Beyond the host: Endophytic microbes from medicinal plants as a treasury of novel bioactive compounds

Endophytic microbes, residing asymptomatically within the tissues of medicinal plants, represent a vast and underexplored frontier for the discovery of novel bioactive compounds. For millennia, humans have relied on medicinal plants for therapeutic purposes, but it is now increasingly evident that a significant portion of this bioactivity may be attributed to the symbiotic microorganisms living within them. This review provides a comprehensive overview of the current state of research on endophytic microbes as a source of natural products with significant pharmacological potential. We delve into the historical context of endophyte research, their immense biodiversity, and the intricate molecular mechanisms governing the host-microbe symbiosis, including horizontal gene transfer and the epigenetic regulation of silent biosynthetic gene clusters. A substantial body of experimental evidence is synthesized, highlighting the discovery of endophytic compounds with potent antimicrobial, anticancer, antiviral, and immunomodulatory activities. Furthermore, we explore the transformative impact of computational and systems biology approaches such as genome mining and metabolomics in accelerating the identification of novel molecules. The clinical and translational relevance of endophytes as a sustainable and scalable platform for drug production is critically examined, alongside the current limitations and knowledge gaps that hinder their full exploitation. Finally, we outline promising future directions, including advanced culturing techniques, synthetic biology applications, and the exploration of untapped ecological niches, which are poised to unlock the full therapeutic potential of this microbial treasury.