- COMPARISON OF CYTOKININ ACTIVITIES OF 9-SUBSTITUTED N6-BENZYLADENINES IN THE CUCUMIS AND AMARANTHUS BIOASSAYS
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9-Substituted N6-benzyladenines were tested for their ability to eliminate the lag phase in and promote chlorophyll synthesis in Cucumis sativus cotyledons and for their effectiveness in eliciting the dark biosynthesis of betacyanin in Amaranthus tricolor cotyledon-hypocotyl explants.The following general relationships were established for dose-responses: (a) 9-ribosidation brought about little (in Amaranthus) or no (in Cucumis) decrease in activity relative to the free base, (b) the presence of a 9-ribose 5'-phosphate group moderately depressed activity in Amaranthus but slightly enhanced activity in Cucumis, (c) the presence of a 9-ribose 3',5'-cyclic phosphate group depressed activity substantially in both systems, more so in Amaranthus, (d) 9-glucosylation greatly decreased activity, as did 7-glucosylation, while 3-glucosylation depressed activity to a much lesser extent, in both systems, (e) 9-substitution with cyclopentyl, methyl, methoxymethyl, and tetrahydropyranyl groups reduced activity, the first two substituents more so than the last two, and (f) alteration of the 9-riboside group to a 9- moiety by oxidation-reduction led to complete (in Amaranthus) or nearly complete (in Cucumis) inactivation.Responses to hormone treatment were detectable after dark incubation times as short as 4 hr (in Cucumis) or 8 hr (in Amaranthus). - Key Word Index: Cucumis sativus; Cucurbitaceae; Amaranthus tricolor; Amaranthaceae; cytokinin activity; chlorophyll synthesis; amaranthin synthesis; bioassays; substituted N6-benzyladenines.
- Gasque, C. Edward
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- ADENOSINE ANALOG AND ITS USE IN REGULATING THE CIRCADIAN CLOCK
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Provided are a kind of nucleoside analogue compounds, and compositions comprising these compounds and pentostatin, their use for modulating circadian rhythm, preferably, for shifting circadian phase, and methods for modulating circadian rhythm, preferably, for shifting circadian phase via these compounds or the compositions.
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Paragraph 0149; 0154; 0155; 0188
(2018/08/12)
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- Preparation, characterization and biological activity of C8-substituted cytokinins
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Naturally occurring cytokinins are adenine-based plant hormones. Although, the effect of various substituents at positions N1, C2, N3, N6, N7, or N9 on the biological activity of cytokinins has been studied, the C8-substituted compounds have received little attention. Here, we report the synthesis and in vitro biological testing of thirty-one cytokinin derivatives substituted at the C8 position of the adenine skeleton and twenty-seven compounds which served as their N9-tetrahydropyranyl protected precursors. The cytokinin activity of all the compounds was determined in classical cytokinin biotests (wheat leaf senescence, Amaranthus and tobacco callus assays). With some exceptions, the compounds with a N9-tetrahydropyranyl group were generally less active than their de-protected analogs. The latter were further tested for their ability to activate the Arabidopsis cytokinin receptors AHK3 and CRE1/AHK4 in bacterial receptor activation assays. Using this approach, we identified derivatives bearing short aliphatic chains and retaining high cytokinin activity. Such compounds are suitable candidates for fluorescence labeling or as protein-affinity ligands. We further found that some C8-substituted cytokinins exhibited no or lower cytotoxicity toward tobacco cells when compared to their parent compound. Therefore, we also present and discuss the cytotoxicity of all the compounds against three normal human cell lines.
- Zahajská, Lenka,Nisler, Jaroslav,Voller, Ji?í,Gucky, Tomá?,Pospí?il, Tomá?,Spíchal, Luká?,Strnad, Miroslav
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p. 115 - 127
(2017/02/05)
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- 6,8-DISUBSTITUTED-9-(HETEROCYCLYL)PURINES, COMPOSITIONS CONTAINING THESE DERIVATIVES AND THEIR USE IN COSMETIC AND MEDICINAL APPLICATIONS
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6,8-Disubstituted-9-(heterocyclyl) purines which can be used in pharmaceutical and cosmetic compositions and/or applications are provided. These 6,8-disubstituted-9-(heterocyclyl) purines have a wide range of biological activities, including for example antioxidant, anti-inflammatory, anti-senescent, as well as well as other activities which are especially useful in pharmaceutical and cosmetic applications.
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- Synthesis, characterization and biological activity of ring-substituted 6-benzylamino-9-tetrahydropyran-2-yl and 9-tetrahydrofuran-2-ylpurine derivatives
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In an attempt to improve specific biological functions of cytokinins routinely used in plant micropropagation, 33 6-benzylamino-9-tetrahydropyran-2-ylpurine (THPP) and 9-tetrahydrofuran-2-ylpurine (THFP) derivatives, with variously positioned hydroxy and methoxy functional groups on the benzyl ring, were prepared. The new derivatives were prepared by condensation of 6-chloropurine with 3,4-dihydro-2H-pyran or 2,3-dihydrofuran and then by the condensation of these intermediates with the corresponding benzylamines. The prepared compounds were characterized by elemental analyses, TLC, HPLC, melting point determinations, CI+ MS and 1H NMR spectroscopy. The cytokinin activity of all the prepared derivatives was assessed in three classical cytokinin bioassays (tobacco callus, wheat leaf senescence and Amaranthus bioassay). The derivatives 6-(3-hydroxybenzylamino)-9-tetrahydropyran-2-ylpurine (3) and 6-(3-hydroxybenzylamino)-9-tetrahydrofuran-2-ylpurine (23) were selected, because of the high affinity of their parent compound meta-topolin (mT, 6-(3-hydroxybenzylamino)purine) to cytokinin receptors, as model compounds for studying their perception by the receptors CRE1/AHK4 and AHK3 in a bacterial assay. Both receptors perceived these two derivatives less well than they perceived the parent compound. Subsequently, the susceptibility of several new derivatives to enzyme degradation by cytokinin oxidase/dehydrogenase was studied. Substitution of tetrahydropyran-2-yl (THP) at the N9 position decreased the turnover rates of all new derivatives to some extent. To provide a practical perspective, the cytotoxicity of the prepared compounds against human diploid fibroblasts (BJ) and the human cancer cell lines K-562 and MCF-7 was also assayed in vitro. The prepared compounds showed none or marginal cytotoxicity compared to the corresponding N9-ribosides. Finally, the pH stability of the two model compounds was assessed in acidic and neutral water solutions (pH 3-7) by high-performance liquid chromatography (HPLC).
- Szuecova, Lucie,Spichal, Lukas,Dolezal, Karel,Zatloukal, Marek,Greplova, Jarmila,Galuszka, Petr,Krystof, Vladimir,Voller, Jiri,Popa, Igor,Massino, Frank J.,Jorgensen, Jan-Elo,Strnad, Miroslav
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experimental part
p. 1938 - 1947
(2009/05/26)
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- Synthesis of 6-alkyl- and arylamino-9-(tetrahydro-2-pyranyl)purines via 6-methylsulfonylpurine
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A series of six potential plant hormones, 6-alky- and arylamino-9- (tetrahydro-2-pyranyl)purines were prepared in three steps in 35 to 45% overall yield from 6-methylthiopurine via 6-methylsulfonylpurine.
- Villar, Jose Daniel Figueroa,Motta, Marita Almeida
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p. 1005 - 1015
(2007/10/03)
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