Browsing by Author "Petkova-Parlapanska K."

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    EPR SPECTROSCOPY INVESTIGATION ON THE ANTIOXIDANT EFFICACY OF SAMBUCUS NIGRA L (DRY FLOWERS/BLOSSOM) EXTRACT
    (2023-01-01) Petkova-Parlapanska K.; Diankov S.; Karsheva M.
    The present study aims to evaluate the antioxidant efficacy and the lipid peroxidation degree of Sambucus nigra L. (S. nigra) blossom extract after induction of biotic stress. Dry stained extracts of S. nigra flowers were analyzed by direct and indirect in vitro EPR spectroscopy. The antioxidant activity of the extract was assessed by DPPH analysis, and the inhibition of lipid peroxidation - by PBN-spin adduction, after UV-B and thermal stress. The direct EPR stable radical structures presence was established either in non-irradiated and UV-B irradiated samples. Furthermore, as before and after UV-B and thermal biotic stress, S. nigra showed well-expressed scavenging abilities and protective properties against reactive oxygen and nitrogen species such as superoxide radicals (•O2̅ ), hydroxyl radicals (•OH), and reduced lipid peroxidation
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    Rheological properties of cosmetic compositions containing rosemary and grapefruit pulp and seeds extracts
    (2014-01-01) Petkova-Parlapanska K.; Nancheva V.; Diankov S.; Hinkov I.; Karsheva M.
    Modern cosmetic formulations represent a combination of synthetic and natural ingredients. Knowledge of the rheological behavior allows managing the structure and the quality of the products by means of supplement addition, regime change or mechanical and technological processing adjustment. The extraction from rosemary and grapefruit pulp and seeds with ethanol-in-water solutions is carried out in a thermostated shaker at 20°C. The total polyphenol content (TPC) and the antioxidant capacity (AOC) of the extracts are determined. The cosmetic compositions prepared are based on stearic acid, with 3-ethanolamine as emulsifier. Extracts are used as a preservative, instead of controversial lately methyl-parabens. The rheological behavior of the cosmetic formulations is studied. It is found that all compositions exhibited thixotropic flow behavior. The cosmetic emulsion containing an alcoholic extract of grapefruit seeds has different rheological behavior which may be described by the Bingham rheological model. This effect can be explained by the composition of the extract and its influence on the pH. It is found that the extract from grapefruit seeds has acidic properties and affects the pH of the medium. The cosmetic formulation with rosemary extract exhibits power low and thixotropic behavior. The purity of the cosmetic formulations was tested against E. Coli bacteria. It is found that no bacterial colonies are observed neither after one day, nor after three months of storage. It can be concluded that the natural extracts from rosemary and grapefruit seeds and pulp exhibit good antibacterial properties, being quite satisfactory substitute of the parabens.
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    THE EFFECT OF RADIATION PRESERVATION ON MACROMOLECULE CONTENT, ANTIMICROBIAL ACTIVITY AND RADICAL - SCAVENGING POTENTIAL OF PORTULACA OLERACEA L. LEAVES EXTRACT
    (2024-01-01) Karamalakova Y.; Petkova-Parlapanska K.; Hinkov I.; Vetskov N.; Georgieva E.; Nikolova G.
    The Portulaca oleracea L. (P. oleracea) phytochemical composition (contains omega-3 fatty acids, quercetin, rutin, gallo tannins, proteins) is responsible for its biological effects, e.g. antioxidative, antibacterial, anti-inflammatory and antiradiation activity. The plant has a C4 metabolism and it is known for its tolerance to different stressors, such as salinity, no water, high - temperature conditions, and 9 kGy radiation. The purpose of the present investigation was focused on the inhibitory effects of P. oleracea leaves extracts against 5 - 10 kGy radiation - induced abiotic stress, and assess to total phenol, flavonoid, and tannins content; antibacterial potential (Staphylococcus aureus ATCC25923, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853) and antioxidant capacity. The free dried, powdered P. oleracea samples were 60Co irradiated, 50 % ethanol solvent (v/v) extracted and compared to 0 kGy extract. 10 kGy irradiated extract provide to be potentially effective against bacterial strains and possessed stable antioxidant activity, towards DPPH (p ˂ 0.002), ABTS•+ (p ˂ 0.05), FRAP (p ˂ 0.05) and NO (p ˂ 0.002). In addition, highly sensitive Electron Paramagnetic Resonance (EPR) was used to evaluate antiradical capacity. Single, symmetrical signal (g = 2.0023) was recorded in 10 kGy irradiated P. oleracea extract, comparable to the EPR signal in non-irradiated sample and depended directly on the antiradical potential. Moreover, in vitro P. oleracea inhibited the superoxide anion (•O2 −), hydroxyl (•OH), alkyl radicals, and exhibited antioxidant properties against 10 kGy irradiation.