In vitro immunomodulatory activity, cytotoxicity and chemistry of some central European polypores

Context: Some mushrooms of the order Polyporales are known for their immunomodulatory actions. Objective: The objective of this study is to evaluate the in vitro phagocytic and cytotoxic effects of extracts from polyporales native to Central Europe. Materials and methods: The effects of ethanol extracts from 27 polypore species on opsonized zymosan-induced phagocytosis of isolated human neutrophils were tested by a chemiluminescence method. Colon epithelial cell lines, Caco-2 and HT-29, were used for cytotoxicity assays, and extracts were chemically characterized in terms of total phenolic and β-glucan content. Results: We observed phagocytosis or respiratory burst enhancing activity in 17 extracts, of which five species, namely Aurantiporus fissilis (Berk. & M.A. Curtis) H. Jahn ex Ryvarden, Trametes gibbosa (Pers.) Fr., Piptoporus betulinus (Bull.) P. Karst, Neolentinus lepideus (Fr.) Redhead & Ginns, Polyporus squamosus (Huds.) Fr., significantly increased phagocytosis in granulocytes by 205, 181, 158, 155 and 141%, respectively. The β-glucan content of the three most potent extracts was 58, 42 and 74 mg/g, respectively, and the polyphenol content was 155.6, 133.5 and 155.2 μmol of gallic acid equivalent/g, respectively. Some extracts showed cytotoxic activity, with higher cytotoxicity in Caco-2 than in HT-29 cells. Pycnoporus cinnabarinus (Jacq.) P. Karst. extract was cytotoxic to both cell lines, with IC50 values of 81 and 31 μg/mL, respectively. Discussion and conclusion: The most promising extracts were from N. lepideus and Polyporus squamosus, which are edible species and may be considered safe. Our findings support their use as culinary preparations or food supplements for various immunological gut disorders

In vitro analysis of iron chelating activity of flavonoids

Flavonoids have been demonstrated to possess miscellaneous health benefits which are, at least partly, associated with iron chelation. In this in vitro study, 26 flavonoids from different subclasses were analyzed for their iron chelating activity and stability of the formed complexes in four patho/physiologically relevant pH conditions (4.5, 5.5, 6.8, and 7.5) and compared with clinically used iron chelator deferoxamine. The study demonstrated that the most effective iron binding site of flavonoids represents 6,7-dihydroxy structure. This site is incorporated in baicalein structure which formed, similarly to deferoxamine, the complexes with iron in the stoichiometry 1:1 and was not inferior in all tested pH to deferoxamine. The 3-hydroxy-4-keto conformation together with 2,3-double bond and the catecholic B ring were associated with a substantial iron chelation although the latter did not play an essential role at more acidic conditions. In agreement, quercetin and myricetin possessing all three structural requirements were similarly active to baicalein or deferoxamine at the neutral conditions, but were clearly less active in lower pH. The 5-hydroxy-4-keto site was less efficient and the complexes of iron in this site were not stable at the acidic conditions. Isolated keto, hydroxyl, methoxyl groups or an ortho methoxy-hydroxy groups were not associated with iron chelation at all. © 2011 Elsevier Inc

Iron reduction potentiates hydroxyl radical formation only in flavonols

Flavonoids, substantial components of the human diet, are generally considered to be beneficial. However, they may possess possible pro-oxidative effects, which could be based on their reducing potential. The aims of this study were to evaluate the ability of 26 flavonoids to reduce ferric ions at relevant pH conditions and to find a possible relationship with potentiation of hydroxyl radical production. A substantial ferric ions reduction was achieved under acidic conditions, particularly by flavonols and flavanols with the catecholic ring B. Apparently corresponding bell-shaped curves displaying the pro-oxidant effect of flavonols quercetin and kaempferol on iron-based Fenton reaction were documented. Several flavonoids were efficient antioxidants at very low concentrations but rather inefficient or pro-oxidative at higher concentrations. Flavonols, morin and rutin were progressively pro-oxidant, while 7-hydroxyflavone and hesperetin were the only flavonoids with dose-dependent inhibition of hydroxyl radical production. Conclusively, administration of flavonoids may lead to unpredictable consequences with few exceptions. (C) 2012 Elsevier Ltd. All rights reserved

In vitro interactions of coumarins with iron

Coumarins are a large group of natural substances with diverse pharmacological properties that may predetermine some of them for the prevention and/or treatment of cardiovascular diseases and also other pathologies. Free iron participates in the production of reactive oxygen species (ROS) and plays an important role in the pathogenesis of cardiovascular diseases. Therefore, chelation of iron may attenuate some ROS consequences, but on the other hand, reduction of ferric ions to ferrous ones is unfavourable and leads to intensification of ROS production. In this study, we have examined the interaction of iron with coumarins which has been rarely analyzed. A series of naturally occurring and chemically synthesized 4-methylcoumarins were analyzed for their ferrous and total iron-chelating properties and compared with standard iron chelator deferoxamine. The iron chelation activity was assessed by a simple spectrophotometric approach based on the specific indicator for ferrous ions - ferrozine. The methodology was also extended for the measurement of total iron. Among the tested coumarins, ortho-dihydroxyderivatives were the most potent iron chelators and 7,8-dihydroxy-4-methylcoumarin even reached the efficiency of deferoxamine in neutral pH. However, these ortho-dihydroxycoumarins did not bind iron firmly in acidic conditions (e.g., in acute myocardial infarction) and, moreover, they reduced ferric ions that could lead to intensification of the Fenton chemistry. Other tested coumarins did not substantially chelate iron with the exception of ortho-diacetoxycoumarins. Conclusively, the use of iron-chelating coumarins in acidic conditions may be disadvantageous in contrast to neutral conditions. (C) 2010 Elsevier Masson SAS. All rights reserved

In vitro platelet antiaggregatory properties of 4-methylcoumarins

Platelets play a crucial role in physiological haemostasis. However, in coronary arteries damaged by atherosclerosis, enhanced platelet aggregation, with subsequent thrombus formation, is a precipitating factor in acute myocardial infarction. Current therapeutic approaches are able to reduce approximately one quarter of cardiovascular events, but they are associated with an increased risk of bleeding and in some resistant patients are not efficient. Some coumarins possess antiplatelet activity and, due to their additional antioxidant effects, may be promising drugs for use in combination with the present therapeutic agents. The aim of this study was to analyse a series of simple 4-methylcoumarins for their antiplatelet activity. Human plasma platelet suspensions were treated with different aggregation inducers [arachidonic acid (AA), collagen and ADP] in the presence of the 4-methylcoumarins. Complementary experiments were performed to explain the mechanism of action. 5,7-Dihydroxy-4-methylcoumarins, in particular those containing a lipophilic side chain at C-3, reached the activity of acetylsalicylic acid on AA-induced aggregation. Other tested coumarins were less active. Some of the tested compounds mildly inhibited either collagen- or ADP-induced aggregation. 5,7-Dihydroxy-4-methylcoumarins did not interfere with the function of thromboxane synthase, but were competitive antagonists of thromboxane A(2) receptors and inhibited cyclooxygenase-1 as well. 5,7-Dihydroxy-4-methylcoumarins appear to be promising candidates for the extension of the current spectrum of antiplatelet drugs. (C) 2012 Elsevier Masson SAS. All rights reserved

In vitro a in silico stanovení inhibiční aktivity thaliktrikavinu a kanadinu vůči acetylcholinesteráze a odhad jejich přestupu přes hematoencefalickou bariéru

In recent studies, several alkaloids acting as cholinesterase inhibitors were isolated from Corydalis cava (Papaveraceae). Inhibitory activities of (+)-thalictricavine (1) and (+)-canadine (2) on human acetylcholinesterase (hAChE) and butyrylcholinesterase (hBChE) were evaluated with the Ellman's spectrophotometric method. Molecular modeling was used to inspect the binding mode of compounds into the active site pocket of hAChE. The possible permeability of 1 and 2 through the blood-brain barrier (BBB) was predicted by the parallel artificial permeation assay (PAMPA) and logBB calculation. In vitro, 1 and 2 were found to be selective hAChE inhibitors with IC50 values of 0.38 +/- 0.05 mu M and 0.70 +/- 0.07 mu M, respectively, but against hBChE were considered inactive (IC50 values > 100 mu M). Furthermore, both alkaloids demonstrated a competitive-type pattern of hAChE inhibition and bind, most probably, in the same AChE sub-site as its substrate. In silico docking experiments allowed us to confirm their binding poses into the active center of hAChE. Based on the PAMPA and logBB calculation, 2 is potentially centrally active, but for 1 BBB crossing is limited. In conclusion, 1 and 2 appear as potential lead compounds for the treatment of Alzheimer's disease.Z Corydalis cava (Papaveraceae) bylo izolováno několik alkaloidů půsbících jako inhibitory cholinesterázy. Inhibiční aktivity (+) - thaliktrikavinu (1) a (+) - kanadinu (2) na lidskou acetylcholinesterázu (hAChE) a butyrylcholinesterázu (hBChE) byly hodnoceny pomocí Ellmanovy spektrofotometrické metody. K ověření způsobu vazby testovaných sloučenin do aktivního místa hAChE bylo použito molekulové modelování. Možná permeabilita 1 a 2 hematoencefalickou bariérou (HEB) ​​byla předpovězena pomocí testu paralelní umělé permeace (PAMPA) a logBB. In vitro bylo zjištěno, že 1 a 2 jsou selektivní inhibitory hAChE s hodnotami IC50 0,38 +/- 0,05 uM, respektive 0,70 +/- 0,07 uM, ale při inhibici hBChE byly považovány za neaktivní (hodnoty IC50> 100 uM). Oba alkaloidy prokázaly kompetitivní typ inhibice hAChE a vážou se s největší pravděpodobností na stejném AChE sub-místě jako jeho substrát. In silico dokovací experimenty potvrdily vazebné pozice v aktivním místě AChE. Na základě výpočtu PAMPA a logBB je 2 potenciálně centrálně aktivní, ale pro 1 je přechod HEB omezen