Natural immune boosters: coumarins as emerging potentiators of immunity in drug discovery

In the wake of increasing global health threats, bolstering host immunity has become a central focus in drug discovery. Coumarins, a class of phenolic compounds abundantly found in plants, have emerged as promising candidates due to their multifaceted biological activities, including antioxidant, anti-inflammatory, and immunomodulatory effects. This review aims to explore the evolving role of coumarins as natural immune boosters with significant therapeutic potential. This goal is achieved by thoroughly looking at how coumarins affect the immune system, their historical uses, their clinical applications, and the challenges in developing them as drugs, showing their ability to influence both innate and adaptive immunity. A literature-based analysis was conducted on the phytochemistry, biosynthesis, and immunological impact of coumarins, supported by in vitro, in vivo , and limited clinical studies. The review highlights key coumarin derivatives and their interactions with immune cells, cytokines, and oxidative stress pathways, while also considering their synergistic effects with conventional drugs. Coumarins influence multiple facets of the immune system by regulating cytokine secretion, enhancing phagocytic activity, and attenuating oxidative stress. Compounds such as umbelliferone, scopoletin, and osthole have demonstrated immunoprotective functions in various disease models. Their traditional use in respiratory and inflammatory disorders aligns with contemporary pharmacological findings. However, poor bioavailability, regulatory ambiguity, and limited clinical data remain major barriers to their therapeutic application. Coumarins represent a potent yet underutilized class of natural immunomodulators. With new delivery methods like nanocarriers and prodrugs, along with thorough clinical testing, they could change the way we treat immune-related diseases and be used alongside other therapies. Interdisciplinary collaboration could be pivotal to translating their potential into real-world treatments.