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result(s) for
"Georgieva, Almira"
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Alpha-Lipoic Acid in Early-Stage Alcohol-Related Brain Damage in Rats: A Comparative Pilot Study
by
Tsvetanova, Elina
,
Stefanova, Miroslava
,
Grigorova, Valya
in
Abstinence
,
Acetylcholinesterase - metabolism
,
Alcohol abuse
2025
Alcohol misuse can lead to alcohol-related brain damage (ARBD), a condition linked to long-term cognitive impairment and considerable disease burden. The pharmacological characteristics of alpha-lipoic acid (ALA) make it a promising candidate for the treatment of ARBD. In this study, adult male Wistar rats were divided into eight experimental groups. Four groups received a 20% (v/v) ethanol–tap water solution ad libitum for 15 weeks to induce early-stage ARBD, while the remaining received only tap water. After 14 weeks, all groups were administered daily injections for one week with either ALA, rivastigmine, or memantine. Behavioral testing included the step-through passive avoidance and rotarod performance tests. Whole-brain biochemical analyses assessed acetylcholinesterase activity, brain-derived neurotrophic factor, and oxidative stress biomarkers. Brain weight, relative brain weight, and brain histopathological changes were also evaluated. Results showed that, similar to memantine and rivastigmine, ALA improved STL at both 24 h and 8 days and reduced ethanol-induced Purkinje cell damage. It also decreased lipid peroxidation levels by 44%, unlike the reference drugs, and superoxide dismutase activity by 33%, similar to them. No other significant changes were detected. Albeit several limitations, this is the first study comparing ALA with rivastigmine and memantine in this experimental context.
Journal Article
Rose Flowers—A Delicate Perfume or a Natural Healer?
2021
Plants from the Rosacea family are rich in natural molecules with beneficial biological properties, and they are widely appreciated and used in the food industry, perfumery, and cosmetics. In this review, we are considering Rosa damascena Mill., Rosa alba L., Rosa centifolia L., and Rosa gallica L. as raw materials important for producing commercial products, analyzing and comparing the main biological activities of their essential oils, hydrolates, and extracts. A literature search was performed to find materials describing (i) botanical characteristics; (ii) the phytochemical profile; and (iii) biological properties of the essential oil sand extracts of these so called “old roses” that are cultivated in Bulgaria, Turkey, India, and the Middle East. The information used is from databases PubMed, Science Direct, and Google Scholar. Roses have beneficial healing properties due to their richness of beneficial components, the secondary metabolites as flavonoids (e.g., flavones, flavonols, anthocyanins), fragrant components (essential oils, e.g., monoterpenes, sesquiterpenes), and hydrolysable and condensed tannins. Rose essential oils and extracts with their therapeutic properties—as respiratory antiseptics, anti-inflammatories, mucolytics, expectorants, decongestants, and antioxidants—are able to act as symptomatic prophylactics and drugs, and in this way alleviate dramatic sufferings during severe diseases.
Journal Article
Antimicrobial and Antioxidant Potential of Scenedesmus obliquus Microalgae in the Context of Integral Biorefinery Concept
by
Mileva, Milka
,
Najdenski, Hristo
,
Georgieva, Almira
in
Algae
,
Anti-Bacterial Agents - pharmacology
,
Antibiotics
2022
Small-scale photobioreactors (PBRs) in the inoculum stage were designed with internal (red or green) and external white LED light as an initial step of a larger-scale installation aimed at fulfilling the integral biorefinery concept for maximum utilization of microalgal biomass in a multifunctional laboratory. The specific growth rate of Scenedesmus obliquus (Turpin) Kützing biomass for given cultural conditions was analyzed by using MAPLE software. For the determination of total polyphenols, flavonoids, chlorophyll “a” and “b”, carotenoids and lipids, UHPLC-HRMS, ISO-20776/1, ISO-10993-5 and CUPRAC tests were carried out. Under red light growing, a higher content of polyphenols was found, while the green light favoured the flavonoid accumulation in the biomass. Chlorophylls, carotenoids and lipids were in the same order of magnitude in both samples. The dichloromethane extracts obtained from the biomass of each PBR synergistically potentiated at low concentrations (0.01–0.05 mg/mL) the antibacterial activity of penicillin, fluoroquinolones or oregano essential oil against the selected food-borne pathogens (Staphylococcus aureus, Escherichia coli and Salmonella typhimurium) without showing any in vitro cytotoxicity. Both extracts exhibited good cupric ion-reducing antioxidant capacity at concentrations above 0.042–0.08 mg/mL. The UHPLC-HRMS analysis revealed that both extracts contained long chain fatty acids and carotenoids thus explaining their antibacterial and antioxidant potential. The applied engineering approach showed a great potential to modify microalgae metabolism for the synthesis of target compounds by S. obliquus with capacity for the development of health-promoting nutraceuticals for poultry farming.
Journal Article
Behavioral and Biochemical Effects of an Arylhydrazone Derivative of 5-Methoxyindole-2-Carboxylic Acid in a Scopolamine-Induced Model of Alzheimer’s Type Dementia in Rats
by
Tsvetanova, Elina
,
Stefanova, Miroslava
,
Alexandrova, Albena
in
Acetylcholine
,
Acetylcholinesterase - metabolism
,
Advertising executives
2024
Alzheimer’s disease (AD) has long proven to be a complex neurodegenerative disorder, with cholinergic dysfunction, oxidative stress, and neuroinflammation being just a few of its pathological features. The complexity of the disease requires a multitargeted treatment covering its many aspects. In the present investigation, an arylhydrazone derivative of 5-methoxyindole-2-carboxylic acid (5MeO), with in vitro strong antioxidant, neuroprotective and monoamine oxidase B-inhibiting effects, was studied in a scopolamine-induced Alzheimer-type dementia in rats. Using behavioral and biochemical methods, we evaluated the effects of 5MeO on learning and memory, and elucidated the mechanisms of these effects. Our experiments demonstrated that 5MeO had a beneficial effect on different types of memory as assessed by the step-through and the Barnes maze tasks. It efficiently restored the decreased by scopolamine brain-derived neurotrophic factor and acetylcholine levels and normalized the increased by scopolamine acetylcholine esterase activity in hippocampus. Most effective 5MeO was in counteracting the induced by scopolamine oxidative stress by decreasing the increased by scopolamine levels of lipid peroxidation and by increasing the reduced by scopolamine catalase activity. Blood biochemical analyses demonstrated a favorable safety profile of 5MeO, prompting further pharmacological studies suggesting 5MeO as a safe and efficient candidate in a multitargeted treatment of AD.
Journal Article
New Myrtenal–Adamantane Conjugates Alleviate Alzheimer’s-Type Dementia in Rat Model
by
Stefanova, Miroslava
,
Georgieva, Almira
,
Suslov, Evgeniy
in
Acetylcholine
,
acetylcholinesterase
,
Advertising executives
2022
Alzheimer’s disease (AD) is a neurodegenerative disease associated with memory impairment and other central nervous system (CNS) symptoms. Two myrtenal–adamantane conjugates (MACs) showed excellent CNS potential against Alzheimer’s models. Adamantane is a common pharmacophore for drug design, and myrtenal (M) demonstrated neuroprotective effects in our previous studies. The aim of this study is to evaluate the MACs’ neuroprotective properties in dementia. Methods: Scopolamine (Scop) was applied intraperitoneally in Wistar rats for 11 days, simultaneously with MACs or M as a referent, respectively. Brain acetylcholine esterase (AChE) activity, noradrenaline and serotonin levels, and oxidative brain status determination followed behavioral tests on memory abilities. Molecular descriptors and docking analyses for AChE activity center affinity were performed. Results: M derivatives have favorable physicochemical parameters to enter the CNS. Both MACs restored memory damaged by Scop, showing significant AChE-inhibitory activity in the cortex, in contrast to M, supported by the modeling analysis. Moderate antioxidant properties were manifested by glutathione elevation and catalase activity modulation. MACs also altered noradrenaline and serotonin content in the hippocampus. Conclusion: For the first time, neuroprotective properties of two MACs in a rat dementia model were observed. They were stronger than the natural M effects, which makes the substances promising candidates for AD treatment.
Journal Article
Antioxidant and Neuroprotective Capacity of Resveratrol-Loaded Polymeric Micelles in In Vitro and In Vivo Models with Generated Oxidative Stress
by
Tsvetanova, Elina
,
Stefanova, Miroslava
,
Georgieva, Almira
in
antioxidant properties
,
Antioxidants
,
Comparative analysis
2025
Background: Resveratrol (3,5,4′-trihydroxy-trans-stilbene, RVT) is one of the most extensively studied natural polyphenols, with numerous health benefits documented in the literature. One of its most characterized biological properties is the strong antioxidant capacity. However, its poor biopharmaceutical properties limit its in vivo applicability. In this study, we conducted a detailed comparative analysis of the antioxidant and protective capacity of pure and loaded into Pluronic micelles resveratrol. Methods: Various in vitro antioxidant assays, such as DPPH, ABTS, superoxide anion radical scavenging, ferric (FRAP), and copper-reducing power assay (CUPPRAC), and iron-induced lipid peroxidation were performed. In addition, the in vitro 6-OHDA model of neurotoxicity in brain synaptosomes and the in vivo scopolamine (Sco)-induced model of cognitive impairment in rats were also employed. The main antioxidant biomarkers—the levels of lipid peroxidation (LPO) and total glutathione (GSH), as well as activities of superoxide dismutase, catalase, and glutathione peroxidase—were measured in the cortex and hippocampus. Results: The results from the in vitro tests demonstrated better ferric-reducing power activity and better neuroprotective capacity of the micellar resveratrol (mRVT), as evidenced by preserved synaptosomal viability and maintained GSH levels in a concentration-dependent manner in 6-OHDA-induced neurotoxicity. Regarding the in vivo results, mRVT (10 µM concentration) was the most effective treatment in supporting recognition memory formation in dementia rats. Further, mRVT demonstrated better LPO protective capacity in the hippocampus and GSH preserving activity in the cortex than the pure drug. Conclusions: The incorporation of resveratrol in polymeric micelles could enhance its antioxidant and neuroprotective effects.
Journal Article
In Vitro Protective Effects of Resveratrol-Loaded Pluronic Micelles Against Hydrogen Peroxide-Induced Oxidative Damage in U87MG Glioblastoma Cells
2025
Numerous studies reported that resveratrol (RVT) exhibits strong antioxidant and cytoprotective effects in brain pathologies, but its low solubility and bioavailability limit its therapeutic potential. Encapsulation of RVT in nanoparticles offers a promising strategy to enhance its effectiveness. The aim of this study was to evaluate the in vitro cytoprotective, DNA protective, and antioxidant capacity of resveratrol-loaded Pluronic (P123/F127) micelles. The effects of micellar (mRVT, water dispersion) and pure RVT (30% hydroethanolic solution) were compared in glioblastoma U87MG cells with H2O2-induced oxidative damage. The cells were pretreated with mRVT or pure RVT (1, 3, 10, and 30 µM) for 24 h before cell damage. The cell viability, DNA damage, acetylcholine esterase (AChE) inhibitory activity, and some biomarkers for oxidative stress like lipid peroxidation (LPO), superoxide dismutase (SOD), and catalase (CAT) were evaluated. In addition, the cellular uptake efficiency of the micelles (50 nm) was tracked using red fluorescent rhodamine B as a marker. Our findings revealed that the micelles were localized in the cytoplasm of U87MG cells within 1 h of incubation. Empty micelles, mRVT, and RVT did not reduce the viability of U87MG cells after 24 h incubation and protect them from H2O2 exposure. The most effective treatment was with mRVT (1 and 3 µM), which significantly reduced the DNA damage index, maintained LPO levels close to the control, and normalized the activities of AChE, SOD, and CAT that were disrupted by H2O2 treatment. These promising results highlight the feasibility and advantages of using resveratrol-loaded nanoparticles for therapeutic applications.
Journal Article
Adaptability of the alien Pacific oyster to the coastal marine environment of the Bulgarian Black Sea and potential implications for ecosystem conservation
by
Tsvetanova, Elina
,
Petrov, Georgi
,
Alexandrova, Albena
in
Analysis
,
Antioxidants
,
Aquaculture industry
2026
Feral individuals of Pacific oysters ( Magallana gigas Thunberg, 1793) in natural habitats are increasingly being reported from the Bulgarian coast. Studies on the interactions of the Pacific oyster with native species in local ecosystems are contradictory and it is not yet definitely established to what extent ecological conditions in the Black Sea are favourable for the Pacific oyster growth and reproduction. For the first time in this study, an assessment has been made of the adaptive capacity and resilience of the alien Pacific oyster allowing its development in the ecological conditions of the Bulgarian Black Sea ecosystems and the risk of a future mass invasion. Oysters were gathered manually by SCUBA diving from natural habitats or obtained from shellfish farms. A set of major oxidative stress (OS) indicators: lipid peroxidation, protein oxidation, glutathione level and activity of anti-oxidant enzymes: superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase and glutathione-S-transferase, were measured spectrophotometrically, using commercially available kits. The adaptive capacity and resilience of the Pacific oysters were assessed by the integral Specific Oxidative Stress (SOS) index. The results indicate that M. gigas from more polluted localities have higher OS, but it was effectively compensated by their anti-oxidant system. A comparison was also made between M. gigas OS and that of the native species Mytilus galloprovincialis Lamarck, 1819, using the SOS index. In some localities, Pacific oysters had an even lower SOS index than the native black mussels. The level of adaptive capacity of the oysters, as indicated by the SOS index, was compared to the phases of Holling’s adaptive cycle theoretical model and showed that the Bulgarian Black Sea oyster population is in an initial growth stage (resource exploitation), which confirms its high adaptive potential and resilience. In conclusion, this study confirms that the Pacific oyster possesses the capacity to cope with the marine environment and the native species, which allows further expansion of the oyster population in the Bulgarian Black Sea. More research and monitoring of the M. gigas population, along with assessment of their impact on biodiversity and the local ecosystems, are urgently needed for taking adequate management decisions.
Journal Article
Redox-Modulating Capacity and Effect of Ethyl Acetate Roots and Aerial Parts Extracts from Geum urbanum L. on the Phenotype Inhibition of the Pseudomonas aeruginosa Las/RhI Quorum Sensing System
by
Dimitrova, Lyudmila
,
Mileva, Milka
,
Najdenski, Hristo
in
Acetic acid
,
Antibiotic resistance
,
Antibiotics
2025
Pseudomonas aeruginosa is an opportunistic pathogen that causes nosocomial infections of the urinary tract, upper respiratory tract, gastrointestinal tract, central nervous system, etc. It is possible to develop bacteremia and sepsis in immunocompromised patients. A major problem in treatment is the development of antibiotic resistance. Therefore, new preparations of natural origin are sought, such as plant extracts, which are phytocomplexes and to which it is practically impossible to develop resistance. Geum urbanum L. (Rosacea) is a perennial herb known for many biological properties. This study aimed to investigate the redox-modulating capacity and effect of ethyl acetate (EtOAc) extracts from roots (EtOAcR) and aerial parts (EtOAcAP) of the Bulgarian plant on the phenotype inhibition of the P. aeruginosa Las/RhI quorum sensing (QS) system, which primarily determines drug resistance in pathogenic bacteria, including biofilm formation, motility, and pigment production. We performed QS assays to account for the effects of the two EtOAc extracts. At sub-minimal inhibitory concentrations (sub-MICs) ranging from 1.56 to 6.25 mg/mL, the biofilm formation was inhibited 85% and 84% by EtOAcR and 62% and 39% by EtOAcAP extracts, respectively. At the same sub-MICs, the pyocyanin synthesis was inhibited by 17–27% after treatment with EtOAcAP and 26–30% with EtOAcR extracts. The motility was fully inhibited at 3.12 mg/mL and 6.25 mg/mL (sub-MICs). We investigated the inhibitory potential of lasI, lasR, rhiI, and rhiR gene expression in biofilm and pyocyanin probes with the PCR method. Interestingly, the genes were inhibited by two extracts at 3.12 mg/mL and 6.25 mg/mL. Antiradical studies, assessed by DPPH, CUPRAC, and ABTS radical scavenging methods and superoxide anion inhibition showed that EtOAcAP extract has effective antioxidant capacity. These results could help in the development of new phytocomplexes that could be applied as biocontrol agents to inhibit the phenotype of the P. aeruginosa QS system and other antibiotic-resistant pathogens.
Journal Article
Anti-Coronavirus Efficiency and Redox-Modulating Capacity of Polyphenol-Rich Extracts from Traditional Bulgarian Medicinal Plants
by
Mileva, Milka
,
Tzvetanova, Elina
,
Trepechova, Madlena
in
Adsorption
,
Antioxidants
,
antiradical and metal-chelating capacity
2022
Background: The use of various herbal therapists as part of traditional medicine in different parts of the world, including Bulgaria, is due to the knowledge accumulated over the centuries by people about their valuable biological activities. In this study, we investigate extracts from widely used Bulgarian medicinal plants for their ability to prevent the coronavirus infection of cells by testing different mechanisms of antiviral protection, their polyphenol content, and redox-modulating capacity. Methods: The influence on the stage of viral adsorption, the inhibition of extracellular virions, and the protective effect on uninfected cells of the plant’s extracts were reported by the end-point dilution method, and virus titer (in Δ lgs) was determined as compared to the untreated controls. The total content of polyphenols and flavonoids was also determined. We tested the antioxidant power of the extracts by their ability to inhibit the generation of superoxide anionic radicals and to scavenge DPPH radicals. We determined their iron-reducing, copper-reducing, and metal-chelating antioxidant powers. Results: Most of the extracts tested suppress the extracellular virions of HCov. They also inhibit the stage of viral adsorption to the host cell to varying degrees and have a protective effect on healthy cells before being subjected to viral invasion. The examined extracts contained significant levels of polyphenols and quercetin-like flavonoids and showed remarkable antioxidant, radical, and redox-modulating effects. Conclusions: All of these 13 extracts from Bulgarian medicinal plants tested can act as antioxidants and antiviral and symptomatic drugs for the management of coronavirus infection.
Journal Article