Cytotoxicity of three novel fluoropyrimidines in cultured L1210 murine lymphocytic leukemia cells.

Cultured L1210 murine lymphocytic leukemia cells were used to compare metabolic activation and cytotoxicity of 5-fluorouracil (FU), Ftorafur (FT), and three novel FU-sulfur analogues. These analogues, 1-(2'-tetrahydrothienyl)-5-fluorouracil (FUS), 1-(2'-tetrahydrothienyl)-5- fluorouracil-1'-oxide (FUSO), and 1-(2'-tetrahydrothienyl)-5-fluorouracil-1'-1'-dioxide (FUSO2), have yet to be fully evaluated for potential therapeutic value based on in vitro cytotoxicity. The role of these FU analogues as prodrugs was evaluated by comparing metabolism of normal pyrimidine pathways and activation by hepatic mixed function oxidases (MFO). Significant differences in biochemical activity and cytotoxicity were measured between FU and FU analogues. FU and FU analogues were cytotoxic to L1210 cells (63-92% growth inhibition of 100 microM concentrations after 72 hr of incubation). However, at equimolar concentration cytotoxicity of the FU analogues after MFO activation (56-66% growth inhibition) was greater than FU (47% growth inhibition). Hypoxanthine, a purine precursor, did not significantly alter fluoropyrimidine cytotoxicity with or without MFO. Thymidine and uridine, pyrimidine precursors, reduced FT and FUS cytotoxicities in the presence (27, 40%) and absence (25, 15%) of MFO but did not modify FU, FUSO, or FUSO2 cytotoxicities.

Facile synthesis of glycol metabolites of phenethylamine drugs.

High yields of potential glycol metabolites of p-synephrine, epinephrine, octopamine, and normacromerine can be obtained from the readily available monosubstituted and disubstituted acetophenones. The general procedure involves alpha-bromination followed by displacement with acetate ion and reduction with lithium aluminum hydride. Yields ranged from 46 to 91%. Furthermore, the procedure minimizes some problems inherent in aromatic glycol synthesis which include dimerization and pinacol-pinacolone rearrangement.

Synthesis and antitumor activity of a series of ftorafur analogues: the effect of varying electronegativity at the 1'-position.

To test the effect of changes in electronegativity within the alicyclic N-1 substituent 5-fluorouracil analogues on cytotoxic activity, a series of derivatives of ftorafur, 1-(2'-tetrahydrofuranyl)-5-fluorouracil, was synthesized and tested for antitumor activity in the P388 lymphocytic leukemia screen and cytotoxic activity in the L1210 cell culture screen. Two compounds of N-1 substituent with high electronegativity, the 2'-tetrahydrothiophene 1'-oxide and the 2'-tetrahydrothiophene 1',1'-dioxide derivatives, demonstrated the highest in vitro L1210 cell inhibition (84.5% and 92.0%, respectively). Furthermore, against P388 lymphocytic leukemia in vivo, the 2'-tetrahydrothiophene 1'-oxide derivative showed significant activity (T/C = 143). Other compounds of similar or lower electronegativity within the N-1 cyclic substituent were inactive against P388 lymphocytic leukemia and less active against L1210 cells.

Effects of 3-chloromethylthiochromone-1,1-dioxide on nucleic acid, protein, and aerobic and anaerobic metabolism of Ehrlich ascites tumor cells.

3-Chloromethylthiochromone-1,1-dioxide was observed to be a potent inhibitor of Ehrlich ascites carcinoma growth and a moderate inhibitor of P-388 lymphocytic leukemia growth at 10 mg/kg/day. Preliminary in vitro studies showed that the agents significantly inhibited RNA and DNA synthesis in Ehrlich ascites cells. In vivo studies after dosing on Days 6, 7, and 8 demonstrated the same reductions in nucleic acid synthesis and a moderate reduction in protein synthesis. The primary site of nucleic acid synthesis, which was blocked by 3-chloromethylthiochromone, was at orotidine monophosphate decarboxylase in the primidine pathway. Other enzymes, in anaerobic and aerobic glycolysis, which were blocked include hexokinase, phosphofructokinase, succinic and alpha-ketoglutarate dehydrogenases, as well as States 3 and 4 of oxidative phosphorylation.

Synthesis and antitumor testing of 3-methenylthiochroman-4-one-1,1-dioxide.

Treatment of thiochroman-4-one-1,1-dioxide (II) with paraformaldehyde and dimethylamine hydrochloride in isopropyl alcohol at reflux afforded directly in 80% yield the dimeric dihydropyran (IV), corresponding to the dimerization of the target compound 3-methenyl-thiochroman-4-one-1,1-dioxide (III). Neither the monomer III nor the expected Mannich base, 3-dimethylaminomethylthiochroman-4-one-1,1-dioxide, were isolated under conditions of the reaction. The monomer III could be prepared in 55% yield by sublimation of the dimer IV at 230-250 degrees; however, redimerization slowly occurred at room temperature. The dimer IV was also prepared by the use of paraformaldehyde and N-methylanilinium trifluoroacetate. The monomer III was found to be marginally active at 10 mg/kg/day versus Ehrlich ascites tumor growth in mice.

Synthesis and antitumor activity of a series of sulfone analogues of 1,4-naphthoquinone.

A series of novel substituted thiochromones and thiochroman-4-ones was synthesized. Compounds were designed as analogues of naphthoquinone and as potential "bioreductive alkylating agents" and were tested for antitumor activity. The lead compound, 3-(chloromethyl)thiochromone 1,1-dioxide (4), inhibited Ehrlich ascites tumor growth by 100% in CF1 male mice at 10 (mg/kg)/day ip. Similarly, 18 of the 29 related compounds demonstrated good activity in this tumor screen. Few definitive structure-activity correlations were evident regarding the nature of the 3-substituent. However, the 2,3 double bond and a sulfone or sulfoxide were required for activity. Four of the compounds synthesized showed marginal but significant activity against P-388 lymphocytic leukemia.

Effects of cis-malonato-diammino platinum (II) on P-388 lymphocytic leukemia cell metabolism.

cis-Malonato-diammino platinum(II) significantly inhibited P-388 lymphocytic leukemia cell proliferation at 10 mg/kg/day. Incorporation studies showed that DNA synthesis was inhibited following in vivo drug therapy. The major inhibitory effects appeared to be on thymidine kinase and dihydrofolate reductase activities and on overall purine synthesis, with marginal effects on DNA polymerase and ribonucleotide reductase activities. In addition to the DNA inhibition, a marked increase in cyclic adenosine 3',5'-monophosphate levels was noted, which correlated with a rapid decrease in histone phosphorylation. Other minor effects of the drug included significant reduction of proteolytic activity, suppression of States 4 and 3 respiration, and an increase in adenosine triphosphatase and acid phosphatase activities of P-388 cells.