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INTRODUCTION: policosanol, a mixture of eight primary aliphatic alcohols purified from sugar cane wax, contains octacosanol as major component. D-002, a mixture of six primary aliphatic alcohols purified from beeswax, presents triacontanol as the main component. Although both substances are high molecular weight alcohol mixtures, they have different compositions and pharmacological effects such as their distinct effects on arachidonic acid metabolism enzymes; whereas policosanol inhibits cyclooxygenase (COX)-1, D-002 inhibits COX and 5-lipoxygenase (5-LOX) activities. OBJECTIVE: to study the effects of octacosanol and triacontanol, which are main components of policosanol and D-002, respectively on the COX and the 5-LOX enzyme in vitro activities. METHODS: triacontanol and octacosanol were suspended in a Tween-20/H2O (2 %) (0.6-5000 g/mL) vehicle. The effects of adding these alcohols on COX-1, COX-2 and 5-LOX enzymes activities were assessed in rat platelet microsomes, rat seminal vesicle microsomes and rat polymorphonuclear (PMN) preparations, respectively. Indomethacin (0.4µg/mL) was used as reference inhibitor of COX-1 and COX-2, and Lyprinol as 5-LOX inhibitor. RESULTS: octacosanol showed significant, marked (70% with highest concentration) (IC50=143.54 g/mL) and dose-dependent (r=0.991, p <0.001) inhibitory action on COX-1 activity. However, Triacontanol did not affect COX-1, but inhibited significantly, depending on dose (r=0.985, p <0.001) the COX-2 activity to 50 % with 1250 g/mL. In contrast, octacosanol did not change COX-2 activity. Indomethacin inhibited both COX-1 and COX-2 by 83 %. Octacosanol addition was ineffective whereas triacontanol had significant, dose-dependent (r=0.978, p<0.001) and marked effect (79 %) on the 5-LOX activity (IC50=58.74 g/mL). Lyprinol inhibited 5-LOX by 89 %. The inhibitions induced by octacosanol and triacontanol were competitive. CONCLUSIONS: in vitro addition of octacosanol and triacontanol caused differential effects on COX-1, COX-2 and 5-LOX enzyme activities. Whereas octacosanol markedly inhibited COX-1 activity and did not change those of COX-2 and 5-LO, triacontanol markedly inhibited 5-LOX activity, but had moderate effect on COX-2 and did not change COX-1 activity.

INTRODUCCIÓN: el policosanol, mezcla de ocho alcoholes purificados de la cera de la caña de azúcar, contiene octacosanol como componente mayoritario. El D-002, mezcla de seis alcoholes alifáticos primarios purificada de la cera de abejas, presenta triacontanol como el componente mayoritario. Aunque ambas sustancias son mezclas de alcoholes de alto peso molecular, exhiben diferente composición y perfil farmacológico como son sus efectos sobre las enzimas del metabolismo del ácido araquidónico: mientras el policosanol inhibe la actividad de ciclooxigenasa (COX)-1, el D-002 inhibe las actividades de la COX y la 5-lipooxigenasa (5-LOX). OBJETIVO: investigar los efectos del octacosanol y el triacontanol, principales componentes del policosanol y el D-002, respectivamente, sobre las actividades de las enzimas COX y 5-LOX in vitro. MÉTODOS: el policosanol y el triacontanol se suspendieron en vehículo Tween-20/H2O (2 %) (0.6-5000g/mL). Los efectos de la adición de estos alcoholes sobre las actividades de las enzimas COX-1, COX-2 y 5-LOX se evaluaron en microsomas de plaquetas de ratas, microsomas de vesículas seminales de ratas y en preparaciones de polimorfonucleares (PMN) de ratas, respectivamente. Se utilizó indometacina (0.4 µg/mL) como inhibidor de referencia de COX-1 and COX-2 y Lyprinol como inhibidor de 5-LOX. RESULTADOS: la adición de octacosanol inhibió la actividad de COX-1 de modo significativo, marcado (70 % con la concentración mayor) (CI50=143.54 g/mL) y dependiente de la dosis (r=0.991, p <0.001). La adición de triacontanol, sin embargo, no afectó COX-1, pero inhibió de modo significativo y dependiente de la dosis (r=0.985, p <0.001) la actividad de la COX-2 hasta 50 % con 1250 g/mL. En contraste, el octacosanol no modificó la actividad de la COX-2. La indometacina inhibió COX-1 y COX-2 en un 83 %. Mientras la adición del octacosanol no fue efectiva, el triacontanol inhibió de modo significativo, dependiente de la dosis r=0.978, p <0.001) y marcadamente (79 %) la actividad de la 5-LOX (CI50=58.74 g/mL). El Lyprinol inhibió la 5-LOX en un 89 %. Las inhibiciones inducidas por el octacosanol y el triacontanol fueron competitivas. CONCLUSIONES: la adición in vitro de octacosanol y triacontanol produjo efectos diferenciales sobre las actividades enzimáticas de COX-1, COX-2 y 5-LOX. Mientras el octacosanol inhibió marcadamente la actividad de COX-1, sin afectar COX-2 y 5-LOX; el triacontanol inhibió marcadamente 5-LOX, pero moderadamente COX-2, y no cambió la actividad de COX-1.

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The ribose-5-phosphate isomerase deficiency is an inherited condition, which results in cerebral d-arabitol and ribitol accumulation. Patients present leukoencephalopathy, mental retardation, and psychomotor impairment. Considering that the pathophysiology of this disorder is still unclear, and literature are sparse and contradictory, reporting pro and antioxidant activities of polyols, the main objective of this study was to investigate some parameters of oxidative homeostasis of prefrontal cortex of rats incubated with d-arabitol and ribitol. We found evidences that ribitol promoted an increase in antioxidant enzymes activity (superoxide dismutase, catalase, and glutathione peroxidase), probably secondary to enhanced production of superoxide radical, measured by flow cytometry. Oxidation of proteins and lipids was not induced by polyols. Our data allow us to conclude that, at least in our methodological conditions, arabitol and ribitol probably have a secondary effect on the pathophysiology of ribose-5-phosphate isomerase deficiency.

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The trans-sialidase, a modified sialidase that transfers sialyl residues among macromolecules, is a unique enzymatic activity expressed by some parasitic trypanosomes being essential for their survival in the mammalian host and/or in the insect vector. The enzyme from Trypanosoma cruzi, the agent of Chagas disease, is found in blood and able to act far from the infection site by inducing apoptosis in cells from the immune system. A central and still unsolved question is whether trans-sialidase-mediated addition or removal of sialic acid to/from host acceptor molecules is the event associated with the apoptosis induced by the enzyme. Here we show that lactitol, a competitive inhibitor that precluded the transference of the sialyl residue to endogenous acceptors but not the hydrolase activity of the enzyme, prevented ex vivo and in vivo the apoptosis caused by the trans-sialidase. By lectin histochemistry, the transference of sialyl residue to the cell surface was demonstrated in vivo and found associated with the apoptosis induction. The sialylation of the CD43 mucin, a key molecule involved in trans-sialidase-apoptotic process, was readily detected and also prevented by lactitol on thymocytes. Therefore, lesions induced by trans-sialidase on the immune system are due to the sialylation of endogenous acceptor molecules.

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Chagas' disease, caused by Trypanosoma cruzi, affects about 18 million people in Latin America, and no effective treatment is available to date. To acquire sialic acid from the host glycoconjugates, T. cruzi expresses an unusual surface sialidase with trans-sialidase activity (TcTS) that transfers the sugar to parasite mucins. Surface sialic acid was shown to have relevant functions in protection of the parasite against the lysis by complement and in mammalian host cell invasion. The recently determined 3D structure of TcTS allowed a detailed analysis of its catalytic site and showed the presence of a lactose-binding site where the beta-linked galactose accepting the sialic acid is placed. In this article, the acceptor substrate specificity of lactose derivatives was studied by high pH anion-exchange chromatography with pulse amperometric detection. The lactose open chain derivatives lactitol and lactobionic acid, as well as other derivatives, were found to be good acceptors of sialic acid. Lactitol, which was the best of the ones tested, effectively inhibited the transfer of sialic acid to N-acetyllactosamine. Furthermore, lactitol inhibited parasite mucins re-sialylation when incubated with live trypanosomes and TcTS. Lactitol also diminished the T. cruzi infection in cultured Vero cells by 20-27%. These results indicate that compounds directed to the lactose binding site might be good inhibitors of TcTS.

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We show that urea inhibits the ATPase activity of MgATP submitochondrial particles (MgATP-SMP) with Ki = 0.7 M, probably as a result of direct interaction with the structure of F0F1-ATPase. Counteracting compounds (sorbitol, mannitol or inositol), despite slightly (10-20%) inhibiting the ATPase activity, also protect the F0F1-ATPase against denaturation by urea. However, this protection was only observed at low urea concentrations (less than 1.5 M), and in the presence of three polyols, the Ki for urea shift from 0.7 M to 1.2 M. Urea also increases the initial activation rate of latent MgATP-SMP in a dose-dependent-manner. However, when the particles (0.5 mg/ml) were preincubated in the presence of 1 M, 2 M or 3 M urea, a decrease in the activation level occurred after 1 h, 30 and 10 min, respectively. At high MgATP-SMP concentration (3 mg/ml) a decrease in activation was observed after 2 h, 1 h and 20 min, respectively. These data indicate that the effect of urea on the activation of MgATP-SMP depends on time, urea and protein concentrations. It was also observed that polyols suppress the activation of latent MgATP-SMP in a dose-dependent manner, and protect the particles against urea denaturation during activation. We suppose that a decrease in membrane mobility promoted by interactions of polyols with phospholipids around the F0F1-ATPase may also increase the compactation of protein structure, explaining the inhibition of natural inhibitor protein of ATPase (IF1) release and the activation of the enzyme.

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The relationship between protein conformational stability in aqueous solution and the magnitude of lyophilization-induced structural changes was investigated employing alpha- and gamma-chymotrypsin. As a measure of the conformational stability the melting temperature T(m) was determined in distilled water at various pH values. The proteins were then lyophilized from those pH values where the conformational stability was maximum (pH 4.5) and minimum (pH 7.8). Protein secondary structure was quantitatively determined utilizing Fourier-transform infrared spectroscopy employing two regions sensitive to protein structure, the amide-I (1600-1700 cm(-1)) and amide-III (1215-1335 cm(-1)). Lyophilization induced significant structural alterations in both proteins, characterized by a slight decrease in the alpha-helix and a significant increase in the beta-sheet content. However, regardless of the pH from which the proteins were lyophilized, the secondary structures in the solid state were indistinguishable. This result shows that there is no relationship between the conformational stability in aqueous solution and the magnitude of lyophilization-induced structural changes. We also investigated whether lyoprotectants could minimize lyophilization-induced structural changes by increasing protein conformational stability in aqueous solution. After having identified trehalose as being efficient in largely preventing lyophilization-induced structural alterations, we conducted co-lyophilization experiments from various pH values. The results obtained exclude any contribution from increased protein conformational stability caused by the additive in aqueous solution to the beneficial structural preservation upon lyophilization. This can be understood because the dehydration and not the freezing process, as shown in an air-drying experiment, mainly causes protein structural alterations.

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The tastes and solution properties of sugar alcohols were studied in an attempt to illuminate the mechanism of sweet taste chemoreception. The SMURF method was used to measure tastetime-intensity of aqueous solutions of sugar alcohols and the results were interpreted using the Stevens power function and kinetic parameters. The apparent molar volumes, apparent specific volumes, partial molar volumes, partial specific volumes and intrinsic viscosities of the solutions were studied. Apparent molar volume reflects the size of the molecule in a hydrostatic state whereas intrinsic viscosity gives a measure of the size of the molecules in a hydrodynamic state. Generally the apparent molar volumes of the polyols are 6-13% greater than those of the parent sugars, indicating less interaction with the water structure. Apparent specific volume values can predict taste quality, and the average apparent specific volume for the sugar alcohols studied fits within the central part of the sweet range, i.e. 0.5-0.68 cm3/g, which accords with their ability to elicit a pure sweet taste response. Intensities and persistences of sweetness in the polyols followed the same trend as intrinsic viscosities.

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