Serum trace element levels and activity of enzymes associated with oxidative stress in endometriosis and endometrial cancer.

Endometriosis and endometrial cancer are closely related to oxidative stress. However, the direct relationship between copper and zinc levels and oxidative stress in the extracellular and intracellular space remains unclear. The presented study is focused on the determination of serum Zn and Cu levels, glutathione concentration and enzyme activity in three groups: patients diagnosed with endometrial cancer (EC), patients diagnosed with endometriosis (EM), and a healthy control group. Spectrophotometric determination of trace elements revealed that levels of zinc and copper were lower in blood plasma of patients with endometriosis as compared with the other groups; however, there were no significant differences in the Cu/Zn ratio. Furthermore, significantly increased blood serum glutathione levels were detected in both EM and EC groups compared with the control group. While the activity of superoxide dismutase (SOD) was similar across the studied groups, we observed differences in the activity of other enzymes associated with oxidative stress, including glutathione peroxidase (GPx), glutathione reductase (GR) and glutathione S-transferase (GST), between the control group and the EM and EC patients. Additionally, analysis of gene expression based on free circulating mRNA indicated significant differences in the expression of SOD isoenzymes between the patient groups and the control group; expression of GPx isoenzymes was also altered. Obtained results may have potential application in diagnostics as well as monitoring of endometriosis and endometrial cancer.

Stage-Dependent Levels of Brain-Derived Neurotrophic Factor and Matrix Metalloproteinase 9 in the Prognosis of Colorectal Cancer.

PURPOSE: The development of sensitive and non-invasive biomarkers for the early detection of CRC and determination of their role in the individual stages of CRC. METHODS: MMP-9 expression in serum and tissue, and BDNF expression in plasma were detected using the ELISA method. MMP-9 and BDNF in the tissue were also determined by immunohistochemical staining. RESULTS: To assess the balance between changes in survival and tumor progression, we compared BDNF/MMP-9 ratios in tissues of living and deceased individuals. The tissue BDNF/MMP-9 ratio (evaluated immunohistochemically) decreased significantly with the progression of the disease in living patients. The BDNF/MMP-9 ratio was statistically significantly reduced in stages II and III compared to the benign group. However, in deceased individuals, the ratio showed an opposite tendency. CONCLUSION: The determination of the tissue BDNF/MMP9 ratio can be used as a prognostic biomarker of CRC.

Tryptophan: Its Metabolism along the Kynurenine, Serotonin, and Indole Pathway in Malignant Melanoma.

(1) Background: Tryptophan metabolism is known to be one of the important mechanisms used by cancer to evade immune surveillance. Altered tryptophan metabolism was studied in patients with pigmented malignant melanoma confirmed histologically by the anatomic stage grouping for cutaneous melanoma using clinical staging on the basis of the Breslow thickness of the melanoma, the degree of spread to regional lymph nodes, and by the presence of distant metastasis. (2) Methods: Urinary tryptophan metabolites were detected by RP-HPLC method. (3) Results: In the present work, we provided evidence of altered metabolism of all tryptophan pathways in melanoma patients. (4) Conclusions: Knowledge of the shifted serotonin pathway toward DHICA formation and kynurenine pathway shifted toward NAD+ production could serve in the early detection of the disease and the initiation of early treatment of malignant melanoma.

The Effect of Oestrogen Supplementation on Antioxidant Enzymes and Mitochondrial Respiratory Function After Myocardial Infarction of Ovariectomized Rats.

ABSTRACT: Acute myocardial infarction (MI) is the leading cause of mortality worldwide with premenopausal women showing a lower incidence of cardiovascular disease compared with men of the same age. After menopause, this advantage disappears, suggesting that sex hormones play a cardioprotective role. This study was aimed to assess on the activity of antioxidant enzymes in plasma and the respiratory function of isolated heart mitochondria after the induction of MI in rats after ovariectomy and estradiol benzoate supplementation. Sprague-Dawley female rats were ovariectomized 3 months before the induction of MI and supplemented/not supplemented with oestrogen 3 months before/7 days after the induction of MI. No significant differences in glutathione peroxidase activities were found in any group. Differences between values were only significant in the ovariectomized not supplemented group (P < 0.01) for the glutathione reductase activity and glutathione concentrations. In isolated mitochondria (7 days after MI), the decline in respiration was observed comparing the ovariectomized and nonovariectomized group. Respiratory functions did not show significant differences between animals supplemented with oestrogen before MI or treated with oestrogen after MI. Ovariectomy worsened mitochondrial dysfunction after MI, and oestrogen supplementation before or after the induction of MI did not improve mitochondrial function.

Zinc(II) niflumato complex effects on MMP activity and gene expression in human endometrial cell lines.

Endometriosis is a chronic inflammatory disease which increasingly affects young women under 35 years of age and leads to subfertility even infertility. Analysis of the cytotoxic effect of zinc(II) niflumato complex with neocuproine ([Zn(neo)(nif)2] or Zn-Nif) on immortalized human endometriotic cell line (12Z) and on control immortalized human endometrial stromal cell line (hTERT) was performed using xCELLigence technology for approximately 72 h following the treatment with Zn-Nif as well as cell viability Trypan Blue Assay. 12Z cell line proliferated more slowly compared to unaffected cells, whereas hTERT cells did not show similar behavior after treatment. The complex probably reduces the effect of pro-inflammatory pathways due to the effect of NSAID, while presence of zinc might reduce the level of ROS and regulate ER2 levels and MMP activity. The observed effects and high selectivity for rapidly proliferating cells with increased inflammatory activity suggest a good prognosis of successful decrease of endometriosis stage with this complex.

Selected In Situ Hybridization Methods: Principles and Application.

We are experiencing rapid progress in all types of imaging techniques used in the detection of various numbers and types of mutation. In situ hybridization (ISH) is the primary technique for the discovery of mutation agents, which are presented in a variety of cells. The ability of DNA to complementary bind is one of the main principles in every method used in ISH. From the first use of in situ techniques, scientists paid attention to the improvement of the probe design and detection, to enhance the fluorescent signal intensity and inhibition of cross-hybrid presence. This article discusses the individual types and modifications, and is focused on explaining the principles and limitations of ISH division on different types of probes. The article describes a design of probes for individual types of in situ hybridization (ISH), as well as the gradual combination of several laboratory procedures to achieve the highest possible sensitivity and to prevent undesirable events accompanying hybridization. The article also informs about applications of the methodology, in practice and in research, to detect cell to cell communication and principles of gene silencing, process of oncogenesis, and many other unknown processes taking place in organisms at the DNA/RNA level.

Effect of hypoxia factors gene silencing on ROS production and metabolic status of A375 malignant melanoma cells.

The innate response of melanocytes to exogenous or endogenous stress stimuli like extreme pH and temperature, metabolite and oxygen deficiency or a high UV dose initiates a cellular stress response. This process activates adaptive processes to minimize the negative impact of the stressor on the pigment cell. Under physiological conditions, a non-cancer cell is directed to apoptosis if the stressor persists. However, malignant melanoma cells will survive persistent stress thanks to distinct "cancerous" signaling pathways (e.g. MEK) and transcription factors that regulate the expression of so-called "survival genes" (e.g. HIF, MITF). In this survival response of cancer cells, MEK pathway directs melanoma cells to deregulate mitochondrial metabolism, to accumulate reduced species (NADH), and to centralize metabolism in the cytosol. The aim of this work was to study the effect of gene silencing in malignant melanoma A375 cells on metabolic processes in cytosol and mitochondria. Gene silencing of HIF-1α, and miR-210 in normoxia and pseudohypoxia, and analysis of its effect on MITF-M, and PDHA1 expression. Detection of cytosolic NADH by Peredox-mCherry Assay. Detection of OCR, and ECAR using Seahorse XF96. Measurement of produced O2•- with MitoTracker Red CMXRos. 1H NMR analysis of metabolites present in cell suspension, and medium. By gene silencing of HIF-1α and miR-210 the expression of PDHA1 was upregulated while that of MITF-M was downregulated, yielding acceleration of mitochondrial respiratory activity and thus elimination of ROS. Hence, we detected a significantly reduced A375 cell viability, an increase in alanine, inositol, nucleotides, and other metabolites that together define apoptosis. Based on the results of measurements of mitochondrial resipiratory activity, ROS production, and changes in the metabolites obtained in cells under the observed conditions, we concluded that silencing of HIF-1α and miR-210 yields apoptosis and, ultimately, apoptotic cell death in A375 melanoma cells.

Strong Dependence between Tryptophan-Related Fluorescence of Urine and Malignant Melanoma.

Urine autofluorescence at 295 nm is significantly higher in patients with malignant melanoma at each clinical stage compared to the healthy group. The largest difference is in the early-stages and without metastases. With increasing stage, the autofluorescence at 295 nm decreases. There is also a significant negative correlation between autofluorescence and Clark classification. Based on our results, it is assumed that the way malignant melanoma grows also affects urinary autofluorescence.

Development of novel parameter for monitoring of malignant melanoma progression.

OBJECTIVE: Increasing HIFs in malignant melanoma, the highly aggressive skin tumour, results in the stimulation of invasiveness. Increased HIF-1α fallouts in inhibition of the activity of some mitochondrial enzymes and leads to preference of cytosol energetic metabolism. Increase of aerobic glycolysis is reflected in an increase of free NADH (Warburg effect) and develops the malignant melanoma.Our goal was to find a link between hypoxia, or hypoxia mimicking factors and the stage of malignant melanoma. Furthermore, we focused on the finding of the experimental parameter which could monitor melanoma patients. PATIENTS AND METHODS: We targeted HIF-1α gene expression and VDR rs2107301 gene polymorphism by PCR analysis. We detected the level of NADH in blood plasma by fluorescence spectroscopy (excitation and emission spectra). RESULTS: Analysis of the obtained data from patient samples has shown an increase in HIF-1α which correlates with the disease stage. Investigation VDR rs2107301 polymorphism of patient samples does not show any significant changes in single nucleotide polymorphism, and the low vitamin D level in blood is not a result of VDR mutation in mitochondria. NADH levels vary under hypoxic and pseudohypoxic conditions and refer to the cancer stage. CONCLUSIONS: The apparent mismatch between HIF-1α expression and NADH fluorescence has become the basis for the design of an algorithm for monitoring malignant melanoma based on the sensing of NADH fluorescence and the determination of HIF-1α.

Specific Urinary Metabolites in Malignant Melanoma.

Background and objectives: Melanin, which has a confirmed role in melanoma cell behaviour, is formed in the process of melanogenesis and is synthesized from tryptophan, L-tyrosine and their metabolites. All these metabolites are easily detectable by chromatography in urine. Materials and Methods: Urine samples of 133 individuals (82 malignant melanoma patients and 51 healthy controls) were analysed by reversed-phase high-performance liquid chromatography (RP-HPLC). The diagnosis of malignant melanoma was confirmed histologically. Results: Chromatograms of melanoma patients showed increased levels of 5,6-dihydroxyindole-2-carboxylic acid, vanilmandelic acid, homovanilic acid, tryptophan, 5-hydroxyindole-3-acetic acid, and indoxyl sulphate compared to healthy controls. Concentration of indoxyl sulphate, homovanilic acid and tryptophan were significantly increased even in the low clinical stage 0 of the disease (indoxyl sulphate, homovanilic acid and tryptophan in patients with clinical stage 0 vs. controls expressed as medium/ interquartile range in µmol/mmol creatinine: 28.37/15.30 vs. 5.00/6.91; 47.97/33.08 vs. 7.33/21.25; and 16.38/15.98 vs. 3.46/6.22, respectively). Conclusions: HPLC detection of metabolites of L-tyrosine and tryptophan in the urine of melanoma patients may play a significant role in diagnostics as well as a therapeutic strategy of melanoma cancer.

The effects of intradialytic resistance training on muscle strength, psychological well-being, clinical outcomes and circulatory micro-ribonucleic acid profiles in haemodialysis patients: Protocol for a quasi-experimental study.

BACKGROUND: Intradialytic resistance training (IRT) protects patients' muscle mass and functions against protein-energy wasting, malnutrition and cachexia. However, the evidence of the effects of such an intervention in haemodialysis patients is limited and not conclusive. To improve the applicability of such interventions, we need a better understanding of molecular, functional and psycho-social adaptation in dialysed patients following a physical training. Therefore, the aim of this study is to investigate the effects of IRT on lower extremity muscle functions, quality of life, and anxiety and depression, clinical outcomes and circulatory micro-ribonucleic acid (miRNA) profiles in patients on chronic haemodialysis therapy. METHODS: We will perform a quasi-experimental study in 3 dialysis centres. Patients will be recruited via their nephrologists and will be allocated to an experimental and a control group based on the location of the patients' dialysis centre. Patients allocated to the experimental group will undergo a 12-week IRT, while the control group will remain physically inactive during dialysis. The primary outcome is the change in the maximal force produced during an isometric contraction of lower extremity muscles. Secondary outcomes regard quality of life, anxiety and depression, clinical outcomes and circulatory miRNA profiles. Patients' level of health literacy defined as the ability to get and understand health information will be also measured in the study as a potential modifier of effects. DISCUSSION: This quasi-experimental study can add in an important way to our understanding of the effects of resistance training on dialysis patients' muscle strength, quality of life and disease-specific outcomes.

The crucial role of emilin 1 gene expression during progression of tumor growth.

BACKGROUND: This study describes the effect of rapid tumor growth of patients suffering from various grades of malignant ductal breast carcinoma associated with the gene expression of ECM protein emilin 1, in correlation with the number of gene copies of emilin 1 and degradation of tumor tissue proteins. METHODS: A total of 40 examined patients participated in the experiment (controls, n = 10, grades GI-GIII, each n = 10). After isolation of total mRNA, transcription of mRNA into the cDNA was performed. Quantification of gene expression changes was detected by the real-time PCR method. Analysis at the protein level was performed via Western blot method. RESULTS: During the detection of changes at the mRNA level, a significantly decreased level of emilin 1 in tumor tissues with grade II (about 54 ± 8 % lower than control) was identified. Protein-level analysis indicated an increased level of emilin 1 in tumors with grade I in comparison with control samples (about 10 ± 3 %). CONCLUSION: Obtained results demonstrated that the suppressive role of emilin 1 is related to the grade of growing breast tumors, and associated with increased hypoxia in the tumor microenvironment followed by elevated unfolding and degradation of tissue proteins.

Vascular marker expression during the development of various types of gynaecological malignancy.

Clinical diagnosis of gynaecological malignancies is usually successful in the advanced stages of the tumour, and this has a major impact on the success of therapy. Therefore, in the last few years, cancer research has tried to identify and characterise new biochemical and molecular markers needed as predictive indicators for the diagnosis of cancer. Our aim has been to search the molecular changes in gene expression of death receptor 6, glycoprotein M6B (Gpm6B) and genes associated with tumours of the female genital system. After isolation of messenger RNA (mRNA), transcription of mRNA into the cDNA was performed. The quantification of gene expression changes was detected using the reverse transcription polymerase chain reaction (RT-PCR) method. Analysis at the protein level was performed using the Western blot method. In both methods, we used actin as a housekeeping gene for normalisation. Numerical quantification of changes in expression and in the level of the specific proteins was evaluated using the Data Syngene program. Significant changes in the levels of protein and mRNA expression were detected, mainly in the death receptor 6 (Dr6) gene of patients suffering from cancer of the corpus and cervix uteri and ovarian cancer, which also corresponded with the level of protein Dr6. At the level of transcription, a significant increase in the expression levels of mRNA for the Gpm6B gene was detected, which led to an increase in corresponding protein in the peripheral blood of patients with gynaecological tumours against the healthy control group. This article could help to find an adequate marker for clinical application that will enable more sensitive detection of the early stages of gynaecological malignancies from the peripheral blood of patients.

Early diagnosis of colorectal cancer in rats with DMH induced carcinogenesis by means of urine autofluorescence analysis.

Cancer is one of the most highlighted topics of current research. Early detection of this disease allows more effective therapy, hence higher chance of cure. Application of fluorescence spectral techniques into oncological diagnostic is one of the potential alternatives. Chemically induced carcinogenesis in rats is widely used model for exploration of various aspects of colorectal cancer. This study shows value of discriminate analysis of urine fluorescent fingerprint between healthy control group of rats and those with dimethylhydrazine induced early lesions of colorectal cancer. Using fluorescence spectroscopy, significant difference (P < 0.05) between both of group was achieved.

Biomarkers associated with obesity and overweight in the Roma population residing in eastern Slovakia.

BACKGROUND: Obesity and overweight are major contributors to the global burden of chronic diseases and disability in both majority and minority populations. METHODS: Data from the cross-sectional population-based HepaMeta study conducted in Slovakia in 2011 were used. The sample comprised a total of 452 Roma. Measurements of special bioactive mediators were taken in final groups consisting of 63 male Roma respondents (mean age = 32.59; SD = 8.63) and 117 female Roma respondents (mean age = 34.55; SD = 8.35). Respondents were divided into three groups: those with normal weight, those with overweight and obese. Values for anthropometric parameters, lipids parameters, C-reactive protein, TNF-alpha, IL-6, leptin, and adiponectin were determined. RESULTS: 27.6% of examined Roma females and 26.9% of males were overweight. Obesity (BMI > 30.0 kg/m2) appeared in a higher proportion of males (28.8%) compared with female (26.5%). Mean levels of total cholesterol, triacylglycerol and LDL-cholesterol were significantly elevated in the overweight and obese subjects compared to normal-weight Roma respondents. The relation was reversed for HDL-C level, with significantly decreased levels in both male and female obese Roma (p < 0.001). The concentration of adiponectin was significantly lower in obese subjects of both genders versus non-obese (Roma male p < 0.001, Roma female p < 0.05). Plasma levels of leptin, IL-6, hs-CRP as well as TNF-alpha increased in Roma significantly with increasing BMI. CONCLUSION: The study is the first one to provide data about selected biomarkers. Results may be useful in predicting obesity and its related diseases in the Roma population from the eastern part of Slovakia.

Does the population living in Roma settlements differ in physical activity, smoking and alcohol consumption from the majority population in Slovakia?

BACKGROUND: Several studies have revealed a high prevalence of risk factors associated with unhealthy lifestyle among individuals with lower socioeconomic status. In Slovakia, one of the most socially and health-disadvantaged groups is the Roma minority. The aim of this study is to explore differences in physical activity, smoking and alcohol consumption between the population living in Roma settlements and the majority population in Slovakia. METHODS: Data from the cross-sectional epidemiological HepaMeta study conducted in Slovakia in 2011 were used. The sample consisted of 452 Roma (mean age = 34.7; 35.2% men) and 403 non-Roma (mean age = 33.5; 45.9% men) respondents. The differences in health-related behaviour between the population living in Roma settlements and the majority population were analysed using logistic models separately for males and females. RESULTS: These data show a clear difference between the population living in Roma settlements and the majority population with regard to leisure-time physical activity (only in women) and smoking, although not alcohol consumption. The prevalence of leisure-time physical activities such as walking or some other type of sport was significantly lower among Roma women than among non-Roma women. Men and women living in Roma settlements are more likely to smoke on a daily basis and they are heavier smokers in comparison with the majority population. HepaMeta study did not find differences in alcohol consumption between the Roma and non-Roma men. However, Roma women reported less frequent recent drinking and binge-drinking of 6 or more doses of alcohol on a single occasion. CONCLUSION: The higher prevalence of unhealthy lifestyle activities among Roma seem to contribute to these inequalities in cardiovascular diseases morbidity and mortality in comparison with the majority population.

Association between metabolic syndrome and hepatitis B virus infection in the Roma population in eastern Slovakia: a population-based study.

BACKGROUND: The simultaneous presence of chronic hepatitis B (CHB) and metabolic syndrome (MS) in the high-risk Roma community constitutes a high risk for liver cirrhosis and potentially hepatocellular carcinoma. This study aims to explore the relationship between MS and CHB. METHODS: Data from the cross-sectional HepaMeta Study conducted in Slovakia in 2011 among Roma living in rural communities were used. Participants were tested for the presence of MS, and lipid levels--total cholesterol, high density lipoproteins (HDL), low density lipoproteins (LDL), triglycerides (TG), apolipoprotein B100, and CHB HBsAg and anti-HBc IgG were also monitored. Viral load was measured in HBsAg-positive patients. RESULTS: A total of 452 patients were screened; MS was diagnosed in 29.6% of patients, and 12.5% had CHB. Anti-HBc IgG antibodies were present in 52.8% of patients. CHB patients had lower levels of total cholesterol (5.45 +/-1.21 vs. 4.71 +/- 1.23 mmol/l; p = 0.035), LDL cholesterol (median 2.2 mmol/l, interquartile range 0.88 mmol/l vs. 2.5 mmol/l, interquartile range 0.9 mmol/l; p = 0.01) and apolipoprotein B100 (median 0.66 mmol/l, interquartile range 0.26 mmol/l vs. 0.74 mmol/l, interquartile range 0.29 mmol/l; p = 0.025). Patients diagnosed with MS had a higher HBV DNA load than patients without MS (1,728.2 +/- 14.33 IU/ml vs. 12,779.1 +/- 20.9 IU/ml; p = 0.037). CHB patients with TC and apolipoprotein B100 within the reference range had a lower hepatitis B DNA (HBV DNA) load than patients with high or low values of TC or apolipoprotein B100. CONCLUSION: The prevalence of chronic hepatitis B and simultaneous presence of MS was high among Roma. HBsAg-positive patients had lower levels of total and LDL cholesterol along with decreased apolipoprotein B100. The viral load of chronic hepatitis B patients with MS was higher than in patients without MS.

Breast carcinoma progression and tumour vascular markers related to apoptotic mechanisms.

BACKGROUND: In the last few years, the cancer research had tried to identify and characterize new biochemical and molecular pathways in which the inhibition induces prosurvival mechanisms. Our work describes the expression of two different members of apoptotic regulatory pathway and their relationship with a progression of breast carcinoma. MATERIALS AND METHODS: We compared expression of genes related to apoptosis (DR6 and Gpm6B) in the blood of patients suffering from stage I of breast cancer in different grades (I-IV), with healthy controls. After isolation of mRNA, transcription of mRNA into the cDNA was performed. The quantification of gene expression changes in DR6 and Gpm6B was detected by RT-PCR method. Analysis at the protein level was performed by the Western blot. RESULTS: In statistical analysis of Dr6 mRNA level changes we detected significant increase starting in Grading 1 (G1) and reached maximal level in G3.This expression on mRNA levels was similar to protein levels, which copy rising tendency with maximal value in G3. The results of Gpm6B were significantly lower. CONCLUSION: This result showed that antiapoptotic signalling during neovascularization is increased significantly. It would be advisable in the future to study the influence of cytostatic treatment on the expression of genes related to apoptotic pathways and their relationship with progression of breast cancer tumours.

Hepatitis B virus infection in patients with metabolic syndrome: a complicated relationship. Results of a population based study.

BACKGROUND: The presence of hepatitis B infection (HBI) and metabolic syndrome (MS) at the same time constitutes a high risk for liver cirrhosis and potentially hepatocellular carcinoma. AIM: In this study we aim to explore the relationship between MS and HBI. METHODS: We used data from the cross-sectional HepaMeta study conducted in 2011 in Slovakia. Patients were tested for presence of MS, while lipid levels (total cholesterol, HDL, LDL, TG, apolipoprotein B100 and HBI (HBsAg and antiHBcIgG)) were also monitored. Viral load was measured in HBsAg positive patients. RESULTS: Altogether 855 patients were screened, MS was diagnosed in 25.1% of patients and 7.9% of patients presented with HBI. AntiHBcIgG antibodies were present in 34.6% patients. HBI patients had lower levels of total and LDL cholesterol along with a decreased apolipoprotein B100 (4.54 ± 0.84 vs. 5.0 ± 0.99 mmol/l, P=0.001; 2.29 ± 0.58 vs. 2.6 ± 0.68 mmol/l, P=0.001 and 0.71 ± 0.21 vs. 0.77 ± 0.23 mmol/l, P=0.013 respectively). Patients diagnosed with MS had higher HBV DNA load than patients without MS - 1300.2 (95% CI 506.06-3440.41) vs. 7661.3 (95% CI 2008.17-29,228.06) IU/ml; P=0.011. HBI patients with TC and apolipoprotein B100 in the reference range had lower HBV DNA load than patients with high or low values of TC or apolipoprotein B100. CONCLUSION: Hepatitis B patients had lower levels of total and LDL cholesterol along with a decreased apolipoprotein B100. Viral load of chronic hepatitis B patients with MS was higher than that in patients without MS.

Hydroxybenzoic acids and their derivatives as peroxynitrite scavengers.

A social challenge of the 21(st) century is to reduce the incidence of chronic diseases. A balanced diet rich in polyphenols could contribute to reduce the risk and to the prevention of diabetes, coronary heart disease, cancer, Alzheimer's diseases and cataract(1). Hydroxybenzoic acids (HBA) and their derivatives, which are one of the substances responsible for these beneficial properties, are known mainly due to their antioxidant properties(2). They are effective scavengers of free radicals and reactive nitrogen species, such as peroxynitrite. Peroxynitrite is resulting from the reaction of nitric oxide with superoxide, causes lipid peroxidation and subsequent cellular damage and is responsible for the inactivation of many enzymes, activation of stress signalling pathways, release of proapoptotic factors, as well as cardiovascular dysfunction in septic schock(3). In this study we have tested 2-HBA, 3-HBA, 4-HBA, acetylsalicylic acid, 4-HBA methyl and propyl esters, 2,3-dihydroxybenzoic acid (DHBA), 2,5-DHBA, 2,4-DHBA, 2,6-DHBA, 3,5-DHBA, 3,4-DHBA, gallic acid and caffeic acid, by UV/VIS spectroscopy. The best ability to scavenge peroxynitrite was observed for gallic acid, 2,4-DHBA, 3,5-DHBA and caffeic acid. Improved comprehension of the complex relationship between the antioxidant properties of substances and their structure is important to understand their proper use in the prevention and treatment of diseases and for the detection of pathological processes. Monitoring and improved understanding of the antioxidant properties of hydroxybenzoic acid derivatives are important due to their frequent use in modern medical nutrition therapies.