Galina Nikolova
Trakia University, Medical Chemistry and biochemistry, Faculty Member
The pathology of diabetes is associated with several mechanisms, one of which is oxidative stress (OS). The relationship between OS and diabetic complications has been extensively investigated. OS has been suggested to be involved in the... more
The pathology of diabetes is associated with several mechanisms, one of which is oxidative stress (OS). The relationship between OS and diabetic complications has been extensively investigated. OS has been suggested to be involved in the genesis of both macroand microangiopathy. In contrast, the relationship between OS and insulin action is a neglected research area. The aim of this study is to elucidate the effect of glycemic control in type 2 diabetic patients by following the serum levels of some real-time oxidative stress biomarkers. The study group consisted of 53 type 2 diabetic patients (31 with poor glycemic control and 22 with good glycemic control) and 24 healthy control subjects. The oxidative stress biomarkers (ROS, Asc• and •NO) were measured by using electron paramagnetic resonance spectroscopy (EPR) methods and compared with clinical parameters. The statistically significantly higher levels of ROS products and •NO in type 2 diabetic patients in both groups compared to...
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Levodopa (L-dopa) is a "gold standard" and most effective symptomatic agent in the Parkinson's disease (PD) treatment. The several treatments have been developed in an attempt to improve PD treatment, but most patients were... more
Levodopa (L-dopa) is a "gold standard" and most effective symptomatic agent in the Parkinson's disease (PD) treatment. The several treatments have been developed in an attempt to improve PD treatment, but most patients were still levodopa dependent. The issue of toxicity was raised in vitro studies, and suggests that L-dopa can be toxic to dopaminergic neurons, but it is not yet entirely proven. L-dopa prolonged treatment is associated with motor complications and some limitations. Combining the L-dopa therapy with antioxidants can reduce related sideeffects and provide symptomatic relief. The natural antioxidants can be isolated from any plant parts such as seeds, leaves, roots, bark, etc., and their extracts riched in phenols can retard the oxidative degradation of the lipids, proteins and DNA. Thus, study suggests that combination of essential oils (Rose oil and Lavender oil), Vitamin C and Trolox with Ldopa can reduce oxidative toxicity, and may play a key role in ...
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This study was carried out to investigate possible protection effect of 1-ethyl-3-[4-(2,2,6,6-tetramethylpiperidine-1-oxyl)]-1-nitrosourea (SLENU), synthesized in our laboratory, against oxidative liver injuries induced in mice treated by... more
This study was carried out to investigate possible protection effect of 1-ethyl-3-[4-(2,2,6,6-tetramethylpiperidine-1-oxyl)]-1-nitrosourea (SLENU), synthesized in our laboratory, against oxidative liver injuries induced in mice treated by antitumor drugs: doxorubicin (DOX), bleomycin (BLM), or gamma irradiation (R). Specifically, alterations in some biomarkers of oxidative stress, such as lipid peroxidation products measured as malondialdehyde (MDA) levels and activities of the antioxidant enzymes, superoxide dismutase (SOD) and catalase (CAT), were studied in liver homogenates isolated from tumor bearing C57 black mice after i.p. treatment with solutions of DOX (60 mg/kg), BLM (60 mg/kg), or after total body gamma-irradiation with a single dose of 5 Gy. The same biomarkers were also measured after i.p. pretreatment of mice with SLENU (100 mg/kg). Statistical significant increased MDA levels and SOD and CAT enzymes activities were found in the liver homogenates of tumor bearing mice...
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In the present paper for the first time using in vitro Electron Paramagnetic Resonance (EPR) spectroscopy methods were studied extracts isolated from stem bark of Piptadeniastrum africanum and leaves of Haberlea rhodopensis. The radical... more
In the present paper for the first time using in vitro Electron Paramagnetic Resonance (EPR) spectroscopy methods were studied extracts isolated from stem bark of Piptadeniastrum africanum and leaves of Haberlea rhodopensis. The radical scavenging activity of these extracts towards the stable free radical 2, 2-diphenyl-1- picrylhydrazyl (DPPH) was investigated and compared, before and after UV irradiation. After UV irradiation radical scavenging abilities of Piptadeniastrum africanum extract was not influenced, while a twofold increased DPPH scavenging activity was found for UV irradiated Haberlea rhodopensis sample compared to that of non-irradiated sample. EPR spectra of Piptadeniastrum africanum and Haberlea rhodopensis extracts were also studied before and after 2h of UV irradiation by direct EPR spectroscopy. After alkalization both non-irradiated samples give rise to EPR singlet signals with equal g values of 2.00564 ± 0.00001G that were ascribed to ortho-semiquinone free radi...
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ABSTRACT Export Date: 18 October 2014
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ABSTRACT Formerly, naturally isolated SQGD exhibited good in vitro radical scavenging capacity towards 1, 1-diphenyl-2-picrylhydrazyl (DPPH). By the present research using EPR in vitro and ex vivomethods we report our further studies on... more
ABSTRACT Formerly, naturally isolated SQGD exhibited good in vitro radical scavenging capacity towards 1, 1-diphenyl-2-picrylhydrazyl (DPPH). By the present research using EPR in vitro and ex vivomethods we report our further studies on the antioxidant and free radical properties of SQGD. SQGD in powder or in solution form was studied before and after 2 h of UV irradiation by direct EPR in vitro spectroscopy. A single almost symmetrical EPR signal with a g value of 2.0056±0.0002 was registered for the powder form and g=2.0044±0.0002 for the solution form. Based on the calculated g values and the strong EPR signal stability we accept that the radical recorded can be safely ascribed to a semiquinone radical. To study in vivo antioxidant properties of SQGD, white laboratory mice were inoculated i.p.: first group with SQGD (20mg/kg), second with anticancer drug N'-cyclohexyl-N-(2-chloroethyl)-N-nitrosourea (CCNU, 80 mg/kg), third with SQGD plus CCNU and the controls were inoculated with the solvent only. At the 3rd h after treatment mice livers were isolated and homogenates in DMSO solution of the spin trap n-tert-butyl-alpha-phenylnitrone (PBN) were prepared and their EPR spectra were recorded. Statistical significant increased level of ROS production was found in liver homogenates of mice treated by CCNU comparing to those of the controls. ROS production in livers of mice treated by SQGD, or by the combination of SQGD plus CCNU was slightly decreased comparing to the controls.
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The importance of Tinospora cordifolia extract was investigated for its possible protective effect in spleen and blood in male ICR albino mice against ochratoxin A-induced toxicity (OTA). OTA instigates oxidative changes and results in... more
The importance of Tinospora cordifolia extract was investigated for its possible protective effect in spleen and blood in male ICR albino mice against ochratoxin A-induced toxicity (OTA). OTA instigates oxidative changes and results in the overproduction of free radicals, changes in body/organ weight, and the food consumption and is considered as a risk factor for animals and humans. Reactive oxygen species (ROS), reactive nitrogen species (RNS), and consequent lipid-peroxidative damages caused by OTA are considered to be the main mechanisms leading to oxidative stress disorders in organs and blood. TC oral administrations prevent the physiological status of animals and improve the biochemical parameters of the urine and plasma. Moreover, EPR analysis show that TC administration decreased Asc • and NO • radicals and ROS productions in the spleen and serum, even in OTA-treated group. The significant decrease in MDA formation in the spleen and serum and the increased expression of SOD activity in TC and TC + OTA groups confirm the positive modulatory effect of TC extract on the cellular antioxidant system. TC and TC + OTA treatment caused significant reduction of genotoxic potential (8-OHdG) of OTA, followed by a decreased oxidative activity and gradual recovery of ROS-induced DNA damage. The results suggested that TC extract protect against OTA-induced oxidative disorders and other abnormalities. As typical antioxidant TC could protect splenic macrophages and regain intracellular antioxidant capacity.