Alejandra Luquita

Effect of Ligaria cuneifolia catechin- and quercetin-enriched fractions on hemorheology and plasma cholesterol

UNLABELLED We tested the in vivo and the in vitro effects of both Ligaria cuneifolia catechin- and quercetin-enriched fractions on erythrocyte shape and deformability, and on plasma cholesterol level. For in vivo studies, adult male Wistar rats were randomized in three experimental groups which received intraperitoneally, once a day, 3 days: CONTROL saline solution (C; n = 6); catechin from L. cuneifolia, 0.60 mg/100 g body weight (CLc; n = 6), or quercetin from L. cuneifolia, 2.3 mg/100 g body weight (QLc; n = 6). For in vitro studies, blood samples obtained from male Wistar rats were divided into three fractions, which were incubated with saline solution (C), catechin (CLc; n = 5) and quercetin (QLc; n = 5), in a concentration equivalent to 0.60 mg/100 g body weight, and 2.3 mg/100 g body weight, respectively. CLc significantly reduced the rigidity index due to a diminished mean concentration volume. QLc induced erythrocyte rigidization (less deformability), thus increasing blood viscosity. Neither of the two treatments produced any changes in plasmatic or biliary excretion of cholesterol. Opposite results were observed in rigidity index with CLc and QLc. In vitro studies showed an interaction of both CLc and QLc with the erythrocyte membrane, which induced changes in the erythrocyte shape from discocyte to stomatocyte.

Evaluation of Hemorrheologic Parameters and Biliary Secretion in Ligaria cuneifolia (Argentine mistletoe) Extract-Treated Rats

Ligaria cuneifolia (R. et P.) Tiegh. (Loranthaceae) (Argentine mistletoe) is usually used in local folk medicine “to produce an increase of blood fluidity and a decrease of plasma cholesterol level”. The present work was carried out to evaluate the effect of L. cuneifolia treatment on blood fluidity and biliary secretion. Adult male Wistar rats were divided into five groups (n = 5): control animals were injected intraperitoneally with water and treated rats received 1.5, 2.5, 3.5 and 5.5 mg/100 g body weight of aqueous extract of L. cuneifolia each 24 h during 3 days. The relative viscosity of blood [(? r) 45/Hct] was measured and the rigidity index (RI) in the diluted red cell suspensions was determined. L. cuneifolia treatment produces a significant increase in (? r) 45/Hct and in RI at doses of 2.5, 3.5 and 5.5 mg/100 g body weight. Also, a decrease of plasma cholesterol level was observed, which showed a negative association with RI increase (rs: -0.65; p < 0.05). Increases in bile flow and biliary output of bile acids and cholesterol were observed in treated rats (2.5, 3.5 and 5.5 mg/100 g body weight). Ligaria cuneifolia -treatment produces a decrease in the plasma cholesterol level increasing red blood rigidity index and producing an increase in blood viscosity. The observed increase of bile acid and cholesterol biliary output causes a decrease of plasma cholesterol level.

Influence of adsorbed plasma proteins on erythrocyte rheological properties: in vitro and ex vivo studies

Abstract. The influence of plasma protein adsorption on the mechanical properties characterizing erythrocyte behaviour under flow was studied in human and rats. The deformability index, elastic modulus and surface viscosity were measured by laser diffractometry. In in vitro studies, human and rat erythrocytes were washed to remove their original protein coating, and then incubated in saline-diluted plasma media. For erythrocytes incubated in the most diluted solutions (plasma/saline 1:3, v/v), the deformability index increased 30% for both species (human, P<0.01 and rat, P<0.2); the elastic modulus decreased 20% (human, P<0.05) and 60% (rat, P<0.01); and surface viscosity decreased 20% (human, P<0.05) and 40% (rat, P<0.01), relative to values for erythrocytes incubated in pure plasma. Ex vivo experiments were performed using rats. Plasma proteins were diluted replacing 15% volemic plasma by saline in three consecutive plasmapheresis steps. The rheological properties of erythrocytes, tested after each step, followed the general trends of the in vitro pattern. These results suggest that the decrease in plasma protein concentration affects blood rheology in two ways. The first is the well known decrease in plasma viscosity, and the second is an improvement of erythrocyte deformability, as has been shown in this work. Thus, a new argument supporting the benefits of normovolemic hemodilution in patients with poor peripheral perfusion is provided.

Effects of subnormal hemoglobin concentration on the deformability of normocytic erythrocytes

Deformability of normocytic hypochromic human erythrocytes was studied as a function of their mean corpuscular hemoglobin content (MCHC). Erythrocyte populations with subnormal MCHC but with normal cell shape and volume and preserved cell surface area, were obtained by incomplete lysis, followed by cell resealing and density gradient separation. Erythrocyte rheological properties were measured in the erythrodeformeter, apparatus in which the erythrocyte laser diffraction pattern is recorded in shear flow. It was found that the deform ability index, proportional to the ellipticity of the diffraction pattern at the maximum shear stress, has a negative correlation with MCHC. Membrane elastic shear modulus and membrane surface viscosity have a positive correlation with MCHC. These facts are indicative of a concentration dependent membrane-hemoglobin interaction, and thus hemoglobin concentration must be included as one of the factors influencing erythrocyte deformability, even at low concentrations. We propose a simple model to demonstrate that the maximum oxygen delivery to tissues occurs at the physiological MCHC values.

Effects of proanthocyanidin enriched extract from Ligaria cuneifolia on plasma cholesterol and hemorheological parameters. In vivo and In vitro studies

UNLABELLED It was demonstrated that Ligaria cuneifolia (Lc) crude extract increased blood viscosity and decreased plasma cholesterol in rats. In the present study, we analyzed the Lc proanthocyanidin enriched fraction (PLc) to determine if it is capable of altering the hemorheological parameters while diminishing the plasma cholesterol. In vivo studies in adult male Wistar rats, randomized in three groups (n = 6 each one) were performed: 1. CONTROL saline intraperitoneal (i.p.); 2. PLc 0.6 mg/100 g body weight (b.w.) i.p. and 3. PLc 3 mg/100 g b.w. i.p., every 24 hours during 3 days. IN VITRO STUDIES with blood obtained by cardiac puncture, separated in aliquots and incubated with: 1. Saline solution (Control); 2. PLc 0.1 mg/mL, and 3. PLc 1.0 mg/mL, equivalent to doses in vivo experiments. The results demonstrated that in vivo PLc 0.6 and PLc 3 reduced plasma cholesterol (Cho) and LDL-Cho. Neither blood nor plasma viscosity was altered. Decrease of plasma cholesterol could be due to an increase of cholesterol and bile salts excretion leading to an increase of bile flow. In vitro experiments showed a direct interaction of PLc, at high concentration, with the erythrocyte membrane, inducing a switch from discocyte to stomatocyte. Only, PLc without hepatic metabolism produces hemorheological changes. Thus, PLc in vivo might be a pharmacological agent capable of decreasing plasma cholesterol.

The Enriched Proanthocyanidin Extract of Ligaria cuneifolia Shows a Marked Hypocholesterolemic Effect in Rats Fed with Cholesterol-Enriched Diet

BACKGROUND Ligaria cuneifolia (Lc) (R. et P.) Tiegh. (Loranthaceae) (Argentine mistletoe) is usually used in local folk medicine. OBJECTIVE We studied the effect of treatment with the Lc proanthocyanidin-enriched fraction (PLc) in rats fed with Cho-enriched diet on plasma lipids levels, the hemorheological parameters, and biliary secretion. METHOD Adult male Wistar rats were fed ad libitum with a Cho-enriched diet (Cho (97% purity) 8 g/kg of diet and corn oil 280 g/kg of diet) during 28 days. Then, were separated in six experimental groups (n=5 each one), which were injected ip every 24 h with: 1) saline solution (control group, C) and 2) PLc, 3 mg/100 g body weight (treated group, C+PLc), during 3, 7 and 10 days. Group C presented an increase in plasma levels of Cho and Triglycerides (TG), and also, accumulation of hepatic lipid droplets. Also, cell shape and their corresponding morphological index (MI) were altered too. RESULTS The treatment with PLc at 3, 7 and 10 days produces a diminution in the plasma Cho, LDL-Cho and serum TG levels, accompanied by a diminution of the lipid accumulation in the liver. The rates of bile acid output in bile can explain the diminution of plasma Cho, evidencing that some of the enzymes involved in the cholesterol conversion into bile acids could be up regulated by the treatment with PLc, leading to the observed increase bile flow. PLc treatment leads to a diminution of plasma levels of Cho and TG. CONCLUSION Essentially, the treatment with PLc, despite the duration produces a modification in hemorheological parameters approaching the values of the experimental group with standard diet. Plasma levels of Cho, LDL-Cho and TG represent selected markers to evaluate the effect of enriched extract from Ligaria cuneifolia. Further work is necessary to better evaluate the mechanisms by which PLc induces modifications in the lipids metabolism.