Ability of bisbenzylputrescine and propanediamine analogs to modulate the intracellular polyamine pool of P388D1 cells

The effects of a series of bisbenzyldiamine analogs have been tested on P38 8D1 cell line in vitro. Their effects on cell growth, polyamine oxidase (PA O) activity and intracellular polyamine content were determined. The cytoto xicity tests were performed in culture medium supplemented with 100 mu mol/ L aminoguanidine (I), 100 mu mol/L aminoguanidine and 100 mu mol/L N,N'-bis (2,3-butadienyl)-1,4-butanediamine (MDL 72,527) (II), and finally 100 mu mo l/L aminoguanidine and 200 mu mol/L D,L-difluoromethylornithine (DFMO) (III ). The IC50 values under conditions I and III were similar, suggesting that inhibition of ornithine decarboxylase by DFMO did not affect the biologica l effect of our derivatives. Spermine and spermidine remained nontoxic in c onditions I and III. However in the condition II, the toxicity of all teste d compounds (excepted spermidine) was increased, suggesting that the inhibi tion of cellular PAO increased their toxicity. The enzymatic test of PAO showed that at high doses inhibition of this enzy me by putrescine analogs occurred, while the N-methylated propanediamine de rivative increased the enzyme activity; however, these results do not corre late with cytotoxicity tests. When these derivatives were incubated for 48 h with the cells, all of them increased the cell content in putrescine (sim ilar to 160%) and spermine (similar to 145%) and decreased the spermidine c ontent (similar to 75%) without any modification of the total amount of pol yamine. The correlation between the cytotoxic results and the intracellular polyami ne determination shows that the increase in spermine content along with the inhibition of retroconverting PAO enzyme increases the toxic effect of tes ted compounds (including spermine), suggesting that spermine toxicity is mo re important in the absence of intracellular oxidation processes.