Antioxidant and acetylcholinesterase-inhibitory properties of long-term stored medicinal plants

Stephen O Amoo,Mack Moyo,Johannes Van Staden,Adeyemi O Aremu

doi:10.1186/1472-6882-12-87

Stephen O Amoo, Mack Moyo + Show 2 more

Open Access

https://doi.org/10.1186/1472-6882-12-87

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Abstract

BackgroundMedicinal plants are possible sources for future novel antioxidant compounds in food and pharmaceutical formulations. Recent attention on medicinal plants emanates from their long historical utilisation in folk medicine as well as their prophylactic properties. However, there is a dearth of scientific data on the efficacy and stability of the bioactive chemical constituents in medicinal plants after prolonged storage. This is a frequent problem in African Traditional Medicine.MethodsThe phytochemical, antioxidant and acetylcholinesterase-inhibitory properties of 21 medicinal plants were evaluated after long-term storage of 12 or 16 years using standard in vitro methods in comparison to freshly harvested materials.ResultsThe total phenolic content of Artemisia afra, Clausena anisata, Cussonia spicata, Leonotis intermedia and Spirostachys africana were significantly higher in stored compared to fresh materials. The flavonoid content were also significantly higher in stored A. afra, C. anisata, C. spicata, L. intermedia, Olea europea and Tetradenia riparia materials. With the exception of Ekebergia capensis and L. intermedia, there were no significant differences between the antioxidant activities of stored and fresh plant materials as measured in the β-carotene-linoleic acid model system. Similarly, the EC50 values based on the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay were generally lower for stored than fresh material. Percentage inhibition of acetylcholinesterase was generally similar for both stored and fresh plant material. Stored plant material of Tetradenia riparia and Trichilia dregeana exhibited significantly higher AChE inhibition than the fresh material.ConclusionsThe current study presents evidence that medicinal plants can retain their biological activity after prolonged storage under dark conditions at room temperature. The high antioxidant activities of stable bioactive compounds in these medicinal plants offer interesting prospects for the identification of novel principles for application in food and pharmaceutical formulations.

Highlights

Medicinal plants are possible sources for future novel antioxidant compounds in food and pharmaceutical formulations
There was no significant difference between the iridoid content of fresh and stored plant materials in approximately 50% of the evaluated plants
With the exception of E. capensis and L. intermedia, there were no significant differences between the antioxidant activities recorded in both the stored and fresh plant materials

Summary

Introduction

Medicinal plants are possible sources for future novel antioxidant compounds in food and pharmaceutical formulations. There is a dearth of scientific data on the efficacy and stability of the bioactive chemical constituents in medicinal plants after prolonged storage. This is a frequent problem in African Traditional Medicine. Though the human body has inherent antioxidative mechanisms to counteract the damaging effects of free radicals, there is often a need to use dietary and/or medicinal antioxidant supplements, during instances of disease attack. The use of natural compounds with high levels of antioxidants has been proposed as an effective therapeutic approach for AD [5]

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