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We studied the effect of five newly synthesized steroidal derivatives of nitrogen mustards. These derivatives have as alkylators either P-N, N-bis(2-chloroethyl)aminophenyl-butyrate (CHL) or P-N, N-bis(2-chloroethyl)aminophenyl-acetate (PHE) groups esterified with different modified steroidal nuclei. We examined them alone or in combination, on sister chromatid exchange rates and on human lymphocyte proliferation kinetics. The antitumor activity of these compounds, alone or in combination, was also tested on Leukemia P388-bearing mice. A pronounced cytogenetic and antineoplastic action was demonstrated by the compounds that contain either PHE or CHL as alkylators and are esterified with a steroidal nucleus having added a cholestene group in the 17 position of the D-ring. The exocyclical insertion of an -NHCO- group in the D-ring of the steroidal nucleus esterified with PHE (amide ester of PHE) yielded a compound demonstrating a distinct cytogenetic and antineoplastic effect. In contrast, the ketone group in the D-ring being inserted endocyclically in the steroidal nucleus (androstene) esterified with either CHL or with PHE gave negative cytogenetic and antineoplastic effects. However, the combined action of cholestene esterified with either CHL or with PHE in combination with either the androstene ester of PHE or with the androstene ester of CHL, respectively, gave synergistic cytogenetic and antineoplastic effects. Also the amide ester of PHE in combination with the androstene ester of CHL gave distinct cytogenetic and antineoplastic effects in a synergistic manner.

Introduction: The aim of this study was to design new potentially antineoplastic agents by combining nitrogen mustard with steroidal skeleton, in an effort to improve specificity and simultaneously to reduce systemic toxicity. The steroidal part is aimed to act as a biological platform enabling the alkylating moiety to approach its site of action by altering its physicochemical properties., Materials and Methods: The compounds tested have, as alkylating agents, either p-N,N-bis(2-chloroethyl)aminophenyl-butyrate or p-N,N-bis(2-chloroethyl)aminophenyl-acetate esterified with a modified steroidal nucleus. The four newly synthesized compounds were compared on a molar basis, regarding their ability to induce sister chromatid exchanges and modify proliferation rate indices in cultured human lymphocytes. Life span of BDF1 mice inoculated with L1210 leukemia was also estimated (antileukemic activity)., Results: A compound having p-N,N-bis(2-chloroethyl)aminophenyl-acetate as the alkylator and two ketone groups in the steroidal part demonstrated the highest statistically significant enhancement of sister chromatid exchanges and suppression of proliferation rate indices, and also caused significant antineoplastic activity. The other compounds proved less active., Conclusion: These results suggest that cytogenetic and antileukemic activity of alkylating steroidal esters depends on the configuration of the whole molecule and the appropriate combination of the alkylator with the steroidal molecule.