Synthesis, characterization and biological activity of ring-substituted 6-benzylamino-9-tetrahydropyran-2-yl and 9-tetrahydrofuran-2-ylpurine derivatives.
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 (1)H 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 N(9) 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 N(9)-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).
Szücová
Lucie
L
Laboratory of Growth Regulators, Palacky University & Institute of Experimental Botany AS CR, Olomouc, Czech Republic. lucie.szucova@upol.cz
Spíchal
Lukás
L
Dolezal
Karel
K
Zatloukal
Marek
M
Greplová
Jarmila
J
Galuszka
Petr
P
Krystof
Vladimír
V
Voller
Jirí
J
Popa
Igor
I
Massino
Frank J
FJ
Jørgensen
Jan-Elo
JE
Strnad
Miroslav
M
D045744:Cell Line, Tumor; D003583:Cytokinins / Q000737:chemistry / Q000378:metabolism; D004355:Drug Stability; D005347:Fibroblasts / Q000187:drug effects; D005663:Furans / Q000138:chemical synthesis* / Q000737:chemistry / Q000633:toxicity*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D011687:Purines / Q000138:chemical synthesis* / Q000737:chemistry / Q000633:toxicity*; D011714:Pyrans / Q000138:chemical synthesis* / Q000737:chemistry / Q000633:toxicity*
C540741:6-(3-hydroxybenzylamino)-9-tetrahydrofuran-2-ylpurine; C540742:6-(3-hydroxybenzylamino)-9-tetrahydropyran-2-ylpurine; D003583:Cytokinins; D005663:Furans; D011687:Purines; D011714:Pyrans