A comprehensive review on medicinal plant extracts as antibacterial agents: Factors, mechanism insights and future prospects

Abstract

Antibiotic resistance, once a manageable concern, has now emerged as one of the most pressing global health threats. In response, there is a growing scientific focus on discovering natural and effective antimicrobial agents. In this review, we aim to address this urgent issue by summarizing recent studies from 2014 to 2024 on medicinal plant extracts exhibiting minimum inhibitory concentrations (MIC) equal to or less than 625 µg/mL. We explore the key factors influencing the antibacterial efficacy of these extracts and provide an in-depth overview of their mechanisms of action. Systematic literature searches were collected from scientific databases, documenting 81 plant species tested against multiple pathogenic bacteria. The results revealed that extracts from Quercus coccifera, Ocimum gratissimum, and Curcuma longa, demonstrated the highest efficacy against the most commonly targeted pathogens, including Pseudomonas aeruginosa (MIC of 4 µg/mL), Staphylococcus aureus (MIC of 5 µg/mL), and Escherichia coli (MIC of 7.58 µg/mL), respectively. The Myrtaceae, Lamiaceae, Apiaceae families demonstrated the highest potency, with Cameroon, Indonesia, and South Africa recognized as primary regions for plant collection. Leaves (50.56 %) were the primary plant parts investigated, with methanol (31.16 %) and ethanol (20.28 %) being the most commonly used solvents in extraction processes. This review not only underscores the significant antibacterial potential of plant extracts but also elucidates how phytochemical composition, extraction methods, and antibacterial screening techniques contribute to their efficacy. This integrative study provides a robust foundation for future research and highlights the promise of plant-based solutions in combating antibiotic resistance.