Sedative-hypnotic and anxiolytic effects and the mechanism of action of aqueous extracts of peanut stems and leaves in mice

INTRODUCTIONPeanut stems and leaves (PSL) have traditionally been used as both a special food and a herbal medicine in Asia. The sedative-hypnotic and anxiolytic effects of PSL have been recorded in classical traditional Chinese literature, and more recently by many other researchers. In a previous study, four sleep-related ingredients (linalool, 5-hydroxy-4,7-dimethoxyflavanone, 2-O-methylisoliquiritigenin and ferulic acid), among which 5-hydroxy-4,7-dimethoxyflavanone and 2-O-methylisoliquiritigenin were newly found in Arachis species, were screened by ultrahigh-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UHPLC/QTOF-MS). In the current study, quantitative examination of the above four ingredients was conducted. Serious fundamental functional studies were done in mice, including locomotor activity, direct sleep tests, pentobarbital-induced sleeping time tests, subthreshold dose of pentobarbital tests and barbital sodium sleep incubation period tests, to determine the material base for the sedative-hypnotic and anxiolytic effects of aqueous extracts of PSL. Furthermore, neurotransmitter levels in three brain regions (cerebrum, cerebellum and brain stem) were determined using UHPLC coupled with triple-quadrupole mass spectrometry (UHPLC/QQQ-MS) in order to elucidate the exact mechanism of action. RESULTSAqueous extract of PSL at a dose of 500 mg kg(-1) (based on previous experience), along with different concentrations of the above four functional ingredients (189.86 mu g kg(-1) linalool, 114.75 mg kg(-1) 5-hydroxy-4,7-dimethoxyflavanone, 32.4mg kg(-1) 2-O-methylisoliquiritigenin and 44.44 mg kg(-1) ferulic acid), had a sedative-hypnotic effect by affecting neurotransmitter levels in mice. CONCLUSIONThe data demonstrate that these four ingredients are the key functional factors for the sedative-hypnotic and anxiolytic effects of PSL aqueous extracts and that these effects occur via changes in neurotransmitter levels and pathways. (c) 2018 Society of Chemical Industry