Exploring the potential of spice-derived phytochemicals as alternative antimicrobial agents

The emergence and spread of pathogenic bacterial resistance to many antibiotics are on the rise globally, thereby posing a significant threat to public health. In response, scientists are actively investigating alternative therapeutic agents to combat antibiotic-resistant microorganisms. This review focuses on the antimicrobial effects of commonly consumed spices, namely garlic, chilli peppers, turmeric, ginger and black pepper, which have shown promising results in previous research. The review highlights the key phytochemicals, including allicin, ajoene, capsaicin, dihydrocapsaicin, curcumin, 6-gingerol, 6-shogaol and piperine, responsible for their antimicrobial activities. Various pharmacological experiments to elucidate the action mechanism and metabolism of those bioactive compounds are described. Moreover, the synergistic effects of these phytochemicals with conventional antibiotics are discussed, emphasizing the potential to reduce the required antibiotic dosage for effective microbial inhibition. The review also addresses the gaps in current research, such as the variations in antimicrobial assay results across different research groups and the incomplete understanding of the synergistic mechanisms between antibiotics and phytochemicals. Finally, future research directions and opportunities are suggested to further explore the antimicrobial potential of these spice-derived phytochemicals and bridge the existing knowledge gaps.