Caffeine, widely consumed in beverages, and many xanthine analogs have had a major impact on biomedical research. Caffeine and various analogs, the latter designed to enhance potency and selectivity toward specific biological targets, have played key roles in defining the nature and role of adenosine receptors, phosphodiesterases, and calcium release channels in physiological processes. Such xanthines and other caffeine-inspired heterocycles now provide important research tools and potential therapeutic agents for intervention in Alzheimer’s disease, asthma, cancer, diabetes, and Parkinson’s disease. Such compounds also have activity as analgesics, antiinflammatories, antitussives, behavioral stimulants, diuretics/natriuretics, and lipolytics. Adverse effects can include anxiety, hypertension, certain drug interactions, and withdrawal symptoms.

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Caffeine analogs: biomedical impact

Publisher Summary This chapter discusses some general information about cyclic nucleotide phosphodiesterases (PDEs). It also discusses the PDE3 gene family, emphasizing the molecular biology, structure/function relationships, and cellular regulation and functional roles of PDE3s, as well as physiological/pharmacological actions, therapeutic applications, and potential benefits of PDE3 inhibitors. The major cause of concern in the use of PDE3 inhibitors as therapeutic agents is the potential for increased mortality in patients with known heart disease. Although caution is certainly warranted in this context, conclusions should not be indiscriminately applied to all PDE3 inhibitors. The pharmacological profiles of newer PDE3 inhibitors differ from those of the PDE3 inhibitors used in earlier heart failure clinical trials. Although milrinone and cilostazol are similar in potency as inhibitors of PDE3, milrinone had greater effects than cilostazol on increasing both cyclic adenosine monophosphate (cAMP) and contractility in isolated rabbit cardiomyocytes. The ability to target PDE3 inhibitors to specific isoforms in specific intracellular compartments and/or specific cells may be critical for improvement in efficacy and safety. The acute benefits and chronic adverse actions of PDE3 inhibitors in patients, with heart failure, may result from the phosphorylation of different substrates of Protein kinase A (PKA) in different intracellular compartments. Newer PDE3 inhibitors that target a specific isoform in the appropriate compartment could potentially confer beneficial hemodynamic effects without adverse effects on mortality.

Regulation and function of the cyclic nucleotide phosphodiesterase (PDE3) gene family.

Inhibitory effects of flavonoids on phosphodiesterase isozymes from guinea pig and their structure-activity relationships.

SPECIFIC AIMSCough is a condition that affects the vast majority of people at some point in their lives and is the most common complaint for which medical attention is sought. Currently, no effective treatment exists. The aim of this study was to investigate the utility of a novel antitussive called theobromine, a methylxanthine derivative present in cocoa and chocolate, on cough and airway sensory nerve function in humans.PRINCIPAL FINDINGS1. Theobromine as a potential antitussiveSeveral synthetic antitussives are characterized by the presence of a 1,2,4-oxadiazole ring in their chemical structure. With the renaissance of the methylxanthine theophylline to treat asthma in the 1970s, a series of novel compounds with an oxadiazolylalkyl substituent at the N7 atom on the basic xanthine skeleton was synthesized and investigated as potential antiasthmatic and antitussive agents.With two of these compounds selected for preclinical testing, 3,7-dihydro-3-methyl-7-/(5-methyl-1,2,4-oxadiazol-3yl)methyl/-1H-purine...

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Theobromine inhibits sensory nerve activation and cough

Endogenous opiates: 1998.

The effect of 1-cyclopentyl-3-ethyl-6-(3-ethoxypyrid-4-yl)-1H-pyrazolo[3,4-d]pyrimidin-4-one (SR 265579), a potent inhibitor of guanosine 3’,5’-cyclic monophosphate (cyclic GMP) phosphodiesterase (PDE5), was examined regarding its specificity toward the other cyclic nucleotide phosphodiesterases, the effect on cyclic nucleotide levels and the bronchodilatory activity, both in vitro and in vivo in guinea-pigs. The effects were compared to those obtained with zaprinast (CAS 37762-06-4), a known PDE5 inhibitor. Anion-exchange chromatography of the soluble fraction of guinea-pig homogenates revealed 5 peaks which corresponded to PDE1, PDE2, PDE3, PDE4 and PDE5. SR 265579 produced a potent and competitive inhibition, with respect to cyclic GMP, of PDE5 with a Ki of 6.4 nmol/l. The compound was 25 fold more potent than zaprinast and demonstrated selectivity toward PDE5. The selectivity index was 14 and 33 with respect to PDE4 and 3, respectively. PDE1 and 2 were only inhibited at considerably higher concentrations. SR 265579 specifically increased the intracellular cyclic GMP levels in guinea-pig tracheal epithelial cells (EC 50 = 117 nmol/l). Moreover, in the guinea pig, plasma cyclic GMP levels were significantly increased after the intravenous or oral administration of doses as low as 1 mg/kg. Isolated guinea-pig trachea were relaxed by the addition of SR 265579 as evaluated by measuring either spontaneous tone or relaxation of histamine and acetylcholine-precontracted preparations. PD 2 values were of 7.64, 6.52 and 5.25, respectively. In vivo, after i.v. administration, bronchodilatory activity was demonstrated in an artifi- cially-ventilated guinea-pig histamine-induced bronchospasm model with an ED 50 of 0.63 mg/ kg. In all experiments, SR-265579 was proved to be more active than zaprinast. These results demonstrate that SR 265579 is an orally active, potent and specific inhibitor of PDE5.

Experimental studies on guanosine 3',5'-cyclic monophosphate levels and airway responsiveness of the novel phosphodiesterase type 5 inhibitor SR 265579 in guinea-pigs.

CH-13584 (formerly: KHL-8425, 1H-purine-2,6-dione, 3,7-dihydro-3-methyl-7[(5-methyl-1,2,4-oxadiazol-3-yl)methyl], CAS 115779-20-9) is a new xanthine derivative synthesized with the purpose to develop a highly safe compound against several pulmonary disorders, especially for the treatment of acute and chronic cough CH-13584 showed acute and chronic antitussive activity on citric acid spray-evoked cough model in guinea-pig CH-13584 was also effective on capsaicine spray and mechanical irritation-induced cough in guinea-pig and rabbit, respectively The effectivity of CH-13584 on antitussive tests reached and in some cases even exceeded the effectivity of the reference compounds The compound increased the mucociliary clearance at lower doses than bromhexine

Experimental studies on the antitussive properties of the new xanthine derivative 1H-purine-2,6-dione, 3,7-dihydro-3-methyl-7[(5-methyl-1,2,4-oxadiazol-3-yl)methyl]. 1st communication: in vivo demonstration of the effects on animal models of cough and of mucociliary clearance.

CH-13584 (formerly: KHL-8425, 1H-purine-2,6-dione, 3,7-dihydro-3-methyl-7[(5-methyl-1,2,4-oxadiazol-3-yl)methyl], CAS 115779-20-9) is a new xanthine derivative, structurally related to theophylline. Potent antitussive activity in the 4 to 8 mg/kg dose range, by the oral route, was already demonstrated for this compound. In the present work, it is shown that contrary to theophylline, CH-13584 does not interact with adenosine A 1 receptor and is a weaker inhibitor of cyclic nucleotide phosphodiesterase. In addition, CH-13584 is a less active bronchodilator in vitro and in vivo. It is also devoid of the cardiovascular and behaviour side-effects of theophylline and of effects on diuresis at dosage well above the antitussive dose. CH-13584, therefore, has a different pharmacological profile compared to theophylline and is devoid of the known side-effects of the latter. Such differences could result from a different biochemical profile.

Experimental studies on the antitussive properties of the new xanthine derivative 1H-purine-2,6-dione, 3,7-dihydro-3-methyl-7[(5-methyl-1,2,4-oxadiazol-3-yl)methyl]. 2nd communication: investigations on theophylline-like activities.

CH-13584 (formerly: KHL-8425, 1H-purine-2,6-dione, 3,7-dihydro-3-methyl-7[(5-methyl-1,2,4-oxadiazol-3-yl)methyl], CAS 115779-20-9) showed antitussive effect on the citric acid spray-induced cough model. The antitussive effect of p.o. CH-13584 was antagonised by i.m. or intracerebroventricular (i.c.v.) naloxone, i.m. nor-binaltorphimine or s.c. beta-funaltrexamine. Intracerebroventricular administration of CH-13584 induced long-lasting antitussive effect which was antagonised by coadministration of i.c.v. naloxone. CH-13584 did not bind to opioid mu, delta, kappa receptor in vitro or inhibit the [3H]diprenorphine binding in vivo. Two-week treatment with CH-13584 up to the dose of 100 mg/kg p.o. did not produce autonomic and behavioural signs of withdrawal induced either by drug withdrawal or by naloxone injection, while morphine and codeine induced characteristic opioid-type physical dependence in rats.

Experimental studies on the antitussive properties of the new xanthine derivative 1H-purine-2,6-dione, 3,7-dihydro-3-methyl-7[(5-methyl-1,2,4-oxadiazol-3-yl) methyl]. 3rd communication: examinations on opioid mechanisms and physical drug dependence.

Mikus Endre

Papers

Experimental studies on guanosine 3',5'-cyclic monophosphate levels and airway responsiveness of the novel phosphodiesterase type 5 inhibitor SR 265579 in guinea-pigs.

Experimental studies on the antitussive properties of the new xanthine derivative 1H-purine-2,6-dione, 3,7-dihydro-3-methyl-7[(5-methyl-1,2,4-oxadiazol-3-yl)methyl]. 1st communication: in vivo demonstration of the effects on animal models of cough and of mucociliary clearance.

Experimental studies on the antitussive properties of the new xanthine derivative 1H-purine-2,6-dione, 3,7-dihydro-3-methyl-7[(5-methyl-1,2,4-oxadiazol-3-yl)methyl]. 2nd communication: investigations on theophylline-like activities.

Experimental studies on the antitussive properties of the new xanthine derivative 1H-purine-2,6-dione, 3,7-dihydro-3-methyl-7[(5-methyl-1,2,4-oxadiazol-3-yl) methyl]. 3rd communication: examinations on opioid mechanisms and physical drug dependence.

Behavioural effects of selective PDE4 inhibitors in relation to inhibition of catalytic activity and competition for [3H]rolipram binding.