Deciphering the iridoids' boundaries: from soil ecology to anti-inflammatory medicines

Iridoid glycosides (IGs) are monoterpenoids that protect against stress and modulate the immune system. A comprehensive analysis of preclinical and clinical data on IGs' adaptogenic and immunogenic properties, molecular processes, and knowledge gaps was conducted. The study found that oral catalpol, aucubin, geniposide, harpagoside, loganin, and globularifolin can reduce stress and depression by diminishing anhedonia, enhancing corticosterone, BDNF, and decreasing COX 2 levels. IGs also enhance cognition and mitochondrial integrity in diabetes encephalopathy and renal oxidative models by preserving redox equilibrium. Aucubin inhibits LPS-induced lung damage by activating Nrf2/HO-1 via AMPK and suppressing NF-κB and pro-inflammatory cytokines. Geniposide inhibits NF-κB/IκB activation in rats, resulting in anti-inflammatory and immuno-resolving effects on adjuvant arthritis symptoms. Harpagoside and harpagide from Harpagophytum procumbens inhibit LPS or TNF-α-induced cytokine surges and osteoclastogenesis via modulating Syk/NF-κB/RANK. Finally, globularifolin is immunomodulating and cytoprotective, lowering inflammatory markers and boosting THP-1 cell survival. It is recommended that well-designed and adequately powered clinical trials be conducted on people to test the efficacy of IG'S in reducing stress and modulating immune responses. Up order to find new immunogenic and adoptogenic therapeutic leads, this review aims to fill up the gaps between iridoid glycosides and the functional processes by which they work.