| In this article, Cudrania tricuspidata (Carr.) Bur. ex Lavallee, Artemisia sacrorum Ledeb, Stenoloma chusanum (L.) Ching and Palhinhaea cernua (L.) Vasc, et Franco that collected from Guilin in Guangxi province were studied.The antimicrobial effects of them were used poison plate method and mycelium growth rate method. The active ingredients were determinated by activity-directed isolation method, what were isolated by organic solvent extraction, silica gel column chromatography and thin-layer chromatography (TLC) and so on. The structure of active ingredients was validated by mass spectrum and Magnetic resonance spectrum。 The antifungal mechanism of four species of plant was also preliminarily studied.The antibacterial activity of methanol extracts of C. tricuspidata, A. sacrorum, S. chusanum and P. cernua against S. typhi, S. dysenteriae, P. vulgaris, M. lysodeikticus, B. subtilis, B.cereus, M. luteus, S. aureus, B. megaterium, P. aeruginosa, E. coli, E.aerogenes, B. anthraci, B. paratyphosum B, C. albicans was used poison plate method。 The results showed that the antibacterial activity of four species of plant extracts were better with Gram-positive bacteria (G+) than Gram-negative bacteria (G-) at10mg/mL. Between seven species of G+bacteria, only B. anthraci could not be completely inhibited growth. For seven species of G" bacteria, only S. typhi, S. dysenteriae, P.vulgaris could be completely inhibited growth. P. aeruginosa could be completely inhibited growth by extract of S. chusanum. C. albicans could be completely inhibited growth by extract of A. sacrorum at24h and could be growth at48h.The MIC of the extracts of four species plant against some animal pathogens was further determined. The results showed that the antibacterial activity of extracts of C. tricuspidata and A. sacrorum was stronger than extracts of S. chusanum and P. cernua. That the MIC of the extract of C. tricuspidata against six species of G+bacteria outside except B. anthracis was less than or equal to0.5mg/mL.The antifungal activity of the methanol extracts of four species plant against nine kinds of plant pathogenic fungus was determined by mycelium growth rate method. The results indicated that extracts of C. tricuspidata and A. sacrorum had inhibition against all plant pathogenic fungi·at10mg/mL. And all the mycelium growth inhibition rates were above60%against seven species of pathogen except Cochliobolus miyabeanus (Ito et Kubibay) Drechsler et Dastur.and Bipolaris maydis (Nisikado et Miyake) Shoeml. The extract of S. chusanum only had good antifungal activity, with the mycelium growth inhibition rates of70.15%against Phytophthora parasitica var. nicotianae (Breda de Hean) Tucker, and all the mycelium growth inhibition rates against other tested plant pathogenic fungi were lower than50%. All the mycelium growth inhibition rates of extract of P.cernua against Alternaria oleracea M.Ibrath, Ceratocystis paradoxa (Dode) Moreau and Ph. parasitica were higher than50%.When the mycelium growth inhibition rate of plant extract against plant pathogenic fungus was more than50%, the toxicity of the plant extracts of plant pathogenic fungi was further determined. The results showed that all EC50value between0.4559～9.9518mg/mL, and the extract of C. tricuspidata had the highest toxicity to Exserohilum turcicum (Pass.) Leonard et Suggs.The methanol extracts from four species of plant were preliminarily separated into petroleum ether fraction, ethyl acetate fraction, normal butanol fraction and water fraction by liquid-liquid extraction. The antibacterial activity of4pants against animal pathogens show that the active ingredients of extracts from C. tricuspidata, A. sacrorum, and S. chusanum mainly consisted in the ethyl acetate fraction, but that the extract from P. cernua declined after organic solvent extraction.The active ingredients were isolated from methanol extracts of4species plant by chromatography separation and activity-directed isolation, which the tested bacterias were S. aureus and S. typhi. Three active compounds were isolated from ethyl acetate fraction of C. tricuspidata, two of them were Cycloartocarpesin and Dihydrokaempferol.Disk diffusion method was used to test the antibacterial activity of three active compounds against nine species of plant pathogenic fungus. The results showed that CPS-1was only had no inhibitory activity against P. vulgaris, that the antibacterial circle diameters of other8species of plant pathogenic fungus were between9.13-9.89mm at5mg/mL. Cycloartocarpesin had inhibitory activity against S. typhi, S. dysenteriae, M. lysodeikticus, B. subtilis, M. luteus, S. aureus, and the antibacterial circle diameters of them were between6.11-6.23mm. Dihydrokaempferol only had inhibitory activity against S. dysenteriae, M. lysodeikticus, B. megaterium, and the antibacterial circle diameters of them were6.12、6.13、6.12mm, respectively. The MIC of3species compounds against S. aureus and S. typhi was used poison plate method. The MIC of CPS-1、Cycloartocarpesin and Dihydrokaempferol against S. aureus were0.025、0.2、0.6mg/mL, respectively. And that for S. typhi were1.4、2、2mg/mL.The effects that the methanol extracts of C. tricuspidata, A. sacrorum, S. chusanum on growth curve of S. aureus, S. typhi and the methanol extracts of C. tricuspidata, A. sacrorum on growth curve of C. albicans were detected with OD value method. All the methanol extracts of C. tricuspidata, A. sacrorum, S. chusanum had main inhibition on the reproduction of logarithmic phase of S. aureus and S. typhi and entered to the decline phase in advance. The methanol extracts of C. tricuspidata, A. sacrorum also inhibited on the reproduction of logarithmic phase of C. albicans.The membrane integrity was indicated by determineing conductivity in liquid culture medium. The result showed that both the methanol extracts of C. tricuspidata, A. sacrorum, S. chusanum, P. cernua and ethyl acetate fractions of extracts from C. tricuspidata, A. sacrorum, and S. chusanum could impact on the membrane permeability of S. aureus and S. typhi. |
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