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[摘要]：contg. a fluorine atom in either the 3a or the 5a positions or in 3a and 5a positions, were prepd. using std. operations (reaction of 3b-alcs. with (diethylamino)sulfur trifluoride, cleavage of epoxide with HF in py or BF3譋t2O). The 5a-fluorine was found to affect chem. reactivity (e.g., electrophilic addn. to the D2-double bond) as well as phys. properties (e.g., NMR, chromatog. behavior) of the products. Cytotoxicity of the products was studied using human normal and cancer cell lines with 28-homocastasterone as pos. control and their brassinolide type activity was established using the bean second-internode test with 24-epibrassinolide as std. The equivalence of F and OH groups was obsd. in some of the active compds. The anticancer and the brassinolide-type activity do not correlate with each other: ergostane derivs. were most active in the former test while androstane derivs. were best in the latter. |
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