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Friday, 11 September 2015

Vanda roxburghii chloroform extract as a potential source of polyphenols with antioxidant and cholinesterase inhibitory activities: identification of a strong phenolic antioxidant

Research article


Md. Nasim Uddin, Rejina Afrin, Md. Josim Uddin, Md. Jalal Uddin, A. H. M. K. Alam, Aziz Abdur Rahman and Golam Sadik*
Department of Pharmacy, University of Rajshahi, Rajshahi 6205, Bangladesh
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BMC Complementary and Alternative Medicine 2015, 15:195  doi:10.1186/s12906-015-0728-y
The electronic version of this article is the complete one and can be found online at: http://www.biomedcentral.com/1472-6882/15/195

Received:2 January 2015
Accepted:16 June 2015
Published:23 June 2015
© 2015 Uddin et al.

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

Abstract

Background

Alzheimer’s disease (AD) is a progressively developing neurodegenerative disorder of the brain in the elderly people. Vanda roxburghii Rbr. root has been used traditionally in Bangladesh as tonic to brain and in the treatment of nervous system disorders including AD. Therefore, we aimed to investigate the cholinesterase inhibitory activities and antioxidant properties of the extracts from V. roxburghii.

Methods

The crude methanol extract from the roots of plant was sequentially fractionated with petroleum ether, chloroform, ethylacetate and water to yield their corresponding extracts. The extracts were assessed for acetylcholinesterase and butyrylcholinesterase inhibitory activity by modified Ellman method and antioxidant property by several assays including ferric reducing antioxidant power, scavenging of 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical and hydroxyl radical, and inhibition of lipid peroxidation. Endogenous substances in the extracts were analyzed by the standard phytochemical methods and active compound was isolated by the chromatographic methods.

Results

Chloroform extract was shown to demonstrate strong ferric-reducing antioxidant power and scavenging activity against DPPH and hydroxyl free radicals when compared with the other extracts and the reference standard catechin. The antioxidant effect was further verified by inhibition of lipid peroxidation in rat brain homogenates. Likewise, the chloroform extract exhibited the highest inhibition against both the acetylcholinesterase and butyrylcholinesterase enzymes with IC 50 values of 221.13 and 82.51 μg/ml, respectively. Phytochemical screening revealed a large amount of phenolics and flavonoids in the chloroform extract. Bioactivity guided separation techniques led to the isolation of a strong antioxidant from the chloroform extract and its structure was determined as gigantol on the basis of spectral studies.

Conclusion

These results suggest that the chloroform extract of V. roxburghii, possibly due to its phenolic compounds, exert potential antioxidant and cholinesterase inhibitory activities, which may be useful in the treatment of AD.
Keywords:
Alzheimer’s disease; Vanda roxburghii ; Cholinesterase inhibition; Antioxidant activity; Gigantol