A review of phytochemicals targeting bacterial biofilm and quorum sensing pathways: molecular, microbiological, and mechanistic insights.

The global escalation of antimicrobial resistance (AMR) due to excessive abuse of antibiotics over time has rendered several conventional antibiotics ineffective. In addition, the formation of biofilms by these microbes, as a survival mechanism against unfavorable conditions, adds to their resistance, making it difficult for standard drugs to treat infections. Biofilm formation is closely regulated by quorum sensing (QS), a cell-density dependent bacterial communication system that regulates transcription of genes associated with pathogenicity and disease progression. Recently, several researchers have investigated compounds from different herbal sources that interfere with the growth of such bacteria without applying selection pressure. Plant-based antimicrobial agents have the innate ability to target a broad spectrum of bacteria owing to the mixture of alkaloids, terpenoids, flavonoids, and phenolics. These phytochemicals have different mechanisms of action, and collectively they can inhibit bacterial growth and interfere with the QS system, thereby suppressing virulence factors and biofilm formation. However, limitations associated with these herbal compounds include the lack of clinical data on their efficacy in humans against various infectious diseases. This review highlights nature’s potential in the form of plant extracts, bioactive compounds, and essential oils (EOs) as a compelling source of anti-infective agents capable of overcoming biofilm-associated infections and AMR.