You are looking at 1 - 8 of 8 items for
- Author or Editor: E. Tyihák x
- Refine by Access: All Content x
Occurrence of ascorbigen (chemically bound L-ascorbic acid) was studied in extracts of different cultivars of cabbage in cotyledonic and primary leaf stages by thin-layer chromatography, UV-VIS spectroscopic and mass spectrometric measurements. The eventual presence of 1’-methylascorbigen was also studied. It has been shown that samples prepared from cotyledons did not contain ascorbigen, in contrast to the plants in primary leaf stage. 1’-methylascorbigen was not identified in the analysed plant samples. These results demonstrate that ascorbigen is already formed in the early (primary leaf stage) development stage of cabbage.
The N-methylated resistance inducers act within two concentration ranges characterized by suppression of infection rates. Between these active ranges there is always an inactive range (5-7 decimal dilutions) characterized in general by a high rate of infection. This unique phenomenon is called the double immune response, which means a non-linear effect. If the time interval between pre-treatment and inoculation increases the active concentration values for the double immune response shift towards original higher dose values because of the continuous metabolism of methylated inducer in the host plant. The inactive range between the two active dose values remains the same. The multiple pre-treatment of plants with the inducer gives contrasting results: the active dose ranges shifted towards the original lower values. It seems that the two active concentrations of the inducer are always the same. Methylated inducers are potential formaldehyde (HCHO) generators. HCHO generates a time- and dose-dependent immunostimulating activity. HCHO (mainly in bound form) and H2O2 can interact and the singlet oxygen and excited HCHO can be formed. The singlet oxygen may participate in the oxidation of water molecules and in biological systems previously unknown oxidants including dihydrogen trioxide and ozone, can be generated. It seems that these reactive molecules-from HCHO to O3- form the biochemical basis of the double immune response of plants to pathogens.
The effect of Se(IV) and Cu(II) ions on the antibacterial activity of aflatoxins and ochratoxin A (mycotoxins) was studied in BioArena as a complex bioautographic system. In the presence of 0.23 and 0.46 mg/100 mL Se(IV) the inhibition zones of mycotoxins were decreased, however, lower concentration (0.046 mg/100 mL) increased the antibacterial effect of aflatoxin B1. Cu(II) (1.53 mg/100 mL) enhanced the toxicity of mycotoxins. The results supported the possible role of formaldehyde and its reaction products (e.g. 1 O 2 , O 3 ) in the antibacterial-toxic action of mycotoxins. Cu(II) can probably generate and mobilise the formaldehyde molecules and so it could increase the toxicity with its potential reaction products. It is possible that the enzymatic or spontaneous methylation of Se(IV) takes place through formaldehyde, which may cause partial formaldehyde depletion in the system. The enhanced antibacterial effect at low concentration Se(IV) is overlapping with the often experienced prooxidant effect in cases of natural antioxidants.
It has been established, by use of bioautographic detection with the phytopathogenic bacteria Pseudomonas savastanoi pv. phaseolicola , that the common aflatoxins have antimicrobial activity after OPLC separation. Our preliminary results suggest this antimicrobial activity originates from the activity of formaldehyde formed by the bacterial cells and/or from the methoxy groups of aflatoxin molecules.
Papaver somniferum produces secondary metabolites, which have important roles in their self-defence processes, in plant biochemistry and in allelochemistry. We can see that different stress effects change the quantity of alkaloids. The object of the experiments is, in what manner changes the content of alkaloids of poppy in case of irregular stress effects. Papaver somniferum (cv. 'Kék Duna', Budakalász) plants were grown for 2 months from seeds in quartz-sand (in natural light, temperature: 24-28 °C, in Knop's nutritive solution). In this paper we studied the alkaloid of poppy treated with two kind of stress factors: mycotoxin and drought, respectively. Both the quantity and the spectrum of alkaloids were measured after different separation procedures. Thin layer chromatography (TLC and HPTLC) and high performance liquid chromatography (HPLC) were applied. Content of the level of formaldehyde (HCHO) also increases in plants with different stress effects. Our presupposition is that the formation of methyl groups of poppy alkaloids takes place through HCHO. It gave us an opportunity to examine changing of formaldehyde (HCHO) level in biotic and abiotic stress situation. Formaldehyde in dimedone adduct form can be detected in injured tissues of Papaver somniferum. As a consequence, the stress effects can be detected in poppy plants by two kinds of method. At first we measured content of alkaloids. Drought stress produced a higher level of the alkaloids, but the mycotoxin stress did not show significant results.
Radiometric method was developed for the analysis of endogenous formaldehyde in human blood and urine using dimedone-14C reagent. The method based on that dimedone /5,5-dimethyl-cyclohexane-1, 3-dione/ can very easily condense with formaldehyde and other aldehydes. With the help of this radiometric method a sensitive technique and a more accurate evaluation have been made possible. Applying this method it could be established that the formaldehyde level in the blood varies between 0.4–0.6 g ml–1 and in urine 2.5–4.0 g ml–1. The error of determination and the chemical bonds of formaldehyde in the biological fluids are discussed.
On the basis of recent observations it is supposed that seminal fluids may contain - mainly in hydroxymethyl groups - formaldehyde (HCHO) and quaternary ammonium compounds as potential HCHO generators, therefore, preliminary investigations were carried out for the identification of these compounds in pig seminal fluids using OPLC, HPLC and MALDI MS techniques. The fresh pig seminal fluid was frozen in liquid nitrogen, powdered and aliquots (0.25 g) were treated with 0.7 ml ethanolic dimedone solution. The suspension was centrifuged and the clear supernatant was used for analysis by OPLC or after dilution with HPLC or MALDI MS technique. After OPLC separation of formaldemethone the fully N-methylated compounds which are stayed on the start point were separated by OPLC using an other eluent system. It has been established that the HCHO is really a normal component of the pig seminal fluid, as well. It can be isolated and identified in dimedone adduct form. The measurable amount of HCHO depended on the concentration applied of dimedone. According to OPLC and MALDI MS investigations L-carnitine is the main quaternary ammonium compound in pig seminal fluid which can generate a protection of the sperm cells against environmental and other influences. Considerable differences have been found among individuals concerning concentrations of quaternary ammonium compounds in the seminal fluid of pigs.