Effect of noxythiolin on experimental peritonitis

An investigation of the in vitro anti-bacterial activity of noxythiolin against 1,000 pathogenic bacterial isolates

The susceptibility of 1,000 recent bacterial isolates to noxythiolin was determined by the disc susceptibility method. No Gram-positive strains were resistant to this method but 56 (5.6%) of Gram-negative strains gave zones of inhibition of 12 mm diameter or less. The minimum inhibitory concentration (MIC) of the latter were determined by the agar incorporation method. No strains had MIC values greater than 4096 mg/litre. Since concentrations of 50,000 mg/litre can be used for topical treatment, these organisms may be considered susceptible.

Mechanisms of antibacterial formaldehyde delivery from noxythiolin and other 'masked-formaldehyde' compounds

Formaldehyde release in aqueous solutions of noxythiolin (N-methyl-N'-hydroxymethyl thiourea) has been monitored by nuclear magnetic resonance (n.m.r.) spectroscopy. The results suggest that antibacterial activity in such solutions resides mainly in the free formaldehyde. N.m.r. spectroscopy also demonstrated slow C-N bond rotation in noxythiolin and N-methylthiourea, with delta G of ca 15 kcal mol-1 (63 kJ mol-1). N-Hydroxymethyl imidazole is marginally more effective than corresponding hydrated formaldehyde solutions, an effect which is attributed to more rapid turnover of unhydrated formaldehyde as detected by saturation transfer n.m.r. spectroscopy. These observations are combined with the known delivery of lethal iminium ions, R2N+ = CH2, by compounds of the form R2NCH2X (X = OH, NR2; R is alkyl) to suggest a single consistent explanation of the antibacterial properties of a wide range of masked formaldehyde compounds.

A comparison of noxythiolin and povidone-iodine in experimentally induced peritoneal infection in mice

Noxythiolin (Noxyflex, Geistlich), given intraperitoneally as a 2.5 per cent solution, protected mice from the lethal effects of an intraperitoneal injection of Escherichia coli. Povidone-iodine (Pevidine, Berk), containing 0.075 per cent iodine, gave no protection.