The effects of aqueous extracts prepared from the leaves of Pistacia lentiscus in experimental liver disease

Abstract

In a previous study, we identified Pistacia lentiscus was worthy for further laboratory evaluation because an aqueous extract of the plant suppressed iron-induced lipid peroxidation in rat liver homogenates without affecting mitochondrial respiration in cultured HepG2 and PC12 cells. The present study was undertaken to evaluate the efficacy of an aqueous extract prepared from the dried leaves of Pistacia lentiscus in a rat model of hepatic injury caused by the hepatotoxin, thioacetamide. We assessed the impact of daily dosing on biochemical and morphological indices and the extent of oxidative stress in the livers of healthy and thioacetamide-treated rats. In healthy rats, long-term administration of the extract induced hepatic fibrosis and an inflammatory response, mild cholestasis and depletion of reduced glutathione associated with an increase in its oxidized form. In thioacetamide-treated rats, long-term administration of extract aggravated the inflammatory and fibrotic and glutathione depleting responses without affecting the extent of lipid peroxidation. Although our previous in vitro study established that extracts prepared from the leaves of Pistacia lentiscus had antioxidant activity, this in vivo study establishes these extracts also contains hepatotoxins whose identity may be quite different from those compounds with antioxidant properties. The results of this study suggest complementing in vitro experiments with those involving animals are essential steps in establishing the safety of medicinal plants. Furthermore, these data confirm that complete reliance on data obtained using in vitro methodologies may lead to erroneous conclusions pertaining to the safety of phytopharmaceuticals.