Purification and inhibition of the acetylcholinesterase from ricania simulans spreading in the Eastern Black Sea region

In this study, it was aimed to be purified the acetylcholinesterases from the nymphs and adults of Ricania simulans (Walker, 1851) (Hemiptera: Ricaniidae) and to struggle this pest through the enzyme inhibition. The acetylcholinesterases were purified in a one-step from the adults and nymphs of Ricania simulans by Edrophonium-Sepharose 6B affinity column. Some kinetic properties of the purified acetylcholinesterases were investigated in the presence of acetylthiocholiniodate substrate. The enzymes showed the highest acetylcholinesterase activity at 40.0 oC and pH 8.0. The Km, Vmax and kcat values of Ricania simulans acetylcholinesterases were calculated as 0.04±0.01 mM, 2.000.0±250 EU/mg protein and 104.5±13 min-1 for adults, 0.02±0.01 mM, 500.0±52 EU/mg protein and 30.3±6.4 min-1 for nymphs, respectively. In the studies with tacrine and edrophonium chloride, known inhibitors of acetylcholinesterase, IC50 values were determined as 18.0±0.3 and 1.2±0.4 µM for adults, 2.4±0.3 and 0.6±0.09 µM for nymphs, respectively. In the inhibition studies with newly having been synthesized compounds, it was determined that the IC50 value of the compound [Zn(HL)(bipy)(OClO3)], which is the most effective in adults of Ricania simulans acetylcholinesterase, was 3.2±0.8 µM, and the IC50 value of [Ni(HL)(bipy)(OClO3)] compound, which is the most effective for nymphs, was 4.6±0.8 µM. In the inhibition studies with the natural plant extracts, the IC50 values of the olive leaf water extract, which was the most effective on these acetylcholinesterases, were determined as 20.3±1.2 and 16.2±0.8 µg dry matter/mL for adults and nymphs, respectively. The result that stands out in this thesis was that the plant extracts effected at low concentrations and they were extracted with water. Without the need for chemical pesticides, it may be struggled by these environmentally friendly extracts with these and similar pests, in either the nymph or adult stages.