Red pepper Capsicum baccatum: source of antiadhesive and antibiofilm compounds against nosocomial bacteria

Abstract

Currently, there is a great interest in the search for new natural bioactive compounds against bacterial biofilms, ubiquitous in natural, clinical and industrial environments, and responsible for the high resistance of bacteria to antimicrobial agents. Several species of Capsicum red peppers are used worldwide in a number of preparations to treat a variety of illnesses, including infections. The aim of this study was to investigate the antiadhesive and antibiofilm activity of Capsicum baccatum, after sequential extraction, against important bacteria. Antimicrobial and antibiofilm activities against Staphylococcus epidermidis and Pseudomonas aeruginosa were performed by the OD600 absorbance and crystal violet method, respectively, and using scanning electron microscopy (SEM). The most active extract of C. baccatum was incorporated in Permanox™ slides by spin-coated technique in order to produce an anti-infective surface. In addition, an in vivo toxicological evaluation was performed using the alternative host model of Galleria mellonella larvae. The residual aqueous extract from C. baccatum seeds (RAqS) was the most active extract, able to inhibit up to 80% and 60% of the S. epidermidis and P. aeruginosa biofilm, respectively, without inhibiting the planktonic bacterial growth, neither promoting acute toxicity in G. mellonella. The surface coating with the RAqS modified the highly hydrophobic feature of Permanox™ slides and prevented the bacterial adhesion and biofilm development. SEM analysis showed the presence of only small clusters or individual cells without the presence of matrix on the RAqS treated samples, even when RAqS was in solution or as coating. The phytochemical evaluation of RAqS indicated the main presence of tannins and amino acids/proteins. The study presented herein demonstrated, for the first time, the ability of C. baccatum to prevent bacterial adhesion and biofilm formation of two significant pathogens. This property of C. baccatum evidences its potential as a promising source of natural compounds for the development of novel strategies, targeting anti-virulence factors, for combating antibiotic-resistant bacteria, and controlling clinical and industrial problems related to biofilms.