Étude de la pénétrationin vivodans la peau de rat du collagène acido-soluble en solution acide ou en mélange dans une crègme cosmétique

Abstract

To detect a foreign collagen in a tissue on a substantially identical protein, a radio-tracer technique appeared ideal but the method is only valuable if the introduction of the tracer element into the micromolecule does not modify its properties. The 1st collagen used was tagged by the introduction of 14C into the peptide chain from marked proline by biosynthesis. A 0.3% concentration in sorbic acid solution was applied to the back of the animal, and the penetration was followed by measuring the activity of tissue sections. No radioactivity was found in the interior of the dermis after 15, 30, 90 and 120 min after application. The method of biosynthetic marking was abandoned as the activity of the protein was considered to be insufficient. The technique of the incorporation of 125I into tyrosine was used to obtain a greater specific activity without modifying the active principle. This chemical treatment resulted from the oxidation of tagged I- in the presence of collagen. The protein was purified by chromatography and successive dialyses, and diluted in unlabeled collagen for subsequent manipulation. Skin applications were made in sorbic acid solution at 0.3% and at 10% in a cosmetic cream. Skin penetration for the same periods as previously was followed by the same sectioning technique. The penetration reached a maximum after 15 min and was greater for the cream than for the solution. Metabolic studies showed that 15 days after application the residual radioactivity was present mainly in the lymphatic glands and in the skin. Treated skin showed more activity than untreated areas. At the end of 10 days the radioactivity excretion dropped to very low levels. Chromatography on molecular sieve of the collagen extracted from the deeper layers of the skin indicated that the largest part of the radioactivity originated in peptide chains.