Lipases from Geotrichum candidum 4013 (extracellular lipase and cell-bound lipase) were immobilized by adsorption on chitosan beads. The enzyme preparations were tested in the synthesis of ester prodrugs from racemic 9-(2,3-dihydroxypropyl)adenine in dimethylformamide with different vinyl esters (acetate, butyrate, decanoate, laurate, palmitate). The transesterification activities of these immobilized enzymes were compared with commercially available lipases (lipase from hog pancreas, Aspergillus niger, Candida antarctica, Pseudomonas fluorescens). Lipase from Candida antarctica was found to be the most efficient enzyme regarding chemical yield of the desired products, while transesterification by lipase from Aspergillus niger resulted in lower yields.

• MeSH
• adenin * analogy a deriváty   chemická syntéza   chemie   MeSH
• chitosan chemie   MeSH
• enzymy imobilizované chemie   metabolismus   MeSH
• esterifikace MeSH
• estery chemie   MeSH
• Geotrichum enzymologie   MeSH
• lipasa chemie   izolace a purifikace   MeSH
• prekurzory léčiv * chemická syntéza   chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• 9-(2,3-dihydroxypropyl)adenine MeSH Prohlížeč
• adenin * MeSH
• chitosan MeSH
• enzymy imobilizované MeSH
• estery MeSH
• lipasa MeSH
• lipase II, Geotrichum candidum MeSH Prohlížeč
• prekurzory léčiv * MeSH

The enzymatic regioselective monopalmitoylation of racemic 9-(2,3-dihydroxypropyl)- adenine (DHPA), an approved antiviral agent, has been performed by an immobilized form of Candida antarctica B lipase (CAL-B) using a 4:1 DMF/hexane mixture as the reaction medium. To improve the chemical yield of the desired monopalmitoylation reaction, solid-phase chemical modifications of the lipase were evaluated. The reaction yield was successfully increased obtaining 100% product after a second treatment of the product solution with fresh immobilised chemically glycosylated-CAL-B.

• Klíčová slova
• chemical modification, glycosylation, palmitoylation, regioselectivity,
• MeSH
• adenin analogy a deriváty   chemie   MeSH
• Candida enzymologie   MeSH
• enzymy imobilizované chemie   MeSH
• fungální proteiny chemie   MeSH
• glykosylace MeSH
• hexany chemie   MeSH
• katalýza * MeSH
• lipasa chemie   MeSH
• lipoylace MeSH
• polymery chemie   MeSH
• rozpouštědla chemie   MeSH
• stereoizomerie MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• 9-(2,3-dihydroxypropyl)adenine MeSH Prohlížeč
• adenin MeSH
• enzymy imobilizované MeSH
• fungální proteiny MeSH
• hexany MeSH
• lipasa MeSH
• lipase B, Candida antarctica MeSH Prohlížeč
• n-hexane MeSH Prohlížeč
• polymery MeSH
• rozpouštědla MeSH

Three adenine derivatives, (R,S)-9-(2,3-dihydroxypropyl)adenine (DHPA), D-eritadenine (EA), and 9-(2-phosphonylmethoxyethyl)adenine (PMEA), prospective antiviral drugs, were subjected to genotoxicity analysis using the somatic mutation and recombination test in Drosophila melanogaster. All three compounds were found to be very potent inducers of mosaic spots on Drosophila wings in a dose-related fashion. Data obtained in inversion-free flies revealed that the compounds, in particular DHPA and EA (nucleoside analogues), are highly effective in the induction of mitotic recombination. PMEA, a nucleotide analogue, exhibited a rather different genotoxic profile from those of DHPA and EA, indicating a different mechanism of genetic action of this compound. Of somatic mutations, chromosome aberrations rather than point mutations seem to play a major role in the genotoxicity of PMEA. In flies carrying an inversion chromosome, which eliminates most products of mitotic recombination, reduced spot frequencies were obtained, which, however, were still unexpectedly high for compounds with strong recombinagenic activities. Most probably, in addition to structural mutations of chromosome, double mitotic crossing-over and non-reciprocal recombination events similar to unequal sister-strand recombination or gene conversion significantly contributed to spot induction in the inversion heterozygous flies. Concerning the mechanism of genotoxic action, we suggest that these adenine derivatives can be incorporated into DNA chains during replication. This would result, via breaks and DNA repair mechanisms, either in various recombination events or in chromosome aberrations.

• MeSH
• abnormality vyvolané léky etiologie   MeSH
• adenin analogy a deriváty   toxicita   MeSH
• antivirové látky toxicita   MeSH
• Drosophila melanogaster účinky léků   MeSH
• křídla zvířecí abnormality   MeSH
• larva účinky léků   MeSH
• mitóza účinky léků   MeSH
• mutageny toxicita   MeSH
• organofosfonáty * MeSH
• rekombinace genetická účinky léků   MeSH
• testy genotoxicity MeSH
• vztah mezi dávkou a účinkem léčiva MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• 9-(2,3-dihydroxypropyl)adenine MeSH Prohlížeč
• adefovir MeSH Prohlížeč
• adenin MeSH
• antivirové látky MeSH
• eritadenine MeSH Prohlížeč
• mutageny MeSH
• organofosfonáty * MeSH

(S)-9-(2,3-dihydroxypropyl) adenine (DHPA), D-eritadenine and some other open-chain nucleoside analogues, which exhibit adverse biological effects in microorganisms, plants and animals, cause pronounced inhibition of intestinal phosphatases in the hemipteran insect Pyrrhocoris apterus. The rate of p-nitrophenylphosphate hydrolysis by homogenates from intestinal epithelium and Malpighian tubules was inhibited up to 94% by 2-10 millimolar concentrations of these drugs. This effect is stronger than that of sodium fluoride, which is recognized as a common inhibitor of phosphatase. We conclude that inhibition of phosphatase activity in the digestive and excretory organs may be responsible for the previously reported massive excretion of phosphorylated derivatives of the nucleoside analogues after their oral administration to insects.

• MeSH
• adenin analogy a deriváty   farmakologie   MeSH
• alkalická fosfatasa antagonisté a inhibitory   MeSH
• fosfatasy antagonisté a inhibitory   MeSH
• Hemiptera enzymologie   MeSH
• kyselá fosfatasa antagonisté a inhibitory   MeSH
• malpighické trubice enzymologie   MeSH
• nitrofenoly metabolismus   MeSH
• organofosforové sloučeniny metabolismus   MeSH
• střeva enzymologie   MeSH
• zvířata MeSH
• Check Tag
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• 9-(2,3-dihydroxypropyl)adenine MeSH Prohlížeč
• adenin MeSH
• alkalická fosfatasa MeSH
• eritadenine MeSH Prohlížeč
• fosfatasy MeSH
• kyselá fosfatasa MeSH
• nitrofenoly MeSH
• nitrophenylphosphate MeSH Prohlížeč
• organofosforové sloučeniny MeSH

We explored the possibility that the cytosine DNA methylation might be regulated by S-adenosyl-L-methionine (AdoMet) and S-adenosyl-L-homocysteine (AdoHcy) pools in plant cells. In order to change the AdoHcy/AdoMet ratio (methylation index), (S)-9-(2,3-dihydroxypropyl)adenine was employed, a selective reversible inhibitor of cellular S-adenosyl-L-homocysteine hydrolase. Micromolar concentrations of the inhibitor increased dramatically (more than 1000-fold) intracellular AdoHcy levels (and concominantly the AdoHcy/AdoMet ratio) in tobacco TBY-2 cells. No toxic effect of the drug was observed and the cells displayed only marginal inhibition of growth at high AdoHcy levels. At near equal intracellular concentrations of AdoHcy and AdoMet, a significant reduction of cytosine methylation in transcribed (5SrDNA) and non-transcribed (HRS60, NTRS) sequences was observed. Interestingly, the CpCpG and CpApG trinucleotide targets appeared to be most sensitive to changes in the methylation index. Methylation of cytosine residues at CpG sites was not affected even at AdoHcy/AdoMet ratio of > 10. These results support the possible regulation of DNA methylation via AdoHcy/AdoMet metabolic pathways in plant cells.

• MeSH
• adenin analogy a deriváty   metabolismus   farmakologie   MeSH
• buněčné linie MeSH
• DNA rostlinná chemie   izolace a purifikace   metabolismus   MeSH
• genom rostlinný * MeSH
• jedovaté rostliny * MeSH
• metylace DNA * účinky léků   MeSH
• ribozomální DNA metabolismus   MeSH
• RNA ribozomální 5S genetika   MeSH
• S-adenosylhomocystein metabolismus   MeSH
• S-adenosylmethionin metabolismus   MeSH
• tabák genetika   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• 9-(2,3-dihydroxypropyl)adenine MeSH Prohlížeč
• adenin MeSH
• DNA rostlinná MeSH
• ribozomální DNA MeSH
• RNA ribozomální 5S MeSH
• S-adenosylhomocystein MeSH
• S-adenosylmethionin MeSH

Metabolism of benzene, an important environmental and industrial carcinogen, produces three electrophilic intermediates, namely, benzene oxide and 1,2- and 1,4-benzoquinone, capable of reacting with the DNA. Numerous DNA adducts formed by these metabolites in vitro have been reported in the literature, but only one of them was hitherto identified in vivo. In a search for urinary DNA adducts, specific LC-ESI-MS methods have been developed for the determination in urine of six nucleobase adducts, namely, 7-phenylguanine, 3-phenyladenine, 3-hydroxy-3,N(4) -benzethenocytosine, N(2) -(4-hydroxyphenyl)guanine, 7-(3,4-dihydroxyphenyl)guanine and 3-(3,4-dihydroxyphenyl)-adenine (DHPA), with detection limits of 200, 10, 260, 50, 400 and 200 pg ml(-1) , respectively. Mice were exposed to benzene vapors at concentrations of 900 and 1800 mg m(-3) , 6 h per day for 15 consecutive days. The only adduct detected in their urine was DHPA. It was found in eight out of 30 urine samples from the high-exposure group at concentrations of 352 ± 146 pg ml(-1) (mean ± SD; n = 8), whereas urines from the low-exposure group were negative. Assuming the DHPA concentration in the negative samples to be half of the detection limit, conversion of benzene to DHPA was estimated to 2.2 × 10(-6) % of the absorbed dose. Thus, despite the known high mutagenic and carcinogenic potential of benzene, only traces of a single DNA adduct in urine were detected. In conclusion, DHPA is an easily depurinating adduct, thus allowing indication of only high recent exposure to benzene, but not long-term damage to DNA in tissues.

• MeSH
• adenin analogy a deriváty   moč   MeSH
• adukty DNA moč   MeSH
• aplikace inhalační MeSH
• benzen toxicita   MeSH
• biologické markery MeSH
• hmotnostní spektrometrie s elektrosprejovou ionizací MeSH
• hmotnostní spektrometrie MeSH
• karcinogeny toxicita   MeSH
• myši MeSH
• referenční standardy MeSH
• vysokoúčinná kapalinová chromatografie MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• 9-(2,3-dihydroxypropyl)adenine MeSH Prohlížeč
• adenin MeSH
• adukty DNA MeSH
• benzen MeSH
• biologické markery MeSH
• karcinogeny MeSH

Developmental processes are closely connected to certain states of epigenetic information which, among others, rely on methylation of chromatin. S-adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH) are key cofactors of enzymes catalyzing DNA and histone methylation. To study the consequences of altered SAH/SAM levels on plant development we applied 9-(S)-(2,3-dihydroxypropyl)-adenine (DHPA), an inhibitor of SAH-hydrolase, on tobacco seeds during a short phase of germination period (6 days). The transient drug treatment induced: (1) dosage-dependent global DNA hypomethylation mitotically transmitted to adult plants; (2) pleiotropic developmental defects including decreased apical dominance, altered leaf and flower symmetry, flower whorl malformations and reduced fertility; (3) dramatic upregulation of floral organ identity genes NTDEF, NTGLO and NAG1 in leaves. We conclude that temporal SAH-hydrolase inhibition deregulated floral genes expression probably via chromatin methylation changes. The data further show that plants might be particularly sensitive to accurate setting of SAH/SAM levels during critical developmental periods.

• MeSH
• adenin analogy a deriváty   toxicita   MeSH
• adenosylhomocysteinasa antagonisté a inhibitory   metabolismus   MeSH
• DNA primery genetika   MeSH
• epigeneze genetická účinky léků   fyziologie   MeSH
• klíčení účinky léků   fyziologie   MeSH
• komplementární DNA genetika   MeSH
• květy anatomie a histologie   fyziologie   MeSH
• metylace DNA MeSH
• neparametrická statistika MeSH
• pyl fyziologie   MeSH
• regulace genové exprese u rostlin účinky léků   genetika   fyziologie   MeSH
• rostlinné proteiny metabolismus   MeSH
• Southernův blotting MeSH
• tabák enzymologie   fyziologie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• 9-(2,3-dihydroxypropyl)adenine MeSH Prohlížeč
• adenin MeSH
• adenosylhomocysteinasa MeSH
• DNA primery MeSH
• GLO protein, Nicotiana tabacum MeSH Prohlížeč
• komplementární DNA MeSH
• rostlinné proteiny MeSH

9-(S)-(3-Hydroxy-2-phosphonylmethoxypropyl)adenine (HPMPA) was prepared from 9-(S)-(2,3-dihydroxypropyl)adenine (DHPA) via its 3-O-chloromethanephosphonate. The latter compound is obtained by treatment of DHPA with chloromethanephosphonyl dichloride and the 3'-isomer separated from its 2'-congener by ion-exchange chromatography. The 3'-isomer is prepared selectively by the same method starting from 2',6-dibenzoyl derivative of DHPA. The 3'-ester is transformed to HPMPA by treatment with aqueous alkali. Alternatively, 9-(S)-(2-hydroxy-3-triphenylmethoxypropyl)-N6-benzoyladenine can be converted to HPMPA by reaction with dialkyl p-tolylsulfonyloxymethane-phosphonates in the presence of NaH followed by successive acid and alkaline treatment.

• MeSH
• adenin analogy a deriváty   chemická syntéza   MeSH
• antivirové látky chemická syntéza   MeSH
• indikátory a reagencie MeSH
• organofosfonáty * MeSH
• organofosforové sloučeniny * MeSH
• stereoizomerie MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• 9-(S)-(3-hydroxy-2-(phosphonomethoxy)propyl)adenine MeSH Prohlížeč
• adenin MeSH
• antivirové látky MeSH
• indikátory a reagencie MeSH
• organofosfonáty * MeSH
• organofosforové sloučeniny * MeSH

Telomere homeostasis is regulated at multiple levels, including the local chromatin structure of telomeres and subtelomeres. Recent reports demonstrated that a decrease in repressive chromatin marks, such as levels of cytosine methylation in subtelomeric regions, results in telomere elongation in mouse cells. Here we show that a considerable fraction of cytosines is methylated not only in subtelomeric, but also in telomeric DNA of tobacco BY-2 cells. Drug-induced hypomethylation (demonstrated at subtelomeric, telomeric, and global DNA levels) results in activation of telomerase. However, in contrast to mouse cells, the decrease in 5-methylcytosine levels and upregulation of telomerase do not result in any changes of telomere lengths. These results demonstrate the involvement of epigenetic mechanisms in the multilevel process of regulation of telomerase activity in plant cells and, at the same time, they indicate that changes in telomerase activity can be overridden by other factors governing telomere length stability.

• MeSH
• adenin analogy a deriváty   farmakologie   MeSH
• aktivace enzymů účinky léků   MeSH
• cytidin analogy a deriváty   farmakologie   MeSH
• DNA rostlinná chemie   účinky léků   MeSH
• epigeneze genetická MeSH
• genetická transkripce účinky léků   MeSH
• kultivované buňky MeSH
• metylace DNA účinky léků   MeSH
• nukleozomy účinky léků   fyziologie   MeSH
• rostlinné proteiny genetika   metabolismus   MeSH
• tabák cytologie   účinky léků   genetika   metabolismus   MeSH
• telomerasa metabolismus   MeSH
• telomery chemie   účinky léků   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• 9-(2,3-dihydroxypropyl)adenine MeSH Prohlížeč
• adenin MeSH
• cytidin MeSH
• DNA rostlinná MeSH
• nukleozomy MeSH
• pyrimidin-2-one beta-ribofuranoside MeSH Prohlížeč
• rostlinné proteiny MeSH
• telomerasa MeSH

1. A method for planimetric measurement of areas of standardized dorsoventral projections of embryonal limbs was elaborated. The method permits a quantitative study of the growth of embryonic limbs at early stages of development, since the stage of flat limb bud until the stage at which the external shape of the limb (bending in joint regions and increase in volume) interferes with the simplification of its three-dimensional characteristics to two-dimensional ones of its dorsoventral projection. (Until stage 31-32HH for the chick embryo, see fig. 1 and 2). 2. A method of linear marking was elaborated (fig. 3). The marker proper are India-ink particles suspended in gelatin. Such stained gelatin is spread over a glass carrier (a glass fibre 10-20 microns thick) in the form of a thin film. After drying the fibre is cut in rods of a length desired for the appropriate linear mark. The marks can be introduced into the tissue by a single stab. After the gelatin film had swollen owing to the presence of tissue fluids, it is detached from the carrier surface and the carrier can be removed from the tissue. After the gelatin had been resorbed, a linear mark remains in the tissue. Deformations of the mark line and the scattering of India-ink particles which actually form the mark facilitates the assessment of the growth pattern of the respective marked tissue (see fig. 4-6). 3. During our studies of the differential growth of the wing bud with the method of linear marking the newly coined term "relative tissue shift" had to be specified. That term has been used for designating changes of the mutual position of tissue areas which could not be defined exactly as to their topography within a region or organ (such as the wing bud), showing fluent transitions between one another. If areas with different growth activities occur in the region studied, such areas undergo an uneven increase (differential growth). Thus another factor is added to those operating in the growth process, namely the direction of expansion of the different growing areas of the region studied to one another. The resultant of the mutual ratios of the voluminal growth of the neighbouring tissue areas and the directions of their expansion are the relative tissue shifts in the sense used in our studies.(ABSTRACT TRUNCATED AT 400 WORDS)

• MeSH
• abnormality vyvolané léky embryologie   MeSH
• adenin analogy a deriváty   MeSH
• citráty MeSH
• daktinomycin MeSH
• ektoderm MeSH
• končetiny embryologie   MeSH
• křídla zvířecí embryologie   MeSH
• kuřecí embryo MeSH
• kyselina citronová MeSH
• mezoderm MeSH
• morfogeneze MeSH
• teratogeny * MeSH
• zvířata MeSH
• Check Tag
• kuřecí embryo MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• 9-(2,3-dihydroxypropyl)adenine MeSH Prohlížeč
• adenin MeSH
• citráty MeSH
• daktinomycin MeSH
• eritadenine MeSH Prohlížeč
• kyselina citronová MeSH
• teratogeny * MeSH