Tibor Past

The effect of carvedilol on enhanced ADP-ribosylation and red blood cell membrane damage caused by free radicals.

OBJECTIVE Previous studies have reported that the beta and alpha adrenoceptor blocker carvedilol has unique protective effects on free radical-induced myocardial injury. The aim of this study was to examine how carvedilol regulates reactive-oxygen-species-mediated signaling and decreases red blood cell membrane damage in heart perfusion and in a rheological model. METHODS The ischemia-reperfusion-induced oxidative cell damage, and changes in the intracellular signaling mediated by reactive oxygen species and peroxynitrite were studied on rat hearts in a Langendorff perfusion system (n=15). The effect of carvedilol on red blood cell suspension viscosity (hematocrit: 60%) incubated with free radical generator (phenazine methosulphate) was also investigated (n=10). The measurements were performed on a capillary viscosimeter. RESULTS In both studies a protective effect of carvedilol was found, as the decrease of red blood cell suspension viscosity and K(+) concentration in the supernatant indicated. Carvedilol significantly decreased the ischemia-reperfusion-induced free radical production and the NAD(+) catabolism and reversed the poly- and mono(ADP-ribosyl)ation. Carvedilol also decreased the lipid peroxidation and membrane damages as determined by free malondialdehyde production and the release of intracellular enzymes. The self ADP-ribosylation of isolated poly(ADP-ribose) polymerase was also significantly inhibited by carvedilol. CONCLUSION Our results show that carvedilol can modulate the reactive-oxygen-species-induced signaling through poly- and mono(ADP-ribosyl)ation reactions, the NAD(+) catabolism in postischemic perfused hearts and has a marked scavenger effect on free radical generator-induced red blood cell membrane damage. All these findings may play an important role in the beneficial effects of carvedilol treatment in different cardiovascular diseases.

Production of Orally Applicable New Drug or Drug Combinations from Natural Origin Capsaicinoids for Human Medical Therapy

It is well known that the capsaicin stimulates (in small doses) or impairs (in high doses) the capsaicin-sensitive afferent nerves and the final effects of capsaicin depend on its applied doses. The effects of capsaicin were analyzed on the gastrointestinal mucosal protection and injury in animal experiments and in human beings (from 1980 up to now). From 2005 to 2008 an interdisciplinary group (21 researchers) participated in the production of orally applicable drug or drug combinations from capsaicin for human medical therapy of patients suffering from cardiovascular, degenerative joint and locomotor diseases, who received in their treatments non-steroidal anti-inflammatory compounds (NSAIDs). Our studies were based on the results of the NSAIDs-induced gastrointestinal side effects could be detected by application of small doses of capsaicin. Because natural (plant origin) capsaicin is chemically does not represent a uniform entity and used in the international research, consequently the authors met a lot of unpredictable scientific problems during the time of production of new capsaicin containing (alone or in combinations) drug before receiving official permissions from the different national and international authorities to start the classical human clinical pharmacological studies. This paper summarizes the different steps from the basic physiological and pharmacological notes (in animals), plant cultivation, chemistry of substance(s), animal (general and germinative) acute and chronic toxicology, human actions, basic clinical pharmacology of natural capsaicin (capsaicinoids) to introduce and to develop a new drug (or drug combinations) in the human medical therapy.

A validated HPLC-FLD method for analysis of intestinal absorption and metabolism of capsaicin and dihydrocapsaicin in the rat

A sensitive and selective reverse-phase high performance liquid chromatographic method with fluorescence detection has been developed for determination of capsaicin (8-methyl-N-vanillyl-(trans)-6-nonenamid) and dihydrocapsaicin (8-methyl-N-vanillylnonanamide) in samples generated in rat small intestine luminal perfusion experiments. The experiments were designed to study the biotransformation of capsaicinoids in the small intestine in the rat. The chromatographic separation was performed at room temperature on a ZORBAX Eclipse(®) XDB-C8 column using isocratic elution with a mobile phase consisting 0.05M orthophosphoric acid solution and acetonitrile (60:40, v/v; pH 3.0) with a flow rate of 1.5mL/min. Fluorescence detection was performed at excitation and emission wavelengths of 230 and 323nm, respectively. The method was evaluated for a number of validation characteristics (accuracy, repeatability and intermediate precision, limit of detection, limit of quantification and calibration range). The limit of detection (LOD) was 50ng/mL and the limit of quantification (LOQ) was 100ng/mL for both capsaicin and dihydrocapsaicin reference standards dissolved in blank perfusate. The method was successfully applied for investigation of intestinal absorption of capsaicin and dihydrocapsaicin while 30μg/mL standardized Capsicum extract - containing capsaicin and dihydrocapsaicin - was luminally perfused for a 90min period. The structure of the glucuronide metabolites of capsaicin and dihydrocapsaicin appeared in the perfusate was identified by mass spectrometry.

Capsaicin is a New Gastrointestinal Mucosal Protecting Drug Candidate in Humans — Pharmaceutical Development and Production Based on Clinical Pharmacology

Backgrounds. 1. The intact gastrointestinal mucosa is a result of excellently well regulated equilibrium between the aggressive (physical and other stress, xenobiotics, wide scale of drugs, chemicals, bacterial and viral infections) and defensive (bicarbonate secretion, mucus secre‐ tion, blood supply, prostaglandins, mucosal energy systems, etc.) factors, which are further controlled by different neural, hormonal and pharmacological mechanisms. 2. The vagal nerve takes an essential place both in the development of gastrointestinal mucosal damage and protection. 3. The physicians have widely been applied the nonsteroidal antiinflammatory drugs (such as aspirin, diclofenac, Naproxen, etc.) as antipyretic, anti-inflammatory, painkiller and platelet aggregation inhibitor agents in healthy humans and in patients with different disorders (such as myocardial infaction, different forms of thrombophylia, rheuma‐ toid arthritis and arthrosis or trauma) in the everyday medical practice. The administration of these drugs produces gastrointestinal complaints (mucosal damages, bleedings, perforations). So in one hand, the applications of these drugs are absolutely indicated, on the other hand, the