Optimization for microbial incorporation and efficiency of photodynamic therapy using variation on curcumin formulation

Introduction: A mixture of curcuminoids: curcumin, desmethoxycurcumin (DMC), and bisdemethoxycurcumin (BDMC) are named natural curcumin. It is a lipophilic photosensitizer (PS) highly soluble in an organic solvent such as dimethyl sulfoxide (DMSO). Curcumin is a PS used for microbial inactivation using photodynamic action. However, this solvent has high cytotoxicity and is unavailable in formulations for clinical use. This study aimed to investigate the interactions of curcuminoids syrup with Streptococcus sp., a gram-positive coccus and one of the major pharyngeal pathogens, responsible for diseases such as pharyngitis.

Methods: Bacteria were incubated with curcuminoids (natural curcumin, synthetic, DMC, BDMC) at 37 °C in formulations: 1) syrup (water + sucrose) 2) solution alcohol + DMSO. Was centrifuged, and the supernatant collected for absorbance analysis. The results obtained correlating the absorbance with the supernatant to the absorbance of the default concentration. A study of microbial metabolism by growth curve was carried out to justify the result.

Results: The incorporation of curcumin in syrup is superior to alcohol/DMSO solution by microorganisms. Curcumin incorporation by S. mutans, S. pyogenes, isolated bacteria was 24, 26, 27 % in syrup and 10, 13, 5 % in alcohol/DMSO, respectively. Also, the presence of carbohydrate in a solution can activate the bacterial metabolism, getting better uptake results and photodynamic inactivation to natural curcumin and DMC. Such finds care optimizes the use of curcumin without complications generated by the solvent.