Effects of Centella Asiatica Extract on Homocysteine-induced injuries in neuronal cell line cultures

Abstract

Asiaticoside, a main triterpene of Centella asiatica, was well known for wound healing effect. In traditional medicine, C. asiatica extracts have been used in the management of central nervous system disorders including neurodegenerative diseases and memory deficit. The present research was designed to investigate the potential ability of C. asiatica extract and asiaticoside to prevent or attenuate the process of neurodegeneration in the in vitro model of homocysteine-induced injuries in cultured neuroblastoma N1E-115 cells. Cell viability and cell death (assessed by MTT reduction and LDH release respectively), glutathione content, and type of cell death were used as the measuring endpoints. Treatment of cultured N1E-115 cells with 1-100 g/ml of Centella asiatica extract or asiaticoside for 24, 48 or 72 hr had no apparent effect on cell viability. Homocysteine, a non-essential sulphur-containing amino acid, induced neuronal injury and death in a concentration-related manner with approximately 50% cell injury occurred after an exposure to 10 mM homocysteine for 72 hr. Pre-treatment with 100 g/ml of Centella asiatica extract or 50-100 g/ml of asiaticoside, and co-treatment with 75-100 g/ml of Centella asiatica extract or 75-100 g/ml of asiaticoside, with homocysteine for 72 hr attenuated homocysteine-induced reduction in cell viability and successive cell death. In addition, Centella asiatica extract and asiaticoside at a concentration of 100 g/ml replenished homocysteine-induced decrease of total glutathione content and attenuated homocysteine-induced apoptotic cell death. In conclusion, the present study suggested that Centella asiatica extract and asiaticoside may possess the marginal in vitro cytoprotective property against homocysteine-induced neuronal injuries. The underlying mechanisms might directly involve antioxidant activity or indirectly involve facilitation of cellular antioxidant defense system of Centella asiatica extract and asiaticoside. In addition, they might antagonize cellular apoptotic cascade of cell death. However, the detailed mechanisms are not fully understood and remain to be further elucidated.