State-of-the-Art Perspectives on Postbiotic-Oriented Systems Derived from Fermented Medicinal Plant Extracts

Fermentation is increasingly used as a controlled bioprocessing approach to modify medicinal plant extracts by selectively transforming phytochemicals while maintaining safety and compositional integrity. Controlled in vitro fermentation has gained attention as a practical method to generate stable, cell-independent bioactivity consistent with postbiotic concepts. This review examines Scopus-indexed studies on fermented medicinal plant extracts, focusing on microbial platforms, fermentation strategies, dominant biotransformation pathways, and functional outcomes. Evidence indicates that fermentation is not a uniform process but follows platform-specific enzymatic pathways that reshape phenolics, flavonoids, alkaloids, and polysaccharides. Lactic acid bacteria (LAB) are most frequently applied due to their safety profile and enzymatic capacity, while yeasts and filamentous fungi enable complementary matrix restructuring and deeper chemical modification. Across systems, fermentation-driven biotransformation produces bioactive profiles that persist independently of microbial viability, supporting a postbiotic-oriented interpretation. Applications have been reported in food, nutraceutical, cosmetic, and animal nutrition contexts, although clinical translation remains limited. Remaining challenges include incomplete mechanistic understanding, limited standardization, and unclear regulatory positioning.