Thermal stability and preliminary antimicrobial evaluation of polylysine-glutathione mixtures

With the increasing severity of antimicrobial compound resistance, exploring the combined effects of novel antibacterial compounds is of significant research value. Polylysine possesses cationic antibacterial activity, while glutathione is renowned for its antioxidant function. However, systematic research on the ionic complexes formed by their electrostatic self-assembly is insufficient. This study preliminarily evaluated the thermal stability and in vitro antibacterial activity of the polylysine-glutathione ionic complex, aiming to optimize its synthesis process and explore its feasibility as a potential anti-infective drug.

Thermogravimetric analysis (TGA) was used to assess the thermal stability of the composite material. In vitro culture experiments were conducted to preliminarily determine its antibacterial activity against Candida albicans and Staphylococcus aureus. Mass spectrometry was used to preliminarily investigate the effect of different drug concentrations on the bacterial proteomic profile.

TGA showed that polylysine began to lose weight at 53 °C, while glutathione began to lose weight at 82 °C, indicating a difference in their thermal stability. In vitro experiments showed that the complex exhibited antibacterial activity against both Candida albicans and Staphylococcus aureus, with an inhibition rate of 93.7% against Candida albicans at the minimum inhibitory concentration (MIC). Mass spectrometry analysis revealed that the intensity of the side peak at 4600 m/z changed in a concentration-dependent manner.

The results indicated that the polylysine-glutathione ion complex possessed certain thermal stability and synergistic antibacterial activity, providing a basic experimental basis for further research on its antibacterial mechanism and preclinical application. However, its detailed mechanism of action and in vivo safety still require further verification.