Antiproliferative activity of parthenolide against three human cancer cell lines and human umbilical vein endothelial cells

Parthenolide is a major sesquiterpene lactone derived from feverfew (Tanacetum parthenium) with known anti-inflammatory activity. Moreover, the anticancer potential of this compound was suggested. In this study, we determined the effect of parthenolide on proliferation of three human cancer cell lines: human lung carcinoma (A549), human medulloblastoma (TE671), human colon adenocarcinoma (HT-29) and human umbilical vein endothelial cells (HUVEC) in vitro. Cell proliferation was assessed by means of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The IC(50) value (the concentration of drug necessary to induce 50% inhibition) together with confidence limits was calculated. Parthenolide inhibited proliferation of all three types of cancer cells (A549, TE671, HT-29) and HUVEC with the following IC(50) values (in muM): 4.3, 6.5, 7.0 and 2.8, respectively. Thus, the antiproliferative potential of parthenolide was confirmed.     

Excitatory amino acid antagonists and memory: effect of drugs acting at N-methyl-D-aspartate receptors in learning and memory tasks

The role of N-methyl-D-aspartate (NMDA) receptors in memory processes was examined using a Y-shaped maze and a step-through passive avoidance task in mice. In the Y-maze, the total number of arm entries, which represents locomotor activity and alternation behaviour, thought to reflect working memory, were measured. Competitive NMDA antagonists, CGS 19755 (cis-4-phosphonomethyl-2-piperidine-carboxylate) and CPP (3-((+)-2-carboxypiperazin-4-yl)-propyl-1-phosphate), impaired spontaneous alternation at doses which reduced locomotion of mice. N-Methyl-D-aspartate prevented the impairment of alternation and decrease of locomotor activity produced by CGS 19755 and CPP. These results suggest that NMDA-dependent processes are involved in the mechanisms of working memory. In contrast, the non-competitive NMDA antagonist, MK 801 ((+)-5-methyl-10,11-dihydro-5H-dibenzo(a,d)cycloheptan-5,10-imine maleate) dramatically enhanced the total number of arm entries, while reducing alternation behaviour, N-Methyl-D-aspartate had no effect on MK 801-induced enhancement of locomotor activity and impairment of alternation. In the passive avoidance task, mice were trained to avoid entry into the dark compartment. At doses which impaired working memory in the alternation task, CPP, CGS 19755 and MK-801 reduced acquisition, when administered before training. N-Methyl-D-aspartate antagonized the effect of CPP, CGS 19755 and MK-801. Neither CPP nor MK-801 affected retention, when administered immediately after training or before testing retention. N-Methyl-D-aspartate had no effect on retention with high-intensity shock, but facilitated retention with low-intensity shock.(ABSTRACT TRUNCATED AT 250 WORDS)     

Parthenolide Inhibits Proliferation of Fibroblast-Like Synoviocytes In Vitro

Parthenolide is a bioactive constituent of an aromatic herb Feverfew (Tanacetum parthenium). It has been found that both parthenolide and extract of feverfew have anti-inflammatory and antinociceptive properties. Moreover, they demonstrate antiproliferative activities on different human tumour cells. The massive hyperplasia of synovial fibroblasts is the one of the most striking features of rheumatoid arthritis. It is not known whether this is due to the proliferation of synovial fibroblasts or to defective apoptosis. We investigated the effect of parthenolide on the proliferation of rabbit synoviocytes cell line HIG-82, rheumatoid arthritis fibroblast-like synoviocytes (RA-FLS) and human skin fibroblasts (HSF) in vitro. Cell proliferation was assessed by means of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and 5'-bromo-2'-deoxy-uridine methods. Parthenolide inhibited proliferation of HIG-82 and human RA-FLS. The proliferation of HSF was inhibited less effectively. The antiproliferative potential of parthenolide was demonstrated.     

Kynurenic acid in human saliva--does it influence oral microflora?

Kynurenic acid (KYNA) is an endogenous antagonist of alpha7 nicotinic receptors and all ionotropic glutamate receptors. Its neuroprotective activity has been suggested. In this study, the presence of KYNAin human saliva and its potential bactericidal role was investigated. KYNAwas found in all samples of human saliva with mean concentration of 3.4 nM. The concentration of KYNA in saliva obtained from patients with odontogenic abscesses was 3.5 times higher than in healthy subjects. We have shown that the human gingival fibroblasts produce KYNAand an inflammatory stimulant, lipopolysaccharide, enhanced its synthesis in vitro. The bactericidal effect of KYNA was also presented. We hypothesize that KYNA may contribute to the control of oral microflora.     

Tiagabine synergistically interacts with gabapentin in the electroconvulsive threshold test in mice.

Polytherapy, based on the rational combining of antiepileptic drugs (AEDs), is required for patients with drug-resistant epilepsy. In such cases, the combinations of AEDs usually offer a significant enhancement of their protective effects against seizures. There has appeared a hypothesis that combining two AEDs, influencing the same neurotransmitter system, results in the potentialization of their anticonvulsant effects. For corroborating this hypothesis, a pharmacological character of interaction between tiagabine (TGB) and gabapentin (GBP)-two novel AEDs affecting the GABA-ergic system, in the maximal electroshock seizure threshold (MEST)-test in mice was evaluated. TGB at the dose of 4 mg/kg and GBP at 75 mg/kg significantly raised the electroconvulsive threshold. Further, using the isobolographic calculations, TGB was coadministered with GBP at three fixed-ratios (1 : 3, 1 : 1, and 3 : 1) of their respective protective drug doses. All examined combinations of TGB with GBP exerted supra-additive (synergistic) interactions against MEST-induced seizures in mice. The interaction index, describing the strength and magnitude of interaction, ranged between 0.25 and 0.50 indicating supra-additivity. Adverse (neurotoxic) effects were evaluated in the chimney (motor performance) and the step-through, light-dark passive avoidance (long-term memory) tests in mice. The examined combinations of TGB with GBP did not affect the motor coordination, except for the fixed-ratio of 1 : 1, at which significant impairment of motor performance was observed. Moreover, all combinations selectively impaired the acquisition of the task in the passive avoidance test, having no impact on consolidation and retrieval in the long-term memory test. The pain threshold test revealed that the observed disturbances in the passive avoidance testing resulted presumably from the antinociceptive activity of these AEDs in combinations. After lengthening the exposing time to the direct current stimulus in the passive avoidance test from 2 to 6 s, the acquisition of the task, in animals receiving the combinations of TGB and GBP was not impaired. Neither the plasma, nor brain concentrations of GBP were affected by TGB application, so pharmacokinetic events that might negatively influence the observed effects are not probable. Results of this study clearly indicate that the activation of the same neurotransmitter system (GABA-ergic) leads to a synergistic interaction. The pain threshold test is a very good paradigm for screening the antinociceptive properties of AEDs, which may disturb the long-term memory testing in animals. Combinations of TGB with GBP (very promising from a preclinical point of view) should be clinically verified for elaborating the most effective treatment regimen in patients with intractable seizures.     

Kynurenic Acid in Plasma and Endometrium in Bitches with Pyometra

Kynurenic acid (KYNA) is produced enzymatically in humans and animals from kynurenine. Reports concerning changes of kynurenine metabolism during inflammation are available in the literature. Pyometra is a pathological condition characterized by the accumulation of pus in the uterine lumen and bacterial infection. The objective of the study was to compare the serum and endometrial KYNA concentrations in healthy bitches and those with pyometra. KYNA was determined by means of high-performance liquid chromatography with fluorometric detection. The serum content of KYNA in bitches with pyometra was significantly higher than in healthy bitches. The KYNA content in the endometrium of bitches with pyometra was higher, yet the difference was not statistically significant. Our result indicates that determination of KYNA might be a marker of pyometra in bitches.     

Changes in Plasma Kynurenic Acid Concentration in Septic Shock Patients Undergoing Continuous Veno-Venous Haemofiltration

Kynurenic acid (KYNA) is one of the end products of tryptophan metabolism. The aim of this study was to analyse plasma KYNA concentration in septic shock patients (SSP) with acute kidney injury (AKI) undergoing continuous veno-venous haemofiltration (CVVH). Changes in KYNA content were compared to alterations in the levels of procalcitonin (PCT), C-reactive protein and lactate. Adult SSP with AKI were examined. Measurements were conducted at seven time points: before beginning CVVH and at 6, 12, 24, 48, 72 and 96 h after the beginning of CVVH. Based on clinical outcomes, the data were analysed separately for survivors and non-survivors. Twenty-seven patients were studied. CVVH was associated with reduced plasma KYNA concentration only in survivors. Plasma KYNA concentration correlated with the levels of lactate and PCT only in survivors. (1) CVVH reduced plasma KYNA concentration only in survivors; (2) lack of this reduction may predict fatal outcomes in SSP.     

Kynurenic acid, an endogenous constituent of rheumatoid arthritis synovial fluid, inhibits proliferation of synoviocytes in vitro

Kynurenic acid is an antagonist of ionotropic glutamate receptors. It has been found that glutamate antagonists inhibit proliferation of different human tumor cells. Since the hyperplasia of synovial fibroblasts is one of the most striking features of inflammatory arthritis, the main goals of this study were detection and quantification of kynurenic acid in synovial fluid obtained from patients with rheumatoid arthritis, and determination of its effect on proliferation of synoviocytes in vitro. Presence of kynurenic acid was determined by HPLC in all 58 samples of synovial fluid. The mean concentration was 15.89 pmol/ml. Kynurenic acid inhibited synoviocyte proliferation with the IC₅₀ value of 5.9 mM. In subthreshold concentration of 0.3 mM it enhanced antiproliferative action of celecoxib and nimesulide. In conclusion, the presence of kynurenic acid in synovial fluid was documented in patients with rheumatoid arthritis. Its potential role as an endogenous substance, controlling synoviocyte proliferation can be suggested.     

Kynurenic acid production in cultured bovine aortic endothelial cells. Homocysteine is a potent inhibitor

Kynurenic acid (KYNA) is a broad-spectrum antagonist at all subtypes of ionotropic glutamate receptors, but is preferentially active at the strychnine-insensitive glycine allosteric site of the N-methyl-d-aspartate (NMDA) receptor and is also a non-competitive antagonist at the alpha7 nicotinic receptor. KYNA occurs in the CNS, urine, serum and amniotic fluid. Whilst it possesses anticonvulsant and neuroprotective properties in the brain, its role in the periphery, however, is unknown. In this study we demonstrated the presence of kynurenine aminotransferase (KAT) I and II in the cytoplasm of bovine aortic endothelial cells (BAEC). BAEC incubated in the presence of the KYNA precursor l-kynurenine synthesized KYNA concentration- and time-dependently. KYNA production was inhibited by the aminotransferase inhibitor aminooxyacetic acid but was not affected by a depolarising concentration of K⁺ or by 4-aminopyridine. The glutamate agonists l-aspartate and l-glutamate depressed KYNA production significantly. The selective ionotropic glutamate receptor agonists -amino-2,3-dihydro-5-methyl-3-oxo-4-isoxazolepropionic acid (AMPA) and NMDA were ineffective in this respect. d,l-Homocysteine and l-homocysteine sulphinic acid lowered KYNA production in BAEC. Further investigations are needed to assess the role and importance of KYNA in vessels and peripheral tissues.