Cosmetic process for attenuating wrinkles

#This application is a National Phase filing under 35 U.S.C. § 371 of PCT/EP2015/079224 filed on Dec. 10, 2015; and this application claims priority to Application No. 1462485 filed in France on Dec. 16, 2014 under 35 U.S.C. § 119. The entire contents of each application are hereby incorporated by reference.

#The present invention relates to a process for attenuating wrinkles on the skin, using a composition comprising a polysaccharide polymer bearing a carboxylic acid group grafted with a particular photoactive group, and exposure of the treated skin to light. The invention also relates to novel polysaccharide polymers bearing a carboxylic acid group grafted with a particular photoactive group.

#During the ageing process, various signs appear on the skin, which are very characteristic of this ageing, resulting in particular in a modification of skin structure and functions. The main clinical signs of skin ageing are in particular the appearance of fine lines and deep wrinkles, which increase with age.

#0.50 g (1.31 mmol) of hyaluronic acid (Hyacare® 50 from Evonik) was dissolved in 50 ml of distilled water in a round-bottomed flask covered with aluminium foil to prevent exposure to light. 0.16 g (1.25 mmol) of 4-azidoaniline was added, followed by addition of 0.27 g (1.24 mmol) of N-hydroxysulfosuccinimide and then addition of 0.24 g (1.25 mmol) of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, with stirring at room temperature (25° C.). The pH of the reaction medium was adjusted to 4.7 by adding aqueous 0.5 M sodium hydroxide solution and aqueous 0.5 M hydrochloric acid solution. The pH was maintained for 3 hours and the flask was equipped with a stopper and stirred for 66 hours. Next, the pH was readjusted to 4.7 and the reaction was continued for 6 hours, the pH being controlled as necessary.

#The reaction mixture was then introduced into a dialysis tube and dialysed in 1 liter of water for 48 hours, the water being replaced 4 times during this dialysis operation.

#The residue deposited in the dialysis tube was washed/extracted with distilled water and lyophilized to obtain a fibrous yellow-coloured solid product.