FIELD OF THE INVENTION

The invention relates to a method, a composition and use of certain peptides for modulating the colour of human skin, particularly to increase the amount of melanin in melanocytes which are present in our skin and hair.

BACKGROUND OF THE INVENTION

Some people are concerned with certain characteristics of their skin. For example, consumers with age spots or freckles often wish that such pigmented spots be less pronounced. Some others may wish to address darkening of skin caused by exposure to sunlight or alternatively may wish to lighten their natural skin color. These needs of consumers led to the development of products that reduce or delay the production of melanin in melanocytes (i.e. reduce melanogenesis).

On the other hand, there are people who desire darker skin tone or a tanned look.

The melanocytes transfer melanin to the keratinocyces which are in their vicinity where it (melanin) serves to protect cellular DNA from UV-induced damage by virtue of its ability to absorb UV-radiation. When the skin is exposed to UV light, the synthesis of melanin increases as does the transfer of melanin to the keratinocytes. This results in visible darkening of the skin color, which is known as a tan. Tanning due to over exposure to UV radiation is a known phenomenon. However, it is also known that such exposure to UV radiation causes accelerated aging which may lead to increased incidences of skin cancer.

Melanin is the black pigment present in our hair and skin and is synthesized by melanosomes from tyrosine. Melanosomes are organelles found in melanocytes, a cell type present at dermis-epidermis junction. Tyrosine is acted upon by an enzyme, tyrosinase, which is the key step in melanogenesis.

In the melanosomes, the melanin is synthesized from monomers and is transferred to the neighboring cells called keratinocytes. The keratinocytes divide and differentiate and thus transport the melanosome to the surface of the skin. The shade or hue of the colour of our skin depends on the number and the size of melanocytes, the melanin content and the rate of formation and migration/transfer of melanosomes to keratinocytes.

There are some peptides/peptidic derivatives known to affect pigmentation of skin. Particularly, tyrosine-containing peptides are known to be directly acted upon by Tyrosinase [Yasunobu et al. J. Biol. Chem. (1959) 234, #12, 3291-3295].

Tyrosine based Pentapeptide activators of Tyrosinase are known (US20150152139 A1, Escape Therapuetics Inc). One of the sequence entries therein is Tyrosine-Serine-X-Y-Z

On the other hand, longer hexameric (U.S. Pat. No. 8,338,364 B2, Hantash Basil M, 2011) and octameric peptides (Schurink et al. Peptides 28 (3):485-495) have been reported as tyrosinase inhibitors.

US2015/0274776 AA (Sederma) discloses peptides containing the amino acid Proline.

SUMMARY OF THE INVENTION

In accordance with a first aspect is disclosed use of a compound of the formula (I) to increase the amount of melanin in melanocytes.

In accordance with a second aspect is disclosed a cosmetic composition comprising a compound of the formula (I).

In accordance with another aspect is disclosed a method of increasing the amount of melanin in melanocytes, comprising a step of applying thereto a compound of the formula (I).

In accordance with another aspect is disclosed use of a compound of the formula (I) in the manufacture of a composition for increasing the amount of melanin in melanocytes.

These and other aspects, features and advantages will become apparent to those of ordinary skill in the art from a reading of the following detailed description and the appended claims. For the avoidance of doubt, any feature of one aspect of the present invention may be utilised in any other aspect of the invention. The word “comprising” is intended to mean “including” but not necessarily “consisting of” or “composed of.” In other words, the listed steps or options need not be exhaustive. It is noted that the examples given in the description below are intended to clarify the invention and are not intended to limit the invention to those examples per se. Similarly, all percentages are weight/weight percentages unless otherwise indicated. Except in the operating and comparative examples, or where otherwise explicitly indicated, all numbers in this description indicating amounts of material or conditions of reaction, physical properties of materials and/or use are to be understood as modified by the word “about”.

Numerical ranges expressed in the format “from x to y” are understood to include x and y. When for a specific feature multiple preferred ranges are described in the format “from x to y”, it is understood that all ranges combining the different end points are also contemplated.

As used herein the term “comprising” encompasses the terms “consisting essentially of” and “consisting of”. Where the term “comprising” is used, the listed steps or options need not be exhaustive. Unless otherwise specified, numerical ranges expressed in the format “from x to y” are understood to include x and y. In specifying any range of values or amounts, any upper value or amount can be associated with any particular lower value or amount. Except in the examples and comparative experiments, or where otherwise explicitly indicated, all numbers are to be understood as modified by the word “about”. All percentages and ratios contained herein are calculated by weight unless otherwise indicated. As used herein, the indefinite article “a” or “an” and its corresponding definite article “the” means at least one, or one or more, unless specified otherwise. The various features of the present invention referred to in individual sections above apply, as appropriate, to other sections mutatis mutandis. Consequently, features specified in one section may be combined with features specified in other sections as appropriate. Any section headings are added for convenience only, and are not intended to limit the disclosure in any way.

