• YAKHAK HOEJI
• /
• v.41 no.2
• /
• pp.181-186
• /
• 1997

A series of 7-deazahypoxanthine and 7-deazaadenine derivatives[6,7.8.9.10,13] as purine antagonists was prepared. The pyrrolidine-5-one derivatives[4,11] were treated vith $(C_2H_5)_3OBF_4$ to give 3- aryl-5-ethoxy-2H-3,4-dihydropyrrole[5,12], which were converted to 7-aryl-7,8-dihydro-7(9H)-deazahy-poxanthine[6,7,8,9,10] and 7-phenyl-2-methyl-7,8- dihydro-7(9H)-deazaadenine[13].

• YAKHAK HOEJI
• /
• v.37 no.3
• /
• pp.228-234
• /
• 1993

A new series of 7-deazapurine derivatives[7,8] as purine antagonists was prepared. Diethyl 4-cyano-N-(diphenyimethylene)-3-arylglutamate[3] were synthesized by LDA-catalyzed Michael addition of N-(diphenylrnethylene)glycine ethyl ester with (E)-2-cyano-3-arylacrylate. Deprotection yields diethyl 4-cyano-3-arylglutamate, which were easily cyclized to 4-cyano-2-ethoxycarbonyl-5-oxo-3-arylpyrrolidine[4]. The compounds[4] were treated with NaBH$_{4}$ and then with (C$_{2}$H$_{5}$)$_{3}$OBF$_{4}$ to give 4-cyano-5-ethoxy-2H-2-ethoxymethyl-3-aryl-3,4-dihydropyrrole[6], which were converted to 7-aryl-6-amino-8-ethoxymethyl-7,8-dihydro-7(3H, 9H)-deazapurine-2-thione[7] and 7-aryl-2,6-diamino-8-ethoxymethyl-7,8-dihydro-7(9H)-deazapurine[8] with possible activity against neoplastic disease.

• The Korean Journal of Pharmacology
• /
• v.19 no.2
• /
• pp.25-34
• /
• 1983

In this isolated study, it was aimed to elucidate the pharmacological properties of non-cholinergic, non-adrenergic inhibitory responses in the longitudinal strips of rabbit portal vein. 1) The portal vein responded inhibitory to electrical field stimulation in a frequency - and calcium-dependent manner after pretreatment with atropine, guanethidine and ergotamine, simultaneously. 2) When exogenous ATP, ADP, adenosine and cyclic AMP were added, respectively, they only showed the relaxations in the higher concentration without mimicing or affecting the inhibitory response induced by the electrical stimulation. The antagonist of purine substances, neither quinine nor isobutyl-methyl xanthine did influence on the relaxation. 3) The inhibitory response was significantly increased in the presence of $1{\mu}g/ml 4-amino-pyrineine (4-AP) which is $K^+-conduction$ blockade, but higher concentration of 4-AP directly decreased the vascular tone. 4) Though repeated application of ATP revealed the inhibitory effect on the relaxation, however, that of adenosine resulted rather increase of the amplitude. 5) After pretreatment with $^3H-adenosine$, $^3H-efflux$ induced by ATP or adenosine was markedly enhanced, but the electrical stimulation caused less $^3H-efflux$. 6) ^3H-efflux by electrical stimulation was not affected by the administration 4-AP, tetrodotoxin and adenosine.

• The Korean Journal of Physiology and Pharmacology
• /
• v.5 no.5
• /
• pp.423-431
• /
• 2001

Some recent investigations revealed that vasodilatory action of adenosine is mainly not mediated by surface A2 receptor and suggested the existence of an intracellular action site. In the present study, we tried to differentiate intracellular from extracellular site of adenosine action in the regulation of coronary flow. In perfused rabbit hearts, concentration-response curve of coronary flow to exogenous adenosine was constructed in the presence or absence of dipyridamole, an inhibitor of transmembrane purine transport. Inhibition of cellular adenosine uptake by dipyridamole suppressed the increase of flow rate while enhancing the decrease in heart rate induced by exogenous adenosine. In another series of experiments, perfused rabbit hearts were subjected to energy deprivation in order to increase the production of endogenous adenosine. Energy deprivation along with dipyridamole administration resulted in higher coronary flow rate. Lower perfusate adenosine concentration was observed along with higher tissue adenosine content in this group. These results implied that coronary flow rate is determined not by interstitial adenosine concentration but by intracellular activity of adenosine. To confirm the effects of dypiridamole in vivo, direct measurement of interstitial adenosine concentration by mycrodialysis along with the assay of intracellular adenosine content was performed after intranenous dipyridamole administration. After dipyridamole infusion, intracellular adenosine content was markedly increased while interstitial adenosine concentration was not altered. In another series of experiments, the right shift of concentration-response curve of adenosine-induced vasodilation by 8-phenyltheophilline, a representative adenosine receptor antagonist, was mostly abolished by prior administration of prazosin, indicating that the influence of 8-PT on the adenosine action is not attributed to the inhibition of A2 receptor but related to the suppression of ${\alpha}-adrenoceptor$ activation. From these results, we concluded that adenosine acts intracellularly to regulate the coronary blood flow.

• Proceedings of the Korean Biophysical Society Conference
• /
• 2003.06a
• /
• pp.55-55
• /
• 2003

P2X$_3$ receptor, a member of P2 purine receptors, is a ligand-gated ion channel activated by extracellular ATP as an endogenous ligand, and highly localized in peripheral and central sensory neurons. The activation of P2X3 receptor by ATP as the pronociceptive effect has been known to initiate the pain signaling involved in chronic inflammatory nociception and neuropathic pain by nerve injury, implicating the possibility of new drug development to control pains. In this study, we have developed a two electrode voltage clamp (TEVC) assay system to evaluate the inhibitory activity of several newly synthesized PPADS and a novel non-ionic antagonist against ATP activation of human P2X3 receptor. PPADS derivatives include several pyridoxine and pyridoxic acid analogs to study the effects of phosphate and aldehyde functional groups in PPADS. All new PPADS analogs were less potent than PPADS at human P2X$_3$ receptors, however, LDD130, a non-ionic analog showed potent antagonistic property with $IC_{50}$/ of 8.34 pM. In order to uncover the structure activity relationships of LDD130, and design new structural analogs, we synthesized and investigated a few structural variants of LDD130, and the results will be discussed in this presentation.

• Childhood Kidney Diseases
• /
• v.2 no.1
• /
• pp.41-49
• /
• 1998

Treatment of $Henoch-Sch\"{o}nlein$ purpura nephritis(HSPN) accomanied by nephrotic syndrome is still controversal, even though both corticosteroids and immunosuppressants have been used for therapy. Azathioprine(AZA) is a chemical analog of the physiologic purines-adenine, guanine, and hyoxanthine and an antagonist to purine metabolism which may inhibit RNA and DNA synthesis and is mainly used for immunosuppressive agent. We studied the effects of AZA in HSPN accompanied by nephrotic syndrome and evaluating the clinical status and histopathologic changes by sequential biopsies following the treatment. Fifteen patients with nehprotic syndrome either initially or during the course of HSPN confirmed by renal biopsies were treated with AZA(2 mg/kg/day) and prednisolone (0.5-1 mg/kg/day qod) for 8months. Folow up renal biopsy was done after treatment in 11 patients. The clinical status of the patients on admission were C(12 cases) and B(3 cases). Improvement of clinical status were showed in 12 cases, but 3 cases were not improved and 1 case was aggrevated after AZA treatment. Complete remission of proteinuria were in 8 cases(53.3%), partial remission were in 4 cases(26.7%) and persistence of proteinuria and hematuria were in 3 cases(20.0%). The loss of hematuria were in 10 cases(66.7%). Histopathologically and immunopathologically, 4 cases were improved. This study suggests that, although control studies are needed, AZA could be used in the treatment of HSPN accompanied by nephrotic syndrome.