WO2005058273A1

WO2005058273A1 - Compositions containing methylthioadenosine (mta) and topical use thereof

Info

Publication number: WO2005058273A1
Application number: PCT/EP2004/053044
Authority: WO
Inventors: Cesare Sangalli; Alberto Reiner; Giorgio Reiner
Original assignee: Apr Applied Pharma Research Sa; M & A Casini Snc
Priority date: 2003-12-05
Filing date: 2004-11-22
Publication date: 2005-06-30
Also published as: ITMI20032393A1

Abstract

This document describes the use of methylthioadenosine (MTA) for the preparation of compositions for topical use for the treatment of irritated, inflamed and/or erythematous skin primarily after exposure to UV radiation and/or atmospheric agents. Methylthioadenosine is present in said compositions in a quantity of between 0.05% and 2% by weight, preferably between 0.2% and 1 by weight.

Description

Compositions containing methylthioadenosine (MTA) and topical use thereof. The present invention describes topical formulations comprising methylthioadenosine (MTA) and the use thereof for the treatment of delicate, sensitive, easily reddened and irritable skin. Methylthioadenosine (MTA) corresponds chemically to the molecule 5'-deoxy- 5'-(methylthio)adenosine and may be considered as a metabolite of S- adenosylmethionine.

Methylthioadenosine (MTA) should also be considered as a physiological molecule which plays a primary role in cellular metabolism; this is because, within eukaryotic cells, MTA is catabolised by the enzyme MTA phosphorylase into adenine and 5-(methylthio)ribose 1 -phosphate.

Methylthioadenosine (MTA) gives rise, by means of the transsulfuration pathway, to the majority of endogenous sulfur compounds, including cysteine, which is itself considered a good sulfur donor.

MTA accordingly supplies tissues with sulfur, an element which is essential to the formation of SH groups and thus to the formation of disulfide bonds (S-S).

It is known that sulfur and the associated S-S bonds are an essential component in the skin's structure, determining its balance, firmness and elasticity; in particular, sulfur is involved in the keratinisation process which leads to the formation of the horny layer of the epidermis. The epidermis is the part of the skin which is most directly in contact with the environment and performs an essential protective function with regard to the aggressions of the external environment.

Another important characteristic of methylthioadenosine (MTA) is its antiinflammatory and protective action towards inflammatory phenomena.

MTA has previously been used as an active molecule in trichological applications:

EP387757 describes the use of MTA in pharmaceutical formulations which are useful in the treatment of baldness, EP387757 describes its use in pharmaceutical formulations for the treatment of seborrhoea and desquamation of the scalp, or as an agent which modulates the production of melanin: US5998423 describes the use of MTA as an antagonist to one of the receptors which controls the production of melanin in the skin and hair. The present invention provides topical compositions with an antireddening and dermoprotective action containing methylthioadenosine (MTA) and the use thereof for skin which is sensitive, irritated by exposure to external agents (cold, wind, sun etc.) or erythematous (sun, contact etc.).

The present invention also provides topical compositions containing methylthioadenosine (MTA) in association with other active ingredients with a soothing and restorative action such as for example aloe, ceramides, vegetable oils, essential oils, vitamins, inorganic salts, bisabolol, zinc oxide, shea butter, potassium glycyrrhizinate, sodium hyaluronate, sulfated polysaccharides extracted from seaweeds etc. and the use thereof in the treatment of sensitive and reddened skin.

The compositions of the present invention may be formulated in a cream, pomade, ointment, lotion, emulsion, gel, milk or cleanser to be applied topically onto the reddened, inflamed or erythematous skin several times daily or as an after sun preparation; preferably in an after sun cream and milk.

The compositions of the invention may preferably be formulated in the form of an oil/water or water/oil cream; more preferably an oil/water cream, or in the form of a gel or as a milk, more preferably as an after sun milk.

The compositions of the present invention contain the active ingredient methylthioadenosine (MTA) in a quantity of between 0.05% and 2% by weight, preferably between 0.2% and 1% by weight, optionally in association with other active ingredients and suitable excipients and auxiliary substances in an appropriate quantity relative to the active ingredient. EXPERIMENTAL SECTION Toxicological testing

Toxicological studies were performed on the product methylthioadenosine (MTA) in order to ascertain the absence of toxic effects of the substance in question; the tests performed are described below. 1) Acute oral toxicity of MTA

The test was performed on 5 female rats weighing between 190 and 201 g. The substance under investigation was prepared as an aqueous solution of a concentration of 200 mg/ml. The test sample, in an amount of 2000 mg of MTA/kg of animal body weight, was administered in a single dose via a gastro- oesophageal tube. The general condition of all the animals was observed daily for 14 days. All activities relating to the study, together with the observations and examinations were recorded daily on forms which were dated and signed. The following parameters were monitored during the study:

- mortality: no mortality was recorded during the study;

- clinical symptoms: the treated animals exhibited piloerection;

- weight gain: the weight gain of the treated animals was in line with the standard for the species and breed during both the first and the second week of the study. Conclusions: on the basis of the results obtained, the substance under investigation (MTA) is found to have acute oral toxicity in the rat of >2000 mg/kg and, according to OECD test no. 420 of 17.12.01, the substance MTA falls within category 5 of the GHS classification.

2) In vitro analysis of the pro-sensitising potential of the functional ingredient (MTA) for cosmetic use.

Test performed at the University of Pavia (Department of Physiological, Pharmacological, Cellular, Molecular Sciences). The test was performed on a monocyte cell line designated U937. Modulation of the expression of two costimulatory molecules CD80 and CD86 was evaluated on these cells using stimulation with typical sensitising substances such as nickel sulfate and a methylchloroisothiazolinone/methylisothiazolinone mixture as positive controls. The product was used at two different dilutions, 0.4 and 0.08 mg/ml. The samples were then dissolved in ethanol and added to the culture medium (RPMI-1640 + 10% FCS) in such a manner as to obtain the desired final concentration in contact with the cells. After 48 hours' contact with the product under test and with the various controls, the cells were examined for vitality with Trypan Blue staining and microscopic observation in a cell-counting chamber, were harvested, washed in an isotonic buffer (PBS) and labelled with a fluoresceinated antibody. On the basis of the analyses performed, MTA did not exhibit any detectable pro- sensitising action.

3) Epicutaneous test to evaluate the irritant potency of the functional ingredient MTA for cosmetic use. Test performed at the University of Pavia (Department of Physiological, Pharmacological, Cellular, Molecular Sciences), test report no. F730703P. The test was performed on 25 healthy volunteers of both sexes aged between 18 and 60 onto whose skin approx. 20 μg of solid product were applied. The area of skin preselected for the test (back) is cleaned with a 70% alcohol solution in order to make it more sensitive to the action of the product.

The product is applied onto the volunteers' skin by means of the "Finn Chambers" device, a 7 mm diameter aluminium chamber containing a disk of absorbent paper as a support for a known quantity of the sample under investigation; using the Finn Chambers device ensures good occlusion of the applied substance under examination. The product is applied onto the skin for a duration of 48 hours. The skin reactions are clinically evaluated 15 minutes, 1 hour and 24 hours after removal of the Finn Chambers device. After removal of the patch, the volunteers are subjected to clinical analysis to detect the presence of erythema and oedema. On the basis of the results obtained, the product MTA should be considered non- irritant.

4) In vitro evaluation of the ocular irritation potential (cytotoxicity) of a product containing MTA.

Test performed at the University of Pavia (Department of Physiological, Pharmacological, Cellular, Molecular Sciences). The test is performed on human keratinocytes in a monolayer by measuring the IC₅₀ (product concentration required to inhibit cell growth by 50%) relative to a reference substance (sodium dodecyl sulfate) acting as the positive control. The sample under investigation (MTA) did not exert cytotoxic effects on keratinocytes in vitro and the product consequently potentially has no cytotoxic/irritant action on the eyes. Efficacy test

Short term test to evaluate the antireddening action of the functional ingredient MTA fo/w cream. 0.5% MTA1 using the Mexameter MX18. The test performed on healthy volunteers to evaluate the antireddening action of the oil/water cream containing 0.5% MTA versus a placebo and versus no treatment is described below. Three healthy volunteers of both sexes aged between 25 and 65 were selected on the basis of the following inclusion criteria: • good state of general health; • absence of skin conditions; • absence of ongoing pharmacological treatment; • negative history for atopy.

The product used to carry out the present test was formulated as described in Table I below. Table I

The samples were tested by being applied uniformly onto specific areas (forearm) which had previously been treated with sodium lauryl sulfate (SLS) with the aim of inducing irritation. The products were applied in their natural state. Three areas were selected on the volunteer's forearm in which an erythematous reaction of identical intensity was produced by application of SLS. The reddening caused was measured quantitatively using the MEXAMETER MX 18 instrument. Onto two of the areas were applied respectively the antireddening cream with MTA and the associated placebo, while the third area was not treated and acted as a control. After 5, 15 and 30 minutes had elapsed after application of the products, the differences in skin reddening between the three areas were evaluated by means of the MEXAMETER MX 18. Burns, mechanical pressure, rubbing, heat or chemicals can bring about erythematous phenomena on the skin's surface. The MEXAMETER MX 18 instrument specifically measures the skin's haemoglobin content. Measurement is based on the absorption principle. The special probe of said apparatus emits lights of three specific wavelengths. A receiver ensures that the light reflected from the skin is measured. Two different wavelengths are used to measure erythema: one corresponding to the spectral absorption of the haemoglobin absoφtion peak, the other is selected to avoid colorimetric interference by other pigments. The results appear on a digital display with a scale running from 0 to 999. The results shown on the following pages summarise the values recorded by the instrument. It must be emphasised that there are no standard references because the erythema value is individual. The instrumental evaluation is complemented by a clinical evaluation by the dermatologist, to which end the variation in erythema is rated in accordance with the clinical score shown in the table below:

In conclusion, the MTA antireddening cream exhibits immediate "antireddening" action in the volunteers subjected to clinical testing. In contrast, in the area of skin onto which the cream without MTA (placebo) was applied, the erythema declines over much longer periods, comparable with those recorded on the untreated area. The above-stated instrumental and clinical results are shown in Tables A-F below and the corresponding attached Figures 1-6. MTA cream

Clinical evaluation Table A

The erythema induced by contact of the skin with SLS was very clearly alleviated by the action of the MTA cream in 2 of the 3 healthy volunteers in as little as 5 minutes after application of the cream; within 15 minutes of application of the cream, all the volunteers exhibited a clearly visible reduction in erythema. Instrumental evaluation Table B

The instrumental data obtained by means of the MEXAMETER confirm the above-stated clinical evaluations (Table A and Figure 1 : within iust 5 minutes of application of the MTA cream, there has already been a significant reduction in the skin reddening caused by contact with SLS. Placebo cream Clinical evaluation Table C

Instrumental evaluation Table D

Untreated area of skin Clinical evaluation Table E

Instrumental evaluation Table F

The attached Figures 7 and 8 summarise the above-stated clinical and instrumental data.

EXAMPLES

Some of the compositions provided by the present invention are described in greater detail in the following Examples, which should not be considered to limit, but instead merely to illustrate the invention.

The compositions shown may be prepared in accordance with standard methods known to the person skilled in the art. EXAMPLES 1-3^* Antireddening cream, batches LCXVI/103, 103a, 103b

EXAMPLES 4-6

After sun milk, batches LCXVI/105, 105a, 105b

Claims

CLAIMS 1. Use of methylthioadenosine (MTA) for the production of compositions for topical use for the treatment of irritated, inflamed and/or erythematous skin.

2. Use of methylthioadenosine (MTA) according to claim 1 following exposure to UV radiation and/or to atmospheric agents.

3. Use of methylthioadenosine (MTA) according to any one of the preceding claims, in which the methylthioadenosine is present in a quantity of between 0.05% and 2% by weight, preferably between 0.2% and 1% by weight.

4. Use of methylthioadenosine (MTA) according to any one of the preceding claims, in which the methylthioadenosine (MTA) is associated with at least one other active ingredient.

5. Use of methylthioadenosine (MTA) according to claim 4, in which said other active ingredient is selected from among: aloe, ceramides, vegetable oils, essential oils, vitamins, inorganic salts, bisabolol, zinc oxide, shea butter, potassium glycyrrhizinate, sodium hyaluronate, sulfated polysaccharides extracted from seaweeds.

6. Use of methylthioadenosine (MTA) according to claims 1-5, in which said compositions are in the form of a cream, pomade, lotion, gel, emulsion, milk or cleanser.

7. Use of methylthioadenosine (MTA) according to claim 6, for use as an after sun preparation.

8. Dermoprotective compositions containing methylthioadenosine (MTA) together with excipients and/or auxiliary substances.

9. Compositions according to claim 8, for use as an after sun preparation.

10. Compositions according to any one of the preceding claims, in which methylthioadenosine (MTA) is present in a quantity of between 0.05% and 2% by weight, preferably between 0.2% and 1% by weight.

11. Compositions according to any one of the preceding claims, in which methylthioadenosine (MTA) is present in association with at least one other active ingredient.

12. Compositions according to claim 11, in which said other active ingredient is selected from among: aloe, ceramides, vegetable oils, essential oils, vitamins, inorganic salts, bisabolol, zinc oxide, shea butter, potassium glycyrrhizinate, sodium hyaluronate, sulfated polysaccharides extracted from seaweeds.

13. Compositions according to claims 8-12 in the form of a cream, pomade, lotion, gel, emulsion, milk or cleanser.