Stela Dimitrova

• PhD
• Medical University Plovdiv

Echinacea purpurea and Onopordum acanthium, which belong to the Asteraceae family, are widely used plants in traditional medicine. Their antioxidant, anti-inflammatory, antiviral, antibacterial, and antitumor effects are well known. However, there are no data on the effects of their combination. The aim of the present study was to combine E. purpur...

The trend towards alternative medicine and naturopathy increases the interest in the use of natural products. This requires larger quantities of qualitative raw material of medicinal plants, including the well-known genus Echinacea. The purpose of this study was to evaluate the quality of E. purpurea and pallida cultivated in Kazanlak, Bulgaria. We...

Introduction: Many chronic somatic and psychiatric diseases are associated with oxidative stress and inflammation, both of which have detrimental effects on human health. Aim: To investigate the in vitro antioxidant and in vivo immunomodulatory activities of Satureja montana dry extract. Material and methods: The in vitro antioxidant activity of Sa...

The aim of the study was to develop polymer matrix tablets with modified release of dry Betula pendula leaf extract and to investigate basic parameters influencing the drug release pattern. To fully assess the statistical significance of the influence of the individual factors in the tablet formulation development as well as the combination of them...

Oxydative stress, anxiety and depression are associated with changes in cytokine levels. Natural products, including individual and combined plant extracts, have the potential to be used in the treatment of neuropsychiatric disorders. The goal of this study is to investigate the effects of two combined plant extracts, rich in flavonoids, on the lev...

Introduction : Satureja montana is a wild growing medicinal plant, part of the Lamiaceae family. This herb is well known as a source of phenolic compounds, which can vary in a broad range depending on different factors and exert many pharmacological activities. Aim : The aim of the study was to investigate the composition and chronic toxicity of dr...

Introduction: Scutellaria extracts and its constituents, especially the characteristic flavonoids such as baicalein and its glycoside baicalin, exhibit significant antimicrobial activity. Aim: To perform a comparative analysis of flavonoid composition and antimicrobial activity of extracts obtained from aerial parts and roots of Scutellaria altissi...

The current study investigates the content of sugars, organic acids, phenolic acids and flavonoids, as well as antioxidant and antimicrobial activity of Balkan-endemic Micromeria frivaldszkyana. Glucose was the most abundant sugar in the plant (2.77%), followed by fructose (1.18%) and galactose (0.82%). Eight organic acids were detected with quinic...

Until now, the interest to plants from genus Scutellaria in Bulgaria has been focused mainly on the terpenes in them. The purpose of this study is to enrich the information on the composition of the Bulgarian Scutellaria species in terms of both polyphenolic content as well as primary metabolites such as mono-, oligosaccharides and organic acids. A...

High-performance liquid chromatographic method with gradient elution and diode-array detection was developed to quantify flavonoids (scutellarin, baicalin, baicalein, wogonin, wogonoside, luteolin, chrysin) and verbascoside. The separation was performed on a Hitachi C18 AQ (250 mm × 4.6 mm, 5 μm) column with detection at 330 nm for verbascoside, sc...

The aim of the study was to investigate the effect of polyphenol-rich Aronia melanocarpa (Michx.) Elliot juice (AMJ) on learning ability and memory, and brain morphology of aged rats. A model of healthy male Wistar rats (24 months of age) divided in 2 groups was used: AMJ group supplemented orally with AMJ (10 mL/kg for 105 days) and old control (C...

Introduction. The increasing popularity of phytotherapy in the 21th century requires a reassessment of the available information about the well-known medical plants in order to clarify their use, pharmacological effects and toxicity. It is often preferred to administer plant extracts combinations due to their better therapeutic effect and less adve...

Background: Chronic stress is one of the main factors which lead to depression - a psychiatric disorder affecting millions of people and predicted to be the second ranked cause of premature death in 2020. Depression is often associated with cognitive disturbances and memory deficit. Plant based therapy could be effective in the treatment of mild t...

The purpose of the study was to investigate the stability and biopharmaceutical characteristics of ketoprofen, loaded in polymeric carriers, which were included into a bigel in a semisolid dosage form. The polymer carriers with in situ-included ketoprofen were obtained by emulsifier-free emulsion polymerization of the monomers in aqueous medium or...

Two high-performance liquid chromatographic methods with gradient elu-tion and diode-array detection were developed to quantify free phenolic acids (caffeic, p-coumaric, ferulic and rosmarinic), flavonoids (rutin, vitexin, api-genin, hyperoside and quercetin), terpenes (valerenic acid and bornyl acetate), hypericin and 20-hydroxyecdyzone in medicin...

In recent years, large number of preclinical and clinical studies support the hypothesis of a link between oxidative stress, anxiety and depression. In search of novel sources of antioxidants in the last years, medicinal plants traditionally used in folk medicine have been extensively studied for their antioxidant activity (AOA). The purpose of thi...

The subject of our research was the study of the effects of Zn²⁺, Cu²⁺ and Fe²⁺ ions and the cultivation conditions on the bioaccumulation of ergosterol, β-carotene, and coenzyme Q10 in Sporobolomyces salmonicolor AL1 biomass and tracing their behaviour at different storage conditions. The yeast strain Sp. salmonicolor AL1 was isolated from soil li...

The aim of the study was to investigate the influence of the nature and composition of the monomer feed, added to the reaction system indomethacin/vinyl acetate/3-dimethyl (methacryloyloxyethyl) aminopropyl sulfonate (IMC/VAc/DMAPS) and the characteristics of the obtained polymer latexes on indomethacin In-situ loading, its kinetic release properti...

Objective: The aim of this study was to investigate the biological activity of dry Folia Betulae (FB) extract. Methods: Extracts from birch leaves were obtained by different technological methods–maceration and percolation, extraction with different concentrations of ethanol, changes in temperature regimen. The influence of the technological factor...

A heterogeneous exopolysaccharide (ЕPS) containing having xylose, mannose, and glucose as monosaccharide components was produced by the Antarctic yeast strain Cryptococcus laurentii AL62 with the use of sucrose as a good and reliable carbon source. The water solubility and the surface activity of the biopolymer were studied. The emulsifying and sta...

The use of plants and parts of plants for treatment of various diseases dates back to antiquity. Our research team came across such a recipe associated with the use of extract of Geranium Sanguineum (Geraniaceae), Astragalus Glycyphyllos (Fabaceae), Erodium Cicutarium (Geraniaceae) and Vincetoxicum officinalis (Apocynaceae) for the treatment of cer...

Seven propolis samples (S1-S7) from different regions of Bulgaria and eight commercial products of propolis extracts (C8-C15) from various European countries were studied. Concentrations of five antitumor compounds: CAPE, quercetin, rutin, p-coumaric acid, and ferulic acid, were determined and a comparison between the propolis extracts from differe...

A heterogeneous exopolysaccharide (ЕPS) containing having xylose, mannose, and glucose as monosaccharide components was produced by the Antarctic yeast strain Cryptococcus laurentii AL62 with the use of sucrose as a good and reliable carbon source. The water solubility and the surface activity of the biopolymer were studied. The emulsifying and sta...

The Sporobolomyces salmonicolor AL(1) Antarctic strain was cultivated and two bioproducts were obtained: exopolysaccharide and biomass. The biologically active substances ergosterol, torularhodin, torulene, β-carotene and CoQ(10) were extracted from the biomass and were quantified as follows: ergosterol 5.2 ± 0.2 mg/g, torularhodin 458.3 ± 24.5 μg/...

An exopolysaccharide-producing Antarctic yeast strain was selected and identified as Cryptococcus laurentii AL₁₀₀. The physiological properties of the strain and its ability to utilize and biotransform different carbon sources (pentoses, hexoses, and oligosaccharides) into exopolysaccharide and biomass were investigated. Sucrose was chosen as a sui...

The effect of different doses of visible (Vis), ultraviolet-capital A, Cyrillic (UVA), and mixed light (UVA + Vis) upon coenzyme Q(10) (CoQ(10)) and beta-carotene synthesis and biomass yield by the Sporobolomyces salmonicolor AL(1), Cryptococcus albidus AS(55), Cryptococcus laurentii AS(56), and C. laurentii AS(58) strains isolated from Antarctic s...

The composition of lipids and other lipophilic compounds from psychro- philic yeast strains isolated from Antarctic samples on the territory of the Bulgarian base on Livingston Island was studied. Rhodotorula glutinis AL107 and Sporobolomyces roseus AL108 strains exhibited the highest content of total lipids in the biomass: 12.8% and 12.0%, sterols...

Propolis is a natural product which exhibits pronounced antimicrobial and anti-inflammatory effects. To analyze the chemical composition and antimicrobial effect of Bulgarian propolis, p-cumaric acid and ferulic acid on certain Gram-positive and Gram-negative microorganisms. Ethanol extract of Bulgarian propolis (Propolin) and water extract of Bulg...