Protective effect of photodegradation product of nifedipine against tumor necrosis factor alpha-induced oxidative stress in human glomerular endothelial cells

Reverse Phase HPLC Methodology for the Determination of Bay K8644

Following ICH guidelines for analytical validation, we report a common C18 column stability indicating isocratic reverse phase high performance liquid chromatography method for the determination of the ion channel modulator Bay K8644. Two main forced degradation products and a minor impurity were also tentatively identified by Mass Spectrometry. The mobile phase consisted of a 50/50 acetonitrile/buffer mixture at a flow rate of 2 mL/min. Mean retention time for Bay K8644 was 3.030 minutes. Excellent linearity (r = 0.9998) was achieved in the range 0.10-1.40 μg/mL at 274 nm wavelength. Analytical limits were 16.56 ± 1.04 ng/mL for detection and 55.21 ± 3.48 ng/mL for quantitation respectively. Accuracy and precision studies showed good results (95-105%). Robustness was assessed by varying ±3%, both temperature and flow rate. Five different stress conditions were applied to assess Bay K8644's stability. Only basic and photolytic treatments yielded degradation products, both correctly resolved in a total runtime of 4 minutes. In conclusion, we developed a fast, simple, sensitive, accurate, precise, reliable and stability indicating method for detecting/quantifying Bay K8644, and tentatively characterized its main impurities/forced degradation products.

Photodegradation profiling of nitrendipine: evaluation of active pharmaceutical ingredient, tablets and its altered forms

Nitrendipine (NTR) is a dihydropyridine drug, which is well-known as a photodegradable pharmaceutical. However, the photochemical reaction of NTR has not been evaluated in detail from now. In this study, we perform the photodegradation profiling of NTR for the elucidation of its photochemical behavior. NTR amounts during ultraviolet light (UV) irradiation were monitored using high performance liquid chromatography (HPLC). NTR was photodegraded almost completely within 24 h along with the generation of some photoproducts. Structural determination of two NTR photoproducts were carried out by means of electrospray ionization liquid chromatography tandem mass spectrometry (LC-ESI-MS/MS). Obtained results from this study clarified one novel NTR photoproduct, a nitroso pyridine analogue, in addition to a pyridine analogue. Furthermore, photodegradation pathway of NTR was speculated based on chemical structures of NTR photoproducts to clarify its photochemical behavior. It was proposed that a singlet oxygen molecule might withdraw two hydrogen radicals resulting in the form of a pyridine analogue, and the following reduction of its nitro group might produce a nitroso pyridine analogue. Finally, we evaluated the photostability of NTR tablets and its altered forms, indicating that the change of the dosage form led to a decrease of the photostability of NTR tablets. The obtained results will be helpful for the additional research to evaluate the effect of NTR photodegradation on its own biological activities.

The evaluation of photochemical behavior of antihistaminic drug triprolidine in an aqueous media

Photodegradation is widely known as a changer of both the quality and the quantity of several chemical compounds. In this study, we sought to examine the photochemical behavior of triprolidine (TRP), which is a member of the first-generation antihistamine and utilized for a relief of an allergic conditions, in an aqueous media. There are no reports focused on its potential photoproducts and photodegradation pathways in detail to the best of our knowledge. TRP photodegradation induced by ultraviolet light (UV) irradiation was monitored utilizing high-performance liquid chromatography (HPLC), and structural elucidation of the TRP photoproduct was performed by electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) and nuclear magnetic resonance (NMR). Finally, the mechanism of TRP photodegradation was speculated based on the identified photoproduct. TRP was photodegraded dependent on the irradiation time of UV in proportion to the generation of one TRP photoproduct (TRP-P). Structural determination by LC-ESI-MS/MS and NMR clarified that TRP-P was the geometrical isomer of TRP, which was formed by the cis-trans conversion of double bond. UV irradiation experiment for TRP-P revealed the conversion from it to TRP. It is clarified that cis-trans conversion between TRP and TRP-P is photo-equilibrium reaction and TRP-P is predominant under the condition as this experiment. Toxicological potencies of TRP and TRP-P might not be observed by ProTox-II in silico toxicity evaluation. This is the first study evaluating the photochemical behavior of TRP.

Nitrosonisoldipine is a selective inhibitor of inflammatory caspases and protects against pyroptosis and related septic shock

Pyroptosis is a type of acute cell death that mainly occurs in immune cells. It is characterized with robust release of inflammatory cytokines and has emerged to play a critical role in the pathogenesis of sepsis-associated immune disorders. In this study, we screened for pyroptotic inhibitors with the ultimate goal to benefit sepsis treatments. Accidentally, we identified that nitrosonisoldipine (NTS), a photodegradation product of calcium channel inhibitor nisoldipine, inhibits noncanonical pyroptosis. Using murine immortalized BM-derived macrophage and human THP-1 cell line, we further discovered that NTS not only inhibits noncanonical pyroptosis mediated by caspase-11 or caspase-4 but also canonical pyroptosis mediated by caspase-1. Mechanistically, NTS directly inhibits the enzyme activities of these inflammatory caspases, and these inhibitory effects persist despite extensive washout of the drug. By contrast, apoptosis mediated by caspase-3/-7 was not affected by NTS. Mice pretreated with NTS intraperitoneally displayed improved survival rate and extended survival time in LPS- and polymicrobe-induced septic models, respectively. In conclusion, NTS is a selective inhibitor of inflammatory caspases that blocks both the noncanonical and canonical pyroptotic pathways. It is safe for intraperitoneal administration and might be used as a prototype to develop drugs for sepsis treatments.

Topical application of nitrosonifedipine, a novel radical scavenger, ameliorates ischemic skin flap necrosis in a mouse model

Ischemic skin flap necrosis can occur in random pattern flaps. An excess amount of reactive oxygen species is generated and causes necrosis in the ischemic tissue. Nitrosonifedipine (NO-NIF) has been demonstrated to possess potent radical scavenging ability. However, there has been no study on the effects of NO-NIF on ischemic skin flap necrosis. Therefore, they evaluated the potential of NO-NIF in ameliorating ischemic skin flap necrosis in a mouse model. A random pattern skin flap (1.0 × 3.0 cm) was elevated on the dorsum of C57BL/6 mice. NO-NIF was administered by topical injection immediately after surgery and every 24 hours thereafter. Flap survival was evaluated on postoperative day 7. Tissue samples from the skin flaps were harvested on postoperative days 1 and 3 to analyze oxidative stress, apoptosis and endothelial dysfunction. The viable area of the flap in the NO-NIF group was significantly increased (78.30 ± 7.041%) compared with that of the control group (47.77 ± 6.549%, p < 0.01). NO-NIF reduced oxidative stress, apoptosis and endothelial dysfunction, which were evidenced by the decrease of malondialdehyde, p22phox protein expression, number of apoptotic cells, phosphorylated p38 MAPK protein expression, and vascular cell adhesion molecule-1 protein expression while endothelial nitric oxide synthase protein expression was increased. In conclusion, they demonstrated that NO-NIF ameliorated ischemic skin flap necrosis by reducing oxidative stress, apoptosis, and endothelial dysfunction. NO-NIF is considered to be a candidate for the treatment of ischemic flap necrosis.

1,4-Dihydropyridine Derivatives: Dihydronicotinamide Analogues-Model Compounds Targeting Oxidative Stress

Many 1,4-dihydropyridines (DHPs) possess redox properties. In this review DHPs are surveyed as protectors against oxidative stress (OS) and related disorders, considering the DHPs as specific group of potential antioxidants with bioprotective capacities. They have several peculiarities related to antioxidant activity (AOA). Several commercially available calcium antagonist, 1,4-DHP drugs, their metabolites, and calcium agonists were shown to express AOA. Synthesis, hydrogen donor properties, AOA, and methods and approaches used to reveal biological activities of various groups of 1,4-DHPs are presented. Examples of DHPs antioxidant activities and protective effects of DHPs against OS induced damage in low density lipoproteins (LDL), mitochondria, microsomes, isolated cells, and cell cultures are highlighted. Comparison of the AOA of different DHPs and other antioxidants is also given. According to the data presented, the DHPs might be considered as bellwether among synthetic compounds targeting OS and potential pharmacological model compounds targeting oxidative stress important for medicinal chemistry.

[Drug development for cardiorenal disease based on oxidative stress control]

Oxidative stress is a key factor involved in the pathogenesis and progression of cardiovascular disease (CVD) and chronic kidney disease (CKD). Reactive oxygen species (ROS), produced as a result of redox reactions in various cells, have been recognized as key chemical mediators causing cellular damage and organ dysfunction in CVD and CKD. Nifedipine, a well-known calcium channel blocker, is extremely sensitive to light which gets converted to its nitroso analog, nitrosonifedipine (NO-NIF) in the presence of ultraviolet and visible light. The so formed NO-NIF blocks calcium channel quite weakly compared to that of nifedipine. However, we elucidated for the first time that NO-NIF is converted to NO-NIF radical which acquires extremely strong antioxidant property via reaction with unsaturated fatty acid or endothelial cells. We have already reported that NO-NIF reduces the cytotoxicity of cumene hydroperoxide, which hampers the integrity of cell membrane through oxidative stress, in endothelial cells. Additionally, we demonstrated that NO-NIF restored acetylcholine-responsive vascular relaxation and suppressed intercellular adhesion molecule-1 expression in the aorta of N(ω)-nitro-L-arginine methyl ester-treated rats, a model of vascular endothelial dysfunction. Recently, we reported that NO-NIF ameliorates angiotensin II-induced vascular remodeling via antioxidative effects in vivo and in vitro. These observations point towards the plausible, unique role of NO-NIF as a novel antioxidant which improves vascular dysfunction for overcoming CVD and CKD and the same has been highlighted in this review.

Nitrosonifedipine ameliorates the progression of type 2 diabetic nephropathy by exerting antioxidative effects

Diabetic nephropathy (DN) is the major cause of end-stage renal failure. Oxidative stress is implicated in the pathogenesis of DN. Nitrosonifedipine (NO-NIF) is a weak calcium channel blocker that is converted from nifedipine under light exposure. Recently, we reported that NO-NIF has potential as a novel antioxidant with radical scavenging abilities and has the capacity to treat vascular dysfunction by exerting an endothelial protective effect. In the present study, we extended these findings by evaluating the efficacy of NO-NIF against DN and by clarifying the mechanisms of its antioxidative effect. In a model of type 2 DN (established in KKAy mice), NO-NIF administration reduced albuminuria and proteinuria as well as glomerular expansion without affecting glucose metabolism or systolic blood pressure. NO-NIF also suppressed renal and systemic oxidative stress and decreased the expression of intercellular adhesion molecule (ICAM)-1, a marker of endothelial cell injury, in the glomeruli of the KKAy mice. Similarly, NO-NIF reduced albuminuria, oxidative stress, and ICAM-1 expression in endothelial nitric oxide synthase (eNOS) knockout mice. Moreover, NO-NIF suppressed urinary angiotensinogen (AGT) excretion and intrarenal AGT protein expression in proximal tubular cells in the KKAy mice. On the other hand, hyperglycemia-induced mitochondrial superoxide production was not attenuated by NO-NIF in cultured endothelial cells. These findings suggest that NO-NIF prevents the progression of type 2 DN associated with endothelial dysfunction through selective antioxidative effects.

Nitrosonifedipine ameliorates angiotensin II-induced vascular remodeling via antioxidative effects

Nifedipine is unstable under light and decomposes to a stable nitroso analog, nitrosonifedipine (NO-NIF). The ability of NO-NIF to block calcium channels is quite weak compared with that of nifedipine. Recently, we have demonstrated that NO-NIF reacts with unsaturated fatty acid leading to generate NO-NIF radical, which acquires radical scavenging activity. However, the effects of NO-NIF on the pathogenesis related with oxidative stress, such as atherosclerosis and hypertension, are unclear. In this study, we investigated the effects of NO-NIF on angiotensin II (Ang II)-induced vascular remodeling. Ang II-induced thickening and fibrosis of aorta were inhibited by NO-NIF in mice. NO-NIF decreased reactive oxygen species (ROS) in the aorta and urinary 8-hydroxy-20-deoxyguanosine. Ang II-stimulated mRNA expressions of p22(phox), CD68, F4/80, monocyte chemoattractant protein-1, and collagen I in the aorta were inhibited by NO-NIF. Moreover, NO-NIF inhibited Ang II-induced cell migration and proliferation of vascular smooth muscle cells (VSMCs). NO-NIF reduced Ang II-induced ROS to the control level detected by dihydroethidium staining and lucigenin chemiluminescence assay in VSMCs. NO-NIF suppressed phosphorylations of Akt and epidermal growth factor receptor induced by Ang II. However, NO-NIF had no effects on intracellular Ca(2+) increase and protein kinase C-δ phosphorylation induced by Ang II in VSMCs. The electron paramagnetic resonance spectra indicated the continuous generation of NO-NIF radical of reaction with cultured VSMCs. These findings suggest that NO-NIF improves Ang II-induced vascular remodeling via the attenuation of oxidative stress.

Angiotensin II receptor blocker improves tumor necrosis factor-α-induced cytotoxicity via antioxidative effect in human glomerular endothelial cells

BACKGROUND/AIMS

Tumor necrosis factor-α (TNF-α) is known to involve the progression of renal dysfunction through its cytotoxicity and proinflammatory effects such as the induction of intercellular adhesion molecule (ICAM)-1 expression in vascular endothelial cells (ECs). Olmesartan, one of the angiotensin II type 1 receptor blockers (ARBs), has been reported to show protective effects on injured ECs by some causal factors of renal disorder other than angiotensin II. However, the effects of olmesartan on TNF-α-induced glomerular EC damage have not been investigated. In the present study, we investigated the effects of RNH-6270, an active metabolite of olmesartan, on TNF-α-induced human glomerular EC (HGEC) damage to clarify the renoprotective mechanisms of ARBs.

METHODS

Cultured HGECs were stimulated by TNF-α, and then cell viability and cytotoxicity were measured by MTT assay and lactate dehydrogenase release assay, respectively. TNF-α-induced oxidative stress was estimated by dihydroethidium assay and lucigenin chemiluminescence assay. ICAM-1 expression and the phosphorylations of mitogen-activated protein kinases were measured using Western blotting assay.

RESULTS

RNH-6270 suppressed cell death and the increase in ICAM-1 expression induced by TNF-α via the inhibition of reactive oxygen species in HGECs.

CONCLUSION

Our findings suggested that olmesartan might have protective effects against TNF-α-induced glomerular EC dysfunction.

Drug discovery for improvement of chronic kidney disease and cardiovascular disease

Chronic kidney disease (CKD) has been increasingly recognized as a major public health problem in the world. Recent studies have showed that CKD is an independent risk factor for the occurrence of cardiovascular disease (CVD). Reactive oxygen species (ROS), generated by reduction-oxidation actions, have been generated by reduction-oxidation actions, recognized as the important chemical mediators that regulate signal transduction in various cells including vascular smooth muscle cells (VSMC) and mesangial cells (MC). It has been showed that increase in ROS generation may relate to a risk for CVD and CKD. In addition, ROS mediate activation of mitogen-activated protein (MAP) kinases, extracellular signal-regulated kinase 1/2, c-Jun N-terminal kinase, p38, and big MAP kinase 1, in various cells leading to change in gene expressions. Control of the oxidative stress and ROS-mediated alterations of signaling molecules including MAP kinases may provide new therapeutic strategy against CKD and CVD. In this review, we summarize mainly our data regarding the pharmacological effects of renin-angiotensin-aldosterone system blockers, bioflavonoids and adiponectin in VSMC and MC. Also we review the data on a possible new class drug against oxidative stress to improve CKD and CVD.