品的开发提供了可行的技术方案。

Moslae Herba is a commonly used aromatic Chinese medicinal with volatile oil as the main effective component and exhibits broad-spectrum antibacterial and antiviral effects. However, the irritation and instability of Moslae Herba volatile oil necessitate the preparation into a specific dosage form. In this study, the steam distillation method was employed to extract the Moslae Herba volatile oil. The content of thymol and carvacrol in Moslae Herba volatile oil was determined by HPLC as(0.111 9±0.001 0) and(0.235 4±0.004 7) mg·mL^(-1), respectively. Pseudo-ternary phase diagrams and surfactants compounding were applied in the selection of the optimal excipients(surfactant and cosurfactant). On this basis, a nanoemulsion was prepared from the Moslae Herba volatile oil and then loaded into pressure vessels to get sprays, whose stability and antibacterial activity were evaluated afterward. With clarity, viscosity, smell and body feeling as comprehensive indexes, the optimal formulation of the Moslae Herba volatile oil nanoemulsion was determined as follows: Moslae Herba volatile oil∶peppermint oil∶cremophor EL∶absolute ethanol∶distilled water 7.78∶1.58∶19.26∶6.15∶65.23. The as-prepared nanoemulsion was a light yellow transparent liquid, with Tyndall effect shown under the irradiation of parallel light. It has the pH of 5.50, conductivity of 125.9 μS·cm^(-1), average particle size of 15.45 nm, polydispersity index(PDI) of 0.156, and Zeta potential of-17.9 mV. Under a transmission electron microscope, the Moslae Herba volatile oil nanoemulsion was presented as regular spheres without adhesion and agglomeration. Stability test revealed that the Moslae Herba volatile oil nanoemulsion was stable at 4-55 ℃, which was free from demulsification and stratification within 30 days. After the centrifugation at 12 000 r·min^(-1) for 30 min, there was no stratification either. The nanoemulsion had good inhibitory effects on Escherichia coli, Staphylococcus aureus and resistant S. aureus strains, with the minimum inhibitory concentrations of 0.39, 3.12 and 1.56 mg·mL^(-1), respectively. The above results demonstrated that the nanoemulsion was prepared feasibly and showed stable physical and chemical properties and good antibacterial effects. This study provides a practicable technical solution for the development of anti-epidemic and anti-infection products from Moslae Herba volatile oil.