Research On Chemical Constituents In Rabdosia Inflexa (Thunb.) Hara And Xanthium Italicum Moretti

In this thesis, phytochemical constituents in extracts from Rabdosia inflexa (Thunb.)Hara and Xanthium italicum Moretti. have been investigated.Twenty-nine compounds were isolated by means of silica gel column chromatography (CC), prepatative thin layer chromatography (Prep-TLC) and recrystallization, etc. The structures of thirteen compounds were elucidated on the basis of spectral evidences, combined with comparison with standard sample or referring to data in literature.Specifically, fourteen compounds were isolated from the ethanol extract of the dried roots of Rabdosia inflexa (Thunb.)Hara, among which compounds R-1, R-2, R-3, R-7 and R-9 were isolated from this plant for the first time.Fifteen compouds were isolated from the ethanol extract of the dried seeds of Xanthium italicum Moretti., among which six compounds were sesquiterpene lactones and compounds X-4, X-5 and X-8 were found in this plant for the first time.In addition, essential oils from roots, stems, leaves and flowers of Rabdosia inflexa (Thunb.) Hara have also been separated by steam distillation, respectively. The chemical composition of essential oils was analyzed by gas chromatography-mass spectrometry (GC-MS) with relative contents being, determined by normalization of peak area. There have been 32,38,39 and 39 compounds identified for essential olis from roots, stems, leaves and flowers of Rabdosia inflexa (Thunb.) Hara, respectively. Chemical composition varies for essential oils from different parts of this plant with main and common components being n-hexadecanoic acid and linolenic acid.Furthermore, antibacterial activity of crude extracts from roots and aerial parts of Rabdosia inflexus (Thunb.) Hara has also been tested Oxford Cup method and diffusion method (punch method). Experimental results indicated that extracts isolated from Rabdosia inflexus (Thunb.) Hara with ethyl acetate and n-butanol provide apparent antibacterial effects against Staphylococcus aureus and Bacillus megaterium while little antibacterial activity toward Escherichia coli and Vibrio parahaemolyticus, while n-butanol extracts are more efficient than ethyl acetate extracts and extracts from aerial parts are more efficient than extracts from roots.In conclusion, chemical constituents in Rabdosia inflexa (Thunb.)Hara and Xanthium italicum Moretti. have been comprehensively studied, which might be very helpful for the exploitation and development of these two species.