Control of zoopathogenic fungi in vitro by polyamine biosynthesis inhibitors.

Effect of inhibitors of polyamine (PA) biosynthesis, alpha-difluoromethylornithine (DFMO), methylglyoxal bis (guanylhydrazone)--MGBG and bis (cyclohexylammonium) sulphate (BCHA) on mycelial growth of three clinically important fungi-Trichophyton mentagrophytes, Microsporum gypseum and Aspergillus flavus was examined in vitro. All inhibitors at concentrations 1 to 50 mM produced greater inhibition of mycelial growth in all fungi tested in a dose-dependent manner. MGBG was the most effective inhibitor, and T. mentagrophytes was the most sensitive fungus to all inhibitors followed by M. gypseum and A. flavus. The results suggested that control of fungal diseases in animals and human beings with specific inhibitors of PA biosynthesis is possible.

Insecticidal activity of inhibitors of polyamine biosynthesis on Spodoptera litura F. larvae.

The inhibitors of polyamine (PA) biosynthesis such as alpha-difluoromethylornithine (DFMO), methylglyoxal bis (guanylhydrazone) (MGBG) and bis (cyclohexylammonium) sulphate (BCHA) have been used to protect crop plants from pathogenic fungi. In this communication the insecticidal activity of these inhibitors on tobacco caterpillar, S. litura has been reported. All the inhibitors exhibited insecticidal activity; MGBG being more effective than others. The results suggest, for the first time, a possible avenue for the control of insect pests by specific inhibition of insect PA biosynthesis.

Action of methylglyoxal bis (guanyl hydrazone) and related antiprotozoals on Acanthamoeba culbertsoni.

Methylglyoxal bis(guanyl hydrazone) (MGBG) and the related diamidine compounds berenil and pentamidine inhibited multiplication of A. culbertsoni. The growth inhibition by MGBG (2.5 mM) in the peptone medium was accompanied by the disappearance of spermidine and a marked reduction in the level of diaminopropane. MGBG and berenil completely inhibited growth in a chemically defined medium at 1 mM and 1-2 microM concentration, respectively. However, there was no decrease in the polyamine levels in the early stages of growth inhibition by these agents. Uptake of putrescine, spermidine and spermine by A. culbertsoni has been demonstrated but addition of exogenous polyamines did not reverse the growth inhibitory action of MGBG and berenil. Inhibition of S-adenosylmethionine decarboxylase and decrease in polyamine synthesis do not seem to be the primary targets for the antiamoebic action of MGBG and berenil.