Abstract: In this study, Mesona chinensis Benth. essential oil (M.EO) was extracted by hydrodistillation and its chemical composition was analyzed by gas chromatography-mass spectrometry (GC-MS). According to their peak areas, alloaromadendrene (25.53%), β-caryophyllene (19.31%), isocaryophyllene (11.30%), α-humulene (8.30%), and eremophilene (7.62%) were found to be the major components of M.EO. Based on pseudo-ternary phase diagram, M.EO microemulsion (M.EO-ME) was fabricated using Tween-60 as the surfactant, ethanol as the cosurfactant, surfactant-to-cosurfactant mass ratio (Km) of 2:1 and mixed surfactant-to-oil phase mass ratio (Smix) of 8:2, and it remained stable after 100- and 200-dilution. The antioxidant activities of M.EO were improved by encapsulation in microemulsion to different degrees; the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity was only slightly increased, while the oxygen radical absorbance capacity (ORAC) and peroxyl radical scavenging capacity (PSC) were increased by 2.6 and 8.4 times, respectively. Besides, microemulsion encapsulation also improved the antiproliferative activity of M.EO against human malignant melanoma cells A375, and the median effective concentration (EC50) of M.EO-ME was approximately one-fifth of that of M.EO. These results indicated that microemulsion encapsulation improved the antioxidant and anti-proliferative activity of M.EO against A375 cells, which could provide a theoretical basis for the high-value development and utilization of Mesona chinensis Benth.

Key words: Mesona chinensis Benth. essential oil; microemulsion; configurational change; antioxidant activity; antiproliferative activity