Antifungal activity of mango peel and seed extracts against clinically pathogenic and food spoilage yeasts.

The antioxidant and antifungal (antiyeast) properties of mango (Mangifera indica) peel and seed by-products were investigated. Nine extracts were obtained using three cultivars and two extraction methods. Significant differences between cultivars and extraction methods were detected in their bioactive compounds and antioxidant activity. The antifungal property was determined using agar diffusion and broth micro-dilution assays against 18 yeast species of the genera Candida, Dekkera, Hanseniaspora, Lodderomyces, Metschnikowia, Pichia, Schizosaccharomyces, Saccharomycodes and Zygosaccharomyces. All mango extracts showed antifungal activity. The minimum inhibitory concentration (MIC) and the minimum fungicidal concentration (MFC) values were lower for seed than for peel extracts. MICs and MFCs ranged from values <0.1 to 5 and 5 to >30 mgGAE/mL, respectively. The multivariate analysis showed a relationship between antifungal activity, the capacity to inhibit lipid peroxidation and total phenol content. These properties were associated with high levels of proanthocyanidins, gallates and gallotannins in the extracts.

P2X7 receptor activation downmodulates Na(+)-dependent high-affinity GABA and glutamate transport into rat brain cortex synaptosomes.

Sodium-dependent high-affinity amino-acid transporters play crucial roles in terminating synaptic transmission in the central nervous system (CNS). However, there is lack of information about the mechanisms underlying the regulation of amino-acid transport by fast-acting neuromodulators, like ATP. Here, we investigated whether activation of the ATP-sensitive P2X7 receptor modulates Na(+)-dependent high-affinity γ-aminobutyric acid (GABA) and glutamate uptake into nerve terminals (synaptosomes) of the rat cerebral cortex. Radiolabeled neurotransmitter accumulation was evaluated by liquid scintillation spectrometry. The cell-permeant sodium-selective fluorescent indicator, SBFI-AM, was used to estimate Na(+) influx across plasma membrane. 2'(3')-O-(4-benzoylbenzoyl)ATP (BzATP, 3-300 µM), a prototypic P2X7 receptor agonist, concentration-dependently decreased [(3)H]GABA (14%) and [(14)C]glutamate (24%) uptake; BzATP decreased transport maximum velocity (Vmax) without affecting the Michaelis constant (Km) values. The selective P2X7 receptor antagonist, A-438079 (3 µM), prevented inhibition of [(3)H]GABA and [(14)C]glutamate uptake by BzATP (100 µM). The inhibitory effect of BzATP coincided with its ability to increase intracellular Na(+) and was mimicked by Na(+) ionophores, like gramicidin and monensin. Increases in intracellular Na(+) (with veratridine or ouabain) or substitution of extracellular Na(+) by N-methyl-D-glucamine (NMDG)(+) all decreased [(3)H]GABA and [(14)C]glutamate uptake and attenuated BzATP effects. Uptake inhibition by BzATP (100 µM) was also attenuated by calmidazolium, which selectively inhibits Na(+) currents through the P2X7 receptor pore. In conclusion, disruption of the Na(+) gradient by P2X7 receptor activation downmodulates high-affinity GABA and glutamate uptake into rat cortical synaptosomes. Interference with amino-acid transport efficacy may constitute a novel target for therapeutic management of cortical excitability.

Changes in postharvest quality of Swiss chard grown using 3 organic preharvest treatments.

Using storage conditions recommended for conventional chard (4 degrees C, 90% RH and 7 d), the chard treated with some organic preharvest treatments [effective microorganisms, a fermented mixture of effective microorganisms with organic matter (EM-Bokashi + EM), and an auxiliary soil product] lost considerable water (> 2%) and weight (> 25%). These results indicate that organic methods tested produce a vegetable that can not sustain its quality when commercialized through the conventional supply chain. Nevertheless, respiration, color, pH, and titratable acidity practically remained constant during conservation. Ascorbic acid content was constant in chard treated with the different preharvest treatments and collected at 8 wk after sowing (normal harvest). However, the ascorbic acid content of the control chard decreased 60% after 7 d of storage. This vitamin diminished (35%) in chard collected after 19 wk after sowing (late harvest) during the postharvest conservation. The greatest difference in chard quality was registered between sampling dates since chard collected during the late harvest had higher levels of dry matter, sugars, acids, proteins, and ascorbic acid than chard collected during the normal harvest.

On the high affinity of 8-cyclohexylcaffeine for the presynaptic inhibitory adenosine receptor present in rat motor nerve terminals.

Rat neuromuscular junction was used to study the characteristics of presynaptic A1 adenosine receptors. We investigated the ability of the 8-substituted caffeine, 8-cyclohexylcaffeine (CHC), as well as of 1,3,8-substituted xanthines, 1,3-dipropyl-8-p-sulfophenylxanthine (DPSPX) and 8-p-sulfophenyl-1-isoamyl-3-isobutylxanthine (SPIIBX) to antagonize the inhibitory effect of 2-chloroadenosine on the amplitude of nerve-evoked twitches of the rat phrenic-hemidiaphragm, and we compared the affinity of these xanthines with that of 1,3-dipropyl-8-cyclopenthylxanthine (DPCPX). CHC, DPSPX and SPIIBX in a near parallel manner shifted to the right the log concentration-response curve for the inhibitory effect of 2-chloroadenosine on nerve-evoked twitch amplitude. Linear Schild plots with slopes near to unity were obtained for all these xanthines. The order of potency of the xanthines was DPCPX (Ki = 0.53 nM) > DPSPX (38 nM) = CHC (41 nM) > SPIIBX (404 nM). The affinities of DPSPX and SPIIBX for the A1 receptor at the rat neuromuscular junction are in agreement with the affinities described for A1 receptors at brain membranes. The now reported affinity of CHC for the presynaptic A1 receptor is 683 times higher than that obtained in binding studies in rat brain membranes, and is only 49 times higher than that obtained in functional assays (adenylate cyclase activity) in non-neuronal preparations (rat fat cells).

Effects of forskolin, dibutyryl cyclic AMP, and 5'-N-ethylcarboxamide adenosine on 22Na uptake by rat brain synaptosomes stimulated by veratridine.

The effects of forskolin, dibutyryl cyclic AMP, and 5'-N-ethylcarboxamide adenosine on specific 22Na uptake by synaptosomes stimulated by veratridine were investigated. All substances inhibited 22Na uptake, with forskolin more potent than 5'-N-ethylcarboxamide and this latter one more potent than dibutyryl cyclic AMP. In the absence of preincubation with forskolin, this substance caused little or no effect on 22Na uptake by synaptosomes. In the presence of the adenosine antagonist dipropylsulfophenylxanthine, the inhibitory effect of 5'-N-ethylcarboxamide adenosine on 22Na uptake was consistently antagonized. The results were interpreted as forskolin and 5'-N-ethylcarboxamide adenosine increasing cyclic AMP accumulation, and dibutyryl cyclic AMP mimicking it, and by these mechanisms decreasing sodium uptake through the sodium channels.