Study of in vitro degradation of brushite cements scaffolds.

An interest path to fabricate supports for tissue engineering is to foam calcium phosphate cement's pastes leading to an increase on material's total porosity and interconnectivity which facilitates cells' adhesion, proliferation and differentiation. The aim of this work is to develop scaffolds of brushite cement and to evaluate its in vitro degradation rate. Macroporosity was obtained by foaming the liquid phase with different non-ionic surfactants (Tween 80 and Lutensol ON-110). The foam stability was achieved by adding chitosan. The scaffolds were immersed in Ringers(®) solution during 7, 14, 21 and 28 days and samples' microstructure, weight loss, mechanical resistance and apparent porosity were evaluated. Both scaffolds presented interconnected macropores with sizes ranging from 100 to 360 µm and total porosities higher than 60%. These properties could facilitate cell infiltration, bone growth and vascularization. The scaffolds obtained in this work should be considered as promising materials for application in bone tissue engineering.

Effect of crude extract and fractions from Vitex megapotamica leaves on hyperglycemia in alloxan-diabetic rats.

The effect of the crude extract, ethyl acetate and n-butanol fractions from Vitex megapotamica (Spreng) Moldenke on glycemia was investigated in diabetic rats. Oral administration of crude extract significantly reduced serum glucose levels in both normal and diabetic animals. In normal rats, serum glucose lowering was observed with 400 and 800 mg/kg at 2 and 2-3h, respectively after oral crude extract treatment. Nevertheless, the hypoglycemic effect of Vitex megapotamica in diabetic rats was evident at 1 and 2h and from 1 to 3h after treatment with 400 and 800 mg/kg, respectively. The ethyl acetate as well as n-butanol fractions were able to diminish glycemia in diabetic animals. The ethyl acetate fraction (400 and 800 mg/kg) produced the maximum hypoglycemic effect (28 and 20%, respectively) in diabetic rats and the same dose of the n-butanol fraction reduced the hyperglycemia only by 11% at 1h after treatment. Additionally, in hyperglycemic normal rats neither crude extract nor ethyl acetate fraction modified the glucose tolerance and the known tolbutamide effect on insulin release was clearly observed in this group. Thus, this study shows that Vitex megapotamica has an anti-hyperglycemic action, is able to ameliorate the diabetic state and, probably, is a source of hypoglycemic compounds.

Follow-up studies on glycosylated flavonoids and their complexes with vanadium: their anti-hyperglycemic potential role in diabetes.

The present study sought to evaluate the hypoglycemic activities of free glycosylated flavonoids and flavonoid complexes with vanadium(IV), (VO(IV)), on glycemia in experimental diabetic rats. Besides free kaempferol-3,7-O-(alpha)-dirhamnoside and kaempferol-3-neohesperidoside, complexes of these flavonoids with VO(IV) were administered by different routes in order to compare the potency of the compounds as well as the efficacy of insulin or VO(IV) in lowering serum glucose. Wistar rats were made diabetic by alloxan. The glycemia was assessed at different times after the administering of compounds. The equilibrium constants were determined by potentiometric study and two species with VO(IV) are proposed at physiological pH, VOH(2)L(2) for kaempferitrin and VOHL for kaempferol-3-neohesperidoside. The latter exhibited hypoglycemic activity at all times examined with 50 and 100 mg/kg and the former reduced the glycemia from 0 to 6h by i.p. route. The administering of the complexes or 0.0146 mmol/kg VO(IV) resulted in a serum glucose-lowering effect over time in the case of i.p. treatment. A marked hypoglycemic effect was observed for 0.5IU of insulin (67.5%); 0.0146 mmol VO(IV) (16.8%); 0.0294 mmol kaempferitrin-VO(IV) (17.8%) and 0.0286 mmol kaempferol-3-neohesperidoside-VO(IV) (56.0%) at 3h after i.p. treatment when compared with respective zero time in diabetic groups. Kaempferol-3-neohesperidoside-VO(IV) was 2.5 times more effective than VO(IV), twice as effective as the free compound and three times more effective than kaempferitrin-VO(IV). This is of particular interest since kaempferol-3-neohesperidoside appears to represent a suitable ligand for VO(IV) to mimic the efficacy of insulin in lowering serum glucose levels.

Insulinomimetic effects of kaempferitrin on glycaemia and on 14C-glucose uptake in rat soleus muscle.

Bauhinia forficata is one of the Bauhinia species mostly used as an antidiabetic herbal remedy in Brazil. Kaempferitrin (kaempferol-3,7-O-(alpha)-L-dirhamnoside) is the predominant flavonol glycoside found in the B. forficata leaves. The aim of the present work was to study the long-term effect of kaempferitrin on glycaemia in diabetic rats, as well as the in vitro effect of this compound on 14C-D-glucose uptake and 14C-leucine incorporation into protein in normal rat soleus muscle. Kaempferitrin was found to have an acute lowering effect on blood glucose in diabetic rats and to stimulate the glucose uptake percentile, as efficiently as insulin in muscle from normal rats. This compound did not have any effect on glucosuria or on protein synthesis in muscle from normal and diabetic animals. However, the protein synthesis in the kaempferitrin-treated groups was maintained at the same level as the respective controls. Thus, the hypoglycaemic effect and the prompt efficiency of the kaempferitrin in stimulating [U-14C]-2-deoxi-D-glucose uptake in muscle -constitute the first evidence to indicate that the acute effect of this compound on blood glucose lowering may occur as a consequence of the altered intrinsic activity of the glucose transporter (Vmax or glucose transporters translocation?) not involving directly the synthesis of new carriers.

Hypoglycemic effect and antioxidant potential of kaempferol-3,7-O-(alpha)-dirhamnoside from Bauhinia forficata leaves.

In vivo and in vitro treatments were carried out to investigate the effects of kaempferol-3,7-O-(alpha)-dirhamnoside (kaempferitrin), a major flavonoid compound of the n-butanol fraction from Bauhiniaforficata leaves, on serum glucose levels, as well as its antioxidant potential. Oral administration of kaempferitrin led to a significant hypoglycemic effect in normal and in alloxan-induced diabetic rats. In normal rats, blood glucose lowering was observed only with the higher dose of kaempferitrin (200 mg/kg) at 1 h after treatment. However, the hypoglycemic effect of kaempferitrin in diabetic rats was evident at all doses tested (50, 100, and 200 mg/kg), and this profile was maintained throughout the period studied for both higher doses. Additionally, in glucose-fed hyperglycemic normal rats, the kaempferitrin failed to decrease blood glucose levels. In vitro antioxidant properties or action against reactive oxygen species of this compound was also evaluated. The compound showed high reactivity with 1,1-diphenyl-2-picryl hydrazyl (DPPH), IC(50) of 84.0 +/- 7.8 microM, inhibited myeloperoxidase activity with K(0.5) = 86 +/- 9.9 microM, and decreased lipid peroxidation, induced by ascorbyl radical either in microsomes or in asolectin and phosphatidylcholine liposomes, with IC(50)'s of 320 +/- 14.1, 223 +/- 8.3, and 112 +/- 8.8 microM, respectively.

Acute effect of Bauhinia forficata on serum glucose levels in normal and alloxan-induced diabetic rats.

Experimental diabetes was used to study the acute effect of the n-butanol fraction of Bauhinia forficata Link (Leguminosae) (BF) leaves on the serum glucose levels of rats. Body weight was measured on the day of diabetes induction and on the day of the experiment. Levels of glucose were determined at different doses and times following treatment with BF or with vehicle in normal, diabetic and hyperglycemic normal rats. Oral administration of n-BuOH fraction led to a significant blood glucose-lowering effect in normal and diabetic rats. However, in glucose-fed hyperglycemic normal rats, the maximum dose of this fraction failed to decrease blood glucose levels. The hypoglycemic effect was observed at doses of 500 and 600 mg/kg after 1 and 2 h treatment respectively, in normal rats. The maximum effect of BF was detected at 1 h with 800 mg/kg in diabetic animals and this profile was maintained for the next 3 h. Treatment of normal and alloxan-induced diabetic rats with BF decreased glucose levels, while this fraction was devoid of hypoglycemic effect in glucose-fed hyperglycemic normal rats.