Skin Penetration Enhancement by Natural Oils for Dihydroquercetin Delivery.

Natural oils are commonly used in topical pharmaceutical formulations as emulsifiers, stabilizers or solubility enhancers. They are presented as safe and inert components, mainly used for formulation purposes. It is confirmed that natural oils can affect the skin penetration of various substances. Fatty acids are mainly responsible for this effect. Current understanding lacks reliable scientific data on penetration of natural oils into the skin and their skin penetration enhancement potential. In the current study, fatty acid content analysis was used to determine the principal fatty acids in soybean, olive, avocado, sea-buckthorn pulp, raspberry seed and coconut oils. Time of flight secondary ion mass spectrometry bioimaging was used to determine the distribution of these fatty acids in human skin ex vivo after application of the oils. Skin penetration enhancement ratios were determined for a perspective antioxidant compound dihydroquercetin. The results demonstrated skin penetration of fatty acids from all oils tested. Only soybean and olive oils significantly increased the skin distribution of dihydroquercetin and can be used as skin penetration enhancers. However, no correlation can be determined between the fatty acids' composition and skin penetration enhancement using currently available methodological approaches. This indicates that potential chemical penetration enhancement should be evaluated during formulation of topically applied products containing natural oils.

MODELING AND BIOPHARMACEUTICAL EVALUATION OF SEMISOLID SYSTEMS WITH ROSEMARY EXTRACT.

Scientific literature provides a great deal of studies supporting antioxidant effects of rosemary, protecting the body's cells against reactive oxygen species and their negative impact. Ethanol rosemary extracts were produced by maceration method. To assess biological activity of rosemary extracts, antioxidant and antimicrobial activity tests were performed. Antimicrobial activity tests revealed that G+ microorganisms are most sensitive to liquid rosemary extract, while G-microorganisms are most resistant to it. For the purposes of experimenting, five types of semisolid systems were modeled: hydrogel, oleogel, absorption-hydrophobic ointment, oil-in-water-type cream and water-in-oil-type cream, which contained rosemary extract as an active ingredient. Study results show that liquid rosemary extract was distributed evenly in the aqueous phase of water-in-oil-type system, forming the stable emulsion systems. The following research aim was chosen to evaluate the semisolid systems with rosemary exctract: to model semisolid preparations with liquid rosemary extract and determine the influence of excipients on their quality, and perform in vitro study of the release of active ingredients and antimicrobial activity. It was found that oil-in-water type gel-cream has antimicrobial activity against Staphylococcus epidermidis bacteria and Candida albicans fungus, while hydrogel affected only Candida albicans. According to the results of biopharmaceutical study, modeled semisolid systems with rosemary extract can be arranged in an ascending order of the release of phenolic compounds from the forms: water-in-oil-type cream < absorption-hydrophobic ointment < Pionier PLW oleogel < oil-in-water-type eucerin cream < hydrogel < oil-in-water-type gel-cream. Study results showed that oil-in-water-type gel-cream is the most suitable vehicle for liquid rosemary extract used as an active ingredient.

Fatty acids penetration into human skin ex vivo: A TOF-SIMS analysis approach.

Linoleic, oleic, palmitoleic, palmitic, and stearic fatty acids (FAs) are commonly used in dermatological formulations. They differ by their structure, presence in the skin, and mode of application in pharmaceuticals and cosmetics compounding. These FAs are also known as chemical penetration enhancers, but their mechanisms of penetration enhancement and effect on barrier characteristics of the skin require additional study. In this study, the authors conducted an ex vivo analysis of the distribution of lipid components in the epidermis and dermis of human skin after applying individual FAs. The goal was to elucidate possible mechanisms of penetration enhancement and FA effects on barrier characteristics of the skin. FA penetration studies were conducted ex vivo on human skin and time-of-flight secondary ion mass spectrometry (TOF-SIMS) bioimaging analysis was performed to visualize and analyze distribution of FAs in skin sections. The current study demonstrated that TOF-SIMS imaging was effective in visualizing the distribution of linoleic, oleic, palmitoleic, palmitic, and stearic acid in the human skin ex vivo after the skin penetration experiment of individual FAs. The integration of the obtained TOF-SIMS images allowed a semiquantitative comparison of the effects induced by individual FA applications on the human skin ex vivo. FAs showed varying abilities to penetrate the skin and disorder the FAs within the skin, based on their structures and physicochemical properties. Linoleic acid penetrated the skin and changed the distribution of all the analyzed FAs. Skin treatment with palmitoleic or oleic acid increased the amounts of singular FAs in the skin. Penetration of saturated FAs was low, but it increased the detected amounts of linoleic acid in both skin layers. The results indicate that application of FAs on the skin surface induce redistribution of native FAs not only in the stratum corneum layer of epidermis but also in the lipid content of full epidermis and dermis layers. The results indicate that topically applied pharmaceutical products should be evaluated for potential chemical penetration enhancement and lipid component redistribution effects during formulation.