Katya Seizova
Bulgarian Academy of Sciences
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Featured researches published by Katya Seizova.
Journal of Plant Physiology | 1995
Kamen Stefanov; Katya Seizova; Ivanka Popova; Valentin Petkov; Georgi Kimenov; Simeon Popov
Summary The composition of the main phospholipids: phosphatidyl choline, phosphatidyl ethanolamine, phosphatidyl inositol and phosphatidyl glycerol in leaves of Z. mays and P. vulgaris , as well as their changes after treatment of the plants with lead and sodium acetate were investigated. The relative concentrations of individual PL were affected significantly by lead and acetate ions. Lead treatment caused an increase of phospholipid concentrations. The relative concentrations of phosphatidyl glycerol decreased and these of phosphatidyl choline increased. Sodium acetate treatment probably leads to some type of salt stress, resulting in an increase of phosphatidyl glycerol concentrations and decrease of phosphatidyl ethanolamine concentrations. The amount of saturated fatty acids decreased and these of linolenic acid increased in all investigated samples.
Food Chemistry | 1995
Kamen Stefanov; Katya Seizova; Nedyalka V. Yanishlieva; Emma M. Marinova; Simeon Popov
Seeds from some plants were collected from metalliferous region in Bulgaria. In this area the concentrations of lead, cadmium and zinc in soil were 3500 mg kg−1, 280 mg kg−1 and 30 mg kg−1, respectively. Plants accumulate heavy metal ions in their seeds selectively. It appears that peanut and corn seeds accumulate mainly Pb (5.2–9.6 mg kg−1), pea seeds accumulate mainly Cd (1.0–1.2 mg kg−1 l), and wheat seeds accumulate mainly Zn (59.4–73.2 mg kg−1). This shows that the accumulation of heavy metals in the seeds of plants from some polluted regions may reach dangerous levels, especially if they are used as forage or food.
Biologia Plantarum | 1995
Kamen Stefanov; S. D. Pandev; Katya Seizova; L. A. Tyankova; Simeon Popov
The effects of lead and sodium acetate treatment on the lipid composition of leaves, thylakoid membranes and cell debris of spinach were investigated. The concentration of lead in leaves and cell debris was higher than that in thylakoid membranes, probably due to a protection of photosynthetic apparatus. The lead treatment lead to decrease of contents of monogalactosyl diacylglycerols and phospholipids and to increase of the other glycolipids in the thylakoid membranes. There were no statistically significant differences between the total lipids of thylakoid membranes after incubation with lead and sodium acetate, which was an indication that in this case the effect of metal ion was not specific.
Medicinal Chemistry Research | 2013
Lyubomir Stoev Georgiev; Maya G. Chochkova; Iskra Totseva; Katya Seizova; Emma M. Marinova; Galya Ivanova; Mariana Ninova; Hristo Najdenski; Tsenka Milkova
Synthetic hydroxycinnamoylamides of amino acids (precursors of aromatic amines) were studied for their antioxidant activity in vitro by two antioxidant assay systems, including 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and inhibition of lipid peroxidation (LPO). Furthermore, these compounds were tested and compared with their corresponding cinnamoylamides of aromatic amines for their inhibitory activity using mushroom tyrosinase. In addition, five hydroxycinnamoyl amino acid amides were investigated for their antimicrobial effect. Structure–activity relationships analysis disclosed that the presence of catechol rest at amino acid or at benzene moieties of substituted cinnamic acid amides significantly scavenged DPPH radical and inhibited LPO. The results obtained by LPO clearly expressed the positive influence of indole moiety on the activity. Moreover, the existence of p-hydroxy substituted cinnamic acid moiety leads to better tyrosinase inhibition. Amongst the tested compounds, amides of p-coumaroyldopamine or tyramine and their corresponding amino acid precursors are the most potent tyrosinase inhibitors.
Comparative Biochemistry and Physiology B | 2002
Kamen Stefanov; Jordan Nechev; Ganina Lavchieva-Nacheva; Nelly Nikolova; Katya Seizova; Michail Kwartirnikov; Valentin Lavchiev; Simeon Popov
Total lipid, fatty acid and sterol composition of larvae and adults of Musca domestica was investigated before and after feeding on sucrose syrup or on the same syrup containing 1% lead nitrate. The effects of sucrose and of lead ions were found to be different. In larvae sucrose diet inhibited the fatty acid elongation and stimulated the first stages of their unsaturation. A significant increase of phytosterol concentrations was obtained. These changes increased the cell membrane permeability. The addition of lead caused a decrease of the fatty acid unsaturation, which decreased the cell membrane permeability. In adults the sucrose diet had no effect on the lipid and sterol composition, while the addition of lead decreased the cholesterol concentration. The composition of lipids and sterols also depends on the diet of larvae before pupation. The data obtained suggested that changes in lipid and sterol composition, which control the permeability of the cell membrane, might be an adaptive response of the organism to the changes of the environment.
Comparative Biochemistry and Physiology B | 1992
B. Nikolava-Damyanova; Kamen Stefanov; Katya Seizova; Simeon Popov
Abstract 1. 1. Different methods for extraction of low molecular weight compunds (lipids, terpenoids, steroids, glycosides, etc.) from Black Sea invertebrates and algae were examined. 2. 2. The composition and quantity of the extracts were found to depend strongly on the type of the organisms and on the solvents used for extraction. 3. 3. Thin-layer chromatography was found to be convenient for rapid identification of low molecular weight compounds in the extracts. 4. 4. An approach has been developed which was suitable for field experimentrsand was successfully applied for the analysis of five algae and seven invertebrates from the Black Sea.
Zeitschrift für Naturforschung C | 2000
Krasimir Slantchev; Kamen Stefanov; Katya Seizova; Simeon Popov; Stoitse Andreev
Abstract Eighteen sterols were identified in Botryllus schlosseri, stanols being the main sterols. The sterol composition is in agreement with our recent paper on taxonomic separation of tunicates into three groups. Again we found in invertebrates of the Black Sea sterols with a (22Z)-double bond. This confirms the presence of such sterols in nature. The composition of the phospholipids appeared to be complex, and twelve groups of them were identified in Botryllus schlossen. The main representatives of phospholipids appeared to be phosphatidylcholine and phosphatidylethanolamine. Only four volatile compounds were identified, which is unusual for marine invertebrates.
Zeitschrift für Naturforschung C | 2006
Salvatore De Rosa; Katya Seizova; Zornitsa Kamenarska; Assia Petrova; Carmine Iodice; Kamen Stefanov; Simeon Popov
Abstract The sterol and fatty acid composition of three Adriatic Sea sponges (Geodia cydonium and two unidentified Tedania sp.), collected at the same time and same place, was established. Twenty-four sterols and forty fatty acids were identified. The identical ecological conditions, including the diet, allowed us to apply the results obtained for taxonomical conclusions, based on the biodiversity of the investigated sponges. On the basis of the sterol composition they can be separated into two groups: Tedania and Geodia sponges. The sterol and fatty acid composition indicates that the two investigated Tedania samples might be different species or subspecies
Journal of Natural Products | 1992
Kamen Stefanov; Katya Seizova; Elizabeth Y. Brechany; William W. Christie
Czech Journal of Food Sciences | 2018
Emma M. Marinova; Lubomir Georgiev; Iskra Totseva; Katya Seizova; Tsenka Milkova