In vivo and in silico Evaluation of Cashew Nut Shell Liquid and Ag-CNSL Nanoparticles for Anxiolytic Activity in Zebrafish via GABAergic Pathways

This paper presents the anxiolytic potential of the major constituents of cashew nut shell liquid (CNSL), anacardic acid (AA), cardanol (CDN), and cardol (CD), and CNSL-derived silver nanoparticles (AgAA and AgCD) compared to diazepam (DZP) in zebrafish (Danio rerio) and in silico by docking on the GABAergic system. CD and CDN were extracted and purified using silica gel column chromatography, and AA was extracted by acid-base reaction. Silver nanoparticles were synthesized through microwave-assisted reduction of silver nitrate with CNSL constituents. UV-Vis spectroscopy presented surface plasmon resonance extinction peaks at 423 (AgAA) and 414 nm (AgCD). Transmission electron microscopy revealed spherical nanoparticles within liposomes of AA and CD. All tested drugs had no toxicity below 40 ppm. CDN (40 ppm) decreased locomotion by 76.98%, approaching DZP (90.67%). AA, CDN, CD, and AgAA surpassed the anxiolytic effect of DZP in the light/dark test, while AgCD was ineffective. Flumazenil reversed the anxiolytic effect of all compounds, confirming GABAergic mediation. Molecular docking revealed that di-unsaturated CD had the highest GABAA affinity, and di-unsaturated AA mimics the hydrophobic profile of DZP. Results confirmed the anxiolytic potential of CNSL, and the synthesis of CNSL-capped AgNPs gives water-soluble anxiolytic drugs with a controlled-release mechanism.