Epilobium angustifolium L. Essential Oil—Biological Activity and Enhancement of the Skin Penetration of Drugs—In Vitro Study

Abstract

Epilobium angustifolium L. is a popular medicinal plant found in many regions of the world. This plant contains small amounts of essential oil whose composition and properties have not been extensively investigated. There are few reports in the literature on the antioxidant and antifungal properties of this essential oil and the possibility of applying it as a potential promoter of the skin penetration of drugs. The essential oil was obtained by distillation using a Clavenger type apparatus. The chemical composition was analyzed by the GC-MS method. The major active compounds of E. angustifolium L. essential oil (EOEa) were terpenes, including α-caryophyllene oxide, eucalyptol, β-linalool, camphor, (S)-carvone, and β-caryophyllene. The analyzed essential oil was also characterized by antioxidant activity amounting to 78% RSA (Radical Scavenging Activity). Antifungal activity against the strains Aspergillus niger, A. ochraceus, A. parasiticum, and Penicillium cyclopium was also determined. The largest inhibition zone was observed for strains from the Aspergillus group. The EOEa enhanced the percutaneous penetration of ibuprofen and lidocaine. After a 24 h test, the content of terpene in the skin and the acceptor fluid was examined. It has been shown that the main compounds contained in the essential oil do not penetrate through the skin, but accumulate in it. Additionally, FTIR-ATR analysis showed a disturbance of the stratum corneum (SC) lipids caused by the essential oil application. Due to its rich composition and high biological activity, EOEa may be a potential candidate to be applied, for example, in the pharmaceutical or cosmetic industries. Moreover, due to the reaction of the essential oil components with SC lipids, the EOEa could be an effective permeation enhancer of topically applied hydrophilic and lipophilic drugs.

Assessment of the Anti-Inflammatory, Antibacterial and Anti-Aging Properties and Possible Use on the Skin of Hydrogels Containing Epilobium angustifolium L. Extracts

“…The analyses on the effect of the HEas on the skin was assessed using the total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), similarly to that reported in our previous study (Nowak et al, 2021b). In brief, the pure skin was cut into 1 cm 2 piece and applied to the HEas for 24 h. Then the skin samples were washed with isopropanol, blotted dry, and air-dried for 2 h. An ATR unit obtained the spectra using Thermo Scientific Nicolet 380 spectrometer (Thermo Fisher Scientific, Waltham, MA, United States).…”

Epilobium angustifolium L. as a Potential Herbal Component of Topical Products for Skin Care and Treatment—A Review

“…Another important group is tannins, among others, oenothein B (OeB), which is mentioned as one of the main substances with the biological activity of this plant [ 6 , 20 , 22 ]. EA also contains a small amount of the essential oil in leaves and stems, composed mainly of terpenes such as anethole, β-bisabolene, α-caryophyllene, and caryophyllene, eugenol, linalool, pelargol, and menthol [ 6 , 23 , 24 ]. Several other groups of compounds such as lignans have also been identified, including pinoresinol, pinoresinol-4-O-glucopyranoside, 4-ketopinoresinol, as well as fatty acids, as follows: arachic acid, arachidic acid, myristic acid, oleic acid, palmitic acid, palmitoleic acid, stearic acid, octacosanic acid, nonacosanic, and 2-hydroxytriacontanic acid.…”

“…In this case, the control only partially reduced the amount of the Hyal-2 and showed a very weak antioxidant effect, unlike the EA extract, which was a very strong antioxidant [ 18 ]. The inhibition of MMPs activity is influenced by secondary metabolites contained in EA, such as flavonoids, tannins, phenolic acids, terpenoids, and tocopherols [ 8 , 24 , 71 ]. The specific effect of these compounds is primarily caused by their structure.…”

“…The secondary metabolites of plants play an important role in the fight against bacterial infection of the skin [ 11 , 79 ]. In the case of EA, they are polyphenols [ 21 ] and terpenes [ 23 , 24 ]. The most common mechanisms of the antimicrobial action elicited by these compounds are based on the following: (1) cell membrane and cell wall permeability increase [ 80 ]; (2) intracellular ATP depletion; (3) inhibition of expression of respiratory chain complex proteins; (4) disturbance in protein and DNA metabolism [ 81 ].…”

“…The most common mechanisms of the antimicrobial action elicited by these compounds are based on the following: (1) cell membrane and cell wall permeability increase [ 80 ]; (2) intracellular ATP depletion; (3) inhibition of expression of respiratory chain complex proteins; (4) disturbance in protein and DNA metabolism [ 81 ]. For example, carvacrol, the component of EA essential oil [ 24 ], which has a phenolic OH group, can cross the bacterial plasma membrane. The carvacrol can bind to molecules such as ATP or monovalent cations such as K + and transport them outside of the bacterial cell [ 82 ].…”