Contribution of Bioactive Compounds to the Antioxidant Capacity of the Edible Mushroom Neolentinus lepideus.

Neolentinus lepideus is a fungus consumed by rural communities in Central America and Asia due to its rich flavor; however, little information on its chemical composition is available. With this in mind, the objective of this work was to determine the content of vitamin E and C, ergosterol, and phenolic compounds of this fungus, as well as its antioxidant capacity. The quantified bioactive compounds were two isoforms of vitamin E, highlighting α-tocopherol (3370.35 mg/100 g dry weight, DW) and ergosterol (11.70 mg/100 g DW). The total phenolic content was 164.80 mg gallic acid equivalents/100 g, and nine phenolic compounds were identified (protocatechuic, p-hydroxybenzoic, caffeic, vanillic, ferulic, salicylic, p-anisic, trans-cinnamic acids, and scopoletin). The highest antioxidant capacity was detected in the lipophilic extract with TEAC (27688 µmoles Trolox equivalents/100 g). These results suggest that lipophilic compounds are among the main bioactive compounds in N. lepideus, and they might exhibit the highest radical scavenging properties in non-polar extracts.

Noticeable Quantities of Functional Compounds and Antioxidant Activities Remain after Cooking of Colored Fleshed Potatoes Native from Southern Chile.

The effect of cooking on the concentrations of phenolic compounds and antioxidant activities in 33 colored-fleshed potatoes genotypes was evaluated. The phenolic profiles, concentrations, and antioxidant activity were evaluated with a liquid chromatography diode array detector coupled to a mass spectrometer with an electrospray ionization interface (HPLC-DAD-ESI-MS/MS). Eleven anthocyanins were detected; in the case of red-fleshed genotypes, these were mainly acyl-glycosides derivatives of pelargonidin, whereas, in purple-fleshed genotypes, acyl-glycosides derivatives of petunidin were the most important. In the case of the purple-fleshed genotypes, the most important compound was petunidin-3-coumaroylrutinoside-5-glucoside. Concentrations of total anthocyanins varied between 1.21 g kg-1 in fresh and 1.05 g kg-1 in cooked potato and the decreases due to cooking ranged between 3% and 59%. The genotypes that showed the highest levels of total phenols also presented the highest levels of antioxidant activity. These results are of relevance because they suggest anthocyanins are important contributors to the antioxidant activity of these potato genotypes, which is significant even after the drastic process of cooking.

γ-Tocotrienol induced cell cycle arrest and apoptosis via activating the Bax-mediated mitochondrial and AMPK signaling pathways in 3T3-L1 adipocytes.

This study aimed to examine the anti-proliferative effects of α-, γ- and δ-tocotrienols (αT3, γT3 and δT3), and α-tocopherol on 3T3-L1 adipocytes. Results showed that compared with other vitamin E analogues, γT3 demonstrated the most potent anti-proliferative effect on 3T3-L1 cells. It significantly caused a reduction in mitochondrial membrane potential (Δψm) and an increase in ROS formation, as well as inducing cell apoptosis and cell cycle arrest at S phase. Further studies showed that it down-regulated Bcl-2 and PPAR-γ expression, suppressed Akt and ERK activation and phosphorylation, and caused cytochrome c release from mitochondria to cytosol, whereas it up-regulated CD95 (APO-1/CD95) and Bax expression, and caused caspase-3 and JNK activation, PARP cleavage and AMPK phosphorylation. Pretreatments with caspase-3 (z-DEVD-fmk) and AMPK (CC) inhibitors significantly suppressed the γT3-induced ROS production and cell death. Caspase-3 inhibitor also efficiently blocked CD95 (APO-1/CD95) and Bax expression, caspase-3 activation and PARP cleavage, whereas antioxidant N-acetyl-l-cysteine, AMPK inhibitor and AMPK siRNA effectively blocked the AMPK phosphorylation. Taken together, these results conclude that the potent anti-proliferative and anti-adipogenic effects of γT3 on 3T3-L1 adipocytes could be through the Bax-mediated mitochondrial and AMPK signaling pathways.

ROS inhibitor N-acetyl-L-cysteine antagonizes the activity of proteasome inhibitors.

NAC (N-acetyl-L-cysteine) is commonly used to identify and test ROS (reactive oxygen species) inducers, and to inhibit ROS. In the present study, we identified inhibition of proteasome inhibitors as a novel activity of NAC. Both NAC and catalase, another known scavenger of ROS, similarly inhibited ROS levels and apoptosis associated with H2O2. However, only NAC, and not catalase or another ROS scavenger Trolox, was able to prevent effects linked to proteasome inhibition, such as protein stabilization, apoptosis and accumulation of ubiquitin conjugates. These observations suggest that NAC has a dual activity as an inhibitor of ROS and proteasome inhibitors. Recently, NAC was used as a ROS inhibitor to functionally characterize a novel anticancer compound, piperlongumine, leading to its description as a ROS inducer. In contrast, our own experiments showed that this compound depicts features of proteasome inhibitors including suppression of FOXM1 (Forkhead box protein M1), stabilization of cellular proteins, induction of ROS-independent apoptosis and enhanced accumulation of ubiquitin conjugates. In addition, NAC, but not catalase or Trolox, interfered with the activity of piperlongumine, further supporting that piperlongumine is a proteasome inhibitor. Most importantly, we showed that NAC, but not other ROS scavengers, directly binds to proteasome inhibitors. To our knowledge, NAC is the first known compound that directly interacts with and antagonizes the activity of proteasome inhibitors. Taken together, the findings of the present study suggest that, as a result of the dual nature of NAC, data interpretation might not be straightforward when NAC is utilized as an antioxidant to demonstrate ROS involvement in drug-induced apoptosis.

Simplified YM-26734 inhibitors of secreted phospholipase A2 group IIA.

Simplified analogs of YM-26734, a known inhibitor of secreted phospholipase A(2) (sPLA(2)) group IIA, were synthesized and found to also display potent inhibition at low nanomolar concentrations. Analogs were based on the didodecanoylphloroglucinol portion of YM-26734 which contains the predicted active site calcium binding group.

Antagonism by ranolazine of the pro-arrhythmic effects of increasing late INa in guinea pig ventricular myocytes.

The new anti-anginal drug ranolazine causes a slight (<10 milliseconds) prolongation of the QT interval, raising the concern that its use may be associated with an increased incidence of torsades de pointes ventricular tachyarrhythmias. The goal of this study was to show that ranolazine inhibits the late component of INa and attenuates prolongation of action potential duration when late INa is increased, both in the absence and presence of IK-blocking drugs. Currents and action potentials of guinea pig isolated ventricular myocytes were measured by whole-cell patch clamp. Sea anemone toxin (ATX)-II was used to increase late INa and mimic the effect of an SCN5A gene mutation. ATX-II (3-5 nmol/L) increased late INa by 5-fold; ranolazine attenuated this increase of late INa by up to 61 +/- 8%. ATX-II (10-20 nmol/L) increased action potential duration (APD) by > 1 seconds, and caused early afterdepolarizations; both actions were attenuated by ranolazine (0.1-30 micromol/L). Ranolazine (10 micromol/L) reduced by 89% the 13.6-fold increase in variability of APD caused by 10 nmol/L ATX-II. The effects of ATX-II (3 nmol/L) in combinations with either the IKr blocker E-4031 or the IKs blocker chromanol 293B to increase APD were attenuated 76 +/- 5% and 71 +/- 4%, respectively, by 10 micromol/L ranolazine. The results demonstrate that ranolazine reduces late INa and has an anti-arrhythmic effect when late INa is increased.

Attenuation by 4-aminopyridine of delayed vasorelaxation by troglitazone.

Troglitazone and other thiazolidinediones (TZDs) are thought to relax arterial smooth muscle by directly inhibiting calcium channels in smooth muscle cell membranes. However, until recently such inhibition was only examined acutely, ie, within only seconds or minutes after administration of these agents to arterial smooth muscle preparations. Recently, a novel experiment was reported in which troglitazone caused a 2-phase relaxation of perfused resistance arteries, namely, an acute relaxation (within the first 20 minutes of treatment), which was blocked by a nonselective calcium channel blocker and a delayed relaxation (after 2 hours), which was not. We sought to determine if any of the 4 major potassium (K) channels in vascular smooth muscle play a role in the delayed relaxation. We incubated vascular contractile rings prepared from ventral tail arteries of rats with physiological buffer containing either 0 or 4 micromol/L troglitazone for 3 hours (4 micromol/L is typical of plasma levels from diabetic patients). Different K channel inhibitors (1 mmol/L 4-aminopyridine [4AP]; 1 mmol/L tetraethylammonium [TEA]; 5 micromol/L glyburide; 20 micromol/L barium) were coadministered with each level of troglitazone in additional preparations. Then these arterial rings were contracted with either norepinephrine (NE), arginine vasopressin (AVP), or high-K buffer. All contractions were significantly relaxed by troglitazone (P <.05). Only 4AP significantly attenuated troglitazone's relaxation of NE and AVP contractions (P <.05), though not high-K-induced contractions. TEA, glyburide, and barium had no such influence. Thus, for both adrenergic (NE) and nonadrenergic (AVP) contractions, the delayed arterial vasorelaxation by troglitazone may be mediated at least in part by activation of 4AP-sensitive K channels. Furthermore, the specific subtype of the channels involved is most likely those bound in the outer cell membrane where their effectiveness in terms of mediating relaxation would depend on an intact transmembrane K ion gradient.

Melatonin prevents delta-aminolevulinic acid-induced oxidative DNA damage in the presence of Fe2+.

Delta-aminolevulinic acid (ALA), a heme precursor which accumulates during lead poisoning and acute intermittent porphyria, is reported to cause liver cancer. The carcinogenic mechanisms of ALA may relate to its ability to generate free radicals through metal-catalyzed oxidation which cause oxidative DNA damage. The aim of this study was to compare the efficacy of melatonin, trolox (vitamin E) and mannitol in altering DNA damage induced by ALA. Herein, we found, in the presence of Fe2+, that ALA-induced formation of 8-hydroxydeoxyguanosine in calf thymus DNA was dose and time-dependent. Melatonin, mannitol and trolox, all of which are free radical scavengers, inhibited the formation of 8-hydroxydeoxyguanosine in a concentration-dependent manner. The concentration of each (melatonin, mannitol and trolox) required to reduce DNA damage by 50%, i.e., the IC50, was 0.52, 0.84 and 0.90 mM, respectively.

Vasorelaxant effects of the potassium channel opener SR 47063 on the isolated human saphenous vein and rat aorta.

The vasorelaxant effects of SR 47063 (4-(2-cyanimino-1, 2-dihydropyrid-1-yl)-2,2-dimethyl-6-nitr ochromene), a new K(+)-channel opener structurally related to levcromakalim, were examined in isolated human saphenous vein (HSV) and rat aorta (RA). HSV or RA rings were precontracted with either KCl or noradrenaline and cumulative relaxant concentration-response curves were obtained for SR 47063 (0.1 nM to 1 microM) in the presence or absence of 3 microM glibenclamide. SR 47063 potently relaxed HSV and RA precontracted with 20 mM (but not 60 mM) KCl or 10 microM noradrenaline in a concentration-dependent manner, showing slightly greater activity in the aorta. The potency of the effect of SR 47063 on HSV and RA was 12- and 58-fold greater, respectively, than that reported for the structurally related K(+)-channel opener levcromakalim. The vasorelaxant action of SR 47063 in both blood vessels was strongly inhibited by 3 microM glibenclamide, consistent with a mechanism of action involving ATP-dependent K(+)-channels.

Vasorelaxant effects of the potassium channel opener SR 47063 on the isolated human saphenous vein and rat aorta

The vasorelaxant effects of SR 47063 (4-(2-cyanimino-1,2-dihydropyrid-1-yl)-2,2-dimethyl-6-nitrochromene), a new K+-channel opener structurally related to levcromakalim, were examined in isolated human saphenous vein (HSV) and rat aorta (RA). HSV or RA rings were precontracted with either KCl or noradrenaline and cumulative relaxant concentration-response curves were obtained for SR 47063 (0.1 nM to 1 µM) in the presence or absence of 3 µM glibenclamide. SR 47063 potently relaxed HSV and RA precontracted with 20 mM (but not 60 mM) KCl or 10 µM noradrenaline in a concentration-dependent manner, showing slightly greater activity in the aorta. The potency of the effect of SR 47063 on HSV and RA was 12- and 58-fold greater, respectively, than that reported for the structurally related K+-channel opener levcromakalim. The vasorelaxant action of SR 47063 in both blood vessels was strongly inhibited by 3 µM glibenclamide, consistent with a mechanism of action involving ATP-dependent K+-channels

Sedative effects of the dopamine D1 receptor agonist A 68930 on rat open-field behavior.

The present results demonstrate sedative effects of the DA D1 receptor agonist A 68930 (0.9-15 micromol kg(-1), s.c.) on rat spontaneous locomotor activity in an open field. The effects were particularly strong, and dose-dependent, for the ambulatory activity in the open-field arena (forward locomotion) and for rearing activity, whereas the suppression of locomotor activity (i.e. total horizontal activity in the open field) was less conspicuous. The distribution of activity within the open field (activity in center vs periphery) was not consistently affected by the A 68930 treatment. In support for DA D1 receptor mediated effects of A 68930, the effects on locomotor activity, forward locomotion, and on rearing behavior, were partially antagonized by the DA D1 receptor antagonist SCH 23390 (15 nmol kg(-1) s.c.). SCH 23390 by itself produced a modest, but statistically significant, suppression of these different items of open-field behavior. The atypical antipsychotic agent clozapine has previously, in this laboratory, been shown to stimulate DA D1 receptors in vivo. There are a number of clinical and laboratory observations, consistent with the notion of a beneficial role for such effects in schizophrenia. Thus, the sedation, apparently not related to extrapyramidal motor functions, produced by DA D1 receptor agonist A 68930 could reflect an important aspect of the mechanism of action for atypical antipsychotic drugs.

Glimepiride (Hoe490) inhibits the rilmakalim induced decrease in intracellular free calcium and contraction of isolated heart muscle cells from guinea pigs to a lesser extent than glibenclamide.

Glibenclamide is a potent inhibitor of the ATP-dependent potassium channel. Opening of the ATP-dependent potassium channel is regarded as a mechanism of ischemic preconditioning. This in vitro study examines the influence of glibenclamide and glimepiride, a new sulfonylurea, on the negative inotropic action of the potassium channel opener rilmakalim in isolated ventricular myocytes. Cardiac myocytes were isolated from adult guinea pig hearts by collagenase perfusion and incubated with rilmakalim (concentration range 0.1-12.0 microM), glibenclamide (concentration range 0.03-3.0 microM) plus rilmakalim (3.0 or 7.5 microM), and glimepiride (0.03-9.0 microM) plus rilmakalim (3.0 or 7.5 microM) and paced by electrical field stimulation. Contractility of the myocytes was evaluated by digital image analysis, intracellular free calcium was determined by means of fura-2 fluorescence measurements, and cell viability was assessed morphologically as well as by measurement of lactate dehydrogenase activity. Rilmakalim reduced the systolic intracellular free calcium and contractility of ventricular myocytes in a concentration dependent manner. This effect was antagonized by glibenclamide at lower concentrations (0.3 microM) than glimepiride (3.0 microM). The smaller antagonistic action of glimepiride on the negative inotropic effect of rilmakalim as compared with glibenclamide most likely reflects a less potent inhibition of ATP-dependent potassium channels by glimepiride.

Behavioural evidence for "D-1-like" dopamine receptor subtypes in rat brain using the new isochroman agonist A 68930 and isoquinoline antagonist BW 737C.

The full efficacy, high potency isochroman D-1 agonist A 68930 demonstrated greater than 220-fold selectivity for D-1 over D-2 receptors. A 68930 (0.06 and 0.25 mg/kg) readily induced intense grooming, together with vacuous chewing; these responses became less evident following higher doses (1.0 and 4.0 mg/kg) and sniffing became prominent. Intense grooming was blocked by three D-1 antagonists, the benzazepines SCH 23390 (0.01-1.0 mg/kg) and NNC-756 (0.01-1.0 mg/kg), and the isoquinoline BW 737C (0.2-5.0 mg/kg); however, vacuous chewing was not antagonised by SCH 23390 and NNC-756, but was blocked by BW 737C. Intense grooming was attenuated by the D-2 antagonist YM 09151 (0.005-0.5 mg/kg) while vacuous chewing was enhanced. These data suggest that intense grooming is mediated by a "D-1 like" receptor that recognises all known chemical classes of D-1-selective compounds, while vacuous chewing may be mediated by a pharmacologically distinct subtype of "D-1-like" receptor that recognises preferentially the isochromans and isoquinolines.

Teratogenicity in rats of two dopaminergic agonists.

The teratogenic potential of 2 structurally related dopaminergic agonists, BRL 16644 (2-[[3,4-dihydro-2,2-dimethyl-4-[3-(trifluoromethyl)phenyl]-2H- 1-benzopyran-7-yl]oxy]-N,N-dimethyl-Ethanamine: Chemical Abstracts No. 59257-18-0) and BRL 16657 (2-[[3,4-dihydro-2,2-dimethyl-4-[4-(trifluoromethyl)phenyl]-2H- 1-benzopyran-7-yl]oxy]-N,N-dimethyl-Ethanamine: Chemical Abstracts No. 59257-24-8), has been investigated in pregnant Sprague-Dawley rats. These compounds were administered orally from Days 6 to 15 of gestation inclusive at dose levels of 10, 20 and 40 mg/kg/day for BRL 16644 and 10, 20 and 35 mg/kg/day for BRL 16657. At caesarean section on Day 21 of gestation increased post-implantation loss, reduced foetal weights and high incidences of gross abnormalities were found with both compounds at their high dose levels. Maternal toxicity was evident at the intermediate and high dose levels but teratogenic effects extended to the low dose of each compound where treatment was well tolerated by the dams. The maternal effects were thought to be due to the dopamine potentiating properties of BRL 16644 and BRL 16657. When pimozide, a specific dopamine antagonist, was co-administered with BRL 16657 the maternal effects were considerably reduced and, although teratogenicity remained, effects of BRL 16657 on the embryo were extensively modified. This suggests that at least certain of the abnormalities were associated with prolonged dopamine potentiation. Pimozide alone was not teratogenic.