RESUMO
The triterpene chikusetsusaponin IVa was isolated from the fruit of Ilex paraguariensis. Using biochemical and pharmacological methods, we demonstrated that chikusetsusaponin IVa (1) prolongs the recalcification time, prothrombin time, activated partial thromboplastin time, and thrombin time of normal human plasma in a dose-dependent manner, (2) inhibits the amidolytic activity of thrombin and factor Xa upon synthetic substrates S2238 and S2222, (3) inhibits thrombin-induced fibrinogen clotting (50% inhibition concentration, 199.4 ± 9.1 µM), and (4) inhibits thrombin- and collagen-induced platelet aggregation. The results also indicate that chikusetsusaponin IVa preferentially inhibits thrombin in a competitive manner (K(i)=219.6 µM). Furthermore, when administered intravenously to rats, chikusetsusaponin IVa inhibited thrombus formation in a stasis model of venous thrombosis, although it did not induce a significant bleeding effect. Chikusetsusaponin IVa also prolonged the ex vivo activated partial thromboplastin time. Altogether, these data suggest that chikusetsusaponin IVa exerts antithrombotic effects, including minor hemorrhagic events. This appears to be important for the development of new therapeutic agents.
Assuntos
Fibrinolíticos/farmacologia , Ilex paraguariensis/química , Ácido Oleanólico/análogos & derivados , Extratos Vegetais/farmacologia , Saponinas/farmacologia , Animais , Tempo de Sangramento , Coagulação Sanguínea/efeitos dos fármacos , Fator Xa/metabolismo , Inibidores do Fator Xa , Hemostasia/efeitos dos fármacos , Humanos , Modelos Lineares , Masculino , Ácido Oleanólico/farmacologia , Tempo de Tromboplastina Parcial , Agregação Plaquetária/efeitos dos fármacos , Inibidores da Agregação Plaquetária/farmacologia , Ratos , Ratos Wistar , Trombina/antagonistas & inibidores , Trombina/metabolismo , Tempo de TrombinaRESUMO
Leaves of Ilex paraguariensis are used to prepare a tea known as maté which is a common beverage in several South American countries. The ethanol extract was fractionated to identify the compounds responsible for the anti-adipogenic activity in 3T3-L1 cells. Extracts of both fresh and dried maté leaves were subjected to column chromatography using molecular permeation to obtain the saponin (20 % yields) and the polyphenol extracts (40 % yields) from the fresh and dried leaves. The phenolic content was determined using high-performance liquid chromatography analysis and the Folin-Ciocalteau method. Also, maté extracts (50 µg/ml to 1,000 µg/ml) did not display citotoxicity using MTT. The polyphenol extract from the dried leaves was the most effective (50 µg/ml) in the inhibition of triglyceride accumulation in 3T3-L1 adipocytes, and rutin (100 µg/ml) likely accounted for a large portion of this activity. Additionally, maté extracts had a modulatory effect on the expression of genes related to the adipogenesis as PPARγ2, leptin, TNF-α and C/EBPα.
