Elevated Antibacterial Activity with Decreased Cytotoxicity of a Polygalacturonic + Caprylic Acid Wound Ointment Compared with Hypochlorous Acid in a Three-Dimensional Wound Biofilm Model

Introduction: Natural, plant-based agents are alternatives to antibiotics and antiseptics in treating bacterially colonized wounds and potentially offer an antimicrobial activity without cytotoxicity. In this study, we used a three-dimensional fibrin-gel wound biofilm (FGWB) model to be more representative of the wound biofilm environment. We compared a common antiseptic wound care agent, hypochlorous acid (HOCl), with a combination of two plant-based agents; polygalacturonic acid (PG) and caprylic acid (CAP) for bacterial biofilm eradication and assessed their cytotoxicities towards fibroblast cells. Material and Methods: The efficacy PG+CAP ointment was compared to HOCl irrigant solution in biofilm eradication using the FGWB against clinical resistant bacterial isolates of MRSA, MDR Pseudomonas aeruginosa, CRE Escherichia coli, and Streptococcus pyogenes. Trypan blue exclusion and Alamar blue conversion assays were used for cytotoxicity assays. Results: PG+CAP produced a significantly greater reduction of viable organisms than HOCl for all tested bacterial isolates in the FGWB model (P≤ 0.05). Also, cytotoxicity tests showed that, PG+CAP was comparable to the non-antimicrobial negative control and was less cytotoxic than HOCl (P≤0.05). Conclusion: PG+CAP was highly effective against biofilms of highly resistant bacterial isolates in the FGWB model, and less cytotoxic than HOCl. PG+CAP merits further in vivo study.