Effects of Osthol Isolated from Cnidium monnieri Fruit on Urate Transporter 1.

(1) Background: Crude drugs used in traditional Japanese Kampo medicine or folk medicine are major sources of new chemical entities for drug discovery. We screened the inhibitory potential of these crude drugs against urate transporter 1 (URAT1) to discover new drugs for hyperuricemia. (2) Methods: We prepared the MeOH extracts of 107 different crude drugs, and screened their inhibitory effects on URAT1 by measuring the uptake of uric acid by HEK293/PDZK1 cells transiently transfected with URAT1. (3) Results: We found that the extract of the dried mature fruit of Cnidium monnieri inhibited urate uptake via URAT1. We isolated and identified osthol as the active ingredient from this extract. Osthol noncompetitively inhibited URAT1 with an IC50 of 78.8 µM. We evaluated the effects of other coumarins and found that the prenyl group, which binds at the 8-position of coumarins, plays an important role in the inhibition of URAT1. (4) Conclusions: Cnidium monnieri fruit may be useful for the treatment of hyperuricemia or gout in traditional medicine, and its active ingredient, osthol, is expected to be a leading compound for the development of new drugs for hyperuricemia.

Pharmacokinetics and pharmacodynamics following intravenous administration of recombinant human hepatocyte growth factor in rats with renal injury.

BACKGROUND/AIM: Hepatocyte growth factor (HGF) plays a role in the regeneration and protection of the kidney, but little information is available concerning the pharmacokinetics of therapeutic treatment with HGF. In this study, HGF was administered after the onset of renal injury, and pharmacokinetic analysis was performed simultaneously with an efficacious dose. METHODS: For the study of pharmacodynamics, recombinant human HGF was intravenously administered to rats with glycerol-induced acute kidney injury (AKI). In the pharmacokinetic study, rats subjected to glycerol injection or renal ischemia-reperfusion were used as models of AKI, and rats subjected to 5/6 nephrectomy were used as models of chronic kidney disease (CKD). RESULTS: After intravenous administration of HGF at doses of 0.5-2.0 mg/kg, the elevation of blood urea nitrogen was suppressed, indicating that HGF had a pharmacodynamic effect. However, no significant difference was seen in the pharmacokinetic parameters such as clearance, distribution volume and half-life between the normal, AKI and CKD groups. CONCLUSION: The intravenous administration of HGF after the onset of renal dysfunction exerted a pharmacological effect on AKI, and renal injury did not affect the clearance of plasma HGF. This unaffected profile may serve as a base for the safety of HGF during therapeutic administration.

Carnitine/organic cation transporter 1 precipitates the progression of interstitial fibrosis through oxidative stress in diabetic nephropathy in mice.

Carnitine/organic cation transporter 1 (OCTN1) is the only known uptake transporter for ergothioneine which is a food-derived strong antioxidant amino acid that is absorbed by OCTN1. We previously reported the roles of OCTN1/ergothioneine in the progression of kidney fibrosis in ischemic kidney disease. In this study, we evaluated the roles of OCTN1 in the progression of diabetic kidney disease. A diabetic kidney disease model was induced in octn1 knockout and wild-type mice by streptozotocin (STZ). Oxidative stress, represented by urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG), were higher in the octn1 knockout mice. Azan- and Sirius red-positive areas increased significantly in the octn1 knockout mice. Gene expression was evaluated by cluster analysis, and shown to be different in the octn1 knockout mice compared with the wild-type mice. In a pathway analysis, the pathway associated with the cytoskeleton and cell adhesion increased. In accordance with interstitial fibrosis in octn1 knockout mice, gene expression of moesin in the injured kidney, known as an associated protein of cytoskeleton and cell membranes, was doubled 28 weeks after STZ injection. In addition, the moesin protein was expressed in a part of α-SMA-positive renal tubular epithelial cells. These findings were confirmed by cultured murine proximal tubular epithelial cells: The expression of moesin was induced under oxidative stress with hydrogen peroxide. These data indicate that OCTN1 would play some roles in progression of interstitial fibrosis under oxidative stress via moesin expression in diabetic kidney disease.