Exploring the Antibacterial Properties of Acmella Species: A Systematic Literature Review

The increasing prevalence of antibiotic-resistant bacteria has intensified the search for alternative antimicrobial agents, with plant-derived extracts emerging as promising candidates. The Acmella genus, known for its rich array of bioactive compounds, has been explored for its antibacterial potential; however, a comprehensive synthesis of the available evidence remains limited. This systematic review aims to evaluate the antibacterial properties of Acmella genus plant extracts by analysing studies retrieved from the Scopus, PubMed, and Web of Science databases. An advanced search identified 111 relevant articles, of which 14 met the inclusion criteria after a rigorous screening process. The selected studies predominantly investigated Acmella oleracea (syn. Spilanthes acmella), along with Acmella ciliata, Acmella caulirhiza, Acmella paniculata, and Acmella uliginosa. Ethanol and methanol were the primary solvents used for extraction, with methanolic extracts generally demonstrating superior antibacterial efficacy. Antibacterial activity was assessed using in vitro methodologies, including minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), disc diffusion, and agar well diffusion assays. The results revealed significant inhibitory effects against Gram-positive bacteria such as Streptococcus mutans and Staphylococcus aureus, as well as Gram-negative bacteria like Escherichia coli and Pseudomonas aeruginosa. Notably, some studies reported biofilm inhibition properties, highlighting the potential of Acmella extracts in managing persistent infections. While these findings underscore the therapeutic promise of Acmella-derived compounds in oral health and wound care, the absence of in vivo and clinical studies limits their translational applicability. Future research should focus on isolating active compounds, evaluating their pharmacokinetics, and exploring synergistic effects with conventional antibiotics to enhance efficacy and minimize resistance development.