Structural characterization of polysaccharides from Lygodium japonicum (Thunb.) Sw. and its inhibition ability in calcium oxalate renal stone.

Background: Kidney stone is a prevalent abnormal mineralization disease characterized by high incidence and recurrence rates. Current pharmacological interventions for kidney stone predominantly rely on potassium citrate (PC), yet its clinical efficacy remains limited. Lygodium japonicum (Thunb.) Sw., which possesses both edible and medicinal values, is one of the most commonly used herbs in traditional Chinese medicine for treating urinary tract stones; however, its material basis and underlying mechanisms remain unclear.

Methods: a l. japonicum polysaccharide (LJP) with a molecular weight of 12.9 kDa was obtained through hot-water extraction and purification. The structure of LJP was characterized, and its role in inhibiting kidney stone formation was investigated.

Results: LJP primarily consists of Glc, Gal-UA, Glc-UA, Gal, Rha, and Ara monosaccharides, with the main chain mainly composed of →4)-α-d-Glcp-(1→ linkages, along with minor amounts of →2)-α-d-Glcp-(1→, →2,6)-α-d-Glcp-(1→, →3,6)-β-d-Glcp-(1→, →4,6)-β-d-Glcp-(1→, →3)-α-d-Glcp-(1→. LJP is able to specifically adsorb onto high-energy (1¯01) crystal surfaces to inhibit calcium oxalate monohydrate (COM) growth, significantly reducing crystal size and promoting phase conversion from COM to calcium oxalate dihydrate (COD). Additionally, it effectively inhibits crystal adhesion and endocytosis. LJP also exhibits excellent antioxidant properties, mitigating cellular oxidative stress induced by nano-COM crystals, reducing mitochondrial, lysosomal, and DNA damage, and inhibiting cell apoptosis. In addition, LJP can be effectively enriched in rat kidneys, significantly inhibiting calcium oxalate (CaOx) crystal formation in vivo and reducing renal injury. Metabolomic profiling revealed that LJP mainly affects the citric acid cycle and purine metabolic pathways. Compared to PC, a conventional stone treatment drug, LJP demonstrates superior performance in modulating CaOx crystalline form and cytoprotection.

Conclusion: LJP may serve as a promising therapeutic option for the treatment of renal stones.