Browsing by Author "Nikolova G."

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    Flavonoids Extraction Kinetics, Antimicrobial Activity and Radical Scavenging Potential of Bulgarian Woundwort (Solidago virgaurea L.)
    (2022-02-01) Yaneva Z.; Simeonov E.; Rusenova N.; Ivanova D.; Nikolova G.; Karamalakova Y.; Chilev C.; Beev G.
    The medicinal plant woundwort (Solidago virgaurea L.) characterizes by diuretic, antimutagenic, anti-inflammatory activity and it has been applied for urinary tract, nephrolithiasis and prostate disorders treatment. The aim of the present study was to analyze the extraction kinetics of catechin, epigallocatechin and quercetin from Bulgarian woundwort extracts, to assess the antibacterial potential of the medicinal plant extracts against four bacterial strains (Staphylococcus aureus ATCC25923, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853 and Bacillus cereus), their antioxidant capacity and radical scavenging potential. The concentrations of the flavonoids in the extracts obtained at different extraction conditions (solvent, temperature, extraction time) were determined by newly-developed by the scientific team RP-HPLC-PDA methodologies. The agar well diffusion method was applied to evaluate the antibacterial activity of the plant extracts. The 70% EtOH extracts at 20◦C displayed significantly higher antibacterial activity against the foodborne pathogenic bacteria S. aureus and P. aeruginosa as compared to the 70% and 98% EtOH extracts at 30◦C and 20◦C, respectively. The medicinal plant exhibited satisfactory antioxidant potential and radical-scavenging activity.
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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.
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    THE GAMMA IRRADIATION EFFECT ON THE ANTIOXIDANT AND LIPID OXIDATION ACTIVITY OF ALMOND (PRUNUS DULCIS L.) OIL
    (2023-01-01) Karamalakova Y.; Slavova-Kazakova A.; Momchilova S.; Karsheva M.; Diankov S.; Nikolova G.
    Almond nuts (Prunus dulcis, Amygdalus subgenus inside the Prunus genus, Rosaceae family) are cultivated globally and 30 % of their worldwide production is derived from the Mediterranean region. The almond nut’s main components, like lipids (oleic, linoleic, palmitic, palmitoleic, and stearic acid), proteins, soluble sugars, minerals, fibrous, and phytochemicals, are responsible for ROS/RNS detection. In recent years, food irradiation has been used to protect against microorganisms, oxidative processes, and radiation-induced toxicity, and this methodology is internationally recognized for effective long-term storage. The ROS/RNS detection by Electron paramagnetic resonance spin - trapping provides useful information on the susceptibility to oxidative stability of gamma (γ) - irradiated food/oils for comparative purposes. In the current study by using two different methods in vitro were evaluate and compared radical-scavenging abilities and lipid oxidative stability of almond oil, at 0 kGy, 10 kGy, 25 kGy radiation, re-oxidized at 50°C. It was found that a 10 kGy irradiation dose increased membrane protection activity in the lipid phase. 10 kGy irradiated almond oil showed high reproducibility, on the 1 min - 60 min (57.3 μmol kg-1 oil), while 25 kGy irradiated extracts showed a slight decrease. Based on the EPR signals, 10 kGy irradiated almond oil show almost commensurate singlet line intensity, but with a slight change in the g value (g = 2.0054; o -semiquinone radical originates from the polyphenol substances), as opposed to 25 kGy doses decreased signal intensity and change the g = 2.0050, compared to non-irradiated oil