| Summary: | 碩士 === 台北醫學院 === 生藥學研究所 === 90 === Colorectal carcinoma is one of the leading causes of cancer deaths in Taiwan. Several previous studies demonstrated chemotherapy for colorectal carcinoma caused resistance and side effects on patients. Therefore, the new anticolorectal tumor drugs are going to develop from Chinese herbs. In this study, the cytotoxicity effects of the 50% ethanol extracts of Chinese herbs were screened by MTT assay in human colon adenocarcinoma cell lines (CoLo 205, HT-29). The cytotoxicity effects of 50% EtOH extracted-Pharbitidis Semen Atrum were exerted stronger in CoLo 205 cells than Chang normal liver cell (CNL). The cytotoxic principles of semen were isolated by bioassay-guided fractionation. The semen were extracted with methanol and chromatographed over Diaion HP-20 column with 70% aqueous acetone Moreover, the cytotoxicity effect of 70% acetone fraction (D-70A) showed stronger than the other fractions in CoLo 205 cells and IC50 was 17.38 μg/ml for 48h. Furthermore, the cytotoxic mechanisms of D-70A were measured by agarose gel electrophoresis, fluorescence flow- cytometry, Giemsa stain, Western blot analysis. The results showed that D-70A could induce apoptosis in CoLo 205 dells. Gibberellin was isolated from D-70A with RP-18 column chromatography. The IC50 value of gibberellin was 20.36 μg/ml and induced apoptosis in CoLo205 cells for 48h. Moreover, treatment with catalase prevented gibberellin-induced cytotoxicity. In according to the results, we suggested that gibberellin might produce free radicals and induce apoptosis in CoLo 205 cells. However, the cytotoxic effect of bibberellin was lesser than D-70A in CoLo 205 cells. Therefore, we suggested the D-70A fraction extract is good for antitumor effects. In the future, gibberellin will be a biosubstance to control the quality of D-70A.
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