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. A. Dominighini et al. / Effect of Ligaria cuneifolia catechin-and quercetin-enriched fractions

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 [(h 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 (h 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.

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.

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.

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