Papers by Danail Georgiev
Investigation of the Potential of Yeast Strains for Phytase Biosynthesis
Molbank
3-(1-Ethylamino-ethylidene)-1-methyl-pyrrolidine-2,4-dione was obtained as an unexpected product ... more 3-(1-Ethylamino-ethylidene)-1-methyl-pyrrolidine-2,4-dione was obtained as an unexpected product in a three-step synthesis starting with o-nitrobenzoyl sarcosine, acetoacetanilide and ethylamine. The compound showed moderate antibacterial activity against S. aureus and E. coli.
Synthesis, antimicrobial and in vitro antiproliferative activity of 4’-
This work presents a method for synthesis, cytotoxicity and antibacterial activity of 4'-brom... more This work presents a method for synthesis, cytotoxicity and antibacterial activity of 4'-bromo- (9'-fluorene)-spiro-5-(2,4-dithiohydantoin). The structure of the obtained product was described by UV-Vis, IR, FT-IR ATR and Raman spectroscopy. In the present investigation we have studied cytotoxic activity of 4'- bromo-(9'-fluorene)-spiro-5-(2,4-dithiohydantoin) on the retinoblastoma cell line WERI-Rb-1 and antibacterial activity against both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli bacteria and the yeasts Candida albicans.
Emirates Journal of Food and Agriculture, 2013
It has been proved that Candida melibiosica 2491 yeast strain, an intracellular phytase producer,... more It has been proved that Candida melibiosica 2491 yeast strain, an intracellular phytase producer, can be well adapted to a nutritious medium with a pH range from 3.0 to 9.0. The best development of the strain was achieved at pH 8.0, which refers to the rarely encountered alkalophylic yeast strains. The maximum biosynthesis was obtained in a medium with pH of 8.5, 24th-hour aged inoculum added at concentration of 6.6% (v/v) with optical density OD600 of 0.68, aeration degree 500 dm 3 /dm 3 .h, stirring speed 300 rpm, and 24h duration of the cultivation in bioreactor. The optimal phytase activity was reached at 60°С and рН 4.5. However, over 80% of the maximum enzymatic activity was observed at the pH interval ranging from 4.0 to 8.5, which provides great potential for practical applications.
European Journal of Medicinal Chemistry, 2014
This paper presents a method for synthesis, cytotoxicity and antibacterial activity of 3-amino-9'... more This paper presents a method for synthesis, cytotoxicity and antibacterial activity of 3-amino-9'-fluorenespiro-5-hydantoin. The structure of the obtained product was verified by UV-Vis, IR, FT-IR ATR, Raman, 1 Hand 13 C-NMR spectroscopy. In the present study, we have examined cytotoxic effect of 3amino-9'-fluorenespiro-5-hydantoin on the retinoblastoma cell line WERI-Rb-1 and antibacterial activity against both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli bacteria and the yeasts Candida albicans.
Epilepsy Research, 2002
This collaborative study by three Italian groups of child neuropsychiatrists was carried on to ev... more This collaborative study by three Italian groups of child neuropsychiatrists was carried on to evaluate the efficacy and safety of the classic 4:1 ketogenic diet as add-on treatment in refractory partial or generalized epilepsy in children, adolescents and young adults. Methods: We performed a prospective add-on study in 56 refractory epilepsy young patients (age 1-23 years, mean 10.4 years), all with both symptomatic and cryptogenic, generalized or partial epilepsies. Child neuropsychiatrists worked with nutritional team for sample selection and patients management. The ketogenic diet was added to the baseline antiepileptic drugs and the efficacy was rated according to seizure type and frequency. During treatment, seizure frequency, side effects, urine and blood ketone levels and other parameters were systematically evaluated. Results: Patients have been treated for 1-18 months (mean 5 months). A \50% reduction in seizure frequency was gained in 37.5 and 26.8% of patients after 3 and 6 months, respectively, at 12 months, this number fell by 8.9%. No significant relationship between diet efficacy and seizure or epilepsy type, age at diet onset, sex and etiology of epilepsy was noted. Nevertheless, it seems noteworthy that 64% of our patients with neuronal migration disorders improved on this diet. Adverse effects occurred, mainly in the first weeks of treatment, in 32 patients (57.1%), but were generally mild and transient. In seven patients (12.5%) it was possible to withdraw one to two AED after 3-4 months on ketogenic diet. Conclusion: This initial experience with the ketogenic diet was effective in difficult-to-treat patients with partial and generalized epilepsies, though its efficacy dropped significantly by 9-12 months.
Vascular lesions of the central nervous system are one of the most important and topical problems... more Vascular lesions of the central nervous system are one of the most important and topical problems in modern neuro-pathology. Bulgaria is among the first in morbidity and mortality from cerebrovascular diseases. Because of the significant medical and social importance of this pathology resulting in severe disabling of most survivors, we aimed to explore the effectiveness of kinesitherapeutic methodology applied in the recovery of a patient with ischemic stroke. We present a case of a 69-old patient admitted in the Neurological Ward of “St. George Hospital in Plovdiv in 2015, Bulgaria with right hemiparesis due to ischemic stroke in the basin of the left middle cerebral artery. The applied Kinesi-therapeutic methodology included various techniques like Kabat’s Bobath’s methods as well as training in equilibrium and walking. The patient obtained satisfactory results in terms of movement of the body and preserving the equilibrium, improvement of voluntary movement of the upper and lower...
Synthesis and Antimicrobial Activity of 2-Substituted Benzothiazoles
Cardiovascular diseases are the main cause of death in Bulgaria and in all of the developed count... more Cardiovascular diseases are the main cause of death in Bulgaria and in all of the developed countries. Hyperlipidemia is a worldwide problem, which is a disorder of the lipid metabolism and is often accompanied by high levels of serum cholesterol and triglycerides. It is one of the major risk factors for cardiovascular diseases.AimThe aim of the study was to analyze the antihyperlipidemic drugs from the group of statins that are available in Bulgaria and presented in Annex 1 of the Positive Drug List issued by NCPR and to assess the level and value of their reimbursement (the value the public insurance company is paying). A secondary task we achieved was to perform a meta-analysis of the effectiveness of the most commonly prescribed statin.Materials and Methods The reimbursement of cardiovascular drugs takes a prominent place in the debate about reforming the Bulgarian health care system. Different pharmacoeconomic issues of antihyperlipidemic drugs from the group of statins have be...
Interactions in Soil-Microbe-Plant System: Adaptation to Stressed Agriculture
Microbial Interventions in Agriculture and Environment
Synthesis and antibacterial activity of hydroxylated 2-arylbenzothiazole derivatives
Synthetic Communications
Revue Roumaine de Chimie, 2019
The present work presents a synthesis, characterization and antimicrobial activitiy of new Pt(IV)... more The present work presents a synthesis, characterization and antimicrobial activitiy of new Pt(IV) and Ru(III) complexes of (9'-fluorene)-spiro-5-hydantoin (HL1) and (9'-fluorene)spiro-5-(2-thiohydantoin) (HL2). The complexes were investigated by elemental analysis, UV-Vis and IR spectroscopy. The free ligands were studied by UV-Vis, IR, 1 H NMR, 13 C NMR and Raman spectroscopy. The antimicrobial tests of HL1 showed week bacteriostatic effect against Staphylococcus aureus ATCC 6538. The results for [Pt(L1) 2 (H 2 O) 2 (OH-) 2 ] complex showed a good antimicrobial activity against Esсherichia coli ATCC 8739, Bacillus licheniformis ATCC 6633, S. aureus and the absence of such effect on the yeasts. The HL2 and its [Pt(L2) 2 (H 2 O) 2 (OH-) 2 ] and [Ru(L2) 3 (H 2 O) 3 ] complexes do not possess antimicrobial activity against the tested bacteria and yeasts.
Acta chimica Slovenica, 2016
This work describes a method for synthesis, as well as in vitro antiproliferative and antibacteri... more This work describes a method for synthesis, as well as in vitro antiproliferative and antibacterial investigation of 3-methyl-9'-fluorenespiro-5-hydantoin. The structure of the substituted fluorenylspirohydantoin derivative was verified by UV-Vis, FT-IR, Raman, 1H-NMR and 13C-NMR spectroscopy, and by using a combination of 2D NMR experiments, which included 1H-1H COSY, HMQC and HMBC sequences. The geometry of the compound was optimized by the B3LYP density functional with 6-31G(d) basis set and the 1H and 13C NMR spectra were predicted with the HF/6-31G(d) calculations at the optimized geometry. The anticancer activity of the 3-methyl-9'-fluorenespiro-5-hydantoin was determined in suspension cell lines originating from tumors in humans (WERI-Rb-1). The cytotoxic effect was evaluated by WST-assay (Roche Applied Science). The antimicrobial effect of the compound against Gram-negative, Gram-positive bacteria and the yeast Candida albicans was investigated.
Доклади на Българската академия на науките Comptes rendus de l'Académie bulgare des Sciences SYNTHESIS, CYTOTOXICITY AND ANTIBACTERIAL ACTIVITY OF 3-AMINO-9'-FLUORENESPIRO-5-HYDANTOIN
Biotechnology Letters
We report for the first time that Candida melibiosica expresses enhanced phytase activity when gr... more We report for the first time that Candida melibiosica expresses enhanced phytase activity when grown under biofuel cell polarization in a nutrient-poor medium, containing only fructose as a carbohydrate source. Phytase activity during the cultivation under polarization reached up to 25 U per g dry biomass, exceeding with 20 ± 3 % those of the control. A participation of the enzyme in the adaptation processes to the stress conditions is proposed. In addition, steady-state electrical outputs were achieved during biofuel cell operation at continuous polarization under constant load. The obtained results show that C. melibiosica yeast-based biofuel cell could be used for simultaneous electricity generation and phytate bioremediation.
Stable current outputs and phytate degradation by yeast-based biofuel cell
Yeast (Chichester, England), 2014
In this paper, we report for the first time that Candida melibiosica 2491 yeast strain expresses ... more In this paper, we report for the first time that Candida melibiosica 2491 yeast strain expresses enhanced phytase activity when used as a biocatalyst in biofuel cells. The polarization also results in an increase of the yeast biomass. Higher steady-state electrical outputs, assigned to earlier production of an endogenous mediator, were achieved at continuous polarization under constant load. The obtained results prove that the C. melibiosica yeast-based biofuel cell could be used for simultaneous electricity generation and phytate bioremediation. In addition, the higher phytase activity obtained by interruptive polarization suggests a new method for increasing the phytase yield from microorganisms.
Purification and properties of a phytase from Candida krusei WZ-001
Journal of Bioscience and Bioengineering - J BIOSCI BIOENG, 2002
A phytase from Candida krusei WZ-001 isolated from soil was purified to electrophoretic homogenei... more A phytase from Candida krusei WZ-001 isolated from soil was purified to electrophoretic homogeneity by ion-exchange chromatography, hydrophobic interaction chromatography, and gel filtration. The phytase is composed of two different subunits with molecular masses of 116 kDa and 31 kDa on SDS-PAGE (or 120 kDa and 30 kDa on gel chromatography), with the larger subunit having a glycosylation rate of around 35%. The phytase has an optimum pH of 4.6, an optimum temperature of 40°C and a pI value of 5.5. The phytase activity was stimulated by 2-mercapto-ethanol and dithiothreitol (DTT), and inhibited by Zn2+, Mg2+, iodoacetate, pI value of 5.5. The phytase activity was stimulated by 2-mercapto-ethanol ethanol and dithiothreitol (DTT), and inhibited by Zn2+, Mg2+, iodoacetate, p-chroloromercuribenzoate (pCMB) and phenylmethylsulfonyl fluoride (PMSF). The phytase displayed a broad substrate specificity and the Km for phytate was 0.03 mM. Phytate was sequentially hydrolyzed by the phytase. F...
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Papers by Danail Georgiev