Essential oil from Prunella vulgaris L. as a valuable source of bioactive constituents: In vitro anti-bacterial, anti-viral, immunoregulatory, anti-inflammatory, and chemical profiles

Abstract

Our preliminary results suggested a favorable therapeutical effect of essential oil from Prunella vulgaris L. (PVO) on pelvic inflammation. In this study, we further analyzed the chemical components of PVO through gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS), and its anti-bacterial, anti-inflammatory, and immunoregulatory properties. Fifty-six chemical components were identified with GC-MS, most of which were fatty acids. The positive and negative ion modes of LC-MS were used to detect 48 and 37 compounds with content above 0.1%, respectively, most of which were terpenoids and lipids. The anti-bacterial experiment revealed that PVO could strongly inhibit both gram-negative and gram-positive bacteria. It had a significant inhibiting effect on influenza virus neuraminidase, with an inhibition ratio of over 50%. Besides, PVO dramatically inhibited the NO release and the levels of IL-6 in RAW264.7 cells induced by LPS. Moreover, immunological results indicated that PVO could synergistically facilitate concanavalin A (ConA) to stimulate the secretion of Th1 and Th2 cytokines from the splenic lymphocytes of mice but also regulate the Th1/Th2 balance to exert dual immunoregulatory effects. Generally, these results proved the anti-bacterial, anti-inflammatory, and immunoregulatory effects of PVO, thus providing a reference for the application of PVO as a food or drug.