Antioxidant activity of extracts of Cynomorium songaricum and their neuroprotective effects against cytotoxicity induced by Aβ25–35 on SK-N-SH neuroblastoma cells

Cynomorium songaricum Rupr. (Cynomoriaceae) is known as a traditional medicine treating dementia in China. In this study, we investigated the antioxidant activity of different extracts of cynomorii herba as well as their protective effects against Aβ_25–35 induced toxicity on SK-N-SH cells. Method: C. songaricum was extracted with methanol. After evaporation, the residue was partitioned between dichloromethane, ethyl acetate and water, respectively. In order to study the antioxidant activity, we used the xanthine-xanthine oxidase system (XO/XTT) [1]. The reaction was initiated by the addition of XO solution and the absorbance change at 470nm was monitored spectrophotometrically. For investigating possible neuroprotective effects, the SK-N-SH cells were cultured at a density of 1.5×10⁴ cells/well in 96-well plates [2]. The cells were treated with the 4 extracts of C. songaricum at concentrations of 100µg/ml, 10µg/ml, 1µg/ml and 0.1µg/ml 4h before addition of the Aβ_25–35 (20µM). Cell viability was quantified using the MTT test after 96hrs. Results and discussion: The methanol as well as the EtOAc- extracts of C. songaricum were effective in scavenging superoxide anions generated by the XO/XTT system (IC₅₀=21.2µg/ml for the MeOH-extract and 2.8µg/ml for the EtOAc-extract). But even more important, they significantly protected the SK-N-SH cells against Aβ_25–35 induced cytotoxicity. As neuronal damage by free radicals as well as direct neurotoxicity of Aβ_25–35 may play a key role in neurodegeneration observed in Alzheimer dementia, these in vitro results with different extracts of C. songaricum might support its traditional use in the AD therapy in China.

References: [1] Ukeda H, Maeda S. et al. (1997) Anal Biochem 251(2):206–9 [2] Ba F, Pang PK (2003) J Neurosci Meth 123(1):11–22