# The Urate-Lowering Effects and Renal Protective Activity of Iridoid Glycosides from Paederia foetida in Rats with Hyperuricemia-Induced Kidney Injury: A Pharmacological and Molecular Docking Study

## TL;DR

This study shows that three compounds from Paederia foetida help lower uric acid and protect the kidneys in rats with high uric acid.

## Contribution

The study identifies three iridoid glycosides that promote uric acid excretion and protect against kidney injury through molecular mechanisms.

## Key findings

- The compounds reduced serum urate, creatinine, and blood urea nitrogen levels in hyperuricemia rats.
- They increased uric acid and creatinine excretion while improving renal filtration capacity.
- Molecular docking confirmed the compounds bind to uric acid transporters via multiple interactions.

## Abstract

(1) Background: The urate-lowering effects of three iridoid glycosides, which are paederosidic acid, paederosidic acid methyl ester, and paederoside, isolated from Paederia foetida and the protection they provide against hyperuricemia-induced kidney injury were investigated in a rat model. (2) Methods: A hyperuricemia (HUA) rat model was established in Sprague-Dawley (SD) rats through intraperitoneal potassium oxonate (PO) and intragastrical adenine for 2 weeks. Subsequently, rats in the pharmaceutical intervention groups received corresponding drug treatments at a concentration of 40 mg/kg/day, maintained consistently for 7 days. (3) Results: The results showed that three compounds reduced serum urate (SU), creatinine (CRE), and blood urea nitrogen (BUN) levels and that the urinary excretion levels of uric acid, urine urea nitrogen, and creatinine increased. Furthermore, the administration of three iridoid glycosides enhanced renal filtration capacity, as demonstrated by the elevated 24 h creatinine clearance rate (CCR) and 24 h uric acid clearance rate (CUA); improved the fraction excretion of uric acid (FEUA); and attenuated renal damage. Finally, three iridoid glycosides promoted uric acid excretion in HUA rats by downregulating URAT1 and GLUT9 and upregulating ABCG2, OAT1, and OAT3. Moreover, the molecular docking results further corroborated the finding that the three compounds can bind to multiple sites of the uric acid transporter via hydrogen, P-π, and hydrophobic bonds. (4) Conclusions: The three iridoid glycosides were found to lower SU levels by increasing uric acid excretion. They are promising natural products for the prevention of HUA and HUA-induced kidney injury.