In vitro effect of diamidines on intracellular polyamines of Acanthamoeba polyphaga

Treatment with the drugs berenil, dibromopropamidine, pentamidine and CGP-4O-215 were found to alter levels of intracellular polyamines of Acanthamoeba polyphagia trophozoites in organisms. While the polyamine, spermidine, consistently remained higher in the control organisms incubated at 8, 16 and 32 h respectively, the level fluctuated significantly from below 5% to 40% in drug-treated organisms. A novel polyamine (polyamine F), yet to be identified, representing 80% of the total polyamine extracts and seen in control organisms after 48 h of incubation (stationary phase), was seen much earlier in the drug treated organisms. Pentamidine, dibromopropamidine and CGP-4O-215 induced the appearance of the novel polyamine in the trophozoites after only 8 h of incubation with the drugs while induction by berenil occurred after 32 h. It is suggested that diamidine drugs either induce encystment or alter the pathway of polyamine metabolism in Acanthamoeba. If inducing encystment is the main mode of reaction, then drugs that induce early encystment will be less effective in treatment than those that delay it.