Acetylcholinesterase Activity in the Brain of Rats: Presence of an Inhibitor of Enzymatic Activity in Heliotropium eichwaldi L. Induced Silver/Gold Allied Bimetallic Nanoparticles

Abstract

A simple green method for the production of silver/gold bimetallic nanoparticles (Ag/Au BNPs) using a Heliotropium eichwaldi L. (HE) extract was designed in this study. The reduction of Ag/Au metals to stable Ag/Au BNPs within 24 h at pH 5 using 1 mL of HE at 40 °C signifies a greater rate of reaction compared with chemically elaborated synthesis. The confirmation of the synthesis and the examination of the size, shape, and elemental composition of these BNPs were performed using visible absorption spectroscopy, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX). Stable, irregular-rod-shaped, and crystalline Ag/Au BNPs with a well-defined 6-nm diameter and a blue shift λ max of 532 nm were synthesized using the HE extract. Moreover, the anti-cholinesterase (anti-AChE) potential of the Ag/Au BNPs was tested as a treatment for Alzheimer's disease (AD). An excellent anti-AChE activity (IC 50 , 71.2 ± 0.22 μg/mL) was observed for these biogenic-synthesized NPs. A statistical analysis revealed that Ag/Au BNPs inhibited AChE competitively, according to a Lineweaver-Burk plot, with K m increasing from 0.019 to 0.063 (288%-1 185.7%) and V max remaining constant. The Ag/Au BNPs also caused an increase in K Iapp , from 128 to 1184 (236%-828%), whereas they did not affect V maxiapp . The K m , K I , and K i values were also calculated to be 0.005 3 mmol/L, 595.25 μg, and 80 μg, respectively. Therefore, it is concluded that small-size, stable, and potent Ag/Au BNPs were synthesized successfully from HE extracts that exhibited anti-AChE activity, which renders them a significant remedy for AD.

Heliotropium eichwaldi‐functionalized gold nanoparticles synthesis, characterization, and biological activities

“…The binding affinity of NPs to AChE may be influenced by both the lipophilicity of the NPs and the hydrophobicity of the enzyme environment in AChE molecules. The deactivation of the enzyme may occur as a result of conformational changes and surface coverage brought on by the adsorption of AChE on the surface of NPs, as claimed in a study 101,102 …”