Screening For Bioactive Microalgae And Study On Active Components Of Two Kinds Of Plants

The thesis is composed of three parts: 1. Screening for bioactive microalgae; 2. Study on active components of tibetan medicinal herbs, Lancea tibetica; 3. Study on active components of Hai zao jing.Microalgae, as one of the most important primary producers, can produce many compounds with neoteric structures. In order to search for active microalgae strains and to guide isolation of structurally novel and biologically active compounds from them, 90 strains of marine microalgae were screened for their lethality against brine shrimp, cytotoxicity against P388 cell line and anti-oxidation against DPPH radicals. The methanol extracts of the mycelium of 10 strains showed lethality against brine shrimp,and 5 strains showed cytotoxicity against P388 cells. The extract of one strain, which showed a series of UV absorptions at 400nm in the HPLC-UV analysis, exhibited anti-oxidation activities against DPPH radical and UV-radiation.Because of special growth environments for their original plants, traditional Tibetan medicines showed attractive specialties in prevention and treatment of human disease like tumor and cardiac disease. A traditional Tibetan medicinal herbs, Lancea tibetica were wildly used in Tibet. It is used for treatment of leukaemia, heart disease, influenza, pneumonia, and asthma. To search for the bioactive components, their chemical constituents were studied.Hai zao jing, as a kind of health care products, not only can provide nutrition, but also can be used for treatment of cerebral paralysis, anaemia, acidism, apokamnosis hyperlipemia, immunity disease, cancer, and so on. To search for the bioactive components, their chemical constituents were studied.The dried aerial parts of L. tibetica Hook. f. et were extracted with 95% EtOH and the obtained ethanol solution was concentrated in vacuo to give the crude bisque. It was chromatographed on macroporous resin column to obtain four fractions. From the fraction 3, thirteen compounds 1-13 were isolated by repeated column chromatography on silica gel, Sephadex LH-20 and RP-18 silica gel, followed by reverse-phase high performance liquid chromatography and recrystallization. By means of spectroscopic methods (UV, IR, MS, 1D-NMR, 2D-NMR) and their physicochemical properties, the structures of compounds 1-13 were elucidated as lantibeside B (1), lantibeside C (2), lantibeside D (3), lantibetin (4), phillyrin (5), simplexoside (6), sesaminol-2′-O-β-D-glucoside (7), phillygenol (8), lantibeside (9), tibeticoside A (10), O-2-(3,4-dihydroxyphenyl)ethyl-3-O-α-L-rhamnopyranosyl-4-O- [(E)-3-(3,4-dihydroxyphenyl)propenoyl]-β-D-glucopyranoside (11), apigenin (12) and 5,4'-dihydroxyflavone (13). From the acetone extract of Laminaria japonica, eight compounds 14-19 were isolated by the same methods. The structures of these compounds were elucidated as Aurantiamide acetate (14), N-Benzoyl-L-phenylalanino (15), Loliolide (16), Fucosterol (17), 26,27-Dinorcholesta-5,24-dien-3β-ol (18), Thymidine (19).The in vitro anti-tumor activities of these compounds against several cancer cell lines were assayed by MTT and SRB methods, and three compounds (2, 3, 18) showed anti-tumor activities. Compounds 2 and 3 exhibited weak cytotoxic activities against HL-60 cell line with IC50 values of 61 and 99μM, respectively. Compound 18 also showed weak cytotoxic activities against P388 cell line with IC50 value of 40μM.