Assessment of in vitro dermal absorption of the kaurenic acid from Coespeletia moriziana extracts.

Espeletiinae are plants which grow above 3000 m of altitude in the Northern Andes and kaurenic acid was extracted from the leaves of Coespeletia moritziana. This compound has shown a wide range of biological activities, including cytotoxicity which is efficient in cancer therapy. The percutaneous penetration of this compound was measured in vitro using Franz cells. At appropriate intervals for up to 24h, diffusion samples were analyzed using HPLC. At the end of the test period, the amount of kaurenic acid was determined in each compartment and approximately 10% of kaurenic acid had been absorbed and was found in the skin layers.

Benzophenone-3 entrapped in solid lipid microspheres: formulation and in vitro skin evaluation.

Solid lipid microspheres (SLM), lipid-in-water formulations made from oil-and-wax mixtures, were studied concerning feasibility. SLMs were then loaded with a benzophenone-3, water insoluble UVAB-filter intended for dermal application. Microspheres were prepared by dispersion with homogenisers and investigated by polarizing micrography and scanning electron micrography. For the selected formulations, investigations on percutaneous penetration of B-3 capacity were performed "in vitro" using Franz cells. Microspheres, 5-50 µm in size, and a spherical shape were obtained from several mixtures. B-3 was added and the loading capacity of this drug in the SLM was obtained for a maximum of 5% when the lipophilic phase was 18%. The lipophilic mixture with non-ionic surfactants in the selected formulation of lipid microspheres has a favorable effect on size. The selected formulation is also cosmetically adapted and it is composed of physiological and biodegradable lipids. B-3 was released and penetrated into skin more quickly and in greater quantity than in SLM form, from vehicles containing free B-3. This work has shown that SLM is an excellent carrier for lipophilic sunscreens like B-3 in order to decrease the release and penetration rate of this UV absorber compared with B-3 in oily solution.

The "in vitro" percutaneous penetration of three antioxidant compounds.

Caffeic acid, chlorogenic acid and oraposide, a natural glycoside, are phenyl-propanoid compounds. These natural products have been reported to have antioxidant activities such as the scavenging of superoxide anions and hydroxyl radicals. These compounds could be used in the dermocosmetic field to protect the skin from oxidative stress induced by UV radiation. To this end, the permeation of caffeic acid, chlorogenic acid, and oraposide, through pig-ear skin was evaluated in vitro. The percutaneous permeation of these three compounds through pig skin was measured and compared using Franz diffusion cells. At appropriate intervals, up to 72 h, diffusion samples were analyzed using an HPLC assay. After 48 h of drug contact the permeation was also evaluated with a fluorescent microscope on vertical microtomed pig skin sections. In this study on excised pig skin, the flux value was found to be equal to 0.32 and 0.48 microgcm(-2)h(-1) for caffeic and chlorogenic acids, respectively; for oraposide the levels were below the limit of detection and the flux was not evaluated. These results were corroborated by fluorescent microscopy. Caffeic and chlorogenic acids were found in all skin sections, and these might represent a systemic activity, whereas oraposide remained in the upper superficial layer of the skin. This latter phenomenon seems to be interesting for dermocosmetic applications.

Benzophenone-3: rapid prediction and evaluation using non-invasive methods of in vivo human penetration.

The study described in this paper constitutes a practical assay system to evaluate in vivo drug penetration using two complementary non-invasive methods. An electrical capacitance test was first applied to the skin on the forearm to evaluate the hydration of the skin, and check the integrity of the stratum corneum. In the first step, the percentage absorption was measured using an occlusive and difference method; following benzophenone-3 application any residual formulation was washed off and the amount removed analyzed. In the second step, the tape stripping method-a useful procedure for selectively removing the skin's outermost layer, the stratum corneum, and measuring the stratum corneum adsorption-was performed. Under these conditions the human skin permeation of this UV-filter over four hours was near to 35% of the applied dose with the occlusive method. The amount of topically applied benzophenone-3 found in the stratum corneum after 30 min exposure using the stripping procedure was evaluated at 4% to the applied dose.

LC analysis of benzophenone-3: II application to determination of 'in vitro' and 'in vivo' skin penetration from solvents, coarse and submicron emulsions.

The aim of this study was to determine the skin penetration of benzophenone-3 in vitro and in vivo in order to investigate a possible influence of formulation. Six different vehicles, three solvents and three different emulsion types were evaluated in vitro and in vivo. Each vehicle was applied to the skin model at 2 mg cm(-2). First, histological studies on ear pigskin and human skin were evaluated. In vitro measurements were performed with static diffusion cells using pigskin at 1, 2, 4, and 8-h. In vivo, benzophenone-3 concentration in stratum corneum was evaluated by the stripping method after 30-min application on forearm of volunteers. It was shown that ear pigskin and human skin appear similar and in both experiments significant differences between vehicles were noticed. The six vehicles could be ranked in the same order of benzophenone-3 skin concentration. At 8-h, the highest concentration of benzophenone-3 in skin was obtained with propylene glycol, and O/W submicron emulsion. On the contrary. the two oily solvents. W/O emulsion and O/W coarse emulsion restrain the concentration of this UV-filter in the skin. At each time, permeability in vitro and in vivo were well correlated. Low concentrations were measured in the receptor fluid suggesting that percutaneous absorption of this UV-filter across the skin would be minimal. The in vitro and in vivo skin penetration capacity of benzophenone-3 from six vehicles was confirmed and quantified. A satisfactory relationship between binary in vitro and in vivo was established.

Bilateral effect of a unilateral occlusal splint on the expression of myosin heavy-chain isoforms in rat deep masseter muscle.

Many studies have shown that various myosin isoforms are involved in muscle contraction. A search for specific antibodies directed against the myosin heavy chain (MHC) resulted in the identification of at least two main classes, referred to as MHC type I and type II. In this study, immunohistology and gel electrophoresis were used to determine the proportion of MHC isoforms in rat deep masseter muscle at different times after the insertion of an unilateral occlusal splint. An increasing proportion of MHC type I isoforms was found in both deep masseters soon after splinting, and this trend continued until 7 days after splint insertion. The type I fibres were clearly distributed on either side of the central axis of the muscle. At 15 days, a significant decrease in the percentage of the type IIb MHC isoform was observed on the occlusal splint side compared to the contralateral side. After 30 days of unilateral splinting, the proportion of type IIb fibres on the splint side returned to baseline whereas on the contralateral side there was an increase in the proportion of this type. The results suggest an initial adaptation after the unilateral occlusal disturbance in which muscles of both sides react in the same way; later, the muscles of each side adapt their expression of MHC isoforms according to altered functional demand.

Effect of the addition of oxybenzone or octyl-methoxycinnamate on particle size of submicron emulsions.

The formulation of sunscreen products requires understanding of the solubilization of these products in different vehicles to obtain aesthetic preparations and to evaluate long-term stability. For this study, two different ultraviolet (UV) filters were selected: oxybenzone (powder) and octyl-methoxycinnamate (liquid). First, the solubility of these UV filters was tested using a three-component simplex-centroid design strategy. The mixtures were prepared with three oily phases used in this field of cosmetics: liquid paraffin, isopropyl myristate, and coconut oil. A phase diagram method was used to carry out a systematic study of submicron oil-in-water emulsions. Phase diagrams were produced by diluting fixed binary mixtures with water. The surfactant consisted of polyoxyethylene-20-sorbitan monostearate/sorbitan monostearate (50/50, w/w). The oily phase contained equal quantities of each oil studied. From this water/surfactant/oil ternary system, we selected two reference emulsions with receptively 75/5/20 and 68/7/25 proportions. Photon correlation spectroscopy (PCS) was used to investigate the influence of these two UV filters at several concentrations on droplet size and distribution of the oil droplets in the material. All emulsions were stored and checked every month for 6 months.

Solubilisation de filtres-UV dans des melanges ternaires de phases apolaires, optimisation par l'utilisation de reseaux centres.

This paper is concerned with the solubility of UV filters. Emulsions are perfect formulations used for sunscreens, but to give the skin silky feel without being greasy, the oily phase content is low. Considerations of sunscreen solubility can help to solve specific problems of stability in formulations. It is important to determine what solvent dissolves them and what mixture of solvent improves their solubility. Two water insoluble sunscreens were tested at several concentrations in various non-polar solvents. A strategy with simplex centroid design was used to optimize this work. The graphical interpretation of the data assists our understanding of the solubility of UV filters.

Influence du protocole opératoire sur les caractéristiques d'une émulsion L/H réalisée avec des surfactifs polymériques non ioniques.

Synopsis The mode of operation has an effect on the properties of emulsions. We have studied the influence of the method of preparation (temperature, stirring rate, time of phase introduction and method of cooling) on the rheological properties of an oil in water emulsion. The importance of factors is classified with the help of two-level full and fractional factorial designs. The most significant factor is the mode of cooling, a progressive cooling produces an increase of viscosity and the influence of the other studied factors is insignificant. Sudden cooling entails a lowering of the viscosity and a diminution of the stability, and shows the influence of the rate of mixing and the temperature of manufacture.

Evaluation expérimentale de l'hydratation et du pouvoir occlusif in vivo et in vitro d'excipients lipophiles et de leurs émulsions phase huile continue.

Synopsis A study was carried out on three water in oil emulsions and their respective oil-phases, petrolatum, liquid paraffin and sweet almond oil, in order to compare their occlusive properties and thus their influence on cutaneous hydration. An in vitro method using 'Patel'cells in a water-saturated atmosphere at controlled temperature enabled, in the first instance, the various emulsions and their oil-phases to be classified according to their permeability to water vapour. The results are in order of increasing degree of occlusion: sweet almond oil, liquid paraffin and petrolatum. In in vivo studies on human volunteers, the influence of the application of the same substances on transepidermal water loss (TEWL) and cutaneous hydration was measured with an evaporimeter and a corneometer, in a temperature and humidity-controlled room. Measurements were performed on the flexor side of the forearm after sodium lauryl sulphate 5% insult on six subjects at times of 0, 30, 120 and 270 min. The different oils, used pure, increased the hydration by an occlusive effect, and this was described by measurements of TEWL. On the other hand, after using the emulsions, the increase in hydration noted does not appear to involve an occlusive mechanism.