Chemical composition and biological activities of essential oils from Calendula officinalis L. flowers and leaves

Calendula officinalis L., commonly known as pot marigold, is a popular ornamental and highly medicinal plant. In fact, it is well recognized for its wide-ranging therapeutic effects conducive to wound healing and for treating various illnesses. In this study, the essential oils from flowers and leaves of C. officinalis were analysed for their chemical constituents and screened for their in vitro antioxidant and enzyme inhibitory properties. Thirty compounds were found in common in both essential oils, with the sesquiterpene alcohol, α-cadinol as the most abundant compound (leaf: 32.3% and flower: 31.3%, respectively). Besides, the essential oils were found to possess antioxidant capacity through free radical scavenging and reducing mechanisms (DPPH: 2.94, 1.52 mg trolox equivalent (TE)/g of oil; ABTS: 20.72, 2.86 mg TE/g; CUPRAC: 31.16, 47.98 mg TE/g; FRAP: 24.84, 23.42 mg TE/g; phosphomolybdenum: 4.01, 4.68 mmol TE/g for leaves and flowers essential oils, respectively). Moreover, the essential oils (leaves and flowers, respectively) were found to inhibit all the tested enzymes, namely amylase (0.46, 0.42 mmol acarbose equivalent (ACAE)/g), glucosidase (1.35, 1.31 mmol ACAE/g), acetylcholinesterase (2.48, 2.36 mg galantamine (GALAE)/g) and butyrylcholinesterase (8.13, 8.20 mg GALAE/g) and tyrosinase (47.73, 54.36 mg kojic acid equivalent/g). Molecular docking was also performed revealing the compounds neophytadiene and α-humulene to show the highest binding affinity with tyrosinase. Therefore, the obtained results demonstrated some appealing activities of C officinalis essential oils as natural pharmacological agents that could be valuable for the potential development of phyto-formulations against the herein targeted diseases and especially for cosmeceutical applications.