Browsing by Author "Schmeda Hirschmann, Guillermo"

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    Antiplatelet, anticoagulant, and fibrinolytic activity in vitro of extracts from selected fruits and vegetables
    (LIPPINCOTT WILLIAMS & WILKINS, 2011) Torres Urrutia, Constanza; Guzman, Luis; Schmeda Hirschmann, Guillermo; Moore Carrasco, Rodrigo; Alarcon, Marcelo; Astudillo, Luis; Gutierrez, Margarita; Carrasco, Gilda; Yuri, Jose A.; Aranda, Eduardo; Palomo, Ivan
    A diet rich in fruits and vegetables is known to decrease the risk of cardiovascular disease. However, the information regarding the antithrombotic activity (antiplatelet, anticoagulant, and fibrinolytic) of fruits and vegetables is scarce. The aim of this study was to assess the antithrombotic activity of extracts from fruits and vegetables widely consumed in central Chile. The study included samples of 19 fruits and 26 vegetables, representative of the local diet. The extracts prepared from each sample included an aqueous (juice or pressed solubles) and/or methanol-soluble fraction. The extracts were evaluated for antiplatelet, anticoagulant, and fibrinolytic activity in vitro at a final concentration of 1 mg/ml. The antiplatelet activity was assessed by platelet aggregation inhibition; anticoagulant activity was measured by the prothrombin time (PT), diluted prothrombin time (dPT), activated partial thromboplastin time (APTT), kaolin clotting time (KCT), and thrombin time. The fibrinolytic effect was determined with the euglobin clot lysis time and fibrin plate methods. Extracts of green beans and tomatoes inhibited platelet aggregation induced by ADP and arachidonic acid, in a concentration-dependent manner. The methanolic extracts of grapes prolonged the PT and dPT. Finally, extracts of raspberry prolonged the APTT and also presented fibrinolytic activity. In conclusion, from a screening that included a variety of fruits and vegetables, we found antiplatelet activity in green beans and tomatoes, anticoagulant activities in grapes and raspberries, whereas fibrinolytic activity was observed only in raspberries. Further investigations are necessary to advance in knowledge of the active compounds of these fruits and vegetables and their mechanisms of action. Blood Coagul Fibrinolysis 22:197-205 (c) 2011 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins.
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    Gastroprotective Effect and Cytotoxicity of Labdeneamides with Amino Acids
    (GEORG THIEME VERLAG KG, 2011) Schmeda Hirschmann, Guillermo; Rodriguez, Jaime A.; Theoduloz, Cristina; Valderrama, Jaime A.
    Semisynthetic aromatic amides from Araucaria araucana diterpene acids have been shown to display a relevant gastroprotective effect with low cytotoxicity. The aim of this work was to assess the gastroprotective effect of amino acid amides from imbricatolic acid and its 8(9)-en isomer in the ethanol/HCl-induced gastric lesions model in mice as well as to determine the cytotoxicity of the obtained compounds on the following human cell lines: normal lung fibroblasts (MRC-5), gastric adenocarcinoma (AGS), and liver hepatocellular carcinoma (Hep G2). The diterpenes 15-acetoxyimbricatolic acid, its 8(9)-en isomer, 15-hydroxyimbricatolic acid, and the 8(9)-en derivative, bearing a COOH function at C-19, were used as starting compounds. New amides with C-protected amino acids were prepared. The study reports the effect of a single oral administration of either compound 50 min before the induction of gastric lesions by ethanol/HCl. Some 20 amino acid monoamides were obtained. Dose-response experiments on the glycyl derivatives showed that at a single oral dose of 100 mg/kg, the compounds presented an effect comparable to the reference drug lansoprazole at 20 mg/kg and at 50 mg/kg reduced gastric lesions by about 50%. All derivatives obtained in amounts >30 mg were compared at a single oral dose of 50 mg/kg. The best gastroprotective effect was observed for the exomethylene derivatives bearing a valine residue at C-19 either with an acetoxy or free hydroxy group at C-15. The tryptophanyl derivative from the acetate belonging to the 8,9-en series presented selective cytotoxicity against hepatocytes. The glycyl amide of 15-acetoxyimbricatolic acid was the most cytotoxic and less selective compound with IC50 values between 47 and 103 mu M for the studied cell lines. This is the first report on the obtention of semisynthetic amino acid amides from labdane diterpenes.
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    Studies on quinones. Part 41 : Synthesis and cytotoxicity of isoquinoline-containing polycyclic quinones
    (2006) Valderrama Guerrero, Jaime Adolfo; González, M. Florencia; Pessoa Mahana, Carlos David; Tapia Apati, Ricardo; Fillion, Houda; Pautet, Félix; Rodríguez, Jaime A.; Theoduloz, Cristina; Schmeda Hirschmann, Guillermo
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    The major chromophore arising from glucose degradation and oxidative stress occurrence during lens proteins glycation induced by glucose
    (2018) Ávila, Felipe; Schmeda Hirschmann, Guillermo; Silva Stevens, Eduardo Andrés