Diazomethyl ketone and chloromethyl ketone analogues prepared from N-tosyl amino acids have been synthesized and tested for antitumor activity in Ehrlich ascites carcinoma and P-388 lymphocytic leukemia screens in mice. The N-tosyl chloromethyl ketone analogues prepared from glycine, L-alanine, beta-alanine, L-valine, and 6-(N-tosyl-amino)caproic acid were the most potent antineoplastic agents in the Ehrlich ascites carcinoma screen. The N-tosyl diazomethyl ketone analogues synthesized from glycine, L-leucine, and L-proline were the most active of this series in the Ehrlich ascites screen, along with 5-keto-1-tosyl-2-(diazoacetyl)pyrrolidine and the diazomethyl ketone analogues prepared from 6-(N-tosylamino)caproic acid. In the P-388 lymphocytic leukemia screen, the N-tosyl chloromethyl ketone prepared from glycine and the compound 5-keto-1-tosyl-2-(diazoacetyl)pyrrolidine were the most active.
A series of N-protected vinyl, 1,2-dihaloethyl, and cyanomethyl esters of phenylalanine was synthesized and these compounds were evaluated for antitumor activity against the growth of Ehrlich ascites carcinoma in CF1 male mice (33 mg/kg/day), Walker 256 carcinosarcoma in Sprague-Dawley male rats (2.5 mg/kg/day), and P388 lymphocytic leukemia in DBA/2 mice (20 mg/kg/day). Structure-activity relationships were evaluated and acute toxicity studies (LD50 determinations) in male CF1 mice were also carried out on selected compounds. Carbobenzoxy-L0phenylalanine vinyl ester (5), N-carbobenzoxy-L-phenylalanine 1,2-dibromoethyl ester (12), and N-carbobenzoxy-L-phenylalanine cyanomethyl ester (8) were found to be very potent inhibitors of Ehrlich ascites tumor growth at nontoxic doses cited above. Compounds 5 and 12 also tripled survival time in the Walker 256 system. LD50 values for compounds 5, 12, and 8 were greater than 2000 mg/kg (greater than 6.15 mmol/kg), 74 mg/kg (0.15 mmol/kg), and 150 mg/kg (0.44 mmol/kg), respectively.
Previously reported work on N-protected activated esters of phenylalanine has been extended to include N-protected vinyl, dibromoethyl, and cyanomethyl esters of several other amino acids. These compounds have been synthesized and evaluated in Ehrlich ascites carcinoma, Walker 256 carcinosarcoma, and and P388 lymphocytic leukemia tests. Among compounds tested were derivatives of tyrosine, tryptophan, glycine, leucine, proline, aspartic acid, glutamic acid, 4-aminobutyric acid, and 6-aminocaproic acid. Compounds of greatest potential interest from this study are N-carbobenzoxyglycine 1,2-dibromoethyl ester and N-carbobenzoxy-L-leucine 1,2-dibromoethyl ester. Both compounds were highly active in Ehrlich ascites test systems (33 mg/kg/day). The glycine derivative was also active in the Walker 256 test (2.5 mg/kg/day. Values for LD50's in mice were 148 mg/kg (0.37 mmol/kg) and 225 mg/kg (0.50 mmol/kg) for glycine and leucine derivatives, respectively; therefore, these compounds do not appear to be toxic at effective dose levels.
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