Abstract
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.