Gut microbiota: A potential enhancing factor for the therapeutic efficacy of bioactive compounds in herbal medicines

The therapeutic efficacy of herbal medicines (HMs) is often compromised by the low bioavailability of their bioactive compounds. However, emerging evidence highlights the crucial role of gut microbiota in enhancing their effectiveness. This review summarizes gut microbiota-mediated metabolism of key herbal components, including terpenoids, flavonoids, alkaloids, and quinones. Particular emphasis is placed on the diverse gut microbiota, enzymes, and metabolites that participate in the biotransformation pathways of these active components of HMs. Exploring the metabolism between the gut microbiota and bioactive compounds gives a better understanding of HMs with multiple components against multiple targets, complex mechanisms of action, and diverse physiological activities. This review underscores the critical importance of gut microbiota in modulating and potentially enhancing the pharmacological effects of HMs, which offers new insights into gut microbiota-mediated transformation pathways and molecular mechanisms of bioactive compounds and deepens the understanding of the therapeutic effects of HMs. Moreover, it suggests new research directions for studying HMs based on gut microbiota-mediated biotransformation.