Trolox down-regulates transforming growth factor-beta and prevents experimental cirrhosis.

Cirrhosis is a very common disease and its treatment is limited due to lack of effective drugs. Some studies indicate that this disease is associated with oxidative stress. Therefore, we decided to study the effect of trolox, an effective antioxidant, on experimental cirrhosis. Cirrhosis was induced by CCl4 administration (0.4 g/kg, intraperitoneally, three times per week, for 8 weeks) to Wistar male rats. Trolox was administered daily (50 mg/kg, orally). Fibrosis was assessed histologically and by measuring liver hydroxyproline content. Glutathione, lipid peroxidation and glycogen were measured in liver; serum markers of liver damage were also quantified. Transforming growth factor-beta (TGF-beta) was determined by Western blot and quantified densitometrically. Alkaline phosphatase, gamma-glutamyl transpeptidase and alanine aminotransferase increased in the group receiving CCl4; trolox completely or partially prevented these alterations. Glycogen was almost depleted by CCl4 but was partially preserved by trolox. Lipid peroxidation increased while glutathione decreased by CCl4 administration; trolox corrected both effects. Histology showed thick bands of collagen, necrosis and distortion of the hepatic parenchyma in the CCl4 group, such effects were prevented by trolox. Hydroxyproline content increased 5-fold by CCl4, while the group receiving both CCl4 and trolox showed no significant difference compared to the control group. CCl4 increased 3-fold TGF-beta, while trolox completely prevented this increase. We found that trolox effectively prevented cirrhosis induced with CCl4 in the rat. Our results suggest that the beneficial effects of trolox may be associated to its antioxidant properties and to its ability to reduce the profibrogenic cytokine TGF-beta expression.

Synthesis and biological evaluation of (-)- and (+)-debromoflustramine B and its analogues as selective butyrylcholinesterase inhibitors.

A series of pyrrolidinoindolines have been synthesized as debromoflustramine B (4a) analogues for their evaluation as cholinesterase inhibitors. Structure-activity studies of this series revealed the optimum pharmacophoric elements required for activity and resulted in the discovery of selective butyrylcholinesterase inhibitors with micromolar potency. Biological testing demonstrated that (-)-4a was 7500 times more potent than its enantiomer (+)-4b. The most active inhibitor against BChE in the series was demethyldebromoflustramine B (5a), with an IC50 value of 0.26 microM. X-ray crystallography of 15 and docking studies of selected compounds into human BChE (PDB 1POI) are presented. Molecular modeling studies showed that pi-hydrogen bond, classical hydrogen bond, and cation-pi interactions are critical for optimum potency.

Trans-3-phenyl-2-propenoic acid (cinnamic acid) derivatives: structure-activity relationship as hepatoprotective agents.

Among various phenolic compounds, caffeic acid (3,4-dihydroxycinnamic acid) exhibited pharmacological antioxidant, anticancer and antimutagenic activities. The antioxidant properties of phenolic compounds depend on their chemical structure, however, the role of the ethylenic side chain in the radical scavenging activity remains controversial. Thus, the aim of this study consisted to test cinnamic acid and 15 cinnamic acid derivatives in the well known CCl(4)-induced acute liver damage model, which is dependent on oxidative stress mechanisms. Cinnamic acid and 15 cinnamic acid derivatives (50 mg/kg, p.o.) were administered to male Wistar rats intoxicated with CCl(4) (4 g/kg, p.o.). The activities of gamma-glutamyl transpeptidase, alkaline phosphatase and alanine aminotransferase were measured in serum. The lipid peroxidation products were determined in liver. Compounds with a methoxy group at position 3 or 4, or a 3,4-methylenedioxy moiety were the most active ones. Also, we observed that the monosubstituted 3 or 4 hydroxy, or the bulky 3,4 dibenzyloxy substituted compounds showed lower activity. The poorest activity was displayed by disubstituted 3,4-dihydroxy, dimethoxy or diacetyl cinnamic acid derivatives, the ester derived from cinnamic acid with an 8 carbon chain and N-dimethyl substituted compound. Thus, the methoxy substituted group at positions 3 or 4 or the 3,4-methylenedioxy moiety in the caffeic acid derivatives; seem to be the main features required for the hepatoprotection in this model.

Renal angiotensin-II receptors expression changes in a model of preeclampsia.

The blunted response to angiotensin II (Ang II) during pregnancy is lost in patients by preeclampsia. This impaired response has been attributed to a change in one or both of the Ang II receptors, type 1 (AT(1)R) and type 2 (AT(2)R). The ratio of the Ang II receptor types in the kidney has not been studied. We postulated that an imbalance exists between AT(1)R/AT(2)R receptors in the renal cortex from rats subjected to an experimental model of preeclampsia, and that this altered ratio can modify the characteristic blunted pressor response to Ang II during pregnancy. The feto-placental units of Wistar rats were made ischemic by subrenal aortic coarctation, thus creating an experimental model of preeclampsia. We measured the AT(1)R and AT(2)R protein expression and the presence of the heterodimer AT(1)R/AT(2)R in the renal cortex and evaluated the pressor response to Ang II in an isolated kidney preparation from non-pregnant, healthy pregnant, and preeclampsia model rats. Pregnancy increased AT(2)R and AT(1)R/AT(2)R heterodimer expression and decreased the pressor response to Ang II. In contrast, AT(1)R increased, while AT(2)R and AT(1)R/AT(2)R heterodimer decreased in the preeclampsia model group. Thus, Ang II hypersensitivity observed in preeclampsia might be related to an increased expression of AT(1)R over AT(2)R and to a decreased presence of the AT(1)R/AT(2)R heterodimer in renal cortex.

Renal vascular responses in an experimental model of preeclampsia.

In pregnancy there is an attenuated response to vasoconstrictors and pressor agents, including Angiotensin II (Ang II). This effect is reverted in preeclampsia. We evaluated the renal pressor response induced by Ang II in an experimental model of preeclampsia based on the development of feto-placental ischemia produced by a subrenal aortic coarctation (SRAC). Dose-response curves for Ang II were obtained in an isolated perfused kidney preparation comparing groups of SRAC pregnant and non-pregnant rats in the presence and absence of losartan (AT1 antagonist) or PD123319 (AT2 antagonist). Kidneys from the experimental model of pre-eclampsia showed an enhanced response to AngII. In addition, losartan (10 nM) inhibited the vasopressor effect to Ang II in this model but not in the control group. PD 123319 (1 nM), increased the response in both groups, but the effect was more evident in the pre-eclamptic group. This suggests modifications in the relative participation of renal vascular receptors AT1/AT2 induced by an experimental model of pre-eclampsia, with an increased participation of AT1 and a decreased participation of AT2.