Crocus sativus L. Extract (Saffron) Effectively Reduces Arthritic and Inflammatory Parameters in Monotherapy and in Combination with Methotrexate in Adjuvant Arthritis

Rheumatoid arthritis (RA), an autoimmune disease, is characterized by inflammation that affects not only the liver but also other organs and the musculoskeletal system. The standard therapy for RA is methotrexate (MTX), which has safety limitations. The extract from Crocus sativus L. (saffron-SF) is also known for its anti-inflammatory effects. Therefore, we decided to investigate the potential benefit of SF in monotherapy via two doses (SF1-25 mg/kg of b.w.; SF2-50 mg/kg of b.w.) and in combination with MTX (0.3 mg/kg of b.w., twice a week) using adjuvant arthritis in rats. To evaluate these therapeutic settings, we used biometric, immunological, and biochemical parameters, as well as the relative gene expression of the mRNA in the liver. Our results showed a statistically significant increase in the experimental animals' body weight and the arthritic score (AS) on day 14 for monotherapy with SF1 and SF2. The change of hind paw volume (CHPV) was significant only for SF2 monotherapy on the 14th day of the experiment. A combination of SF1 and SF2 with MTX significantly modulated all the biometric parameters during the experimental period. Additionally, AS and CHPV improved considerably compared to MTX monotherapy on day 21. Furthermore, all monotherapies and combination therapies were significant for the biochemical parameter γ-glutamyl transferase (GGT) in the joint. GGT activity in the spleen was less pronounced; only MTX in combination with SF1 significantly modified this parameter. The higher dose of SF monotherapy (SF2) was similarly significant with respect to immunological parameters, such as plasmatic IL-17A, IL-1β, and MMP-9 on day 21. The combination of both doses of SF with MTX significantly improved these immunological parameters, except for C-reactive protein (CRP), which was influenced only by the higher dose of SF2 in combination with MTX in plasma at the end of the experiment. A different effect was found for the relative expression of CD36 mRNA, where only SF1 significantly decreased gene expression in the liver. However, the relative gene mRNA expression of IL-1β in the liver was significantly reduced by the SF monotherapies and the combination of both SF doses with MTX. Our findings showed SF's partial antiarthritic and anti-inflammatory potential in monotherapy, but the effect was stronger in combination with MTX.

Treatment with coenzyme Q10, omega-3-polyunsaturated fatty acids and their combination improved bioenergetics and levels of coenzyme Q9 and Q10 in skeletal muscle mitochondria in experimental model of arthritis

Rheumatoid arthritis (RA) and its animal model adjuvant arthritis (AA) are inflammatory diseases characterized by chronic inflammation, systemic oxidative stress and disturbed mitochondrial bioenergetics of skeletal muscle. The present study aimed to evaluate the effects of coenzyme Q10 - CoQ10 (100 mg/kg b.w.), omega-3-polyunsaturated fatty acids - omega-3-PUFA (400 mg/kg b.w.) and their combined treatment in AA on impaired skeletal muscle mitochondrial bioenergetics, inflammation and changes in levels CoQ9 and CoQ10 in plasma. Markers of inflammation (C-reactive protein, monocyte-chemotactic protein-1), antioxidant capacity of plasma, respiratory chain parameters of skeletal muscle mitochondria and concentrations of CoQ9 and CoQ10 in plasma and in muscle tissue were estimated. Treatment of the arthritic rats with CoQ10, omega-3-PUFA alone and in combination partially reduced markers of inflammation and increased antioxidant capacity of plasma, significantly increased concentrations of coenzyme Q in mitochondria and improved mitochondrial function in the skeletal muscle. Combined treatment has similar effect on the mitochondrial function as monotherapies; however, it has affected inflammation and antioxidant status more intensively than monotherapies. Long-term supplementary administration of coenzyme Q10 and omega-3-PUFA and especially their combination is able to restore the impaired mitochondrial bioenergetics and antioxidant status in AA.

Microemulsions as Solubilizers and Penetration Enhancers for Minoxidil Release from Gels

Micro- and nanoemulsions are potential drug solubilizers and penetration enhancers through the high surfactant/co-surfactant content. This study aimed to evaluate the influence of minoxidil (MXD) solubilized in the microemulsions (MEs) on drug release by in vitro/ex vivo diffusion through the semi-permeable membrane Spectra/Por^® (Spectrum Laboratory, Gardena, CA, USA) and porcine ear skin. Moreover, a residual amount of drug in the skin after ex vivo diffusion was evaluated. The reference ME_R, lecithin-containing ME_L, and gelatin-containing ME_G were characterized in terms of their size, polydispersity index, density, viscosity, electrical conductivity and surface tension. Based on the in vitro diffusion, it can be argued that ME_L slowed down the drug release, while ME_R and ME_G have no significant effect compared to the sample, in which propylene glycol (PG) was used as a solubilizer. Determination of the residual drug amount in the skin after 6 h of the ex vivo permeation was demonstrated as the most valuable method to evaluate the effectiveness of the ME’s application. The results indicate that the most optimal MXD permeation enhancers in alginate gel were the natural surfactants containing MEs. MXD solubilization in ME_G and ME_L had caused more than 5% of the drug remaining in the skin, which is almost a 1.5-fold higher amount compared to the reference gel.

Possibilities of the microemulsion use as indomethacin solubilizer and its effect on in vitro and ex vivo drug permeation from dermal gels in comparison with transcutol®

OBJECTIVE

Transcutol^® is a perfect solubilizer and an effective permeation enhancer of many active substances commonly used in cosmetics. Microemulsions due to the content of surfactant and co-surfactant could be also considered as chemical permeation enhancers that may support transdermal delivery of poorly water- soluble drugs. The purpose of this study was to investigate the effect of Transcutol^® and potential microemulsions on diffusion of poorly soluble indomethacin through an artificial membrane and excised rat skin.

METHODS

After drug solubilization in different enhancers, drug was dispersed in sodium alginate or carbopol gel used as dermal basis. For characterization of the microemulsions, the basic physico-chemical properties were determined. In vitro as well as ex vivo drug release was determined by vertical Franz cells.

RESULTS

Enhancing effect of the examined microemulsions was observed only in carbopol gel. There was an increase in cumulative drug amount released through synthetic membrane by 37.7-39.8% from the microemulsion formulation and 90.6% from Transcutol^® formulation within 6 h compared to the control samples. The differences between the permeation curves with or without the content of the enhancers were statistically significant (p < .05). Pearson correlation coefficients indicate a very high degree of dependence (r > 0.9) between in vitro and ex vivo drug release from all dermal vehicles used.

CONCLUSION

It can be stated that Transcutol^® is the best solubilizer and also penetration enhancer from the examined, and therefore it seems to be effective excipient/solubilizer in topical IND formulation.

Study of anti-inflammatory activity of Fatsiphloginum™ (Fatsia japonica) and a new purified triterpene-rich extract of saponins (PS-551) in experimental model of arthritis

In this study, two extracts from Fatsia japonica-Fatsiphloginum™ (extract of triterpene glycosides containing 45-50 % of fatsiosides (FS)) and purified triterpene-rich extract of saponins with code name PS-551 (PS) were administered in combination with methotrexate (MTX) and in monotherapy to rats suffering adjuvant arthritis (AA). The anti-inflammatory activities of extracts were evaluated as monotherapies in comparison with untreated AA. PS administered in higher dose showed on day 28 effective decrease of hind paw volume (HPV), decreased activity of gamma-glutamyl transferase (GGT) in joints, and also interleukin-17A was decreased significantly on day 14. The higher dose of PS was more effective than both doses of FS. Further, we evaluated the higher doses of PS and FS in combination with MTX. PS improved the effect of MTX in combination more effective than FS (HPV, body weight and activity of GGT in joint). However, FS was more effective in reducing the level of IL-17A on day 14 and activity of GGT in spleen than PS. In conclusion, our study showed that generally FS has higher anti-arthritic activity comparing to PS. Thus, the novel combination of Fatsiphloginum™ and methotrexate could be interesting for future clinical studies in patients suffering auto-immune diseases.

Inhibition of oxidative stress in brain during rat adjuvant arthritis by carnosine, trolox and novel trolox-carnosine

Carnosine (CARN) is an anti-glycating agent able to quench superoxide, and to neutralize 4-hydroxynonenal. Trolox-carnosine (CARN-T) was synthesized because of its resistance against degradation and to improve CARN antioxidant capacity. We evaluated the impact of trolox (TRO), CARN and its derivative CARN-T on oxidative stress (OS) in brain during rat adjuvant arthritis (AA). The experiments were done on healthy, control arthritic and arthritic animals with administration of CARN 150 mg/kg b.w., TRO 41 mg/kg b.w. and CARN-T 75 mg/kg b.w. in a daily dose during 28 days. Antioxidants did not affect the body weight on day 14, but on day 28 TRO enhanced the weight reduction. On day 14 and 28 CARN-T and TRO reduced arthritic score. IL-1beta, MCP-1 and MMP-9 were measured in plasma on day 14. MCP-1 was decreased by CARN-T and TRO. All antioxidants reduced IL-1beta and MMP-9 levels. Malondialdehyde, 4-hydroxynonenal and protein carbonyls were increased in brain. CARN, CARN-T and TRO prevented higher lipid and protein oxidation in brain. CARN and CARN-T caused no weight reduction like TRO that has an advantage in inflammatory arthritis. Moreover the antioxidants administered had a similar therapeutic effects on arthritic score, markers of inflammation in plasma and OS in brain.

Effect of Aminoguanidine and Copper(II) Ions on the Formation of Advanced Glycosylation End Products

Nonenzymatic glycosylation of proteins is a weighty consequence of hyperglycaemia in diabetes. This study examines the possible effect of copper(II) ions on the glycosylation of human serum albumin (HSA) and the resulting formation of advanced glycosylation end products (AGEs). HSA in phosphate-buffered saline was incubated with 100 mmol/l glucose. The effect of addition of copper(II) ions and/or aminoguanidine bicarbonate (CAS 2582-30-1) was investigated. The determination of AGE levels derived from glycosylated/glycoxidated HSA was performed using a specific spectrofluorometric assay (excitation 346 nm; emission 418 nm). The results showed that the addition of copper(II) ions to the incubation medium containing glucose increased the formation of AGEs. Further, in the presence of copper(II) ions, a significant blockade of aminoguanidine inhibitory effect on the formation of AGEs was observed.

Effect of methotrexate on inflammatory cells redistribution in experimental adjuvant arthritis

The aim of this study was to evaluate the morphological changes in the spleen, the thymus and the knee joints of rats with experimental adjuvant arthritis induced by Mycobacterium butyricum in the incomplete Freund's adjuvant and the effect of treatment with methotrexate (MTX). Particular attention was aimed on the redistribution of granulocytes in the tissues during the inflammatory process. Clinical parameters, e.g., joint edema, body weight and of gamma glutamyl transferase (GGT) activity as an inflammatory marker, have also been determined. Induction of adjuvant arthritis caused a significant decrease in granulocyte number in the spleen and vice versa a significant increase in the knee joints, but without significant changes in the thymus. Treatment with methotrexate reversed this phenomenon by increasing the granulocyte number in the spleen and decreasing it in knee joints. MTX decreased the joint edema as well as the activity of GGT in the spleen, modified the size of the white pulp of the spleen and increased the cortex/medulla ratio in the thymus. The observed changes support the anti-inflammatory and immunomodulatory properties of MTX supporting its use as the first-line medication in patients with rheumatoid arthritis.

Aurothiomalate as preventive and chain-breaking antioxidant in radical degradation of high-molar-mass hyaluronan

The potential anti- or pro-oxidative effects of a disease-modifying antirheumatic drug, aurothiomalate, to protect high-molar-mass hyaluronan against radical degradation were investigated along with L-glutathione - tested in similar functions. Hyaluronan degradation was induced by the oxidative system Cu(II) plus ascorbate known as the Weissberger's oxidative system. The time- and dose-dependent changes of the dynamic viscosity of the hyaluronan solutions were studied by the method of rotational viscometry. Additionally, the antioxidative activity of aurothiomalate expressed as a radical-scavenging capacity based on a decolorization 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assay was inspected. At the higher concentrations tested, L-glutathione showed excellent scavenging of (.) OH and peroxyl-type radicals, however, at the lowest concentration applied, its pro-oxidative effect was revealed. The effects of aurothiomalate on hyaluronan degradation were similar to that of L-glutathione, however, at the lowest concentration tested, no significant pro-oxidant effect was observed.

Pharmacological regulation of neutrophil activity and apoptosis: Contribution to new strategy for modulation of inflammatory processes

Novel strategies of antiinflammatory therapy are based upon pharmacological agents capable to enhance the resolution - i.e. the termination of the beneficial inflammation before it may turn into an adverse chronic stage. In contrast to the current therapy, which antagonises the formation of proinflammatory mediators, the "proresolving" therapy promotes natural antiinflammatory processes. It is likely that several drugs and phytochemicals would act in this way, but this point has not been investigated and thus might be totally overlooked. In this paper, effects of curcumin (diferuloylmethane) were analysed, considering the ability of this natural compound to affect resolution of inflammation through modulation of its important inputs - activity and apoptosis of neutrophils. The presented data indicate that, besides its well-known ability to suppress mechanisms engaged at the onset and progression of inflammation, curcumin could support resolution of inflammation through decreased activity and enhanced apoptosis of neutrophils. This substance decreased the formation of oxidants in neutrophils, both under in vitro conditions and after oral administration to arthritic rats. Moreover, curcumin accelerated spontaneous apoptosis of neutrophils, as indicated by increased externalisation of phosphatidylserine, by intercalation of propidium iodide and by enhanced activity of the executioner caspase-3.

Does stereochemistry influence transdermal permeation of flurbiprofen through the rat skin?

The possible enantioselectivity in the permeation of the chiral anti-inflammatory drug flurbiprofen across hairless rat skin was studied. The transdermal permeability of individual enantiomers from donor solution containing racemic flurbiprofen (0.1%) and pure enantiomers (0.05%) in isopropyl myristate solution was determined using side-by-side diffusion cells. The permeation profiles of enantiomers (R)- and (S)-flurbiprofen from donor solution containing racemic (RS)-flurbiprofen are comparable. When donor solution contained pure enantiomers, marked differences were observed between the permeation rates of (R)- and (S)-flurbiprofen. The steady-state flux and permeability coefficient were significantly higher for (R)-flurbiprofen in comparison with (S)-flurbiprofen (the flux ratio R/S = 2.04; p < 0.05).

Reduction of oxidative stress in adjuvant arthritis. Comparison of efficacy of two pyridoindoles: stobadine dipalmitate and SMe1.2HCl

The aim of this study was to evaluate the therapeutic potential of oxidative stress (OS) reduction by using pyridoindole (PI) antioxidants in adjuvant arthritis (AA). The substances tested were stobadine dipalmitate (STB) and SMe1. AA was used as animal model. The experiments included healthy animals, control arthritic animals and arthritic animals with administration of PI in the oral daily dose of 15 mg/kg b.m during 28 experimental days. The rats were sacrificed on day 28. Clinical and biochemical parameters were determined. The effect of PI administration was evaluated on the basis of the following parameters: (a) arthritis (volume of hind paws - HPW, change of animal body mass - CBM), (b) OS (chemiluminescence of whole blood - CWB, levels of thiobarbituric acid reacting substance - TBARS and of HNE- and MDA-protein adducts in plasma and activity of gamma-glutamyltransferase (GGT) in hind paw joint homogenates). The PI studied significantly increased the CBM of animals and corrected the HPW. STB also significantly decreased the activity of GGT in joint homogenates. SMe1 was more effective in decreasing plasmatic TBARS levels, but STB was more effective in reducing plasmatic HNE- and MDA-protein adducts. The assay for HNE- and MDA-adducts in plasma as a function of time was applied for the first time in AA. STB markedly decreased spontaneous and PMA-stimulated CWB and reduced neutrophil count. In summary, STB was more effective than SMe1 in reducing OS in AA. Our results showed that the reduction of OS in arthritis also corrected the clinical manifestations of the disease.

Study of new ways of supplementary and combinatory therapy of rheumatoid arthritis with immunomodulators. Glucomannan and Imunoglukán®in adjuvant arthritis

We studied the anti-arthritic activity of glucomannan (GM) isolated from Candida utilis and of Imunoglukán®, a beta-(1,3/1,6)-d-glucan (IMG) isolated from Pleurotus ostreatus. Adjuvant arthritis (AA) was induced intradermally by the injection of Mycobacterium butyricum in incomplete Freund’s adjuvant to Lewis rats. Blood for biochemical and immunological analysis was collected on experimental days 1, 14, 21, and 28. A clinical parameter – hind paw volume (HPV) – was also measured. The detection of IL-1 alpha, IL-4, TNF alpha, and MCP-1 was done by immunoflowcytometry. On day 28 – the end of the experiment – we determined spectrophotometrically: the total anti-oxidant status (TAS) of plasma samples along with thiobarbituric acid-reacting substances (TBARS) levels in plasma and we assessed the activity of gamma-glutamyl transferase (GGT) in hind paw joint homogenate. The experiments included healthy animals, arthritic animals without treatment, and arthritic animals with administration of glucomannan (GM-AA) in the oral daily dose of 15 mg/kg b.w. and of IMG (IMG-AA) in the oral daily dose of 2 mg/kg b.w. The progress of AA was manifested by all parameters monitored. Both substances had beneficial effects on HPV, TBARS levels, GGT activity, and TAS levels. For cytokine assessment, only IMG-AA samples were selected, considering the significant HPV improvement accompanied with the observed anti-oxidant action. IMG administration had a positive immunomodulating effect on all cytokine plasma levels measured, changed markedly due to arthritis progression. Thus, IMG may be considered as a candidate for combinatorial therapy of rheumatoid arthritis.

Decreased activity of neutrophils in the presence of diferuloylmethane (curcumin) involves protein kinase C inhibition

Diferuloylmethane (curcumin) has been shown to act beneficially in arthritis, particularly through downregulated expression of proinflammatory cytokines and collagenase as well as through the modulated activities of T lymphocytes and macrophages. In this study its impact on activated neutrophils was investigated both in vitro and in experimental arthritis. Formation of reactive oxygen species in neutrophils was recorded on the basis of luminol- or isoluminol-enhanced chemiluminescence. Phosphorylation of neutrophil protein kinases C alpha and beta II was assessed by Western blotting, using phosphospecific antibodies. Adjuvant arthritis was induced in Lewis rats by heat-killed Mycobacterium butyricum. Diferuloylmethane or methotrexate was administered over a period of 28 days after arthritis induction. Under in vitro conditions, diferuloylmethane (1-100 microM) reduced dose-dependently oxidant formation both at extra- and intracellular level and it effectively reduced protein kinase C activation. Adjuvant arthritis was accompanied by an increased number of neutrophils in blood and by a more pronounced spontaneous as well as PMA (phorbol myristate acetate) stimulated chemiluminescence. Whereas the arthritis-related alterations in neutrophil count and in spontaneous chemiluminescence were not modified by diferuloylmethane, the increased reactivity of neutrophils to PMA was less evident in diferuloylmethane-treated animals. The effects of diferuloylmethane were comparable with those of methotrexate. Diferuloylmethane was found to be a potent inhibitor of neutrophil functions both in vitro and in experimental arthritis. As neutrophils are considered to be cells with the greatest capacity to inflict damage within diseased joints, the observed effects could represent a further mechanism involved in the antirheumatic activity of diferuloylmethane.

Glucomannan reduces neutrophil free radical production in vitro and in rats with adjuvant arthritis

The effect of glucomannan (GM), a natural polysaccharide isolated from the yeast Candida utilis, on reactive oxygen species (ROS) generation in human neutrophils in vitro and in rats with Mycobacterium butyricum induced adjuvant arthritis (AA) was tested by the luminol/isoluminol-enhanced chemiluminescence (CL) method. In vitro, GM (500 microg/ml) significantly decreased spontaneous CL of human whole blood, while PMA (4beta-phorbol-12beta-myristate-alpha13acetate)-stimulated CL was decreased by GM in the concentrations of 100 and 500 microg/ml. To specify the site of action of GM, its effect on extra- and intracellular ROS generation in isolated neutrophils was evaluated. GM significantly decreased spontaneous and PMA-stimulated CL and it was more effective extracellularly than intracellularly. In vivo experiments included healthy animals as controls, arthritic animals without any drug administration, and arthritic animals with GM administration (once daily in the oral dose of 15 mg/kg, over a period of 28 days). On day 28, CL in whole blood, spleen and joint was monitored. Arthritic animals treated with GM showed decrease in spontaneous and PMA-stimulated CL of whole blood as well as CL of the joint, in comparison with untreated animals. The obtained findings demonstrated an antioxidant effect of GM in vitro and in rats with AA, which may be due to its free radical scavenger activity and to interaction with different receptors and/or modulation of postreceptor intracellular signalling pathways. The specific physicochemical parameters, such as structure of GM, its low molecular weight and good water solubility, play an important role in the above effects.

Association between tissue gamma-glutamyl-transferase and clinical markers of adjuvant arthritis in Lewis rats

OBJECTIVES

To assess glucomannan and pyridoindole derivatives for possible antioxidant therapy of rheumatoid arthritis (RA) by using the model of adjuvant arthritis (AA). We evaluated the association between clinical markers of the adjuvant arthritis model used - increase of hind paw volume (HPV), changes of body mass (CBM), and tissue gamma-glutamyl transferase (GGT) activity assessed in the spleen and the joint.

METHODS

AA was induced in Lewis rats by a single intradermal injection of Mycobacterium butyricum. The two independent experiments included healthy animals as reference, arthritic animals without any drug administration and arthritic animals with pyridoindole administration in one dose tested or glucomannan administration in two different doses. The pyridoindoles (PI) studied were stobadine dipalmitate and its derivatives SMe1.2HCl and SMe1EC2.HCl. We monitored CBM and HPV twice a week. Parameter of inflammation - GGT in the spleen and the joint from the hind paw (cartilage and soft tissue without bone) was determined on day 28. The correlation coefficient of GGT activity with CBM and with HPV was calculated.

RESULTS

The antioxidants tested were effective in slowing down the progress of adjuvant arhritis. The association between tissue GGT activity and the clinical marker of adjuvant arthritis - CBM was higher in the spleen than in the joint. The other clinical marker assessed - HPV, gave a better association with GGT activity measured in the joint than in the spleen.

CONCLUSIONS

It may be concluded that GGT activity in tissues as the spleen and the joint could provide a simple and inexpensive marker for AA and RA development at systemic as well as local level; all the antioxidants studied were effective in slowing down the progress of adjuvant arhritis.

Contribution to safe anti-inflammatory therapy with indomethacin

Non-steroidal anti-inflammatory drugs possess not only therapeutic but also adverse effects, mainly on the gastrointestinal tract. The aim of this pilot study was to establish the ulcerogenic dose caused by daily administration of indomethacin to male Lewis rats. Further, the model of rat adjuvant arthritis (AA) was used to evaluate the protective effect of stobadine dipalmitate against indomethacin-induced gastroenteropathy. Indomethacin was administered subcutaneously in the daily dose of 5, 7, 10, 20 and 30 mg/kg b.w. Survival of the animals and damage of gastric and intestinal mucosa were monitored, and some biochemical parameters were determined. In AA rats stobadine dipalmitate was administered orally in the daily dose of 15 mg/kg. For the chronical experiments on AA rats the subcutaneous indomethacin dose of 5 mg/kg was selected as the therapeutic dose and the dose of 7 mg/kg was chosen as the adequate dose for gastropathy induction. The additive adverse effect of arthritis induction and indomethacin administration was demonstrated on the basis of gastric mucosa damage observations. The supposed stobadine gastro-protection was not confirmed.

Cardiac effects of endothelin-1 (ET-1) and related C terminal peptide fragment: increased inotropy or contribution to heart failure?

The contrasting pattern of cardiac inotropy induced by human peptide endothelin-1 (ET-1) has not been satisfactorily explained. It is not clear whether ET-1 is primarily responsible for increased myocardial ET-1 expression and release with resultant inotropic effects, or for the induction of myocardial hypertrophy and heart failure. There are at least two subtypes of endothelin receptors (ET(A) and ET(B)) and the inotropic effects of ET-1 differ depending on the receptor involved. Along with some other groups, we reported significant subtype-ET(B) endothelin receptor down-regulation in human cardiac cells preincubated with endothelin agonists (Drímal et al. 1999, 2000). The present study was therefore designed to clarify the subtype-selective mechanisms underlying the inotropic response to ET-1 and to its ET(B)-selective fragment (8-21)ET-1 in the isolated rat heart. The hearts were subjected to (1-21)ET-1 and to (8-21)ET-1, or to 30 min of stop-flow ischemia followed by 40 min of reperfusion, both before and after selective blockade of endothelin receptors. The present study revealed that both peptides, ET-1 and its (8-21)ET-1 fragment, significantly reduced coronary blood flow in nmolar and higher concentrations. The concomitant negative inotropy and chronotropy were marked after ET-1, while the infusion of the ET-1(8-21) fragment produced a slight but significant positive inotropic effect. Among the four endothelin antagonists tested in continuous infusion only the non-selective PD145065 and ET(B1/B2) selective BQ788 (in molar concentrations) slightly reduced the early contractile dysfunction of the heart induced by ischemia, whereas ET(A)-selective PD155080 partially protected the rat heart on reperfusion.

Serum levels of advanced glycation end products in poorly metabolically controlled children with diabetes mellitus: relation to HbA1c

Serum levels of advanced glycation end products (s-AGEs) were investigated in children with poorly metabolically controlled diabetes to determine whether they may be correlated with HbA1c, fructosamine, glycaemia, albumin excretion rate, duration of diabetes and age. In this study, 17 children with Type 1 diabetes mellitus (age range 9 to 18 yr) and 8 healthy children (age range 7 to 17 yr) served as subjects. S-AGEs were found to be increased in poorly metabolically controlled children with diabetes (HbA1c>9%). A significant correlation (r=0.65;p<0.01) was found between s-AGEs and HbA1c in the group of diabetic children. In poorly metabolically controlled children with diabetes of pre-pubertal and pubertal age, the level of s-AGEs should be monitored as the risk of microvascular complications may be already present at this early stage of life.

Contribution to the penetration of radionuclides across the skin. Concentration dependence of strontium through the skin in vitro

Toxicological studies of radionuclide passage across the skin, which represents a crucial barrier of radiation, are important for ensuring the quality of the environment. Both (137)Cs and (90)Sr are most frequently involved in radionuclide contamination of the human body. In our study, we selected (90)Sr because this radionuclide is chemically very close to the bio-element calcium. The permeation of (90)Sr from donor solution across the intact skin of 5- or 9-day-old rats (5DR, 9DR) and across stripped and split skin of the 5DR was studied. The experiments in vitro were carried out using vertical diffusion cells. Strontium chloride (SrCl(2)) was used as carrier in the donor solution in different concentrations. Liquid scintillation spectrometry was applied for radiation detection. The experiments showed that: the permeated fraction of (90)Sr(2+) was indirectly proportional to the carrier concentration in the donor solution; the stratum corneum was found to be the principal penetration barrier of strontium; and in the case of the 9DR the dominant route of strontium penetration was along the follicles.

Chemical enhancers for transdermal drug transport

In its first part, this review paper discusses skin morphology and barrier function of the stratum corneum for drug permeation after its transdermal administration or topical application. Further, the paper presents the main methods for overcoming the skin permeation barrier, which plays an important role for transdermal drug administration. Focus is on the method of chemical permeation enhancement. The chemical enhancers are categorised by their chemical structure. Examples of the most effective enhancers are given for the chemical groups of alcohols, amines and amides, polyalcohols, terpenes, fatty acids and their esters, macro cyclic compounds, sulfoxides, tensides, and others, as e.g. soft enhancers.

Pharmacokinetic study of stobadine

The aim of this paper is to provide a brief overview of most important results of stobadine kinetic studies in rats, dogs, and human volunteers. In these studies, stobadine dihydrochloride and stobadine dipalmitate was used for intravenous and oral administration, respectively. To evaluate kinetic properties of stobadine and its metabolites, TLC, HPLC, GLC, GC-MS, radiometric, and fluorometric methods were developed and used.

Role of reactive oxygen and nitrogen species in etiopathogenesis of rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic disease affecting up to 3% of the population in most countries. The causes of RA have not been completely elucidated. This paper aims to review the role of reactive oxygen and nitrogen species in the etiopathogenesis of RA. Reactive oxygen species (ROS), such as superoxide radical, hydrogen peroxide, hydroxyl radical and hypochlorous acid, as well as reactive nitrogen species (RNS), such as nitric oxide and peroxynitrite, contribute significantly to tissue injury in RA. Several mechanisms are involved in the generation and action of ROS and RNS. Superoxide radical, hydrogen peroxide and nitric oxide do not directly damage the majority of biological molecules. They are however converted into the highly reactive hydroxyl radical, which reacts with almost all molecules in living cells. The resulting chronic inflammation process can be reduced with antioxidant therapy. To date, scavenging, preventive, and enzyme antioxidants are available. The most important mode is scavenging of the hydroxyl radical and of hypochlorous acid. Another important way is to inhibit production of RNS and ROS by neutrophils, monocytes, and macrophages. The control of inflammation in arthritic patients by natural as well as synthetic antioxidants could become a relevant component of antirheumatic prevention and therapy.

Bioavailability and pharmacokinetic studies in the development of an oral formulation of stobadine dipalmitate

The pyridoindole stobadine is a novel drug with antioxidant and cardioprotective properties. The objective of this study was to compare the bioavailability and the main pharmacokinetic parameters of two different stobadine dosage forms, STBtest and STBref, after single oral dosing in the form of gelatine capsules to 6 dogs. The dose ranged from 2.9 to 4.7 mg/kg and a randomized two-period crossover design was applied. To quantify the drug in plasma, a GC/MS method was developed with a quantification limit of 1 ng/ml. The time profiles of stobadine plasma concentrations were fitted by pharmacokinetic models. The extent of relative bioavailability ranged between 0.71 and 1.56. Practically no difference was found between the bioavailability rate of the two capsules, expressed as Cmax/AUC, with values ranging from 0.0022-0.0047 min-1 for STBtest and 0.0022-0.0045 min-1 for STBref. In conclusion, the technological difference of the capsules investigated did not yield deviations in either their extent or rate of absorption. Therefore the two stobadine formulations were concluded to be bioequivalent.

Overview of stobadine bioanalysis: evaluation and application in pharmacokinetics

Besides its many pharmacodynamic actions, the pyridoindole stobadine was found to exert antioxidant activity and thus possesses the potential to protect various tissues against oxidative stress. This overview is focussed on both the evaluation of the chemical procedures used in the bioassay of stobadine and its metabolites and on the comparison of their quality in the light of applicability for preclinical and clinical pharmacokinetic experiments. All methods and applications were performed at the Institute of Experimental Pharmacology, SASc in Bratislava, Slovakia. In pharmacokinetic and toxicokinetic studies, [3H]-labeled stobadine dihydrochloride was administered intravenously or orally to rats in single and repeated doses. Liquid-liquid extraction was used for selective isolation of stobadine and its metabolites from biological matrix, followed by liquid scintillation quantification. A TLRC method was developed both to check the radiochemical purity of [3H]-stobadine and to quantify the labeled drug in rat plasma. A spectrofluorometric approach was used for determination of stobadine in dog serum and urine after its administration in the form of either the dihydrochloride or the dipalmitate. The method allowed us to perform a bioavailability study and a long-term toxicological study. The HPLC method with a limit of detection of 10 ng/ml of plasma proved suitable for calculating the compartmental pharmacokinetic parameters of both salt forms of stobadine administered to dog and man. This method was based on solid-phase extraction procedure by using Separcol SI C18 cartridges. In a GC method, the combination of capillary column separation and nitrogen-specific detection permitted the assay of serum stobadine concentrations as low as 5 ng/ml. The detection limit of the GC/MS method was 1 ng/ml of plasma or of phosphate buffer saline. This method was used for a bioequivalence study of two stobadine dipalmitate dosage forms and for a transdermal penetration study of stobadine acyl derivatives. All the developed assays proved to be appropriate for low-concentration determination of stobadine in a wide range of pharmacokinetic studies.

Study of the solid phase extraction of pentoxifylline and its major metabolite as a basis of their rapid low concentration gas chromatographic determination in serum

A gas-liquid chromatographic method for the determination of pentoxifylline and its secondary alcohol metabolite in serum has been developed. The method is based on the combination of solid phase extraction, capillary column separation and nitrogen-phosphorus detection of the analytes. Optimization of the solid phase extraction conditions permitted a low concentration determination, with limits of determination of 2 ng/mL and 10 ng/mL for pentoxifylline and its metabolite, respectively. The simplicity and rapidity of the extraction step was preserved.

Determination of pentoxifylline in serum by high-performance thin-layer chromatography

An analytical method to study the bioavailability of newly developed pentoxifylline sustained-release tablets has been developed and assessed in experiments on dogs. For the isolation of pentoxifylline and its metabolites from serum solid-liquid extraction was applied by involving the internal standard probe. HPTLC plates with a preconcentration zone were used for separation of the analysed substances, using chloroform-methanol (95:5, v/v). Quantification was by densitometric detection. The detector response was linear in the concentration range investigated for pentoxifylline: 0.02-1.5 micrograms ml-1 of serum.

Fate of 14C-terpolymer (methylmethacrylate-14C, 2-hydroxyethylmethacrylate, butylacrylate) nanoparticles after peroral administration to rats

The fate of 14C-terpolymer (methylmethacrylate-14C, 2-hydroxyethylmethacrylate, butylacrylate) nanoparticles was studied in male Wistar rats after peroral administration. These nanoparticles may reach systemic circulation as evidenced by the plasma 14C level, excretion of the label in the urine, as well as organ label deposition. It was found that at least 2% of the dose of 14C was absorbed from the gastrointestinal tract. As expected, the radioactive nanoparticles were excreted predominantly via the feces. The amount of the label in the gastrointestinal tract, liver, and carcasses fell below the limit of detection on day seven after administration. However in the spleen and lung some slight radioactivity persisted after 7 d of experiment.