In Alzheimer’s disease (AD), reduced brain acetylcholine (Ach) neurotransmitter is seen. Cognition and behavior changes in AD are reported to be related to these reduced levels. The hypothesis is that inhibition of the enzymes that break down Ach is beneficial in treating neurodegenerative disorders. For example, cetylcholinesterase (AChE) enzyme activity breaks down acetylcholine neurotransmitter in animals. Inhibition of AChE activity then blocks the normal breakdown of Ach so that higher levels of ACh can be achieved. This is beneficial in AD.
Cloves (Syzygium aromaticum) contain a large amount of oil, mostly eugenol. Traditional uses are as an antiseptic, analgesic, anti-oxidant and neuroprotectant. Clove oil is used as a cognitive enhancer in Ayurveda and Iranian traditional medicine. This study was done to determine the anti-cholinesterase activity of cloves and clove oil.
Testing showed the eugenol in clove oil to be 0.5 microgm/ml. This was tested for AChE and BChE inhibitory activity and was found to be positive for inhibition.* Eugenol was the best inhibitor in cloves, but was less active than galantamine used as a standard. The affinity to BChE was weak. Other such treatments from plant sources to increase acetylcholine activity include huperzine, rivastigmine, and galantamine.**
CONCLUSION: S. aromaticum extract, oil, and eugenol have anti-cholinesterase activity. Clove products should be tested for use in Alzheimer’s disease and related disorders.
NOTES: *Acetylcholinesterase exists naturally in multiple molecular forms, including AChE and BChE
**Huperzine is available in health foods and vitamin stores.
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