Almira Georgieva

Dr. Almira Georgieva

The Stefan Angeloff Institute of Microbiology
orcid

Research Focus & Metrics

Academic Career Length

19Years (2008-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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19 January 2021 in Biomolecules
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Milka MilevaMilka Mileva
Milka Mileva
Yana IlievaYana Ilieva
Yana Ilieva
GJGabriele Jovtchev
Gabriele Jovtchev
SGSvetla Gateva
Svetla Gateva
Maya Margaritova ZaharievaMaya Margaritova Zaharieva
Maya Margaritova Zaharieva
Hristo NajdenskiHristo Najdenski
Hristo Najdenski
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.

14 January 2022 in Molecules
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Maya Margaritova ZaharievaMaya Margaritova Zaharieva
Maya Margaritova Zaharieva
Dimitrina Zheleva-DimitrovaDimitrina Zheleva-Dimitrova
Dimitrina Zheleva-Dimitrova
SRSnezhana Rusinova-Videva
Snezhana Rusinova-Videva
Yana IlievaYana Ilieva
Yana Ilieva
ABAnna Brachkova
Anna Brachkova
AKAlexander Dimitrov Kroumov
Alexander Dimitrov Kroumov
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.

30 January 2008 in Cell Biochemistry and Function
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AAAlbena Alexandrova
Albena Alexandrova
Lubomir PetorvLubomir Petorv
Lubomir Petorv
AGAlmira Georgieva
Almira Georgieva
MKMargarita Kirkova
Margarita Kirkova
MKMarian Kukan
Marian Kukan

14 October 2021 in Antioxidants
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AGAlmira Georgieva
Almira Georgieva
Yana IlievaYana Ilieva
Yana Ilieva
ZKZlatina Krasimirova Kokanova-Nedialkova
Zlatina Krasimirova Kokanova-Nedialkova
Maya Margaritova ZaharievaMaya Margaritova Zaharieva
Maya Margaritova Zaharieva
PNParaskev Todorov Nedialkov
Paraskev Todorov Nedialkov
Milka MilevaMilka Mileva
Milka Mileva
The wastewater from the distillation of rose oils is discharged directly into the soil because it has a limited potential for future applications. The aim of the present study was to determine in vitro the chromatographic profile, redox-modulating capacity, and antineoplastic activity of wastewater obtained by distillation of essential oils from the Bulgarian Rosa alba L., Rosa damascena Mill., Rosa gallica L., and Rosa centifolia L. We applied UHPLC-HRMS for chromatographic analysis of rose wastewaters, studied their metal-chelating and Fe(III)-reducing ability, and performed MTT assay for the evaluation of cytotoxic potential against three tumorigenic (HEPG2—hepatocellular adenocarcinoma, A-375—malignant melanoma, A-431—non-melanoma epidermoid squamous skin carcinoma) and one non-tumorigenic human cell lines (HaCaT—immortalized keratinocytes). The median inhibitory concentrations (IC50) were calculated with nonlinear modeling using the MAPLE® platform. The potential of the wastewaters to induce apoptosis was also examined. Mono-, di-, and acylated glycosides of quercetin and kaempferol, ellagic acid and its derivatives as main chemical components, and gallic acid and its derivatives—such as catechin and epicatechin—were identified. The redox-modulating capacity of the samples (TPTZ test) showed that all four wastewaters exhibited the properties of excellent heavy metal cleaners, but did not exert very strong cytotoxic effects. The lowest IC50 rate was provided in wastewater from R. centifolia (34–35 µg/mL of gallic acid equivalents after a 72 h period for all cell lines). At 24 and 48 hours, the most resistant cell line was HEPG2, followed by HaCaT. After 72 h of exposure, the IC50 values were similar for tumor and normal cells. Still, R. damascena had a selectivity index over 2.0 regarding A-431 non-melanoma skin cancer cells, showing a good toxicological safety profile in addition to moderate activity—IC50 of 35 µg/mL polyphenols. The obtained results related to wastewaters acquired after the distillation of essential oils from the Bulgarian R. alba, R. damascena, R. gallica, and R. centifolia direct our attention to further studies for in-depth elucidation of their application as detoxifying agents under oxidative damage conditions in other experimental datasets.

14 April 2022 in Plants
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Yana IlievaYana Ilieva
Yana Ilieva
Lyudmila DimitrovaLyudmila Dimitrova
Lyudmila Dimitrova
AGAlmira Georgieva
Almira Georgieva
NVNeli Milenova Vilhelmova-Ilieva
Neli Milenova Vilhelmova-Ilieva
Maya Margaritova ZaharievaMaya Margaritova Zaharieva
Maya Margaritova Zaharieva
Milka MilevaMilka Mileva
Milka Mileva
The wastewater after rose oil distillation is usually discharged into the drainage systems and it represents a serious environmental problem. While being rich in polyphenols, which have beneficial biological activity and application in the pharmaceutical industry, limited research has been carried out about the biological activity of the specific wastewaters per se. Wastewaters after distillation of the four Bulgarian oil-bearing roses Rosa damascena Mill., R. alba L., R. centifolia L., and R. gallica L. exerted significant antioxidant activity and good antiherpes simplex virus type-1 (HSV-1) activity while maintaining a good toxicological safety profile (low cytotoxic effect) towards normal cell lines. More precisely, the non-tumorigenic cells were a human (HEK-293 embryonic kidney cells) and a mouse cell line (CCL-1 fibroblasts, which are recommended as a standard for cytotoxicity evaluation in Annex C of ISO 10993-5). The concentrations that achieved antioxidant and radical scavenging effects (0.04–0.92% v/v) were much lower than most of the maximum tolerated concentrations for the tissue culture cells (0.2–3.4% v/v). The wastewaters had a weak antiproliferative effect against Staphylococcus aureus. None of the wastewaters had activity against Gram-negative bacteria or a bactericidal or antifungal effect. We can conclude that these four species, which are the most preferred species worldwide for producing high-quality rose oil, have the potential to be developed as promising antioxidant and antiherpesvirus nutraceuticals.

5 December 2023 in Nature Conservation
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IZIvelina Zlateva
Ivelina Zlateva
Violin Stoyanov RaykovViolin Stoyanov Raykov
Violin Stoyanov Raykov
AAAlbena Alexandrova
Albena Alexandrova
PIPetya Ivanova
Petya Ivanova
NCNesho Chipev
Nesho Chipev
KPKonstantin Petrov
Konstantin Petrov
The red mullet (Mullus barbatus Linnaeus, 1758) is a keynote species for the Bulgarian Black Sea ecosystem and fisheries; nevertheless, existing knowledge on population status is very scarce. The present study was intended to assess the health status and adaptive potential of M. barbatus populations inhabiting the Bulgarian waters of the Black Sea. Our findings revealed that populations of M. barbatus are exposed to a variety of anthropogenic and environmental stressors. The species’ status was assessed using representative genetic, morphological, biochemical and chemical biomarkers from specimens obtained in the research area’s northern and southern regions. Based on mtDNA markers, genetic analysis revealed low haplotype and nucleotide diversity, typically observed in overexploited or “threatened” populations. Examining the morphology of the specimens revealed no discernible pattern of differentiation. Except for aluminium and chrome, metal and PAH concentrations in fish were below the regulatory thresholds. The specimens from the southern region ingested more microplastics than those from the northern region. The majority of specimens collected from the southern region also exhibited elevated levels of oxidative stress and decreased antioxidant defence, which can be interpreted as an early indication that they had reached the limits of their adaptive potential. Further research on the composite effects of the stressogenic environment on the Black Sea biota are critically needed, as well as the introduction of new indicators and thresholds at molecular and cellular levels for adequate monitoring of both the ecological state of the marine environment and its biota.