Insulin Sensitization by PPARγ and GLUT-4 Overexpression/Translocation Mediates the Antidiabetic Effect of Plantago australis.

Plantago australis Lam. Subsp. hirtella (Kunth) Rahn is a medicinal plant used as a diuretic, anti-inflammatory, antibacterial, throat cancer treatment and for the control of diabetes. P. australis was collected in the state of Morelos, México. The hydroalcoholic extract (HAEPa) of P. australis was obtained by maceration and concentrated in vacuo. Once dry, it was evaluated through an oral glucose tolerance test (OGTT) in normoglycemic mice and in a non-insulin-dependent diabetic mice model. The expression of PPARγ and GLUT-4 mRNA was determined by rt-PCR, and GLUT-4 translocation was confirmed by confocal microscopy. The toxicological studies were conducted in accordance with the guidelines suggested by the OECD, sections 423 and 407, with some modifications. HAEPa significantly decreased glycemia in OGTT curves, as well as in the experimental diabetes model compared to the vehicle group. In vitro tests showed that HAEPa induced an α-glucosidase inhibition and increased PPARγ and GLUT-4 expression in cell culture. The LD50 of HAEPa was greater than 2000 mg/kg, and sub-chronic toxicity studies revealed that 100 mg/kg/day for 28 days did not generate toxicity. Finally, LC-MS analysis led to the identification of verbascoside, caffeic acid and geniposidic acid, and phytochemical approaches allowed for the isolation of ursolic acid, which showed significant PPARγ overexpression and augmented GLUT-4 translocation. In conclusion, HAEPa induced significant antidiabetic action by insulin sensitization through PPARγ/GLUT-4 overexpression.

A Pharmacokinetic Study of Mix-160 by LC-MS/MS: Oral Bioavailability of a Dosage Form of Citroflavonoids Mixture.

This study was performed to evaluate and compare the pharmacokinetic parameters between two dosage formulations of hesperidin and naringenin: mixture and tablet. Our objective was to determine that the flavonoid tablet does not significantly modify the pharmacokinetic parameters compared with the mixture. For this study, we administered 161 mg/kg of either mixture (Mix-160) or tablet composed of hesperidin and by intragastric administration. Blood microsamples were collected from tail vein up to 24 h. Serum flavonoid extraction was performed by solid phase extraction and analyzed by LC-MS/MS of triple quadrupole (QqQ). Serum concentration vs. time plot showed that data fitted for a first-order model. The pharmacokinetic parameters were calculated by a noncompartmental model. The results showed that the absorption constant is higher than the elimination constant. The first concentration was found at five minutes, and minimal concentration at 24 h after administration, suggesting a enterohepatic recirculation phenomena and regulation of liver cytochromes' activity. We did not find meaningful differences between the pharmacokinetic parameters of both samples. We concluded that tablet form did not interfere with the bioavailability of hesperidin and naringenin, and it could be a suitable candidate for developing a drug product.

Characterization of Fungal Endophytes Isolated from the Metal Hyperaccumulator Plant Vachellia farnesiana Growing in Mine Tailings.

Heavy metal pollution has become an environmental and health problem worldwide. With the aim of finding novel strategies for metal bioremediation, endophytic fungi from the heavy metal hyperaccumulator plant Vachellia farnesiana were isolated and characterized. The plants were growing in mine tailings, rich in Zn, Pb, and Cu. Morphological and phylogenetic analyses indicated that the fungal strains belonged to Neocosmospora and Aspergillus genera. The Neocosmospora isolate belongs to the Fusarium solani species complex (FSSC) that groups phytopathogen species. However, in this case the plants from which it was isolated did not show any signs of disease. Both fungal strains were able to remove significant amounts of heavy metals from liquid cultures, either in a mixture of the three metals or each metal in a single culture. In response to lead exposure, the Neocosmospora sp. strain secreted specific novel phenolic compounds other than anthraquinones or naphtoquinones, which have been described in similar situations. The Aspergillus sp. dropped the pH in the medium. High-performance liquid chromatography determinations indicated that this strain secreted mainly glutamic acid in response to lead, a novel mechanism, which has not been reported elsewhere. Malic and succinic acids were also produced in response to lead exposure. Possibly, glutamic and succinic acids (synthesized in the Krebs cycle) can be used to cope with metal toxicity due to the plant providing photosynthates to the fungus. These fungi showed the potential to be used for bioremediation or restoration of metal-polluted environments.

Functional mechanism of tracheal relaxation, antiasthmatic, and toxicological studies of 6-hydroxyflavone.

Previously, we described tracheal rat rings relaxation by several flavonoids, being 6-hydroxyflavone (6-HOF) the most active derivative of the series. Thus, its mechanism of action was determined in an ex vivo tracheal rat ring bioassay. The anti-asthmatic effect was assayed in in vivo OVAlbumin (OVA)-sensitized guinea pigs. Finally, the toxicological profile of 6-HOF was studied based on Organization of Economic Cooperation and Development guidelines with modifications. 6-HOF-induced relaxation appears to be related with receptor-operated calcium channel and voltage-operated calcium channel blockade as the main mechanism of action, and also through the production of relaxant second messengers NO and cGMP. Molecular docking supports that 6-HOF acts as calcium channel blocker and by activation of nitric oxide synthase. In addition, the in vivo anti-asthmatic experiments demonstrate the dose-dependent significant anti-allergic effect of 6-HOF induced by OVA, with best activity at 50 /kg. Finally, toxicological studies determined a LD50 > 2,000 mg/kg and, after 28 day of treatment with 6-HOF (50 mg/kg) by intragastric route, mice did not exhibit evidence of any significant toxicity. In conclusion, experiments showed that 6-HOF exerts significant relaxant activity through calcium channel blockade, and possibly, by NO/cGMP-system stimulation on rat trachea, which interferes with the contraction mechanism of smooth muscle cells in the airways. In addition, the flavonoid shows potential anti-asthmatic properties in an anti-allergic pathway. Furthermore, because the pharmacological and safety evidence, we propose this flavonoid as lead for the development of a novel therapeutic agent for the treatment of asthma and related respiratory diseases.

Biopharmaceutical Characterization and Bioavailability Study of a Tetrazole Analog of Clofibric Acid in Rat.

In the current investigation, the physicochemical, biopharmaceutical and pharmacokinetic characterization of a new clofibric acid analog (Compound 1) was evaluated. Compound 1 showed affinity by lipophilic phase in 1 to 5 pH interval, indicating that this compound would be absorbed favorably in duodenum or jejunum. Also, Compound 1 possess two ionic species, first above of pH 4.43 and, the second one is present over pH 6.08. The apparent permeability in everted sac rat intestine model was 8.73 × 10-6 cm/s in duodenum and 1.62 × 10-5 cm/s in jejunum, suggesting that Compound 1 has low permeability. Elimination constant after an oral administration of 50 µg/kg in Wistar rat was 1.81 h-1, absorption constant was 3.05 h-1, Cmax was 3.57 µg/mL at 0.33 h, AUC0-α was 956.54 µ/mL·h and distribution volume was 419.4 mL. To IV administration at the same dose, ke was 1.21 h-1, Vd was 399.6 mL and AUC0-α was 747.81 µ/mL·h. No significant differences were observed between pharmacokinetic parameters at every administration route. Bioavailability evaluated was 10.4%. Compound 1 is metabolized to Compound 2 probably by enzymatic hydrolysis, and it showed a half-life of 9.24 h. With these properties, Compound 1 would be considered as a prodrug of Compound 2 with potential as an antidiabetic and anti dyslipidemic agent.

Hydrocortisone release from tablets based on bioresorbable poly(ether-ester-urethane)s

Abstract Bioresorbable linear poly(ether-ester-urethane)s with different hydrophilic characteristics were synthesized from triblock copolymers of poly(ε-caprolactone)-poly(ethylene oxide)-poly(ε-caprolactone) (PCL-PEO) as macrodiols, and L-lysine diisocyanate (LDI) or hexamethylenediisocyanate (HDI) were used as the required diisocyanates. Macrodiols were obtained by ring-opening polymerization (ROP) of ε-caprolactone (CL). Polyurethanes were synthesized by the reaction of the triblock copolymers with LDI or HDI in solution using stannous 2-ethylhexanoate as catalyst. Polyurethane tablets were fabricated and investigated as prospective drug delivery systems. The effect of the PEO content on the polymers' performance as drug carriers was evaluated. It was found that water provoked more swelling and erosion of polymers with higher contents of PEO. The hydrocortisone release profiles were analyzed using the Ritger-Peppas approximation. An anomalous release behaviour (values of n higher than 0.5) was found for most of the analyzed samples.

Evaluation of the neuroprotective activity of stansin 6, a resin glycoside from Ipomoea stans.

Stansin 6 a tetrasaccharide resin glycoside isolated from the root of Ipomoea stans was evaluated as anticonvulsant and neuroprotective in kainic acid-induced seizures of rats. Intraperitoneal injection of kainic acid (10 mg/kg) induced typical behavioral seizures such as wet dog shakes and limbic seizures, and histopathological changes in the hippocampus (degeneration and loss of pyramidal cells in CA1 to CA4 areas). Stansin 6 (10-80 mg/kg) had no effect on the behavior of rats and did not induce hippocampal damage. Pretreatment with stansin 6 inhibited convulsions in rats from kainic acid-induced seizures, reduced the degeneration pattern in the CA3 region, decreased astrocytic reactivity, and reduced the expression of IL-1ß and TNF-α induced by kainic acid. These results suggest that stansin 6 possesses neuroprotective and anticonvulsant activities.

Effect of melatonin administration on DNA damage and repair responses in lymphocytes of rats subchronically exposed to lead.

Lead exposure induces DNA damage, oxidative stress, and apoptosis, and alters DNA repair. We investigated the effects of melatonin co-administered to rats during exposure to lead. Three doses of lead acetate (10, 50 and 100mg/kg/day) were administered to rats during a 6-week period. Lymphocytes were analyzed. Lead exposure decreased glutathione (GSH) levels in blood, and at doses of 100mg/kg/day and 50mg/kg/day without melatonin, caused high levels of DNA damage, induced apoptosis, and altered DNA repair. Melatonin co-treatment did not attenuate the effects of lead at 100mg/kg/day, indicating that the effect of melatonin on GSH reduction is not sufficient to reduce the genotoxic effects of lead at this high dose. After 6 weeks of treatment, decreased weight gain was observed in high lead-dose groups (100mg/kg/day), with or without melatonin, and in medium-dose groups (50mg/kg/day) with melatonin, compared with the control group. The protective action of melatonin against lead toxicity is dependent on the dose of lead. Further pharmacological studies are needed to determine whether melatonin acts via melatonin membrane receptors on lymphocytes.

Synthesis, vasorelaxant activity and antihypertensive effect of benzo[d]imidazole derivatives.

A series of 1H-benzo[d]imidazole analogues of Pimobendan, substituted at position 5 with either -CF(3) or -NO(2), were synthesized using a short synthetic route. All the nitro derivatives were potent, and exhibited a concentration- and partial endothelium-dependent vasorelaxant effects, with EC(50)s <5microM. 2-Methoxy-4-[5-nitro-1H-benzo[d]imidazol-2-yl]phenol (compound 13) was the most potent derivative of the series, showing an EC(50) value of 1.81microM and E(max) of 91.7% for ex vivo relaxant response in intact aortic rings, resulting in a 2.5-fold higher activity compared to Pimobendan. The closely related 5-CF(3) analogue (compound 8), was 19 times less potent than 13. The antihypertensive activity of compound 13 was evaluated at doses of 25, 50 and 100mgkg(-1), using spontaneously hypertensive rats (SHR), showing a statistically significant dose-dependent effect.