Andrej Veljkovic

Two 6-(propan-2-yl)-4-methyl-morpholine-2,5-diones as new non-purine xanthine oxidase inhibitors and anti-inflammatory agents

Two cyclodidepsipeptides, 3-(2-methylpropyl)-6-(propan-2-yl)-4-methyl-morpholine-2,5-dione (1) and 3,6-di(propan-2-yl)-4-methyl-morpholine-2,5-dione (2), were evaluated for inhibitory activity against commercial enzyme xanthine oxidase (XO) in vitro and XO in rat liver homogenate as well as for anti-inflammatory response on human peripheral blood mononuclear cells (PBMCs). Both of cyclodidepsipeptides were excellent inhibitors of XO and significantly suppressed the nuclear factor of κB (NF-κB) activation. Allopurinol, a widely used XO inhibitor and drug to treat gout, relevated stronger inhibitory effect on rat liver XO activity than those of compounds 1 and 2. Molecular docking studies were performed to gain an insight into their binding modes with XO. The studied morpholine-diones derivatives exerting XO inhibition and anti-inflammatory effect may give a promise to be used in the treatment of gout and other excessive uric acid production or inflammatory conditions.

The effect of ursodeoxycholic acid on oxidative stress level and DNase activity in rat liver after bile duct ligation

Accumulation of hydrophobic bile acids (BAs) during cholestasis plays an important role in apoptosis initiation as well as oxidative stress increase in liver cells. Ursodeoxycholic acid (UDCA) acts as a protector in BA-induced cell injury.The aim of the study was to evaluate the effect of UDCA on oxidative stress level and DNase I and II activity caused by liver injury in bile duct ligation (BDL) rats.Wistar rats were divided in four groups: group 1, control (sham-operated); group 2, sham-operated and injected with UDCA (30 mg/kg); group 3,animals with BDL; and group 4,UDCA-treatedcholestatic rats. Animals were sacrificed after 9 days. Malondialdehyde (MDA; lipid peroxidation end-product) level and protein-molecule oxidative modification (carbonyl group content) significantly increased in BDL rat liver. Catalase (CAT) activity in liver tissue was found to be decreased in BDL rats. In addition, xanthine oxidase (XO) activity, which is thought to be one of the key enzymes producing reactive oxygen species, was found to be increased in the cholestatic group. The apoptotic effect in cholestasis was probably triggered by the increased activation of DNase I and II. The protective effect of UDCA on liver tissue damage in BDL rats, in comparison to cholestatic liver, were 1) decrease of MDA levels, 2) increased CAT activity, 3) reduced XO activity, and 4) effect on terminal apoptotic reaction, shown as a decrease in DNase I and II activity.Therefore, UDCA may be useful in the preservation of liver function in cholestasis treatment.

The Effects of Melatonin on Oxidative Stress Parameters and DNA Fragmentation in Testicular Tissue of Rats Exposed to Microwave Radiation

BACKGROUND Microwaves from mobile phones are one of the environmental toxicants that are capable of compromising male fertility by inducing oxidative stress and apoptosis in the testes. Melatonin is a lipophilic tryptophan indole amine and a potent antioxidant. OBJECTIVES The aim of the study was to evaluate the effect of melatonin treatment on oxidative stress parameters and DNA fragmentation in the testicular tissue of rats exposed to microwave radiation (4 h/day). MATERIAL AND METHODS Adult Wistar rats were divided in 4 groups: I--treated with saline; II--treated with melatonin; III--exposed to microwaves; IV--exposed to microwaves and treated with melatonin. The melatonin (2 mg/kg ip) was administered daily. The animals were sacrificed after 20, 40 and 60 days. RESULTS Melatonin treatment prevented previously registered increases in malondialdehyde after only 20 days. Furthermore, it reversed the effects of microwave exposure on xanthine oxidase (after 40 days) and acid-DNase activity (after 20 days). However, neither protein carbonyl content nor catalase and alkaline Dnase activity were changed due to melatonin treatment. CONCLUSIONS Melatonin exerts potent antioxidant effects in the testes of rats exposed to microwaves by decreasing the intensity of oxidative stress; it also reduces DNA fragmentation.

Chemopreventive potential of alpha lipoic acid in the treatment of colon and cervix cancer cell lines.

OBJECTIVES The nuclear factor κB regulates the expression of genes involved in many processes that play a key role in the development and progression of cancer. The aim of this study was to examine the influence of the alpha lipoic acid in the chemoprevention of colon and cervix carcinoma in vitro. BACKGROUND In recent years, special attention has been paid to the potential chemopreventive properties of antioxidants. There are no published data on the impact of alpha lipoc acid of chemoprevention of cervix and colon cancer. METHODS We examined the effect of alpha lipoic acid alone or in combination with cisplatin and 5-fluorouracil on proliferation of the two cell lines, HeLa (human cervical carcinoma cells) and Caco-2 (human colon cancer cells) by MTT test. The measurement of the level of transcription factor NF-κB was also performed in the cells of both cell lines. RESULTS At least one of the mechanisms of the antiproliferative and/or cytotoxic effect of alpha lipoic acid on Caco-2 and HeLa cells at high concentrations, the transcription factor NF-κB, may be involved, as well as the products of transcription of genes that are under its control. CONCLUSION The alpha lipoic acid has proven to be a promising candidate in the combat arena against cancer (Tab. 4, Ref. 31).

Protective Effects of Glutathione and Lipoic Acid against Cadmium- Induced Oxidative Stress in Rat's Kidney

Cadmium is a widespread, toxic industrial pollutant. The proximal tubule of the mammalian kidney is a major target of Cd-induced toxicity. We analyzed the effects of cadmium exposure on the model system of experimental animals, the thiobarbituric acid (TBA)-reactive substance (TBARS) level, and the activity of xanthine oxidase (XO) and catalase in kidney of rats, with and without glutathione and lipoic acid (LA). The experimental animals were classified into six groups, regarding cadmium, glutathione, and LA intake. The concentration of TBARSs in the homogenate was determined by spectrophotometric method according to Nabavi et al. The specific activity of XO was determined spectrophotometrically by the method of Aygul et al. Catalase activity in tissues was determined by spectrophotometric method according to Nabavi et al. The increased level of TBARS and the increased activity of XO in kidney tissue in cadmium poisoning are statistically significant compared to control (p < 0.001). Glutathione and LA applied along with cadmium lowered TBARS concentration and reduced XO activity (p < 0.001). Catalase activity in the kidney tissue was increased in the group, which was administered cadmium (p < 0.001). In conclusion, glutathione and LA, as physiological antioxidants applied with cadmium, have reduced the level of lipid peroxide and the activity of XO, and can be used as protectors in conditions of cadmium poisoning.

The effect of melatonin on body mass and behaviour of rats during an exposure to microwave radiation from mobile phone.

BACKGROUND Microwave radiation (MW) produced by wireless telecommunications and a number of electrical devices used in household or in healthcare institutions may cause various disorders in human organism. On the other hand, melatonin is a potent antioxidant, immunostimulator and neuromodulator. The aim of this research was to determine body mass and behaviour changes in rats after a chronic microwave exposure, as well as to determine the effects of melatonin on body mass and behaviour in irradiated rats. METHODS Wistar rats were divided into the four experimental groups: I group (control) - rats treated with 0,9 % saline, II group (Mel) - rats treated with melatonin (2 mg/kg), III group (MW) - rats exposed to MW radiation (4 h/day), IV group (MW+Mel) - rats, which were both exposed to MW radiation and received melatonin premedication (2 mg/kg). RESULTS A significant body mass reduction was noted in animals exposed to MW radiation when compared to controls after 20, 40 and 60 days (p<0.001). Furthermore, body weight was significantly increased (p<0.05) in irradiated rats, which received melatonin pretreatment (MW+Mel) in comparison to irradiated group (MW) after 20 days. Microwave radiation exposed animals showed an anxiety related behaviour (agitation, irritability) after 10 days of exposure. After the radiation source removal, changes in behaviour were less noticeable. Melatonin administration to irradiated rats caused a decrease in the stress induced behaviour. CONCLUSION Microwave radiation causes body mass decrease and anxiety related behaviour in rats, however melatonin causes a reverse of those effects on both body weight and behaviour of irradiated animals (Fig. 2, Ref. 32).

Circulating nucleic acids as possible damage-associated molecular patterns in different stages of renal failure

Chronic renal failure (CRF) is a condition associated with the risk of cardiovascular complications. Systemic inflammatory response, initiated by the pathogen-associated molecular-pattern (PAMP) molecules, exerts many similarities with the damage-associated molecular-pattern (DAMP) molecule-induced systemic response. Up to now, a number of DAMP molecules were identified. We hypothesized that the available circulating nucleic acids, acting as DAMPs, may modulate immunoinflammatory reaction in CRF. Patients with the different stages of chronic kidney disease, kidney transplantation, and patients on dialysis were included in the study. Obtained results about higher concentration of circulating ribonucleic acid (RNA), according to the stages of kidney diseases, may contribute to the hypothesis that damaged kidney tissue releases nucleic acids. Circulating RNAs expressed maximal absorbance peak at 270 nm in spectrophotometric scan analysis, which corresponded to polyC, compared to different standard samples. During in vitro conditions, by using the culture of human residential macrophages, circulating RNA isolated from patients with IV–V-stage renal diseases, patients on hemodialysis, and patients who underwent renal transplantation were able to significantly change signal transduction proteins related to inflammation and antiviral response. They significantly increased the intracellular concentration of active nuclear transcription factor nuclear factor kappa B (NF-κB), interferon regulatory factors (IRF)-3, and IRF-7 and significantly decreased melanoma differentiation-associated protein-5 (MDA-5) and p38. In this way, it seems that circulating RNA, acting as DAMP, may contribute to the mechanisms of additional inflammatory reaction, possible immune destruction, and decreased antiviral response, related to complications in kidney diseases.

Gene Polymorphisms of Tumor Necrosis Factor Alpha and Antioxidant Enzymes in Bronchial Asthma

BACKGROUND Bronchial asthma is an inflammatory disease resulting from a combination of genetic and environmental factors. Single nucleotide polymorphisms in the regulatory regions of cytokine and antioxidant enzyme genes may affect cytokine production and enzyme activity, and thus play a contributory role in asthma pathogenesis. OBJECTIVES The aim of this study was to examine the association of manganese superoxide dismutase (MnSOD) Ala16Val, catalase (CAT) A-21T and tumor necrosis factor alpha (TNF-α) G-308A polymorphisms with bronchial asthma. MATERIAL AND METHODS A total of 79 patients with asthma and 95 healthy controls were screened for MnSOD Ala16Val, CAT A-21T and TNF-α G-308A polymorphisms using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. RESULTS The results obtained showed significantly higher prevalence of the MnSOD ValVal genotype (χ2=14.463, df=2, p=0.001) and MnSOD 16Val allele (χ2=12.862, p=0.026, OR=0.451, 95% CI=0.291-0.699) in patients with asthma compared to controls. The genotype and allele frequencies distribution of CAT A-21T and TNF-α G-308A gene polymorphisms did not show differences between patients and controls. CONCLUSIONS Our results show an association of MnSOD Ala16Val genetic polymorphism with asthma in a Serbian population and suggest a protective role of the MnSOD 16Ala allele.

The effect of melatonin on the liver of rats exposed to microwave radiation.

OBJECTIVES We aimed to clarify if melatonin treatment (2 mg/kg i.p.) may favorably impact the liver tissue in rats exposed to microwave radiation. The experiment was performed on 84 six-weeks-old Wistar male rats exposed for 4h a day, for 20, 40 and 60 days, respectively, to microwaves (900 MHz, 100-300 microT, 54-160 V/m). Rats were divided in to four groups: I (control) - rats treated with saline, II (Mel) - rats treated with melatonin, III (MWs) - microwave exposed rats, IV (MWs + Mel) - MWs exposed rats treated with melatonin. We evaluated oxidative stress parameters (malondialdehyde and carbonyl group content), catalase, xanthine oxidase, deoxyribonuclease I and II activity. BACKGROUND Oxidative stress is the key mechanism of the microwave induced tissue injury. Melatonin, a lipophilic indoleamine primarily synthesized and released from the pineal gland is a powerful antioxidant. RESULTS Exposure to microwaves caused an increase in malondialdehyde after 40 (p < 0.01), protein carbonyl content after 20 (p < 0.05), catalase (p < 0.05) and xantine oxidase activity (p < 0.05) after 40 days. Increase in deoxyribonuclease I activity was observed after 60 days (p < 0.05), while deoxyribonuclease II activity was unaffected. Melatonin treatment led to malondialdehyde decrease after 40 days (p< 0.05), but surprisingly had no effect on other analyzed parameters. CONCLUSION Melatonin exerts certain antioxidant effects in the liver of rats exposed to microwaves, by diminishing the intensity of lipid peroxidation(Fig. 6, Ref. 32).

Crosstalk between possible cytostatic and antiinflammatory potential of ketoprofen in the treatment of culture of colon and cervix cancer cell lines.

OBJECTIVES The aim of this study was to test the cytostatic potential of ketoprofen in the in vitro treatment of cells derived from colon and cervix cancer. BACKGROUND NF-κB and cyclooxygenase can have a role in different stages of the development and progression of cancer. In recent years, special attention has been paid to the possible cytostatic potential of nonsteroidal anti-inflammatory drugs. There are no published data on the use of ketoprofen in pharmacotherapy of the colon and cervical carcinoma. METHODS We examined the effect of ketoprofen alone or in combination with cisplatin and 5-fluorouracil on proliferation of the two cell lines, HeLa (human cervical carcinoma cells) and Caco-2 (human colon cancer cells) by MTT test. Measurement of the level of NF-κB was also performed in the cells of both cell lines. RESULTS The results of present study have shown that at least one of the mechanisms of antiproliferating and/or cytostatic effects of different concentrations of ketoprofen on Caco-2 and HeLa cells could include the transcription factor NF-κB. CONCLUSIONS Since this transcription factor is controlled by the altered expression of COX-2, the inhibition of this enzyme by ketoprofen may represent a significant step in synergistic cascade of the therapy and prevention of colon and cervical cancer (Tab. 4, Ref. 31).