Effect of some psychotropic drugs and a barbiturate on mycoplasmas

Area of Science:

• Microbiology
• Pharmacology
• Biochemistry

Background:

• Mycoplasma species are significant human pathogens.
• Current treatments for mycoplasma infections have limitations.
• Membrane stabilizers are not typically considered antimicrobials.

Purpose of the Study:

• To investigate the in vitro inhibitory effects of selected membrane stabilizers on pathogenic Mycoplasma species.
• To evaluate the impact of these compounds on mycoplasma growth and enzymatic functions.
• To explore the potential of membrane stabilizers as a basis for novel antimicrobial drug development.

Main Methods:

• In vitro susceptibility testing of Mycoplasma pneumoniae, M. hominis, Ureaplasma urealyticum, M. gallisepticum, and Acholeplasma laidlawii.
• Assessing growth inhibition and enzymatic activity (glucose, arginine, urea breakdown) in the presence of chlorpromazine (CPZ), thiopental, and thioxanthene derivatives.
• Comparing the effects of different stereoisomers of thioxanthene derivatives.

Main Results:

• Chlorpromazine (CPZ), thiopental, and four thioxanthene derivatives demonstrated antimycoplasmal activity against all tested strains, with effective concentrations ranging from 3.9-312 mg/l.
• CPZ and thiopental inhibited mycoplasma enzymatic functions at concentrations lower than those inhibiting growth.
• Thioxanthene derivatives showed growth inhibition independent of their stereoisomeric configuration, with clopenthixol isomers also affecting color change at lower concentrations than growth inhibition.

Conclusions:

• Membrane stabilizers like phenothiazines and thioxanthenes possess significant antimycoplasmal activity.
• These compounds uniquely inhibit mycoplasma enzymatic functions at sub-growth-inhibitory concentrations.
• Membrane stabilizers represent promising candidates for developing novel antimycoplasmal agents with unique mechanisms of action.