Anticholinesterase activity of an endemic Atlantic rain forest bamboo species

Alzheimer’s disease is characterized by cognitive and memory disturbances. It is associated with a reduction of acetylcholine levels. Thus, it is interesting to find drugs that inhibit the activity of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) [1]. Asian bamboos are reported to improve spatial memory capacity and to reduce AChE activity [2]. Therefore, this study aimed to evaluate the anticholinesterase potential of Merostachys neesii Rupr., an endemic Brazilian woody bamboo. Leaves and culms of M. neesii (n=3) were collected during the dry (August/2016) and rainy (February/2017) seasons. Plant material was submitted to two extraction processes: serial maceration using hexane and 70% ethanol; and infusion. AChE and BChE inhibitory activity was evaluated by Ellman’s colorimetric method using a microplate reader. Results were expressed as minimal inhibitory concentration to reach 50% inhibition (MIC₅₀). MIC₅₀ values were compared by the t-test or Wilcoxon test for two samples (non-parametric data) using R software to verify if there was a significant difference (p 0.05) caused by seasonality. In general, hexane extract of leaves (HE-L: 376.92 ± 48.14 μg mL^-1) and culms (HE-C: 592.24 ± 164.14 μg mL^-1) from the rainy season showed the lowest MIC₅₀, but still higher than that of neostigmine (33.84 ng mL^-1). AChE inhibition has also been reported for M. magellanica [3]. Also, HE-L showed a significant difference between the seasons, with lower MIC₅₀ value in the rainy season [Fig. 1]. No inhibition of BChE was observed. In conclusion, seasonality influenced the AChE inhibitory activity of HE-L; however, no extract showed promising anticholinesterase activity.

Fig. 1 Seasonality effect on inhibition of acetylcholinesterase (AChE) by Merostachys neesii Rupr. Data are presented as the mean ± standard deviation (n=3). Means were compared between seasons of the same extract. Different letters represent significantly different means (p 0.05). MIC₅₀: minimal inhibitory concentration to reach 50% inhibition. HE-L: hexane extract of leaves; EE-L: ethanolic extract of leaves; AE-L: aqueous extract of leaves; HE-C: hexane extract of culms; EE-C: ethanolic extract of culms; AE-C: aqueous extract of culms.

• References

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