Saponarin, a Di-glycosyl Flavone from Barley (Hordeum vulgare L.): An Effective Compound for Plant Defense and Therapeutic Application

Saponarin (SA) is a major di-C-glycosyl-O-glycosyl flavone, which is predominantly accumulated inthe young green leaves of barley (Hordeum vulgare L.), with numerous biological functions in plants, such as protectionagainst environmental stresses. Generally, SA synthesis and its localizationin the mesophyll vacuole or leaf epidermis are largely stimulatedin response to biotic and abiotic stresses to participate in a plant'sdefense response. In addition, SA is also credited for its pharmacologicalproperties, such as the regulation of signaling pathways associatedwith antioxidant and anti-inflammatory responses. In recent years,many researchers have shown the potential of SA to treat oxidativeand inflammatory disorders, such as in protection against liver diseases,and reducing blood glucose, along with antiobesity effects. This reviewaims to highlight natural variations of SA in plants, biosynthesispathway, and SA's role in response to environmental stressand implications in various therapeutic applications. In addition,we also discuss the challenges and knowledge gaps concerning SA useand commercialization.