Constituents And Antibacterial Activities Of Vitex Negundo Linn. Var. Cannabifolia

Vitex negundo Linn. var. cannabifolia is a plant of Vitex L. widely distributed in China, of which the aerial parts, roots and fruits are used as traditional medicine. Constituents and biological activities of Vitex L.(Vitex agnus-castus L., Vitex negundo L., Vitex rotunbifolia L. f., etc.) have been studied. Plenty of flavonoids, diterpenes, steroids, iridoids, phenylpropanoids, essencial oils, etc. have been isolated from plants of Vitex L.. Their main bioactivities include regulating levels of hormone, antitumor, antiinflammatory, antimicrobial, antioxidation, and so on. In our research, we mainly study on the chemical constituents with antibacterial activities of dry aerial parts of Vitex negundo Linn. var. cannabifolia harvested from Xuancheng City, Anhui Province. This work will contribute significantly on the systematically reseach of chemical constituents and developing neotype preservative from Vitex cannabifolia Sieb.et Zucc.We screened the active part of Vitex negundo Linn. var. cannabifolia through investigating antibacterial activities of ethanol extract and its petroleum fraction, chloroform fraction and n-butanol fraction. The volatile compositions in the essential oil from aerial parts of Vitex negundo Linn. var. cannabifolia were analyzed by gas chromatography-mass spectrometry. Chemical constituents of active part were isolated by chromatograph of silica gel, ODS, sephadex LH-20, MCI-gel CHP20P, etc. The structures of isolated compositions were characterized by spectroscopic analysis. Beating holes method and broth micro-dilution method was employed to evaluate the antibacterial activities of the isolated compositions, essential oil and its main constituents against Escherichia coli, Micrococcus Tetragenus, Bacillus subtilis and Pseudomonas fluorescen.The results showed that the essential oil of the plant was mainly composed of caryophyllene(43.12%),β-elemene(4.03%) and sabinene(3.82%). Eight compounds were isolated from petroleum and n-butanol fraction, five of which have been identified asγ-tocopherol(1),α-tocoquinone(2), stigmast-5-en-3-ol(3), 5, 3', 4'-trihydroxy-3, 6, 7-trimethoxyflavone(6), isovitex(8). Compouds 4 and 5 were just identified by gas chromatography-mass spectrometry asα-methyl linolenate and steroids mixture (ergost-5-en-3-ol, stigmasta-5,22-dien-3-ol and stigmast-5-en-3-ol). And compound 1, 2, 3 and 4 were isolated from Vitex L. family for the first time.Ethanol extract of Vitex negundo Linn. var. cannabifolia showed notable inhibition activities against Escherichia coli, Micrococcus Tetragenus, Bacillus subtilis and Pseudomonas fluorescen. The main active parts of ethanol extract were petroleum and n-butanol fraction. The further antibacterial activities research on chemical constituents of petroleum and n-butanol fraction showed that essential oil and its main constituents (caryophyllene andβ-elemene) had strong inhibition activities against Escherichia coli, Micrococcus Tetragenus, and Bacillus subtilis. And just 5, 3', 4'-trihydroxy-3, 6, 7-trimethoxyflavone(6) showed inhibition activities with the contents less than 1000μg/mL in culture medium. The essential oil, its main constituents(caryophyllene andβ-elemene) and 5, 3', 4'-trihydroxy-3, 6, 7-trimethoxyflavone(6) were suggested as the significant antibacterial compounds in Vitex cannabifolia Sieb.et Zucc. These results suggest that Vitex negundo Linn. var. cannabifoliamay can be used as a potential preservative.