Antitumor Activity Of 73 Natural Products In Vitro And Their Structure-activity Relationship

OBJECTIVE: The antitumor activities of 73 natural products (crude extracts or compounds including phenols, terpenes glucosides et.al) isolated from plants of YUNNAN were tested using human tumor cell lines. The cytotoxicities on lymphocytes of 9 products were further assayed using mouse spleen lymphocytes and preliminary analysis of the structure-activity relationship of diterphenoids. METHODS: The cytotoxicity of 73 natural products in 9 human tumor cell lines was measured by modified MTT or SRB assay. RESULTS: (1) The IC50 of 19 compounds out of 41 is less than 30 μ g/ml in K562 and Bcap-37 cell lines. The IC50 of Ir-20 is less than 1 μ g/ml in 7 human tumor cell lines. The IC50 of Ir-18, Xe-B are less than 10 μ g/ml in 7 human rumor cell lines. The IC50 of Ir-13, 11-2, Xe-A, Ma-B is less than 10μg/ml in several human tumor cell lines. The IC50 of the above 6 compounds is less than that of cisplatin in several human tumor cell lines tested. (2) 6 crude extract and 1 compounds are found to have strong cytotoxicity to human tumor cell out of 32 natural products. The IC50 of Y20 is less than 10μg/ml in 7 tumor cells, The IC50 of a crude extract YP43 in 7 tumor cell lines is less than 30μg/ml .CONCLUSION:(1 )Diterpenoids Ir-20, Ir-18. Xe-B show significant cytotoxicity in all human tumor cell lines tested. Diterpenoids Ir-13, 11-2, Xe-B, Ma-B show significant cytotoxicity in 5-6human tumor cell lines. Analysis of the structural-activity relationship reveals that the a-methylene cyclopentanone moity is responsible for the antitumor activity of the diterpenoids tested. (2) Compound Y20 and crude exact YP43 presents strong cytotoxicity for 7 human tumor cell lines, crude extracts YP46, YP47, YP48, YP49, YP41 show significant cytotoxicity in several human tumor cell lines.