Huperzia saururus: Anticholinesterase activity and action on memory and learning

Abstract

Huperzia saururus (Lam.) Trevis. (Lycopodiaceae) is used widely in Argentinean traditional medicine as aphrodisiac and for memory improvement. Its chemical analysis revealed the presence of the following Lycopodium alkaloids: sauroine (novel alkaloid), sauroxine, 6-hydroxylycopodine, N-acetyllycodine, lycopodine, lycodine, N-methyllycodine, huperzine A and clavolonine. The alkaloid extract showed a marked inhibition of true acetylcholinesterase with an IC50 value of 0.58 µg/ml. Electrophysiological experiments with purified alkaloid extract were performed on rat hippocampus slices, thus eliciting long-term potentation (LTP). Results showed a marked increase of the hippocampus synaptic plasticity. The threshold value for LTP generation was 22 ± 1.01 Hz for alkaloid extract and 86 ± 0.92 Hz for controls. Studies about the effects of the intrahippocampal administration of alkaloid extract on memory retention in vivo (rats), using a step down test showed increased latency time, 180.00 ± 5.74 s (10 ng/rat) compared to control animals (14.89 ± 2.38 s). These same experiments were assayed with sauroine, demonstrating a significant increase of hippocampal plasticity and memory retention.