Benzbromarone mitigates cisplatin nephrotoxicity involving enhanced peroxisome proliferator-activated receptor-alpha (PPAR-α) expression

Drug repurposing and structure-based discovery of new PDE4 and PDE5 inhibitors

Phosphodiesterase-4 (PDE4) and PDE5 responsible for the hydrolysis of intracellular cAMP and cGMP, respectively, are promising targets for therapeutic intervention in a wide variety of diseases. Here, we report the discovery of novel, drug-like PDE4 inhibitors by performing a high-throughput drug repurposing screening of 2560 approved drugs and drug candidates in clinical trial studies. It allowed us to identify eight potent PDE4 inhibitors with IC50 values ranging from 0.41 to 2.46 μM. Crystal structures of PDE4 in complex with four compounds, namely ethaverine hydrochloride (EH), benzbromarone (BBR), CX-4945, and CVT-313, were further solved to elucidate molecular mechanisms of action of these new inhibitors, providing a solid foundation for optimizing the inhibitors to improve their potency as well as selectivity. Unexpectedly, selectivity profiling of other PDE subfamilies followed by crystal structure determination revealed that CVT-313 was also a potent PDE5 inhibitor with a binding mode similar to that of tadalafil, a marketed PDE5 inhibitor, but distinctively different from the binding mode of CVT-313 with PDE4. Structure-guided modification of CVT-313 led to the discovery of a new inhibitor, compound 2, with significantly improved inhibitory activity as well as selectivity towards PDE5 over PDE4. Together, these results highlight the utility of the drug repurposing in combination with structure-based drug design in identifying novel inhibitors of PDE4 and PDE5, which provides a prime example for efficient discovery of drug-like hits towards a given target protein.

Balancing renal Ang-II/Ang-(1-7) by xanthenone; an ACE2 activator; contributes to the attenuation of Ang-II/p38 MAPK/NF-κB p65 and Bax/caspase-3 pathways in amphotericin B-induced nephrotoxicity in rats

Despite the great importance of amphotericin B for the management of life-threatening systemic fungal infections, its nephrotoxic effect restricts its repeated administration. This study was designed to examine the prospective modulatory effects of xanthenone, an ACE2 activator, against amphotericin B nephrotoxicity. Male Wistar rats were allocated into four groups; control (1^st), Xanthenone (2^nd), Amphotericin B (3^rd), and Xanthenone + Amphotericin B (4^th). The second and fourth groups received xanthenone (2 mg/kg; s.c.) daily for 14 consecutive days. Amphotericin B (18.5 mg/kg; i.p.) was administered to the third and fourth groups daily starting from day 8. After 2 weeks, samples were withdrawn for analysis. The histopathological findings, molecular and biochemical markers showed that amphotericin B caused marked renal injury. Pretreatment with xanthenone ameliorated amphotericin B-induced deterioration in kidney function biomarkers (creatinine, urea, cystatin C, KIM-1) and guarded against the disturbance of serum electrolytes (Na⁺, K⁺, Mg²⁺) due to amphotericin B-induced tubular dysfunction. Besides, the ACE2 activator xanthenone-balanced renal Ang-II/Ang-(1-7), and so the inflammatory signaling p38 MAPK/NF-κB p65 and its downstream inflammatory cytokines (TNF-α, IL-6) were attenuated. Meanwhile, the anti-oxidant signaling Nrf2/HO-1 and glutathione content were preserved, but the lipid peroxidation marker MDA was declined. These regulatory effects of xanthenone eventually enhanced Bcl-2 (anti-apoptotic), but reduced Bax (pro-apoptotic) and cleaved caspase-3 (apoptotic executioner) protein expressions. Collectively, the regulatory effects of xanthenone on renal Ang-II/Ang-(1-7) could at least partially contribute to the mitigation of amphotericin B nephrotoxicity by attenuating inflammatory signaling, oxidative stress, and apoptosis, thus improving the tolerability to amphotericin B.

Development of Heterocyclic PPAR Ligands for Potential Therapeutic Applications

The family of nuclear peroxisome proliferator-activated receptors (PPARα, PPARβ/δ, and PPARγ) is a set of ligand-activated transcription factors that regulate different functions in the body. Whereas activation of PPARα is known to reduce the levels of circulating triglycerides and regulate energy homeostasis, the activation of PPARγ brings about insulin sensitization and increases the metabolism of glucose. On the other hand, PPARβ when activated increases the metabolism of fatty acids. Further, these PPARs have been claimed to be utilized in various metabolic, neurological, and inflammatory diseases, neurodegenerative disorders, fertility or reproduction, pain, and obesity. A series of different heterocyclic scaffolds have been synthesized and evaluated for their ability to act as PPAR agonists. This review is a compilation of efforts on the part of medicinal chemists around the world to find novel compounds that may act as PPAR ligands along with patents in regards to PPAR ligands. The structure-activity relationship, as well as docking studies, have been documented to better understand the mechanistic investigations of various compounds, which will eventually aid in the design and development of new PPAR ligands. From the results of the structural activity relationship through the pharmacological and in silico evaluation the potency of heterocycles as PPAR ligands can be described in terms of their hydrogen bonding, hydrophobic interactions, and other interactions with PPAR.

Hypouricemic effect of 2,4-dihydroxybenzoic acid methyl ester in hyperuricemic mice through inhibiting XOD and down-regulating URAT1

In this paper, we reported the hypouricemic effect of 2,4-dihydroxybenzoic acid methyl ester (DAE), a component of Ganoderma applanatum, in hyperuricemic mice through inhibiting XOD and down-regulating URAT1. Computationally, DAE showed a high similarity to allopurinol and depicted a high affinity in docking to XOD. In vitro, DAE exhibited an inhibitory effect against XOD. Importantly, DAE demonstrated a remarkable hypouricemic effect, decreasing serum uric acids (SUAs) of hyperuricemic mice (407 ± 31 μmol/L) to 195 ± 23, 145 ± 33 and 134 ± 16 μmol/L (P < 0.01) at the doses of 20, 40, and 80 mg/kg with a dose-dependent manner and showing efficacies at 54-68 %, which were close to the efficacies of allopurinol (61 %) and benzbromarone (57 %). DAE depicted higher and negatively dose-independent urinary uric acids in comparison with that of the hyperuricemic control, implying DAE exerted an uricosuric effect and also a reduction effect on uric acid production. Unlike toxic allopurinol and benzbromarone, no general toxicity on body weights and no negative influence on liver, kidney, spleen and thymus were observed for DAE. Mechanistically, DAE inhibited XOD activities in vivo. Moreover, DAE up-regulated OAT1 and down-regulated GLUT9, URAT1 and CNT2. Overall, DAE may present a hypouricemic effect through inhibiting XOD and up-regulating OAT1 and down-regulating GLUT9, URAT1 and CNT2. This work provided novel insights into the hypouricemic effect of DAE and G. applanatum.

Renoprotective effect of vinpocetine against ischemia/reperfusion injury: Modulation of NADPH oxidase/Nrf2, IKKβ/NF-κB p65, and cleaved caspase-3 expressions

Ischemia/reperfusion injury (IRI) during kidney transplantation is a serious clinical problem with a high mortality rate and a lack of therapy. Therefore, there is a need to improve the ability of the kidney to tolerate IRI during transplantation. This study aimed to investigate the possible protective effect of vinpocetine; a derivative of vincamine alkaloid; against renal IRI in rats with the elucidation of the involved mechanisms. Vinpocetine (25 mg/kg; i.p.) was administered for 10 successive days before the induction of ischemia by bilateral clamping of both renal pedicles for 45 min followed by 24 h of reperfusion. Blood and renal tissue samples were then collected for biochemical, molecular, and histopathological investigations. Vinpocetine significantly reduced serum creatinine and blood urea nitrogen levels in rats subjected to IRI. It also reduced mRNA expression of NADPH oxidase and renal content of malondialdehyde, while enhanced Nrf2 protein expression and renal content of reduced glutathione. The suppression of the provoked inflammatory response was evident by the downregulation of IKKβ and NF-κB p65 protein expressions, as well as their downstream inflammatory markers; tumor necrosis factor-α, interleukin-6, and myeloperoxidase. In addition, vinpocetine reduced protein expression of the apoptotic executioner cleaved caspase-3. These nephroprotective effects were confirmed by the improvement in histopathological features. Collectively, the protective effect of vinpocetine against IRI could be attributed to modulation of NADPH oxidase/Nrf2, IKKβ/NF-κB p65, and cleaved caspase-3 expressions. Thus, vinpocetine could improve oxidant/antioxidant balance, suppress triggered inflammatory response, and promote renal cell survival after IRI.

A Case of Recent Liver Injury Induced by Benzbromarone

A 39-year-old male had a stomachache for 10 days before abnormal liver function tests were detected by a local doctor. Then, he was referred to us and admitted to our hospital for examination and treatment of elevated transaminases. He had taken benzbromarone to treat his hyperuricemia for seven months, and we diagnosed him with benzbromarone-induced liver injury. After the termination of benzbromarone, he finally recovered from his illness. There are several reports about benzbromarone-induced liver injury. In conclusion, as periodic liver function tests seem not to be completely performed, clinicians should regularly monitor liver function tests in patients taking benzbromarone.

Nuclear receptors in renal health and disease

As a major social and economic burden for the healthcare system, kidney diseases contribute to the constant increase of worldwide deaths. A deeper understanding of the underlying mechanisms governing the etiology, development and progression of kidney diseases may help to identify potential therapeutic targets. As a superfamily of ligand-dependent transcription factors, nuclear receptors (NRs) are critical for the maintenance of normal renal function and their dysfunction is associated with a variety of kidney diseases. Increasing evidence suggests that ligands for NRs protect patients from renal ischemia/reperfusion (I/R) injury, drug-induced acute kidney injury (AKI), diabetic nephropathy (DN), renal fibrosis and kidney cancers. In the past decade, some breakthroughs have been made for the translation of NR ligands into clinical use. This review summarizes the current understanding of several important NRs in renal physiology and pathophysiology and discusses recent findings and applications of NR ligands in the management of kidney diseases.

Antioxidant and Anti-inflammatory Properties Mediate the Neuroprotective Effects of Hydro-ethanolic Extract of Tiliacora triandra Against Cisplatin-induced Neurotoxicity

Background

Cisplatin (CDDP) is an efficacious anticancer agent used widely in chemotherapy despite its severe side effect related to neurotoxicity. Redox imbalance and inflammatory mechanism have been implicated in the pathophysiology of CDDP-induced neurotoxicity. Herein, we investigated whether Tiliacora triandra (TT) extract could inhibit  CDDP-induced redox-mediated neurotoxicity and behavioural deficit in rats.

Materials and Methods

CDDP-induced redox-mediated neurotoxicity and behavioral deficit in rats. Rats were administered TT for five consecutive weeks (250 and 500 mg/kg bw), while weekly i.p. injection of CDDP commenced on the second week (2.5 mg/kg bw) of the TT administration.

Results

CCDDP caused significant body weight reduction and cognitive diminution as revealed by Morris water maze and Y maze tests. In the CDDP-induced cognitive impairment (CICI) rats, there were remarkable increases in the brain levels of TNF-α, IL-6 and IL-1β and malondialdehyde (MDA), whereas catalase (CAT), glutathione (GSH), glutathione peroxidase (GPx) and superoxide dismutase (SOD) activities considerably decreased compared to normal control. The brain acetylcholinesterase (AChE) activity in CDDP control rats was significantly increased compared to the normal control. The expression of caspase-3 and p53 proteins was upregulated by CDDP injection, whereas Bcl2 was downregulated coupled with histopathological alterations in the rat brain. Interestingly, treatment with TT significantly abated neurobehavioral deficits, MDA and cytokine levels and restored CAT, GPx, GSH, SOD, and AChE activities compared to the CDDP control rats. Caspase-3 level as well as Bcl2 and p53 expressions were modulated with alleviated changes in histopathology.

Conclusion

The findings highlight neuroprotective and cognitive function improvement efficacy of TT against CICI via redox-inflammatory balance and antiapoptotic mechanism in rats.

TRPA1 promotes cisplatin-induced nephrotoxicity through inflammation mediated by the MAPK/NF-κB signaling pathway

Background

The nephrotoxicity induced by cisplatin (DDP) has been a severe obstacle for its clinical use in anticancer treatment. The apoptosis and inflammation induced by DDP are the main causes of the nephrotoxicity. Transient receptor potential ankyrin 1 (TRPA1) is a non-selective cation ligand-gated channel that is involved in the inflammation progress.

Methods

The apoptosis, inflammation, MAPK/NF-κB signaling pathway, and TRPA1 expression were assessed after HEK293 cells had been induced by DDP, and the role of TRPA1 in apoptosis and inflammation of DDP-induced HEK293 cells treated with TRPA1 antagonist HC-030031 was also evaluated by quantitative reverse transcription-polymerase chain reaction (qRT-PCR), flow cytometry, and western blot assays.

Results

The cell viability was reduced by DDP in both a time-dependent and dose-dependent manner with a minimal cytotoxic concentration of 10 μM. Moreover, DDP induced an enhancement of the apoptosis and inflammation in a dose-dependent manner, as indicated by the increase of the relative protein level of cleaved-caspase3 (cleaved-cas3), the cleavage product of caspase-3 substrate poly-ADP-ribose polymerase (cleaved-PARP) and inducible nitric oxide synthase (iNOS), and the messenger RNA (mRNA) expression level of interleukin (IL)-1β, IL-6, tumor necrosis factor-α (TNF-α), and interferon-γ (INF-γ). Additionally, DDP treatment increased the protein phosphorylation expression of IKKβ, JNK, ERK, and p38 in a dose-dependent manner, which was antagonized by the treatment of NF-κB-specific inhibitor BAY 11-7082 and pan-MAPK inhibitor U0126. It was also found that DDP upregulated the expression of TRPA1 at both the mRNA and protein levels in a dose-dependent manner. Besides, block of TRPA1 with HC-030031 relieved the apoptosis, diminished the level of IL-1β, IL-6, TNF-α, and INF-γ, reduced the level of cleaved-cas3, cleaved-PARP, and iNOS, decreased the p-IKKβ, p-JNK, p-ERK, and p-p38 expression, and enhanced the expression of IκBα.

Conclusions

Taken together, these results indicate that TRPA1 regulates DDP-induced nephrotoxicity via inflammation mediated by the MAPK/NF-κB signaling pathway in HEK293 cells.

Protective Effect of 20(R)-Ginsenoside Rg3 Against Cisplatin-Induced Renal Toxicity via PI3K/AKT and NF-[Formula: see text]B Signaling Pathways Based on the Premise of Ensuring Anticancer Effect

Although the protective effect of ginsenoside on cisplatin-induced renal injury has been extensively studied, whether ginsenoside interferes with the antitumor effect of cisplatin has not been confirmed. In this paper, we verified the main molecular mechanism of 20(R)-ginsenoside Rg3 (R-Rg3) antagonizing cisplatin-induced acute kidney injury (AKI) through the combination of in vivo and in vitro models. It is worth mentioning that the two cell models of HK-2 and HepG2 were used simultaneously for the first time to explore the effect of the activation site of tumor-associated protein p53 on apoptosis and tumor suppression. The results showed that a single injection of cisplatin (20 mg/kg) led to weight loss, the kidney index of the mice increased, and creatinine (CRE) and blood urea nitrogen (BUN) levels in mice sharply increased. Continuous administration of R-Rg3 at doses of 10 and 20 mg/kg for 10 days could significantly alleviate this symptom. Similarly, R-Rg3 treatment reduced oxidative stress damage caused by cisplatin. Moreover, R-Rg3 could observably reduce the apoptosis and inflammatory infiltration of renal tubular cells induced by cisplatin. We used western blotting analysis to demonstrate that R-Rg3 restored cisplatin-induced AKI might be related to PI3K/AKT and NF-[Formula: see text]B mediated apoptosis and inflammation pathways. In the meantime, we also verified that R-Rg3 could activate different sites of p53 to control renal cell apoptosis induced by cisplatin without affecting its antitumor effect.

Synergistic protective effects of lycopene and N-acetylcysteine against cisplatin-induced hepatorenal toxicity in rats

Cisplatin (CP) is one of the most frequently used chemotherapy agents. The objective of this design was to determine the ameliorative effect of lycopene (LP) and/or N-acetylcysteine (NAC) in rats with hepatic and renal toxicity induced by CP. Rats were divided randomly into 7 groups (7 rats/group): control vehicle group (saline only), the LP group (10 mg/kg, orally), the NAC group (150 mg/kg, orally), the CP group (7.5 mg/kg, IP on day 27), the LP-CP group, the NAC-CP group, and the LP-NAC-CP group. The activities of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (APK), and levels of urea, creatinine, and lipids (cholesterol, triglycerides, and low-density lipoprotein-cholesterol) increased after CP injection in the serum. Moreover, CP decreased levels of protein, albumin, and HDL cholesterol. Meanwhile, malondialdehyde significantly increased with a decrease in reduced glutathione, superoxide dismutase, and catalase in the liver and kidney tissues. CP also induced some pathological lesions and increased the expression of caspase-3 in the liver and kidney tissues. Administration of LP and NAC alone or in combinations ameliorated hepatorenal toxicity and apoptosis induced by CP.

Amlodipine alleviates cisplatin-induced nephrotoxicity in rats through gamma-glutamyl transpeptidase (GGT) enzyme inhibition, associated with regulation of Nrf2/HO-1, MAPK/NF-κB, and Bax/Bcl-2 signaling

BACKGROUND

The therapeutic utility of the effective chemotherapeutic agent cisplatin is hampered by its nephrotoxic effect. We aimed from the current study to examine the possible protective effects of amlodipine through gamma-glutamyl transpeptidase (GGT) enzyme inhibition against cisplatin nephrotoxicity.

METHODS

Amlodipine (5 mg/kg, po) was administered to rats for 14 successive days. On the 10th day, nephrotoxicity was induced by a single dose of cisplatin (6.5 mg/kg, ip). On the last day, blood samples were collected for estimation of kidney function, while kidney samples were used for determination of GGT activity, oxidative stress, inflammatory, and apoptotic markers, along with histopathological evaluation.

RESULTS

Amlodipine alleviated renal injury that was manifested by significantly diminished serum creatinine and blood urea nitrogen levels, compared to cisplatin group. Amlodipine inhibited GGT enzyme, which participates in the metabolism of extracellular glutathione (GSH) and platinum-GSH-conjugates to a reactive toxic thiol. Besides, amlodipine diminished mRNA expression of NADPH oxidase in the kidney, while enhanced the anti-oxidant defense by activating Nrf2/HO-1 signaling. Additionally, it showed marked anti-inflammatory response by reducing expressions of p38 mitogen-activated protein kinase (p38 MAPK) and nuclear factor-kappa B (NF-κB), with subsequent down-regulation of tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and vascular cell adhesion molecule-1 (VCAM-1). Moreover, amlodipine reduced Bax/Bcl-2 ratio and elevated hepatocyte growth factor (HGF), thus favoring renal cell survival.

CONCLUSIONS

Effective GGT inhibition by amlodipine associated with enhancement of anti-oxidant defense and suppression of inflammatory signaling and apoptosis support our suggestion that amlodipine could replace toxic GGT inhibitors in protection against cisplatin nephrotoxicity.

L-Carnitine Mitigates Oxidative Stress and Disorganization of Cytoskeleton Intermediate Filaments in Cisplatin-Induced Hepato-Renal Toxicity in Rats

Cisplatin (CP) is one of the most active medications in cancer treatment and has some adverse effects such as hepatotoxicity and nephrotoxicity. The present research was planned to determine the protective effects of L-carnitine (LC) against CP-induced hepato-renal oxidative stress in rats, via investigating of some serum biochemical and tissue oxidative/antioxidant parameters, histological alterations, and immunohistochemical expressions of two different intermediate filaments (IFs) proteins; vimentin (VIM) and cytokeratin 18 (CK18). Twenty-eight rats were divided into four groups (7 rats each). Groups I and II were orally administered saline and LC (100 mg/kg body weight), respectively, once daily for 30 consecutive days. Group III received saline orally once daily and a single dose of CP on the 27th day of the experiment [7.5 mg/kg, intraperitoneal (IP)]. Group IV received both LC and CP. Injection of CP significantly (P ≤ 0.05) increased serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP) activities and creatinine and urea levels, while serum total protein, albumin, and globulin concentrations significantly (P ≤ 0.05) decreased. In addition, CP induced a dramatic increase in the Malondialdehyde (MDA) level along with a substantial decrease in reduced glutathione (GSH) and catalase (CAT) in the hepato-renal tissues. Histologically, both liver and kidney of the CP treated group revealed marked degenerative changes. Moreover, overexpression of both VIM and CK18 in hepato-renal tissues were noted after CP injection. On the other hand, the administration of LC in the CP injected group (Group IV) restored the biochemical parameters, histological, and immunohistochemical pictures toward the normalcy. In conclusion, LC may be supplemented for chemotherapy with CP to ameliorate its oxidative stress and restore the normal organization of IFs, especially VIM and CK18 within the CP intoxicated hepato-renal cells.