Obtaining carvacrol from Origanum onites L. essential oil and developing carvacrol-loaded nanoformulation for use in cosmetics

Carvacrol molecule is a monoterpenic essential oil compound with many important biological activities. It is found as a major component in many Origanum species and is considered as the compound responsible for the activity in the essential oil in those plants. However, in addition to its biological activities, the easy oxidation of carvacrol, strong odor and irritating properties make its use difficult. In this study, carvacrol was obtained from the essential oil of Origanum onites L. plant, which has an important commercial value in our country, and formulated as polycaprolactone (PCL) nanoparticles (NP) to be used as a potential anti-aging product in cosmetics. First of all, the carvacrol extract obtained from the essential oil was analyzed by GC-MS. Carvacrol was loaded onto PCL nanoparticles by single emulsion method and the synthesized carvacrol-PCL-NPs were characterized by Dynamic Light Scattering (DLS), UV-Vis spectroscopy and Scanning Electron Microscopy (SEM). For the characterized carvacrol-PCL-NPs, anticollagenase activity and cytotoxic activity studies were carried out using HaCaT cell line. According to the results, carvacrol was detected in the essential oil at a rate of 85%. The result of characterization by DLS, polydispersity index (PdI) was found to be 0.070 ± 0.015; zeta potential (ZP) was - 8.51 ± 0.76 mV and mean particle size was 199.5 ± 0.91 nm. Morphological analyzes performed by SEM showed results compatible with the mean particle size and confirmed the presence of nanoparticle structures showing homogeneous distribution. Carvacrol-PCL-NPs showed 98.55% encapsulation efficiency, and 20% loading efficiency was determined. In vitro controlled release studies showed that carvacrol was released at a rate of 95.55% from carvacrol-PCL-NPs in 48 hours. Anticollagenase activity results showed that carvacrol-PCL-NPs had twice the activity of free carvacrol. According to in vitro cytotoxicity studies, while free carvacrol showed toxic effects even at the lowest concentration (0.125 mg/mL), encapsulation with PCL eliminated this effect and carvacrol-PCL-NPs showed 81.45 ± 1.84% cell viability at 1 mg/mL concentration. Thus, thanks to the successfully synthesized carvacrol-PCL NPs, the toxic effect of the obtained carvacrol was eliminated and the anticollagenase activity was doubled. At the same time, the pungent odor of free carvacrol was eliminated and its biocompatibility was increased. As a result, it was predicted that carvacrol-PCL-NPs, which have high anticollagenase activity and low toxicity and increased biocompatibility, could be potential antiaging product candidates for the cosmetics industry. Keywords: Origanum onites L.; carvacrol; polycaprolactone; nanoparticle; anti collagenase activity; in vitro cell culture