Publication: Cognitive-enhancing and antioxidant activities of the aqueous root extract of hypericum revolutum subspecies keniense (schweinf.)
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2020-11
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Mount Kenya University
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Abstract
Cognitive deficit is linked to the brain dysfunction mostly manifested by loss or distortion of
Learning, memory, attention and many other symptoms. These cognitive functions are normally
Controlled by acetylcholine a neurotransmitter present in the amagdala, hippocampus and striatal
Parts of the brain. Therefore, any damage to these parts or the inefficient activity of
Acetylcholine results into cognitive deficit. Oxidative damage of the brain occurs due to the
Imbalance between the reactive oxygen species and the antioxidants and has been implicated in
The development of cognitive impairment. The management of cognitive deficits in Alzheimer’s
Disease involves the use of conventional drugs such as rivastigmine, donezepil, tacrine and
Galantamine. However, these drugs only relief symptoms without curing the impairment. In
Addition, they are associated with adverse effects, are less efficacious and though not costly, the
Cost of managing patients with cognitive impairment and related conditions is high. Therefore,
There is an urgent need for an alternative that is potent, efficacious, safe, accessible, affordable in
Terms of cost and curative. Plants are a potential source for such drugs with the desired
Properties. Various plants including Hypericum revolutum subspecies keniense have been used
In traditional medicine to manage cognitive deficits and related disorders. However, the efficacy
Of such plants have not been scientifically investigated. Therefore, this present study was
Designed to investigate the cognitive – enhancing and antioxidant activities of the aqueous root
Extract of Hypericum revolutum subspecies keniense (Schweinf) as a potential alternative source
Of cognitive deficit curing agent. In this study, the Morris water maze technique was adopted to
Investigate the cognitive enhancing activities of the aqueous root extract of Hypericum
Revolutum subspecies keniense (Schweinf) in the scopolamine induced cognitively impaired
Mice. In addition, ex-vivo antioxidant efficacy in the brain tissue of the cognitively impaired
Mice was determined following the MWM test. The mice which were treated with hrkaq
250mg/kg bwt took a significantly shorter latency time compared to the negative control
(p<0.05) in the MWM test. Similarly, the mice treated with hrkaq 250mg/kg bwt showed
Increased % activity of SOD and Glutathione antioxidants as compared to all the other groups
(p<0.05). Moreover, the mice treated with hrkaq 10mg/kg bwt showed significantly low
Concentration of hydrogen peroxide (catalase enzyme activity increased) as compared to all the
Other groups (p<0.05). From the results, it is evident that the aqueous root extract of Hypericum
Revolutum subspecies keniense has both the cognitive enhancing and antioxidant properties. The
Cognitive enhancing effects of this plant could be attributed to the presence of antioxidant
Phytochemicals which quench oxidative stress and promote health. Further studies aimed at
Investigating agents that; inhibits fast iron accumulation in the brain in oxidative stress,
Inhibitors of tau plaques, inhibitors of mediators of neuroinflammation and anti-Parkinson’s
Disease should be done.
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Keywords
Oxidative, acetylcholine, impairment