Ischemia-reperfusion damage is attenuated by GQ-11, a peroxisome proliferator-activated receptor (PPAR)-α/γ agonist, after aorta clamping in rats.

INTRODUCTION: Ischemia-Reperfusion (I/R) damage is one of the major challenges in cardiothoracic surgeries and in a pathological manner, is identified by exacerbated damage signals resulted from blood supply restriction and subsequent flow restoration and re­oxygenation. I/R damage includes cellular dysfunction and death, impairing tissue and organ function. Inflammation and oxidative stress are known to underlie either ischemia or reperfusion, leaded by HIF, TNF-α, NF-κB, IL-6 and ROS formation. However, the available approaches to prevent I/R damage has been unsuccessful so far. As agonists of peroxisome-proliferation activation receptor (PPAR) are described as transcription factors related to anti-inflammatory factors, we proposed to observe the effects of novel dual agonist, GQ-11, in I/R-related damage. METHODS: Male, Wistar rats, 60 days age and 305 g body weight average were treated with vehicle, pioglitazone or GQ-11 (20 mg/kg) for 7 consecutive days and were submitted to aorta clamping for 30 min followed by 3 h of reperfusion. 18F-fluorodeoxyglucose (18F-FDG), an analog of glucose associated with inflammation when accumulated, was observed in liver and bowel by positron emission tomography (PET). RESULTS: GQ-11 decreased 18F-FDG uptake in liver and bowel when compared to vehicle and pioglitazone. The treatment also modulated inflammatory markers IL-10, TGF-ß, IL-6, IL1-ß, TNFα, and CCL-2, besides antioxidant enzymes such as catalase, GPx and SOD. CONCLUSION: Inflammation and oxidative stress showed to be important processes to be regulated in I/R in order to prevent exacerbated responses that leads to cell/tissue dysfunction and death. PPAR agonists - including GQ-11 - might be promising agents in a strategy to avoid tissue dysfunction and death after cardiothoracic surgeries.

New Pioglitazone Metabolites and Absence of Opened-Ring Metabolites in New N-Substituted Thiazolidinedione.

Thiazolidinediones (TZDs) are drugs used to treat type 2 diabetes mellitus; however, several safety concerns remain regarding the available drugs in this class. Therefore, the search for new TZD candidates is ongoing; metabolism studies play a crucial step in the development of new candidates. Pioglitazone, one of the most commonly used TZDs, and GQ-11, a new N-substituted TZD, were investigated in terms of their metabolic activity in rat and human liver microsomes to assess their metabolic stability and investigate their metabolites. Methods for preparation of samples were based on liquid-liquid extraction and protein precipitation. Quantitation was performed using liquid chromatography (LC)-tandem mass spectrometry, and the metabolite investigation was performed using ultraperformance LC coupled to a hybrid quadrupole-time of flight mass spectrometer. The predicted intrinsic clearance of GQ-11 was 70.3 and 46.1 ml/kg per minute for rats and humans, respectively. The predicted intrinsic clearance of pioglitazone was 24.1 and 15.9 ml/kg per minute for rats and humans, respectively. The pioglitazone metabolite investigation revealed two unpublished metabolites (M-D and M-A). M-A is a hydration product and may be related to the mechanism of ring opening and the toxicity of pioglitazone. The metabolites of GQ-11 are products of oxidation; no ring-opening metabolite was observed for GQ-11. In conclusion, under the same experimental conditions, a ring-opening metabolite was observed only for pioglitazone. The resistance of GQ-11 to the ring opening is probably related to N-substitution in the TZD ring.

PPARγ partial agonist GQ-16 strongly represses a subset of genes in 3T3-L1 adipocytes.

Thiazolidinediones (TZDs) are peroxisome proliferator-activated receptor gamma (PPARγ) agonists that improve insulin resistance but trigger side effects such as weight gain, edema, congestive heart failure and bone loss. GQ-16 is a PPARγ partial agonist that improves glucose tolerance and insulin sensitivity in mouse models of obesity and diabetes without inducing weight gain or edema. It is not clear whether GQ-16 acts as a partial agonist at all PPARγ target genes, or whether it displays gene-selective actions. To determine how GQ-16 influences PPARγ activity on a gene by gene basis, we compared effects of rosiglitazone (Rosi) and GQ-16 in mature 3T3-L1 adipocytes using microarray and qRT-PCR. Rosi changed expression of 1156 genes in 3T3-L1, but GQ-16 only changed 89 genes. GQ-16 generally showed weak effects upon Rosi induced genes, consistent with partial agonist actions, but a subset of modestly Rosi induced and strongly repressed genes displayed disproportionately strong GQ-16 responses. PPARγ partial agonists MLR24 and SR1664 also exhibit disproportionately strong effects on transcriptional repression. We conclude that GQ-16 displays a continuum of weak partial agonist effects but efficiently represses some negatively regulated PPARγ responsive genes. Strong repressive effects could contribute to physiologic actions of GQ-16.

Validation of a UV-spectrophotometric analytical method for determination of LPSF/AC04 from inclusion complex and liposomes

The aim of this study was to develop and validate a UV spectrophotometric method for determination of LPSF/AC04 from inclusion complex and encapsulated into liposomes. The validation parameters were determined according to the International Conference on Harmonisation (ICH) and National Health Surveillance Agency (ANVISA) guidelines. LPSF/AC04 was determined at 250 nm in methanol by a UV spectrophotometric method, exhibiting linearity in the range from 0.3 to 2 µg.mL−1 (Absorbance=0.18068 x [LPSF/AC04 µg.mL-1] + 0.00348), (r2=0.9995). The limits of detection and quantification were 0.047µg.mL−1 and 0.143µg.mL−1, respectively. The method was accurate, precise, reproducible and robust since all the samples analyzed had coefficient of variation of less than 5% and no statistically significant difference between theoretical and practical concentrations was detected. Thus, a rapid, simple, low cost and sensitive spectrophotometric method was developed and validated for determining the content of inclusion complex and liposomes containing LPSF/AC04.

O objetivo deste estudo foi desenvolver e validar um método espectrofotométrico para determinação do LPSF/AC04 em complexo de inclusão e encapsulado em lipossomas. Os parâmetros de validação foram determinados de acordo com o International Conference on Harmonisation (ICH) e Agência Nacional de Vigilância Sanitária (ANVISA). OLPSF/AC04 foi determinado a 250 nm em metanol pelo método espectrofotométrico UV, que apresenta linearidade na faixa de 0,3 a 2 µg/mL (Absorbância = 0,18068 x [LPSF/AC04 µg/mL] + 0,00348), (r2 = 0,9995). Os limites de detecção e quantificação foi 0,047 µg/mL e 0,143 µg/mL, respectivamente. O método foi exato, preciso, reprodutível e robusto e todas as amostras analisadas apresentaram coeficiente de variação menor que 5% e não houve diferença estatisticamente significante entre a concentração teórica e a prática. Assim, um método espectrofotométrico rápido, simples, sensível e de baixo custo foi desenvolvido e validado para determinar o conteúdo do LPSF/AC04 em complexos de inclusão e encapsulados em lipossomas.

Chemical synthesis, docking studies and biological effects of a pan peroxisome proliferator-activated receptor agonist and cyclooxygenase inhibitor.

The compound (5Z)-5-[(5-bromo-1H-indol-3-yl)methylene]-3-(4-chlorobenzyl)-thiazolidine-2,4-dione (LYSO-7) was synthesised in order to obtain a new type of anti-inflammatory drug, designed with hybrid features to inhibit cyclooxygenase (COX) and also to activate peroxisome proliferator-activated receptor (PPAR). Results obtained from docking (in silico) studies corroborated with experimental data, showing the potential affinity between the studied ligand and targets. The specificity of LYSO-7 for COX-enzymes was detected by the inhibition of COX-1 and COX-2 activities by 30% and 20%, respectively. In transactivation reporter gene assays LYSO-07 showed a pan partial agonist effect on the three PPAR subtypes (PPARγ, PPARα and PPARß/δ). The agonist action on PPARγ was also observed by a pharmacological approach, as the reduction in the Escherichia coli lipopolysaccharide (LPS)-induced interleukin 1 beta (IL-1ß) secretion and nitric oxide (NO) production by mouse neutrophils was blocked by GW9962, a specific PPARγ antagonist. Additionally, the in vivo effect was measured by reduced carrageenan-induced neutrophil influx into the subcutaneous tissue of mice. Taken together, these data show that LYSO-7 displays a potent in vivo anti-inflammatory effect during the innate acute response, which is dependent on its associated COX inhibitory activities and PPAR activation.