Compounds provided with antioxidant activity against free radicals, and pharmaceutical and cosmetic compositions containing them

This is a U.S. national stage entry of International Application No. PCT/IB2011/051767, filed on Apr. 22, 2011, which in turn claims priority to Italian Patent Application No. MI2010A000691, filed on Apr. 22, 2010, each of which is hereby incorporated by reference herein in its entirety.

The present invention relates to compounds provided with antioxidant activity against free radicals, for use as active ingredients for preparation of pharmaceutical or cosmetic compositions.

Antioxidant activity against free radicals has been and is the object of numerous studies both in the pharmaceutical field and in the cosmetic field. For example, EP1328268 B1 of the same applicant relates to a composition provided with said kind of activity produced by certain flavonoids extracted from red wine, in particular a combination of quercetin and catechin active ingredients formulated for oral use, which can be used in various applications in the pharmaceutical or nutritional or cosmetic field essentially based on said antioxidant activity against free radicals.

According to the present invention, it has now been found, surprisingly, that a remarkable antioxidant activity against free radicals is generated by compounds of general formula (I):

CH 3 (—CH═CH) 3 —R  (I)

wherein R is selected from CO—O—R′ or CO—O (−) , R′ being selected from H, alkyl or alkenyl from C 1 to C 22 , or sugars, and their pharmaceutically acceptable salts, preferably such as sodium, potassium, or lysine salts.

An experimental study, reported hereunder in the present description, in fact showed that surprisingly for said compounds of the invention it is possible to obtain significant antioxidant activity against free radicals.

The invention also relates to pharmaceutical and cosmetic compositions derived therefrom, each compound of general formula (I) being used in said compositions as such or mixed with the others.

The invention therefore relates to the use of the compounds of formula (I) as active ingredients for any therapeutic or cosmetic application in which said antioxidant activity against free radicals produces an advantageous effect. In particular this relates to applications on the human skin and scalp to combat the oxidant action of free radicals and preserve the physiological conditions of the epidermis and of the hair subjected to said action.

Characterizing data and formulae of some of the preferred compounds of general formula (I) are given below, with reference to octatrienoic acid and its salts or esters:

C 8 H 10 O 2 MW 138.17

2E,4E,6E-Octa-2,4,6-trienoic acid

CAS #: 5205-32-3

C 8 H 9 O 2 .K MW 176.26

2E,4E,6E-Octa-2,4,6-trienoic acid potassium salt

CAS #: 1147842-10-1

C 8 H 9 O 2 .Na MW 160.15

2E,4E,6E-Octa-2,4,6-trienoic acid sodium salt

CAS #: not available

C 8 H 9 O 2 .C 6 H 15 N 2 O 2 MW 284.36

2E,4E,6E-Octa-2,4,6-trienoic acid L-lysine salt

CAS #: not available

C 10 H 14 O 2 MW 166.22

2E,4E,6E-Octa-2,4,6-trienoic acid ethyl ester

CAS #5941-49-1

A composition of the invention is preferably formulated for topical administration on the skin or on the scalp, and comprises said active ingredient in a quantity ranging from 0.0003 to 0.0036 mol/100 g.

This range corresponds to a range from 0.04 to 0.6 wt. % of the composition for octatrienoic acid, or for the corresponding sodium or potassium salt or for the corresponding ethyl ester, whereas it corresponds to a range from 0.11 to 1.4 wt. % of the composition in the case of the corresponding lysine salt.

Examples are given below—not intended to be in any way limiting—of compositions suitable in particular for the cosmetic use specified herein.

The quantities of the components, identified according to the INCI nomenclature, are expressed as percentages by weight varying over the stated ranges:

FIGS. 1 and 2 of the appended drawings show graphs taken from an experimental study as described hereunder.

Experimental Study: In-Vitro Evaluation of the Antioxidant Effects of the Compounds of the Invention

The purpose of the study was to evaluate in vitro the modulation of the production of ROS (reactive oxygen species), according to FIG. 1 , and lipid lipoperoxidation, according to FIG. 2 , by the following compounds of the invention:

compound 1: 2E,4E,6E-octatrienoic acid

compound 2: potassium 2E,4E,6E-octatrienoate

compound 3: 2E,4E,6E-octatrienoic acid, L-lysine salt,

compared with a control.

Experimental Models

Two cellular systems were used: NCTC 2544, a line of human keratinocytes, and THP-1, a human promyelocytic line. The results were expressed as mean±standard deviation. Each experiment was repeated at least twice.

Parameters Evaluated and Results Obtained

a) Modulation of the Production of ROS

Tributyltin (TBT) and lipopolysaccharide (LPS) are used as endogenous inducers of radical species. The production of ROS was evaluated by cytofluorometry techniques for the THP-1 cell line, using DCFH as stain.

The optimum times and concentrations for cytofluorometric measurement of ROS were identified in preliminary experiments.

The vitamin E derivative 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox), at a concentration of 100 μM, was used as positive control.

The results obtained are shown in the graph in FIG. 1 .

The THP-1 cells were treated for 1 hour with compounds 1 and 2 of the invention at a concentration of 100 μg/ml, with compound 3 at a concentration of 200 μg/ml and with Trolox 100 μM in serum-free medium, loaded in the last 30 minutes with DCFH (10 μM) and then treated in the presence or absence of LPS (0.1 μg/ml) and analysed in the cytofluorometer. As can be seen from the graph, the compounds of the invention proved to be capable of nullifying the production of ROS induced by LPS 0.1 μg/ml to an extent not less than Trolox.

b) Lipid Lipoperoxidation

Lipid peroxidation was evaluated on the NCTC 2544 cells by measuring the content of malondialdehyde, one of the main by-products of lipid peroxidation, through its reactivity with thiobarbituric acid. The results are expressed as absorbance/mg protein. The protein content was evaluated by the Bradford method.

The NCTC cells were treated for 24 hours in the presence or in the absence of the maximum tolerated concentration of said compounds 1, 2, 3, and then stimulated with TBT 1-2.5 μM for a further 24 hours.

Trolox 100 μM was used as positive control.

The results obtained are presented in the graph in FIG. 2 .

As can be seen, for the cells treated with said compounds 1, 2, 3, a statistically significant (p<0.05) decrease of lipoperoxidation induced by TBT 2.5 μM was observed at 24 hours, confirming the effect of the invention.