Chemical profile of essential oil from Pimenta racemosa leaves, antioxidant potential, and its enzyme inhibitory properties

Pimenta racemosa var. recemosa (Mill.) J. W. Moore is an aromatic plant belonging to the family Myrtaceae, native to Venezuela, Puerto Rico, and Jamaica and well-known for its traditional and medicinal uses. Our study was designated to explore the chemical composition of essential oil isolated from P. racemosa leaves growing in Egypt via Gas Chromatography/Mass Spectrometry (GC-MS) analysis, alongside investigation of its antioxidant properties and enzyme inhibitory activities against acetylcholinesterase (AChE), butyrylcholinesterase (BChE), tyrosinase, α-glucosidase, and α-amylase. The GC-MS analysis of the leaf oil revealed the presence of fourteen compounds (99.76%), predominated by eugenol (70.87%), β-myrcene (12.88%) and D-limonene (8.35%). The oil demonstrated the highest antioxidant capability in ferric ion-reducing antioxidant power (FRAP; 1506.62 mg TE/g), followed by 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS; 1346.85 mg TE/g), 1,1-diphenyl-2-picrylhydrazyl (DPPH; 1032.83 mg TE/g) and cupric-reducing antioxidant capacity (CUPRAC; 1001.03 mg TE/g). Further, it showed a metal chelating ability (MCA) of 25.63 mg EDTAE/, and phosphomolybdenum (PBD) activity of 209.59 mmol TE/g. The oil displayed significant AChE and BChE inhibitory activities, with values of 1.96 mg GALAE/g and 1.42 mg GALAE/g, respectively. Additionally, it exhibited a moderate level of tyrosinase inhibitory activity (38.83 mg KAE/g) and a significantly higher α-glucosidase inhibitory activity (2.38 mmol ACAE/g) than α-amylase (0.08 mmol ACAE/g). Consequently, the leaf oil of Pimenta racemosa could be used as adjuvant therapy for management of oxidative stress-related conditions and chronic diseases such as Alzheimer's, diabetes mellitus, and skin pigmentation. However, further toxicological, in vivo and clinical studies are recommended.