Chemical Composition, Antioxidant Potential, and Acetylcholinesterase Inhibitory Activity of the Essential Oil from Croton alnifolius Lam.

This study reports the first chemical characterization of the essential oil of <i>Croton alnifolius</i>. A very low yield of 0.028% ± 0.0012 (<i>w</i>/<i>w</i>) was obtained by steam distillation for 4 h using a Clevenger-type apparatus. The chemical composition of the oil was analyzed by gas chromatography coupled with mass spectrometry (GC-MS) for compound identification and by gas chromatography with a flame ionization detector (GC-FID) for quantification. A total of 49 compounds were identified, representing 94.65% of the total oil composition. The chemical profile was dominated by hydrocarbon sesquiterpenes (53.11%) and hydrocarbon monoterpenes (32.20%). The major constituents included (<i>E</i>)-caryophyllene (17.42%), α-pinene (14.53%), myrcene (9.51%), germacrene D (9.92%), and β-chamigrene (5.48%). The biological activity of the essential oil was also evaluated: it exhibited weak antimicrobial activity against <i>Enterococcus faecium</i> with a Minimum Inhibitory Concentration (MIC) value of 1000 μg/mL, strong antioxidant potential in the ABTS assay (SC₅₀ = 28.43 ± 1.0 μg/mL), and moderate acetylcholinesterase inhibitory activity (61.74 ± 1.02 μg/mL). These results indicate that the unique sesquiterpene rich chemical profile of <i>C. alnifolius</i> contributes to its antioxidant and neuroprotective potential, supporting its relevance as a promising source of bioactive natural products.