| Summary: | 碩士 === 國立屏東科技大學 === 生物科技研究所 === 94 === Diospyros discolor Willd. (Ebenaceae), a medium-sized to large evergreen tree, is indigenous to Philippines and Taiwan. Plants of the Diospyros genus (Ebenacea) are well documented as a rich sources of naphthoquinones and triterpenes, which have been found to exhibit antimicrobial and antitumor activities. The MeOH extract of the twigs of D. discolor exhibited cytotoxic and antioxidant activities, which led us to investigate the bioactive principles from this plant. The dried twigs of D. discolor were cut into sections and extracted with MeOH. The extract was evaporated in vacuo to yield a black residue, which was suspended in H2O, and then partitioned with EtOAc. The aqueous layer was partitioned again with n-BuOH. Bioassay-guided fractionation of those extracts led to the isolation of twenty-three compounds including sixteen triterpenoids, one napthene, two naphthoquinones, three steroids and one flavans. Among those, 3β-methoxy-24-methylenelanost-9(11)-en-25-ol (T1), 3β-methoxy-24-methyllanosta-9(11),25-dien-24-ol (T2), 3β-methoxy-25-methyl-24-methylenelanost-9(11)-en-21-ol (T3), 24-ethyl-3β-methoxylanost-9(11)-en-25-ol (T4) are new compounds. In addition, betulinic acid and ursolic acid showed strong cytotoxic activity against SK-Hep 1 cell lines with IC50 values of 9.2, 14.5 μM, respectively.
Myristica ceylanica A. DC. var. cagayanensis (Myristicaceae), a medium-sized to large evergreen tree, is indigenous to Lanyu and Taiwan. Plants of the Myristica genus (Myristicaceae) are well documented as a rich sources of lignans, which have been found to exhibit antimicrobial activity. The MeOH extract of the twigs of M. cagayanensis exhibited cytotoxic and antioxidant activities, which led us to investigate the bioactive principles from this plant. The dried twigs of M. cagayanensis were cut into sections and extracted with MeOH. The extract was suspended in H2O, and then partitioned with EtOAc. The aqueous layer was partitioned again with n-BuOH. Bioassay-guided fractionation of those extracts led to the isolation of twenty-two compounds including two flavans, two chalcones, four flavonoids, four aromatics, four lignans, one isocoumarins, three steroids, one polyketides and one diarylnonanoid. Among those, (2S)-3’-hydroxy-4’,7-dimethoxyflavan (Fl2) are new compounds, (+)-oxo-parabenzlactone (L3) were found from the natural products for the first time. In addition, biochanin A (F3) and 1-(2,6-dihydroxyphenyl)-9-
(3,4-methylenedioxyphenyl)nonan-1-one (D1) showed strong cytotoxic activity against SK-Hep 1 cell lines with IC50 values of 60.6, 20.3 μM, respectively.
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