Chemical Compositions and Anti-Skin-Ageing Activities of Origanum vulgare L. Essential Oil from Tropical and Mediterranean Region.

Origanum vulgare L. has been used as a culinary ingredient worldwide. This study revealed the cosmeceutical potential of O. vulgare essential oil as a skin-ageing retardant. The O. vulgare essential oil from a highland area of a tropical country (HO), obtained by hydrodistillation was investigated and compared to a commercial oil from the Mediterranean region (CO). Their chemical compositions were investigated by gas chromatography-mass spectrometry. Antioxidant activities were investigated by ferric reducing antioxidant power, 1,1-diphenyl-2-picrylhydrazyl, and ferric thiocyanate assay. Anti-skin-ageing activities were determined by means of collagenase, elastase, and hyaluronidase inhibition. Carvacrol was the major component in both oils, but a higher amount was detected in HO (79.5%) than CO (64.6%). HO possessed comparable radical scavenging activity to CO (IC50 = 1.8 ± 0.8 mg/mL) but significantly higher lipid peroxidation inhibition (38.0 ± 0.8%). Carvacrol was remarked as the major compound responsible for the reducing power of both oils. Interestingly, HO possessed significant superior anti-skin-ageing activity than ascorbic acid (P < 0.01), with inhibition against collagenase, elastase, and hyaluronidase of 92.0 ± 9.7%, 53.1 ± 13.3%, and 16.7 ± 0.3%, at the concentration of 67, 25, and 4 µg/mL, respectively. Since HO possessed comparable anti-hyaluronidase activity to CO and superior anti-collagenase and anti-elastase (P < 0.01), HO was suggested to be used as a natural skin-ageing retardant in a cosmetic industry.

Transdermal delivery enhancement of carvacrol from Origanum vulgare L. essential oil by microemulsion.

Carvacrol has been reported for analgesic and anti-inflammatory activity by cyclooxygenase inhibition but it could induce gastrointestinal toxicity because of its non-selective inhibition. Therefore, the present study aimed to develop transdermal microemulsion from Origanum vulgare essential oil to deliver carvacrol into and through the skin which would overwhelm the gastrointestinal problems. O. vulgare essential oil was extracted by hydrodistillation and its carvacrol content was determined using high performance liquid chromatography. Pseudoternary phase diagrams were constructed using water dilution method to investigate the suitable microemulsion components. Microemulsions were then characterized for external appearance, particle size, size distribution, zeta potential, electrical conductivity, refractive index, viscosity, transmittance, pH, and stability. Additionally, the irritation property of microemulsions were investigated by hen's egg on the chorioallantoic membrane assay. The release profile, percutaneous absorption, and skin retention were investigated using dialysis bag and Franz diffusion cell, respectively. The interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) were investigated using the enzyme-linked immunosorbent assay. The results remarked that carvacrol was a major component of O. vulgare essential oil with high concentration of 83.7%. The most suitable microemulsion (ME 1), composing of 5% w/w O. vulgare essential oil, 25%w/w Tween 60, 25%w/w butylene glycol, and 45%w/w deionized water, had the smallest internal droplet size (179.5 ± 27.9 nm), the narrowest polydispersity index (0.30 ± 0.07), the highest transmittance (93.13 ± 0.04%), and Newtonian flow behavior with low viscosity of 0.30 ± 0.07 Pas. ME 1 could reduce the irritation effect of O. vulgare essential oil since ME 1 (IS = 3.1 ± 0.10) exhibited significantly lower irritation effect than its blank formulation (IS = 4.8 ± 0.02) and O. vulgare oil solution (IS = 5.0 ± 0.01) (p < 0.05). Furthermore, ME 1 sustain released carvacrol from the formulation, remarkedly deliver more carvacrol through the skin layer (2.6 ± 2.2%) and significantly retained carvacrol in the skin layer (2.60 ± 1.25%). Additionally, ME 1 significantly enhanced IL-6 inhibition of O. vulgaris oil and carvacrol (p < 0.05). Therefore, O. vulgaris oil microemulsion was suggested to be used for the transdermal delivery and anti-inflammatory activities enhancement of carvacrol.