Dietary Supplementation with Yerba Mate (Ilex paraguariensis) Infusion Increases IRS-1 and PI3K mRNA Levels and Enhances Insulin Sensitivity and Secretion in Rat Pancreatic Islets.

"Yerba mate" (YM), an aqueous extract of Ilex paraguariensis, has antioxidant, diuretic, cardio-protective and hypoglycaemic properties. Since its effect on the pancreatic islets remains unclear, we evaluated insulin sensitivity and glucose-stimulated insulin secretion (GSIS) in rats consuming YM or tap water (C) for 21 days. Glucose tolerance, glycemia, triglyceridemia, insulinemia, TBARS and FRAP serum levels were evaluated. GSIS and mRNA levels of insulin signaling pathway and inflammatory markers were measured in isolated pancreatic islets from both groups. In C rats, islets were incubated with YM extract or its phenolic components to measure GSIS. YM improved glucose tolerance, enhanced GSIS, increased FRAP plasma levels and islet mRNA levels of IRS-1 and PI3K (p110), and decreased TBARS plasma levels and islet gene expression of TNF-α and PAI-1. Islets from C rats incubated with 100 µg/mL dry YM extract, 1 µM chlorogenic acid, 0.1 and 1 µM rutin, 1 µM caffeic acid or 1 µM quercetin showed an increase in GSIS. Our results suggest that YM enhances glucose tolerance because of its positive effects on GSIS, oxidative stress rate and insulin sensitivity in rat islets, suggesting that long-term dietary supplementation with YM may improve glucose homeostasis in pre-diabetes or type 2 diabetes.

Anti-Inflammatory and Antioxidant Chinese Herbal Medicines: Links between Traditional Characters and the Skin Lipoperoxidation "Western" Model.

The relationship between lipid peroxidation and inflammation has been accepted as a paradigm in the field of topical inflammation. The underlying biochemical mechanisms may be summarised as unspecific oxidative damage followed by specific oxidative processes as the physio pathological response in skin tissues. In this experimental review we hypothesise that the characteristics attributed by Traditional Chinese Medicine (TCM) to herbal drugs can be linked to their biomolecular activities within the framework of the above paradigm. To this end, we review and collect experimental data from several TCM herbal drugs to create 2D-3D pharmacological and biochemical spaces that are further reduced to a bidimensional combined space. When multivariate analysis is applied to the latter, it unveils a series of links between TCM herbal characters and the skin lipoperoxidation "Western" model. With the help of these patterns and a focused review on their chemical, pharmacological and antioxidant properties we show that cleansing herbs of bitter and cold nature acting through removal of toxins-including P. amurense, Coptis chinensis, S. baicalensis and F. suspensa-are highly correlated with strong inhibition of both lipid peroxidation and eicosanoids production. Sweet drugs-such as A. membranaceus, A. sinensis and P. cocos-act through a specific inhibition of the eicosanoids production. The therapeutic value of the remaining drugs-with low antioxidant or anti-inflammatory activity-seems to be based on their actions on the Qi with the exception of furanocoumarin containing herbs-A. dahurica and A. pubescens-which "expel wind". A further observation from our results is that the drugs present in the highly active "Cleansing herbs" cluster are commonly used and may be interchangeable. Our work may pave the way to a translation between two medical systems with radically different philosophies and help the prioritisation of active ingredients with specific biomolecular activities of interest for the treatment of skin conditions.

Phenolics as GABAA Receptor Ligands: An Updated Review.

Natural products can act as potential GABA modulators, avoiding the undesirable effects of traditional pharmacology used for the inhibition of the central nervous system such as benzodiazepines (BZD). Phenolics, especially flavonoids and phlorotannins, have been considered as modulators of the BZD-site of GABAA receptors (GABAARs), with sedative, anxiolytic or anticonvulsant effects. However, the wide chemical structural variability of flavonoids shows their potential action at more than one additional binding site on GABAARs, which may act either negatively, positively, by neutralizing GABAARs, or directly as allosteric agonists. Therefore, the aim of the present review is to compile and discuss an update of the role of phenolics, namely as pharmacological targets involving dysfunctions of the GABA system, analyzing both their different compounds and their mechanism as GABAergic modulators. We focus this review on articles written in English since the year 2010 until the present. Of course, although more research would be necessary to fully establish the type specificity of phenolics and their pharmacological activity, the evidence supports their potential as GABAAR modulators, thereby favoring their inclusion in the development of new therapeutic targets based on natural products. Specifically, the data compiled in this review allows for the directing of future research towards ortho-dihydroxy diterpene galdosol, the flavonoids isoliquiritigenin (chalcone), rhusflavone and agathisflavone (biflavonoids), as well as the phlorotannins, dieckol and triphlorethol A. Clinically, flavonoids are the most interesting phenolics due to their potential as anticonvulsant and anxiolytic drugs, and phlorotannins are also of interest as sedative agents.

Structural analysis of a natural apolipoprotein A-I variant (L60R) associated with amyloidosis.

The reason that determines the pathological deposition of human apolipoprotein A-I variants inducing organ failure has been under research since the early description of natural mutations in patients. To shed light into the events associated with protein aggregation, we studied the structural perturbations that may occur in the natural variant that shows a substitution of a Leucine by an Arginine in position 60 (L60R). Circular dichroism, intrinsic fluorescence measurements, and proteolysis analysis indicated that L60R was more unstable, more sensitive to cleavage and the N-terminus was more disorganized than the protein with the native sequence (Wt). A higher tendency to aggregate was also detected when L60R was incubated at physiological pH. In addition, the small structural rearrangement observed for the freshly folded variant led to the release of tumor necrosis factor-α and interleukin-1ß from a model of macrophages. However, the mutant preserved both its dimeric conformation and its lipid-binding capacity. Our results strongly suggest that the chronic disease may be a consequence of the native conformation loss which elicits the release of protein conformations that could be either cytotoxic or precursors of amyloid conformations.

Fibrillar conformation of an apolipoprotein A-I variant involved in amyloidosis and atherosclerosis.

BACKGROUND: Different protein conformations may be involved in the development of clinical manifestations associated with human amyloidosis. Although a fibrillar conformation is usually the signature of damage in the tissues of patients, it is not clear whether this species is per se the cause or the consequence of the disease. Hereditary amyloidosis due to variants of apolipoprotein A-I (apoA-I) with a substitution of a single amino acid is characterized by the presence of fibrillar protein within the lesions. Thus mutations result in increased protein aggregation. Here we set up to characterize the folding of a natural variant with a mutation leading to a deletion at position 107 (apoA-I Lys107-0). Patients carrying this variant show amyloidosis and severe atherosclerosis. METHODS: We oxidized this variant under controlled concentrations of hydrogen peroxide and analyzed the structure obtained after 30-day incubation by fluorescence, circular dichroism and microscopy approaches. Neutrophils activation was characterized by confocal microscopy. RESULTS: We obtained a high yield of well-defined stable fibrillar structures of apoA-I Lys107-0. In an in vitro neutrophils system, we were able to detect the induction of Neutrophils Extracellular Traps (NETs) when we incubated with oxidized apoA-I variants. This effect was exacerbated by the fibrillar structure of oxidized Lys 107-0. CONCLUSIONS: We conclude that a pro-inflammatory microenvironment could result in the formation of aggregation-prone species, which, in addition may induce a positive feed-back in the activation of an inflammatory response. GENERAL SIGNIFICANCE: These events may explain a close association between amyloidosis due to apoA-I Lys107-0 and atherosclerosis.

Cacao extract enriched in polyphenols prevents endocrine-metabolic disturbances in a rat model of prediabetes triggered by a sucrose rich diet.

ETHNOPHARMACOLOGICAL RELEVANCE: Cocoa extracts rich in polyphenols are used as potential agent for treating diabetes. Cocoa polyphenols have been proved to ameliorate important hallmarks of type-2 diabetes (T2D). They can regulate glucose levels by increasing insulin secretion, promoting ß-cell proliferation and a reduction of insulin resistance. In addition, epidemiological evidence indicates that consumption of flavonoid decreases the incidence of T2D. AIM OF THE STUDY: T2D is preceded by a prediabetic state in which the endocrine-metabolic changes described in T2D are already present. Since epidemiological evidence indicates that consumption of flavonoid decreases its incidence, we evaluated possible preventive effects of polyphenol-enriched cocoa extract on a model of prediabetes induced by sucrose. MATERIALS AND METHODS: We determined circulating parameters and insulin sensitivity indexes, liver protein carbonyl groups and reduced glutathione, liver mRNA expression levels of lipogenic enzymes, expression of different pro-inflammatory mediators, fructokinase activity and liver glycogen content. For that, radioimmunoassay, real-time polymerase chain reaction, Western blot, spectrophotometry, and immunohistochemistry were used. RESULTS: We demonstrated that sucrose administration triggered hypertriglyceridemia, insulin-resistance, and liver increased oxidative stress and inflammation markers compared to control rats. Additionally, we found an increase in glycogen deposit, fructokinase activity, and lipogenic genes expression (SREBP-1c, FAS and GPAT) together with a decrease in P-Akt and P-eNOS protein content (P < 0.05). Sucrose-induced insulin resistance, hepatic carbohydrate and lipid dysmetabolism, oxidative stress, and inflammation were effectively disrupted by polyphenol-enriched cocoa extract (PECE) co-administration (P < 0.05). CONCLUSION: Dietary administration of cocoa flavanols may be an effective and complementary tool for preventing or reverting T2D at an early stage of its development (prediabetes).

Isoespintanol, a monoterpene isolated from oxandra cf xylopioides, ameliorates the myocardial ischemia-reperfusion injury by AKT/PKCε/eNOS-dependent pathways.

PURPOSE: To determine the actions of isoespintanol (Isoesp) on post-ischemic myocardial and mitochondrial alterations. METHODS: Hearts removed from Wistar rats were perfused by 20 min. After this period, the coronary flow was interrupted by half an hour and re-established during 1 h. In the treated group, Isoesp was administered at the beginning of reperfusion. To assess the participation of ε isoform of protein kinase C (PKCε), protein kinase B (PKB/Akt), and nitric oxide synthase (NOS), hearts were treated with Isoesp plus the respective inhibitors (chelerythrine, wortmannin, and N-nitro-L-arginine methyl ester). Cell death was determined by triphenyl tetrazolium chloride staining technique. Post-ischemic recovery of contractility, oxidative stress, and content of phosphorylated forms of PKCε, Akt, and eNOS were also examined. Mitochondrial state was assessed through the measurement of calcium-mediated response, calcium retention capacity, and mitochondrial potential. RESULTS: Isoesp limited cell death, decreased post-ischemic dysfunction and oxidative stress, improved mitochondrial state, and increased the expression of PKCε, Akt, and eNOS phosphorylated. All these beneficial effects achieved by Isoesp were annulled by the inhibitors. CONCLUSION: These findings suggest that activation of Akt/eNOS and PKCε signaling pathways are involved in the development of Isoesp-induced cardiac and mitochondria tolerance to ischemia-reperfusion.

Modulation of Diabetes by Natural Products and Medicinal Plants via Incretins.

Incretins are metabolic hormones released after a meal that increase insulin secretion from pancreatic ß-cells. The two main incretins are the intestinal peptides glucagon-like peptide-1 and glucose-dependent insulinotropic polypeptide. Both induce a decrease in glycemia, slow down the absorption of nutrients, and are inactivated by the enzyme dipeptidyl peptidase-4. Recently, incretin-based therapies have become a useful tool to treat diabetic patients, and different studies have focused on the identification of glucagon-like peptide-1 receptor agonists, including those of natural origin. This review focuses on the new findings of medicinal plants and natural products as possible active agents on the potentiation of incretin receptor signaling. Among these, soluble fiber from species of Plantago and guar gum show promising effects, iridoid derivatives are relevant activators of incretin receptors, and derivatives of cyanidin, especially diglycosylated ones, are an interesting source of dipeptidyl peptidase-4 inhibitors.

Activation of AMPK by Medicinal Plants and Natural Products: Its Role in Type 2 Diabetes Mellitus.

Type-2 Diabetes (T2D) is a metabolic disease characterized by permanent hyperglycemia, whose development can be prevented or delayed by using therapeutic agents and implementing lifestyle changes. Some therapeutic alternatives include regulation of glycemia through modulation of different mediators and enzymes, such as AMP-activated protein kinase (AMPK), a highly relevant cellular energy sensor for metabolic homeostasis regulation, with particular relevance in the modulation of liver and muscle insulin sensitivity. This makes it a potential therapeutic target for antidiabetic drugs. In fact, some of them are standard drugs used for treatment of T2D, such as biguanides and thiazolidindiones. In this review, we compile the principal natural products that are activators of AMPK and their effect on glucose metabolism, which could make them candidates as future antidiabetic agents. Phenolics such as flavonoids and resveratrol, alkaloids such as berberine, and some saponins are potential natural activators of AMPK with a potential future as antidiabetic drugs.

Cardioprotection and natural polyphenols: an update of clinical and experimental studies.

Myocardial ischemia is the leading cause of death worldwide. Despite better outcomes with early coronary artery reperfusion strategies, morbidity and mortality remain significant. The principal myocardial hallmark of myocardial ischemia is cell death and the associated impairment of cardiac contractility. In this way, the use of extracts from medicinal plants versus synthetic drugs to mitigate post-ischemic damage constitutes an alternative. Despite their proven beneficial effects in cardiovascular disorders, the use of many plants is questioned. Our aim is to update the clinical and experimental studies about the actions of medicinal plants and polyphenol-enriched extracts against ischemia-reperfusion injury and the involved mechanisms. A review of the recent scientific literature (last ten years) on cardioprotective medicinal plants was developed using the following bibliographic databases: PubMed, Scopus, Web of Knowledge and Google Scholar. Herein, the clinical and experimental studies on medicinal plants and their phenolic compounds have been reviewed. The second part of this review was centered on the search for medicinal plant extracts and natural products isolated from them as potential cardioprotective agents. The botanical names of the cited plants have been authenticated by searching the Plant List and Royal Botanical Garden, Kew databases. The data collected show that treatment with natural products diminishes post-ischemic damage through an improvement of the mitochondrial functionality mainly mediated by enhanced nitric oxide bioavailability. Despite these results, further studies must be carried out to validate their use to prevent or mitigate ischemia-reperfusion injury in the clinical setting.

Intestinal, urinary and uterine antispasmodic effects of isoespintanol, metabolite from Oxandra xylopioides leaves.

BACKGROUND: Isoespintanol is a monoterpene isolated from the leaves of Oxandra xylopioides Diels. (Annonaceae) with antioxidant and antiinflammatory effects. It was of interest to know whether it has antispasmodic effects such as other known drugs, phloroglucinol and trimethoxybenzene, used in therapeutics for treating biliary, urinary and uterine spasms. PURPOSE: To assess whether isoespintanol possesses antispasmodic effects on intestine, uterus and bladder. STUDY DESIGN: A preclinical study was performed in which isoespintanol, phloroglucinol and trimethoxybenzene were evaluated with concentration-contractile response curves (CRC) of carbachol in isolated rat intestine and bladder, and with CRC of serotonin (5-HT) in rat uterus. Moreover, it was assessed whether isoespintanol interferes with Ca2+ influx by making CRC of Ca2+ in high-K+ medium in intestine and bladder. RESULTS: Isoespintanol non-competitively inhibited the CRC of carbachol with affinity constant (pK) of 4.78 ±â€¯0.09 in intestine and 4.60 ±â€¯0.09 in bladder. Phloroglucinol and trimethoxybenzene were also non-competitive antagonists, but isoespintanol was 8 times more potent than trimethoxybenzene and similarly potent than phloroglucinol in intestine. In bladder, isoespintanol resulted 8 times more potent than trimethoxybenzene. The maximal inhibition of contraction followed the order of isoespintanol > trimethoxybenzene > phloroglucinol in intestine, and isoespintanol > trimethoxybenzene in bladder. Moreover, isoespintanol also completely and non-competitively inhibited the CRC of Ca2+, with a pK of 5.1 ±â€¯0.1 in intestine, and 4.32 ±â€¯0.07 in bladder. In uterus isoespintanol reduced, completely and non-competitively, the contraction produced by 5-HT with pK of 5.05 ±â€¯0.07. CONCLUSION: Results demonstrate that isoespintanol is a very good intestinal, urinary and uterine antispasmodic, with higher potency than the other drugs used in therapeutics. The mechanism of action of isoespintanol is the interference with Ca2+ influx, at a difference of trimethoxybenzene and phloroglucinol.

Human apolipoprotein A-I Gly26Arg stimulation of inflammatory responses via NF-kB activation: Potential roles in amyloidosis?

The cascade of molecular events leading to Human apolipoprotein A-I (apoA-I) amyloidosis is not completely understood, not even the pathways that determine clinical manifestations associated to systemic protein deposition in organs such as liver, kidney and heart. About twenty natural variants of apoA-I were described as inducing amyloidosis, but the mechanisms driving their aggregation and deposition are still unclear. We previously identified that the mutant Gly26Arg but not Lys107-0 induced the release of cytokines and reactive oxygen species from cultured RAW 264.7 murine macrophages, suggesting that part of the pathogenic pathway could elicit of an inflammatory signal. In this work we gained deep insight into this mechanism and determined that Gly26Arg induced a specific pro-inflammatory cascade involving activation of NF-κB and its translocation into the nucleus. These findings suggest that some but not all apoA-I natural variants might promote a pro-oxidant microenvironment which could in turn result in oxidative processing of the variants into a misfolded conformation.

Reversible redox modifications of ryanodine receptor ameliorate ventricular arrhythmias in the ischemic-reperfused heart.

Previous results from our laboratory showed that phosphorylation of ryanodine receptor 2 (RyR2) by Ca(2+) calmodulin-dependent kinase II (CaMKII) was a critical but not the unique event responsible for the production of reperfusion-induced arrhythmogenesis, suggesting the existence of other mechanisms cooperating in an additive way to produce these rhythm alterations. Oxidative stress is a prominent feature of ischemia/reperfusion injury. Both CaMKII and RyR2 are proteins susceptible to alteration by redox modifications. This study was designed to elucidate whether CaMKII and RyR2 redox changes occur during reperfusion and whether these changes are involved in the genesis of arrhythmias. Langendorff-perfused hearts from rats or transgenic mice with genetic ablation of CaMKII phosphorylation site on RyR2 (S2814A) were subjected to ischemia-reperfusion in the presence or absence of a free radical scavenger (mercaptopropionylglycine, MPG) or inhibitors of NADPH oxidase and nitric oxide synthase. Left ventricular contractile parameters and monophasic action potentials were recorded. Oxidation and phosphorylation of CaMKII and RyR2 were assessed. Increased oxidation of CaMKII during reperfusion had no consequences on the level of RyR2 phosphorylation. Avoiding the reperfusion-induced thiol oxidation of RyR2 with MPG produced a reduction in the number of arrhythmias and did not modify the contractile recovery. Conversely, selective prevention of S-nitrosylation and S-glutathionylation of RyR2 was associated with higher numbers of arrhythmias and impaired contractility. In S2814A mice, treatment with MPG further reduced the incidence of arrhythmias. Taken together, the results suggest that redox modification of RyR2 synergistically with CaMKII phosphorylation modulates reperfusion arrhythmias.

Ex Vivo Treatment with a Polyphenol-Enriched Cocoa Extract Ameliorates Myocardial Infarct and Postischemic Mitochondrial Injury in Normotensive and Hypertensive Rats.

Our objective was to determine the effects of a polyphenol-enriched cocoa extract (PCE) on myocardial postischemic alterations in normotensive (Wistar rats, W) and spontaneously hypertensive rats (SHR). Isolated hearts were submitted to 110 min of perfusion or 20 min stabilization, 30 min global ischemia, and 60 min reperfusion (R). Other hearts were treated with PCE at the onset of R. Infarct size, the reduced glutathione (GSH), and the expression of phospho-Akt, P-GSK-3ß, and P-eNOS were assessed. In isolated mitochondria, the Ca(2+)-mediated response of mitochondrial permeability transition pore (mPTP), membrane potential (Δψm), and superoxide production were determined. PCE decreased infarct size, partly preserved GSH, increased the P-Akt, P-GSK-3ß, and P-eNOS contents, improved mPTP response to Ca(2+), decreased the superoxide production, and restored Δψm. These data show that PCE decreases the cardiac postischemic damage in W rats and SHR and suggest that Akt/GSK-3ß/eNOS dependent pathways are involved.

Effect of an Ilex paraguariensis (yerba mate) extract on infarct size in isolated rat hearts: the mechanisms involved.

Tea made from Ilex paraguariensis (IP) dried and minced leaves is a beverage widely consumed by large populations in South America as a source of caffeine (stimulant action) and for its medicinal properties. However, there is little information about the action of IP on the myocardium in the ischemia-reperfusion condition. Therefore, the objective of this study was to examine the effects of an aqueous extract of IP on infarct size in a model of regional ischemia. Isolated rat hearts were perfused by the Langendorff technique and subjected to 40 min of coronary artery occlusion followed by 60 min of reperfusion (ischemic control hearts). Other hearts received IP 30 µg mL(-1) during the first 10 min of reperfusion in the absence or presence of l(G)-nitro-l-arginine methyl ester [l-NAME, a nitric oxide synthase (NOS) inhibitor]. The infarct size was determined by triphenyltetrazolium chloride (TTC) staining. Post-ischemic myocardial function and coronary perfusion were also assessed. Cardiac oxidative damage was evaluated by using the thiobarbituric acid reactive substance (TBARS) concentration and the reduced glutathione (GSH) content. To analyze the mechanisms involved, the expressions of phosphorylated forms of eNOS and Akt were measured. In isolated mitochondria the Ca(2+)-induced mitochondrial permeability transition pore (mPTP) opening was determined. IP significantly decreased the infarct size and improved post-ischemic myocardial function and coronary perfusion. TBARS decreased, GSH was partially preserved, the levels of P-eNOS and P-Akt increased and mPTP opening diminished after IP addition. These changes were abolished by l-NAME. Therefore, our data demonstrate that acute treatment with IP only during reperfusion was effective in reducing myocardial post-ischemic alterations. These actions would be mediated by a decrease of mitochondrial permeability through IP-activated Akt/eNOS-dependent pathways.

Natural Products for the Treatment of Type 2 Diabetes Mellitus.

Type 2 diabetes mellitus is a metabolic disease characterized by persistent hyperglycemia. High blood sugar can produce long-term complications such as cardiovascular and renal disorders, retinopathy, and poor blood flow. Its development can be prevented or delayed in people with impaired glucose tolerance by implementing lifestyle changes or the use of therapeutic agents. Some of these drugs have been obtained from plants or have a microbial origin, such as galegine isolated from Galega officinalis, which has a great similarity to the antidiabetic drug metformin. Picnogenol, acarbose, miglitol, and voglibose are other antidiabetic products of natural origin. This review compiles the principal articles on medicinal plants used for treating diabetes and its comorbidities, as well as mechanisms of natural products as antidiabetic agents. Inhibition of α-glucosidase and α-amylase, effects on glucose uptake and glucose transporters, modification of mechanisms mediated by the peroxisome proliferator-activated receptor, inhibition of protein tyrosine phosphatase 1B activity, modification of gene expression, and activities of hormones involved in glucose homeostasis such as adiponectin, resistin, and incretin, and reduction of oxidative stress are some of the mechanisms in which natural products are involved. We also review the most relevant clinical trials performed with medicinal plants and natural products such as aloe, banaba, bitter melon, caper, cinnamon, cocoa, coffee, fenugreek, garlic, guava, gymnema, nettle, sage, soybean, green and black tea, turmeric, walnut, and yerba mate. Compounds of high interest as potential antidiabetics are: fukugetin, palmatine, berberine, honokiol, amorfrutins, trigonelline, gymnemic acids, gurmarin, and phlorizin.

Modulation of Cox-1, 5-, 12- and 15-Lox by popular herbal remedies used in southern Italy against psoriasis and other skin diseases.

Acanthus mollis (Acanthaceae), Achillea ligustica, Artemisia arborescens and Inula viscosa (Asteraceae) are used in Southern Italy against psoriasis and other skin diseases that occur with an imbalanced production of eicosanoids. We here assessed their in vitro effects upon 5-, 12-, 15-LOX and COX-1 enzymes as well as NFκB activation in intact cells as their possible therapeutic targets. All methanol crude extracts inhibited both 5-LOX and COX-1 activities under 200 µg/mL, without significant effects on the 12-LOX pathway or any relevant in vitro free radical scavenging activity. NFκB activation was prevented by all extracts but A. mollis. Interestingly, A. ligustica, A. arborescens and A. mollis increased the biosynthesis of 15(S)-HETE, an anti-inflammatory eicosanoid. A. ligustica (IC50 =49.5 µg/mL) was superior to Silybum marianum (IC50 =147.8 µg/mL), which we used as antipsoriatic herbal medicine of reference. Its n-hexane, dichloromethane and ethyl acetate fractions had also inhibitory effects on the LTB4 biosynthesis (IC50 s=9.6, 20.3 and 68 µg/mL, respectively) evidencing that the apolar extracts of A. ligustica are promising active herbal ingredients for future phytotherapeutical products targeting psoriasis.

Modulation of COX, LOX and NFκB activities by Xanthium spinosum L. root extract and ziniolide.

Xanthium spinosum L. (Asteraceae) is a medicinal weed distributed worldwide. Many of its diverse ethnopharmacological uses - namely diarrhoea, inflammation, liver disorders, snake bite and fever - are linked - at least in part - to an uncontrolled release of arachidonic acid metabolites. The crude extract of X. spinosum roots from Jordanian origin dose-dependently inhibited the 5-LOX (IC50 is approximately equal to 10 µg/mL), COX-1(IC50 is approximately equal to 50 µg/mL), and 12-LOX (IC50 is approximately equal to 170 µg/mL) enzymatic pathways in intact pro-inflammatory cells. A direct activity at the level of PLA2 is not probable, but the extract induced the synthesis of the anti-inflammatory eicosanoid 15(S)-HETE, which may in turn inhibit this enzyme. 5-LOX bioguided fractionation of the crude extract led to the isolation of ziniolide, a known 12,8-guaianolide sesquiterpene lactone, from the hydro-alcoholic fraction of the n-hexane extract (IC50=69 µM). Both the plant extract and ziniolide are in vitro inhibitors of the phorbol-induced NFκB activation, a key regulator of the arachidonic pathway.

Participation of mitochondrial permeability transition pore in the effects of ischemic preconditioning in hypertrophied hearts: role of NO and mitoKATP.

BACKGROUND: The mitochondrial permeability transition pore (mPTP) plays an important role in ischemia-reperfusion in normotensive animals. Our study aims to define their participation in the ischemic preconditioning (IP) in hypertrophied hearts and to assess the role played by NO and mitochondrial ATP-dependent K channels (mitoKATP). MATERIAL AND METHODS: Isolated hearts from spontaneously hypertensive rats (SHR) and age-matched normotensive rats Wistar Kyoto (WKY) were subjected to 35-min or 50-min global ischemia (GI) followed by 2-hour reperfusion (R). IP was induced by a single cycle of 5-min GI and 10-min R (IP1) or three cycles of 2-min GI and 5-min R (IP3) applied before to prolonged ischemia. L-NAME (NOS inhibitor) or 5-HD (mitoKATP blocker) to investigate the role played by NO and mitoKATP, respectively were administered. Infarct size (IS), myocardial function, reduced glutathione (GSH) - as marker of oxidative stress and MnSOD cytosolic activity - as an index of mPTP opening were determined. RESULTS: IP1 significantly decreased the IS in WKY hearts at both ischemia duration times. In SHR, IP1 decreased the IS observed in GI35 but it did not modify that detected at 50-min GI, which was limited by IP3. IP preserved GSH content and decreased MnSOD cytosolic activity in both rat strains. These protective effects were annulled by L-NAME and 5-HD for both ischemic periods in SHR, whereas in WKY they were only effective for 50-min GI. CONCLUSION: Our data demonstrate that the cardioprotection achieved by ischemic preconditioning in hearts from SHR hearts involves an attenuation of mPTP opening NO and mitoKATP-mediated.

Human apolipoprotein A-I natural variants: molecular mechanisms underlying amyloidogenic propensity.

Human apolipoprotein A-I (apoA-I)-derived amyloidosis can present with either wild-type (Wt) protein deposits in atherosclerotic plaques or as a hereditary form in which apoA-I variants deposit causing multiple organ failure. More than 15 single amino acid replacement amyloidogenic apoA-I variants have been described, but the molecular mechanisms involved in amyloid-associated pathology remain largely unknown. Here, we have investigated by fluorescence and biochemical approaches the stabilities and propensities to aggregate of two disease-associated apoA-I variants, apoA-IGly26Arg, associated with polyneuropathy and kidney dysfunction, and apoA-ILys107-0, implicated in amyloidosis in severe atherosclerosis. Results showed that both variants share common structural properties including decreased stability compared to Wt apoA-I and a more flexible structure that gives rise to formation of partially folded states. Interestingly, however, distinct features appear to determine their pathogenic mechanisms. ApoA-ILys107-0 has an increased propensity to aggregate at physiological pH and in a pro-inflammatory microenvironment than Wt apoA-I, whereas apoA-IGly26Arg elicited macrophage activation, thus stimulating local chronic inflammation. Our results strongly suggest that some natural mutations in apoA-I variants elicit protein tendency to aggregate, but in addition the specific interaction of different variants with macrophages may contribute to cellular stress and toxicity in hereditary amyloidosis.