Hypouricemic effect of gallic acid, a bioactive compound from Sonneratia apetala leaves and branches, on hyperuricemic mice

As a tropical medicinal plant, Sonneratia apetala is mainly distributed in the southeast coastal areas of China. Recently, the hypouricemic effect of Sonneratia apetala leaves and branches (SAL) has been reported, but the active compound and its mechanism are unclear. Thus, this study aims to explore the effective fraction of SAL and the mechanism of its active compound on uric acid formation and excretion. SAL was extracted with ethyl acetate and concentrated to obtain solvent-free extracts (SAL-EA). The remains fraction (SAL-E) and the supernatant fraction (SAL-S) of SAL resulting from water extraction and alcohol precipitation were collected and dried. The effects of different fractions were explored on hyperuricemic mice. SAL-S showed excellent activities in decreasing the levels of uric acid (UA), blood urea nitrogen (BUN), and creatinine (CRE) in serum and in attenuating kidney damage. Then, the active compound gallic acid (GA) identified by HPLC was assayed for its mechanism of regulating uric acid metabolism in hyperuricemic mice. The hypouricemic effect of GA was probably associated with the downregulation of URAT1 and GLUT9, upregulation of ABCG2 and decreased activities of adenosine deaminase (ADA) and xanthine oxidase (XOD). Moreover, GA suppressed the level of MDA, IL-6, IL-1β, TNF-α, TGF-β1, COX-2 and cystatin-C (Cys-C), and enhanced the activities of SOD, GSH-Px, CAT, and Na⁺-K⁺-ATPase (NKA) in the kidneys. These results indicated that GA protects against hyperuricemia-induced kidney injury via suppressing oxidative stress and inflammation as well as decreasing the serum levels of UA by regulating urate transporters.

A brief review of urate transporter 1 (URAT1) inhibitors for the treatment of hyperuricemia and gout: Current therapeutic options and potential applications

Hyperuricemia is a common metabolic condition, cause by increased levels of serum urate (SUA). Reduced excretion of uric acid is reported as the key factor of primary hyperuricemia, accounting for approximately 90% of the cases. Urate transporter 1 (URAT1) is a major protein involved in uric acid reabsorption (about 90%). Therefore, URAT1 inhibitors are considered to be a highly effective and promising class of uricosuric agents for treating hyperuricemia. This review summarizes the development of URAT1 inhibitors for the treatment of hyperuricemia, including approved URAT1 inhibitors, URAT1 inhibitors under development in clinical trials, substances with URAT1 inhibitory effects from derivatives and natural products, and conventional drugs with new uses. This review provides new ideas regarding research on URAT1 inhibitors by introducing the structure, properties, and side effects of chemical drugs, as well as the sources and categories of natural drugs. We also discuss new mechanisms of classic drugs, which may provide guidance to many practicing clinicians. The research and discovery of new inhibitors remain in full swing, and tremendous developments are expected in the field.

Novel Human Urate Transporter 1 Inhibitors as Hypouricemic Drug Candidates with Favorable Druggability

Lesinurad, a human urate transporter 1 (URAT1) inhibitor approved as a medication for the treatment of hyperuricemia associated with gout in 2015, can cause liver and renal toxicity. Here, we modified all three structural components of lesinurad by applying scaffold hopping, bioisosterism, and substituent-decorating strategies. In a mouse model of acute hyperuricemia, 21 of the synthesized compounds showed increased serum uric acid (SUA)-reducing activity; SUA was about 4-fold lower in animals treated with 44, 54, and 83 compared with lesinurad or benzbromarone. In the URAT1 inhibition assay, 44 was over 8-fold more potent than lesinurad (IC₅₀: 1.57 μM vs 13.21 μM). Notably, 83 also displayed potent inhibitory activity (IC₅₀ = 31.73 μM) against GLUT9. Furthermore, we also preliminarily explored the effect of chirality on the potency of the promising derivatives 44 and 54. Compounds 44, 54, and 83 showed favorable drug-like pharmacokinetics and appear to be promising candidates for the treatment of hyperuricemia and gout.

Recent approaches to gout drug discovery: an update

INTRODUCTION

Inflammation induced by urate deposition in joints causes gout. Healthy individuals maintain serum levels of urate by balancing urate production/excretion, whereas a production/excretion imbalance increases urate levels. Hyperuricemia is diagnosed when the serum urate level is continuously above 7 mg/dl as the solubility limit, and urate accumulates in the kidneys and joints. Because hyperuricemia increases the risk of gout, therapies aim to eliminate urate deposition to prevent gouty arthritis and kidney injury.

AREAS COVERED

This review discusses the mechanism underlying hyperuricemia with respect to urate production and urate transport, along with urate-lowering therapeutics, including urate synthesis inhibitors, uricolytic enzymes, and uricosuric agents. The authors asses published data on relevant commercial therapy development projects and clinical trials.

EXPERT OPINION

Available treatment options for hyperuricemia are limited. Allopurinol, a urate synthesis inhibitor, is generally administered at a reduced dosage to patients with renal impairment. Some URAT1 inhibitors have an unfavorable side effect profile. A promising strategy for treatment is the use of uricosuric agents that inhibit transporters (e.g. URAT1, URATv1/GLUT9, OAT10) which reabsorb urate from the urine.

Physiology of Hyperuricemia and Urate-Lowering Treatments

Gout is the most common form of inflammatory arthritis and is a multifactorial disease typically characterized by hyperuricemia and monosodium urate crystal deposition predominantly in, but not limited to, the joints and the urinary tract. The prevalence of gout and hyperuricemia has increased in developed countries over the past two decades and research into the area has become progressively more active. We review the current field of knowledge with emphasis on active areas of hyperuricemia research including the underlying physiology, genetics and epidemiology, with a focus on studies which suggest association of hyperuricemia with common comorbidities including cardiovascular disease, renal insufficiency, metabolic syndrome and diabetes. Finally, we discuss current therapies and emerging drug discovery efforts aimed at delivering an optimized clinical treatment strategy.

The development of an effective synthetic route of lesinurad (RDEA594)

Background

Lesinurad is a novel selective uric acid salt transport protein 1 (URAT1) inhibitor which is approved in the USA for the treatment of gout. However, there are some shortcomings among the reported synthetic routes, such as expensive materials, environmental pollution and poor yield.

Results

In this study, an efficient, practical and environmentally-friendly synthetic route of lesinurad is reported. The main advantages of this route include inexpensive starting materials, mild conditions and acceptable overall yield (38.8%).

Conclusion

Generally, this procedure is reasonable, reliable and suitable for industrial production.Graphical abstract

The discovery and evaluation of diaryl ether heterocyclic sulfonamides as URAT1 inhibitors for the treatment of gout

A series of acidic heterocyclic sulfonamides that are potent and selective URAT1 inhibitors is described.