Taxifolin and gastro-adhesive microparticles containing taxifolin promotes gastric healing in vivo, inhibits Helicobacter pylori in vitro and proton pump reversibly in silico.

Taxifolin (3,5,7,3,4-pentahydroxy flavanone or dihydroquercetin, Tax) was identified as a gastroprotective compound and a gastroadhesive formulation was recently developed to prolong its residence time and release in the stomach. So, the gastric healing effectiveness of Tax and gastro-mucoadhesive microparticles containing Tax (MPTax) against the acetic acid induced-gastric ulcer in rats was investigated in this study. Moreover, the interactions between Tax and H+/K+-ATPase were investigated in silico, and its anti- H. pylori activity was determined in vitro. The oral treatment with MPTax (81.37 mg/kg, containing 12.29% of Tax) twice a day for seven days reduced the ulcer area by 63%, compared to vehicle-treated group (Veh: 91.9 ± 10.3 mm2). Tax (10 mg/kg, p.o) reduced the ulcer by 40% but with a p = 0.07 versus Veh group. Histological analysis confirmed these effects. Tax and MPTax increased the gastric mucin amount, reduced the myeloperoxidase activity, and increased the glutathione reduced content at ulcer site. However, only MPTax decreased the lipoperoxide accumulation at ulcer site. Besides, Tax and MPTax normalize the catalase and glutathione S-transferase activity. Tax showed reversible interaction with H+/K+-ATPase in silico and its anti-H. pylori effects was confirmed (MIC = 625 µg/mL). These results suggest that the antiulcer property of Tax involves the strengthening of the gastric protective factors in parallel to its inhibitory interaction with H+/K+-ATPase and H. pylori. Considering that ulcer healing action displayed by Tax was favored by gastroadhesive microparticles, this approach seems to be promising for its oral delivery to treat acid-peptic diseases.

Mitochondria and reactive oxygen species.

Mitochondria are a quantitatively relevant source of reactive oxygen species (ROS) in the majority of cell types. Here we review the sources and metabolism of ROS in this organelle, including the conditions that regulate the production of these species, such as mild uncoupling, oxygen tension, respiratory inhibition, Ca2+ and K+ transport, and mitochondrial content and morphology. We discuss substrate-, tissue-, and organism-specific characteristics of mitochondrial oxidant generation. Several aspects of the physiological and pathological roles of mitochondrial ROS production are also addressed.

Effects of salts on aerobic metabolism of Debaryomyces hansenii.

Debaryomyces hansenii was grown in YPD medium without or with 1.0 M NaCl or KCl. Respiration was higher with salt, but decreased if it was present during incubation. However, carbonylcyanide-3-chlorophenylhydrazone (CCCP) markedly increased respiration when salt was present during incubation. Salt also stimulated proton pumping that was partially inhibited by CCCP; this uncoupling of proton pumping may contribute to the increased respiratory rate. The ADP increase produced by CCCP in cells grown in NaCl was similar to that observed in cells incubated with or without salts. The alternative oxidase is not involved. Cells grown with salts showed increased levels of succinate and fumarate, and a decrease in isocitrate and malate. Undetectable levels of citrate and low-glutamate dehydrogenase activity were present only in NaCl cells. Both isocitrate dehydrogenase decreased, and isocitrate lyase and malate synthase increased. Glyoxylate did not increase, indicating an active metabolism of this intermediary. Higher phosphate levels were also found in the cells grown in salt. An activation of the glyoxylate cycle results from the salt stress, as well as an increased respiratory capacity, when cells are grown with salt, and a 'coupling' effect on respiration when incubated in the presence of salt.

Enhancement of antibiotic activity by sub-lethal concentrations of enterocin CRL35.

OBJECTIVE: The aim of this study was to evaluate the interaction of several conventional antibiotics with sub-lethal concentrations of enterocin CRL35, a cationic peptide, on Listeria innocua 7. METHODS: Susceptibility of L. innocua 7 cells to the combination of enterocin CRL35 and non-peptide antibiotics (cefalexin, ampicillin, ciprofloxacin, nalidixic acid, erythromycin, chloramphenicol, vancomycin and tetracycline) was assayed using the broth dilution method and killing curves. Fractional inhibitory concentration (FIC) index was calculated to assess synergy. The transmembrane electrical potential and pH gradient were determined by specific fluorescent probes. RESULTS: We found positive interactions between the cationic peptide and three conventional antibiotics (tetracycline, erythromycin and chloramphenicol) which are excluded from the cells by efflux pumps dependent on the membrane proton gradient. Furthermore, enterocin CRL35 even at sub-lethal concentrations induced the dissipation of both components of the proton motive force (Deltap), i.e. transmembrane electrical potential and pH gradient and hence the alteration of processes dependent on it. CONCLUSION: We hypothesize that enterocin CRL35 increases the effectiveness of these antibiotics by impairment of the bacterial active efflux systems and the consequent accumulation of these toxic compounds in the cytoplasm.

[Role of H+ ATPases in plasma membranes of airway smooth muscle]. / Papel de las H+ ATPasas en las membranas plasmaticas del musculo liso de las vias aereas.

Protons generated inside the cells during metabolic activity have to be extruded through active mechanisms from the intracellular to the extracellular space. One of the systems involved in proton transport across membranes are the V-ATPases, which are oligomeric complexes that have been found in several subcellular organelles energizing such organelle through a proton gradient and a membrane potential. In this paper, a V-ATPase activity has been described at the plasma membranes fractions isolated from airway smooth muscle. This activity was measured as a Cl- stimulated Mg2+ ATPase. This Cl- activating effect was also shared by others halogens as I- and Br- but not F-. This Cl- stimulated ATPase is a nucleotide triphosphatase being unable to hydrolyze mono and dinucleotides. The divalent cations showed the following sequence of activation (Mg2+ > Mn2+ > Ca2+) of the Cl- activated Mg2+ ATPase. This Cl- stimulated Mg2+ ATPase was insensitive to ouabain, vanadate, sodium azide and rutamicina. NEM (N-ethylmaleimide) partially inhibited this activity but a complete inhibition was observed with p-CMB (p-chloromercurbenzoate ). Several specific proton transport inhibitors were employed to show the presence of a H+ pump activity. Thus, the strong inhibition induced by DCCD suggest the existence of hydrophobic subunits related to a proton channel. In addition, protonophores as 1799 and FCCP stimulated the Cl- stimulated ATPase indicating the presence of a H+ pump in these plasma membranes vesicles. The chloride requirement could be explained by the existence of a chloride conductor coupled to the proton pump (H+ ATPase-type V) due to the inhibitory effect of duramycin.(ABSTRACT TRUNCATED AT 250 WORDS)