Volatile components, pharmacological profile, and computational studies of essential oil from Aegle marmelos (Bael) leaves: A functional approach

The increasing therapeutic use of plant essential oil (EO) in aromatherapy has urged scientists to investigate into its biological potency. We report the phytochemical composition of the EO of Aegle marmelos (L.) Corrêa using GC-MS analysis, together with its pharmacological properties (antibacterial, antioxidant, and enzyme inhibitory properties). Molecular docking of the major identified compounds against tyrosinase and α-glucosidase was also performed. The EO displayed the highest total antioxidant potential in the phosphomolybdenum assay (24.70 mmol TE/g sample), but showed mild scavenging (DPPH = 0.03 mmol TE/g sample), and reducing effect (CUPRAC = 0.54 mmol TE/g sample, FRAP = 0.21 mmol TE/g sample). Moreover, the EO of A. marmelos showed the greatest inhibitory property against tyrosinase 53.68 (mg KAE/g sample) and good inhibitory effect on α-glucosidase (39.08 mmol ACAE/g sample) compared with α-amylase (0.19 mmol ACAE/g sample). In addition, the EO exhibited moderate AChE inhibition (2.75 mg GALAE/g sample) and BChE inhibition (4.93 mg GALAE/g sample). Disc diffusion assay revealed that S. aureus (Zone of inhibition (ZOI) = 21.4 mm) was most susceptible to the EO followed by C. diphtheriae (ZOI = 17.2 mm) while the lowest MIC value was observed against B. cereus and C. diphtheriae (MIC = 125 μg/ml). The EO of A. marmelos was abundant in limonene (74.9%) followed by β-phellandrene (4.4%), p-cymene (4.2%), and β-caryophyllene (2.0%). Humulene and cryptone exhibited higher docking score after docking to tyrosinase while the best docking scores observed against α-glucosidase was found for humulene and carveol. The EO of A. marmelos showed promising inhibitory activities against vital enzymes related to diabetes, neurological, and skin disorders, and mild antioxidant ability, thus highlighting the quenching abilities of surplus reactive oxygen species related to these disorders. It is predicted that the results obtained will stimulate further research to probe into the therapeutic properties of A. marmelos.