Efficiency of the extracellular polymeric matrix disruptor Zerumbone in combination with Photodithazine® in the photodynamic inactivation of monospecies biofilms

Abstract

Zerumbone (ZER), a sesquiterpene extracted from Zingiber zerumbet (L.) Smith, enhances the antibiofilm effects of antimicrobial photodynamic therapy (aPDT) by reducing the extracellular matrix of biofilms and increasing the generation of reactive oxygen species (ROS) when applied prior to aPDT. To reduce treatment application time, ZER was combined with Photodithazine® (PDZ) in a single solution. Then, this study investigated the potential of aPDT mediated by a mixture of ZER with PDZ in the inactivation of Staphylococcus aureus, Escherichia coli, fluconazole-susceptible (CaS) and resistant (CaR) Candida albicans biofilms. The solutions of ZER, PDZ and their mixture (ZER + PDZ) were analyzed using absorbance spectroscopy (AS), high-performance liquid chromatography (HPLC), and mass spectrometry (MS) to confirm the absence of molecular alterations in the mixture of ZER + PDZ. 48 h-biofilms were growth and treatments were performed: 1-ZER (256 µg/mL); 2-PDZ (200 µg/mL); 3-PDZ + LED; 4-ZER + PDZ + LED; 5- MIX (ZER + PDZ) + LED; Control (without treatment). Irradiation was performed using a red LED (660 nm, 50 J/cm², 30 mW/cm²). Sterile PBS was employed as the control group. For cytotoxicity assessments ffi broblast (HGF) and keratinocyte (NOK-si) oral cells were cultured for 24 h and submitted to treatments. Both ZER + PDZ + LED and MIX (ZER + PDZ) + LED groups showed the greatest statistically significant reduction in CFU/mL when compared to the control group (p ≤ 0.011) in all evaluated strain, with no significant difference between them (p ≥ 0.218). The reduction observed was 2.74, 2.89, 2.45 and 2.07 log10 for S. aureus, E. coli, CaS, CaR, respectively. Cell viability reduction in NOK-si and FGH did not exceed 17%. AS, HPLC, and MS analyses demonstrated that PDZ retained its original characteristics following combination with ZER. Zerumbone combined with PDZ enhances the effect of antimicrobial photodynamic treatment regardless of strain characteristics and showed no cytotoxic effects.