Extract Of Effective Components And Molluscicidal Bioactivity Research In Leaves Of Eucalyptus Growing In Guangdong

The chemical composition, molluscicidal activities of the chemical componentsfrom leaves of six Eucalyptus species(Corymbia torelliana, Corymbia citriodoraHook.f, Eucalyptus grandis, Eucalyptus urophylla, Eucalyptus camaldulensis,Eucalyptus urophylla×Eucalyptus grandis) growing at zhangmutou forest farm inGuangdong were investigated, and then the chemical components from theEucalyptus leaves were extracted, separated and analyzed. This Paper did a researchon its chemical constituents and molluscicidal activities.The research results willguide the planting and application of Eucalyptus in Guangdong. The main researchfindings are as follows:(1) During experimentation，oil fraction, water-soluble fraction, water extract andalcohol precipitation extract from the six Eucalyptus species were obtained throughWater extraction and alcohol precipitation methods. Then, combined with activetracking methods, the chemical constituents were studied on molluscicidal effects testfor screening of the effective composition. The effective composition with waterextract was distributed with solvents of different polarity into seven fractions. And,the effective composition with oil fraction was distributed some parts by lowtemperature crystallization, Silica gel column chromatography and recrystallizationmethods. These parts combined with active tracking methods for further screening of the molluscicidal effective composition.(2) First, with orthogonal experiment, extraction process was studied on Volatileoil from leaves of Corymbia citriodora Hook.f. And the optimum extraction processwas A1B3C1D3.The volatile oils from the six Eucalyptus species were obtained bysteam distillation and the volatile components were analyzed by gaschromatography-mass spectrometry(GC-MS) method accorrding to the nationalstandard of ChP.2010with the first appendix“Determination of volatile oil”.The totalextraction rate ranged from0.04%～3.05%.The volatile components from leaves ofthe six Eucalyptus species featured a high relatively content of terpenoids,monoterpenes(52.58～90.93%)and sesquiterpenes(1.51%～33.58%).The constituentsof volatile components from leaves of the six Eucalyptus species are summarized：Corymbia torelliana: The main constituents in volatile oil were alpha.-terpineol,benzaldehyde and longifolene. Corymbia citriodora Hook.f: The main constituents involatile oil were rhodinal and citronellol. Eucalyptus grandis: The main constituentsin volatile oil were alpha.-pinene, p-cymene and eucalyptol. Eucalyptus urophylla:The main constituents in volatile oil were eucalyptol and alpha.-pinene. Eucalyptuscamaldulensis: The main constituents in volatile oil were alpha.-pinene, eucalyptoland2-carene. Eucalyptus urophylla×Eucalyptus grandis: The main constituents involatile oil were eucalyptol, alpha.-pinene and globulol.(3) In Pharmacological studies，through the molluscicidal effects test, the volatileoils from leaves of six Eucalyptus species and Water extract from Eucalyptusurophylla leaves have repellent effects on molluscicidal activity under laboratoryconditions. But, compare with other Eucalyptus oils, the volatile oils from leaves ofCorymbia citriodora Hook.f and Eucalyptus urophylla have stronger repellentactivitiy to against Oncomelania hupensis. An excellent molluscicidal effect of theextracts from benzine and chloroform in Water extract from leaves of Eucalyptusurophylla, were demonstrated by the immersion test. But the asmolluscacide of thechloroform extract was better than the other solvent extract.(4)Through the further tracking molluscicidal effects test, in the volatile oilsfrom leaves of Corymbia citriodora Hook.f, elution fractions with benzene-ethyl acetate (100:0),(100:5),(9:1) have repellent effects on molluscicidal activity underlaboratory conditions. Also, in the volatile oils from leaves of Eucalyptus urophylla,elution fractions with benzene-ethyl acetate (100:1),(100:2),(100:3),(5:1) were testedfor repellent effects against Oncomelania hupensis.(5)The six Eucalyptus oils and their terpenes (rhodinal,1,8-cineole,alpha-terpineol, et al.) were tested for repellency against Oncomelania hupensis. Thedose-effect relationship showed that all the mortality rates of Oncomelania hupensishad some variation with different time and concentration in processing liquid. Thelonger the dip time and the greater the concentration for Oncomelania hupensis, themore power repellent activity of chemical constituents from Eucalyptus plants.Therange of the mortality rate was from40%to100%after snails exposed to the extractfrom Eucalyptus plants immersed at the concentrations of10,50,100mg/L. Themortality rate was up to60%at the concentrations of50mg/L for48h after snailsexposed to the extracts respectively. By researching the correlation between terpenesand repellent, insecticidal activity of essential oils from Eucalyptus plants, we canfind that molluscicidal effect composition are the active components to the repellentactivity in Eucalyptus oils. According to the research about the chemical constituentsand pharmacological activity of Eucalyptus plants, the molluscicidal effectcomposition and its molluscicidal mechanism should be pay in depth research in thefuture. These results which have provided the foundation for further comprehensiveutilization with the molluscicidal effect on Oncomelania hupensis and to exploit plantmolluscicides.