Determination of cholinesterase, tyrosinase, urease enzyme inhibitory and antioxidant activity of some oak galls

In the current study, the enzyme inhibition and antioxidant activity of the methanol extract of galls induced by the Andricus quercustozae and Andricus. cecconii on Quercus brantii L. and Andricus quercusramuli on Quercus infectoria were investigated. The enzyme inhibition activity was determined by spectrophotometric measurement of acetyl-butyryl cholinesterase, tyrosinase and urease enzyme inhibitions. Total phenolic and total flavonoid contents of the extracts were determined as gallic acid and quercetin equivalents, respectively and their antioxidant activity was carried out by using three different methods; DPPH free radical scavenging activity, ABTS cation radical scavenging activity and CUPRAC assays. As a result of the cholinesterase inhibition activity, while the extracts were not active on acetylcholinesterase enzyme inhibition, they showed activity in the inhibition of butyrylcholinesterase enzyme. According to the results, the highest activity showed by A. quercustozae gall extract with an inhibition rate of 31.33 ± 1.25%. The highest tyrosinase enzyme inhibition activity recorded by A. quercustozae gal extract with an inhibition rate of 61.16 ± 0.72%. As a result of the urease inhibition activity, A. quercustozae gal extract showed activity (40.98 ± 1.41%), whereas A. quercusramuli and A. cecconii gal extracts did not show activity. Total phenolic contents of the extracts were found to be higher than total flavonoid contents. Extracts showed high antioxidant activity in general. That is, some extracts showed higher activity than positive controls. In this thesis, A. quercustozae, A. cecconii and A. quercusramuli gall extracts were investigated for the first time in terms of mentioned biological activities.