2011 YÜksek lisans tez özetleri

Inhibition Of Acetylcholinesterase By Some Medicinal Plants

Due to the fact that several synthetic chemicals lead to undesirable effects in daily usage, the interest in natural drugs and organic foods have augmented nowadays. Today plant extracts are standardized in industry and used as food supplement to help various diseases.

Acetylcholine (ACh) is one of the neurotransmitters that provides neural transmission between the various cells. Neurodegenerative diseases such as Alzheimer's are closely related to acetylcholinesterase (AChE) which performs the hydrolysis of acetylcholine to choline and acetic acid after nerve transmission. This study aimed to investigate the inhibition of the enzyme acetylcholinesterase. In Alzheimer’s disease most of the degenerative changes in brain anatomy are originated from the lack of ACh in the cortex. This regional damage leads to reduction in certain brain functions particularly memory and other cognitive skills. It is known that reduction of cholinergic activity is closely related to the clinical symptoms, thus keeping ACh on the synaptic cleft longer, is nowadays the most frequently applied strategy in the symptomatic treatment of disease. For this purpose, acetylcholinesterase inhibitors are used mostly.

In our study, we examined 20 different plant extracts which are thought to have direct or indirect effects on the brain and nervous system, and 20 different chemicals with inhibitory effects on enzyme activities. The extracts were prepared by using water, ethyl alcohol, acetone and ethyl acetate. Acetylcholinesterase activity has been appointed spectrophotometrically according to the modified Ellman method on a microplate reader.

Studying with the aqueous plant extracts, due to the projection of the lowest IC₅₀ values, the highest inhibition of AChE was respectively shown by sage, onion, lemon balm, caper and banana extracts. For the ethyl alcohol extracts, due to the projection of the lowest IC₅₀ values, the highest inhibition of AChE was respectively provided by fumitory, gumwood, banana, rosemary and onion. For the acetone extracts, the highest inhibition of AChE respectively found in green tea, nettle, garlic, banana, carrot, onion, fumitory and fava bean extracts. Working with ethyl acetate extracts, due to the lowest IC₅₀ values, the highest inhibition of AChE was shown by banana, fava bean, fumitory, onion and caper. Within the chemical substances, the highest AChE inhibition was observed with kojic acid. β-carotene, (-)-epicatechin, L-proline, edaravone and (+)-α-lipoic acid have shown potent inhibitory effects on AChE.

As a result, all the plants examined showed certain inhibitory activity. However, it was observed that among them, especially banana (Musa sapientum) and onion (Allium cepa), exhibited potent acetylcholinesterase inhibitory effects, for each extract prepared with four different solvents.

  

DUMANLI Ayşe

Danışman : Doç.Dr. Kubilay GÜÇLÜ

Anabilim Dalı : Kimya

Programı : Analitik Kimya

Mezuniyet Yılı : 2011

Tez Savunma Jürisi : Doç. Dr. Kubilay GÜÇLÜ

Prof. Dr. Reşat APAK

Prof. Dr. Mehmet MAHRAMANLIOĞLU

Prof. Dr. Hayati FİLİK

Yard. Doç. Dr. M.A. Faruk ÖKSÜZÖMER