Phytochemical screening and antityrosinase activity of carvacrol, thymoquinone, and four essential oils of Lebanese plants

Objective In our study, we aim to explore the ability of four essential oils (EO) of Lebanese plants to inhibit the tyrosinase activity and to correlate their efficiency level to their phytochemical compositions. Methods The EO have been extracted by hydrodistillation using a Clevenger apparatus and have been studied by GC-MS analysis. Active compounds of Origanum species were identified and antityrosinase activities of EO and active molecules (carvacrol and thymoquinone) have been tested in tubo. Results Antityrosinase activities were obtained as follows: EO of Origanum syriacum (80.41% +/- 2.00%), EO of Origanum ehrenbergii (45.33% +/- 2.20%), EO of Salvia fruticosa (14.62% +/- 2.30%), EO of Calamintha origanifolia (16.51% +/- 5.80%), Carvacrol (56.55% +/- 3.10%), and Thymoquinone (19.49% +/- 1.50%). Conclusion Origanum essential oils resulted in the highest antityrosinase activity due to their high content in carvacrol. However, when present together with carvacrol, thymoquinone decreases the efficiency of carvacrol, which is the case of O. ehrenbergii essential oil. Thus, for improved antityrosinase activity, O. syriacum and O. ehrenbergii should be harvested during flowering stage where carvacrol is present at its highest dosage and thymoquinone at its lowest.