Unsaturation-Driven Modulation of Antioxidant and Acetylcholinesterase Inhibitory Activities of Cardanol Derivatives

Background: Cardanol, a bioactive alkylphenol obtained from technical cashew nutshell liquid (CNSL), consists of mono-, di-, and tri unsaturated side chain derivatives. These compounds are of increasing interest for their diverse industrial applications. Methods: In this study, three major cardanol components-3-[(8E)-8-pentadecen-1-yl] phenol (C1), 3-[(8E,11E)-8,11-pentadecadien-1-yl] phenol (C2), and 3-[(8E,11E,14E)-8,11,14-pentadecatrien-1-yl] phenol (C3)-were isolated from CNSL via chromatographic separation. Their structures were confirmed by FTIR and detailed ¹H and ¹³C NMR spectroscopy, with complete carbon and proton assignments reported. Results: Among the three, C3 exhibited the highest antioxidant potential, with a DPPH IC₅₀ value of 0.179 ± 0.005 mg/mL, approximately five times more potent than C1 (IC₅₀ = 1.000 ± 0.200 mg/mL). C3 also showed the highest lethality against Artemia salina (LC₅₀ = 4.118 ± 0.328 mg/mL) and the most pronounced inhibition of acetylcholinesterase (AChE), with a 0.8 cm inhibition zone. Computational studies using molecular docking and molecular dynamics simulations further supported the interaction of these compounds with both the catalytic active site (CAS) and the peripheral anionic site (PAS) of AChE. Conclusions: These results expand our understanding of the chemical composition and potential applications of CNSL. The identified unsaturated alkylphenols, particularly the triene compound, demonstrate promise as sustainable candidates for the development of new materials and pharmaceuticals that combat oxidative stress and neurodegenerative diseases.