Tyrosinase inhibitors from plants

Details Tyrosinase inhibitors from plants Tyrosinase inhibitors from plants

2001-04-09

2003-02-18

Tate, Christopher R. (Department: 1651)

Drug, bio-affecting and body treating compositions

Plant material or plant extract of undetermined constitution...

C424S062000

Reexamination Certificate

active

06521267

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to a product comprising a tyrosinase inhibiting extract derived from a dicotyledonous plant species indigenous to Canada. The present invention also relates to compositions comprising the product and a suitable diluent or carrier for the treatment of skin or of fruit, vegetables or beverages. The present invention further relates to a method for identifying plant extracts that are capable of inhibiting the enzyme tyrosinase.
BACKGROUND OF THE INVENTION
Tyrosinase (tyrosine oxidase, EC 1.10.3.1) is an enzyme or closely homologous group of enzymes of universal occurrence in microbes, plants and animals. Its primary metabolic function is to catalyze the oxidative degradation of the amino acid tyrosine. This degradation takes slightly different routes in animals, plants and microbes, but the rate-controlling first steps—those catalyzed by tyrosinase—are the same in virtually all living species. In animals, including man, tyrosinase first transforms tyrosine into 3,4-dihydroxyphenylalanine (DOPA), thence to the corresponding quinone (DOPAquinone), and finally to 2-carboxy-2,3-dihydroindole-5,6-quinone (DOPAchrome) which is further converted by other enzymes to still more highly oxidized materials which include the melanin substances responsible for skin pigmentation.
Skin pigmentation thus depends upon the action of tyrosinase. If this enzyme is not active, normal pigmentation does not occur, and skin loses or fails to acquire its normal tan-to-brown coloration. The effect is independent of racial or environmental factors. Pigmentation loss manifests itself in lentigo senile, so-called “age spots”, a small-scale, patchy color loss often seen in skin of people over 50 years of age; typically the de-pigmented patches will be 1-3 mm across and can be very numerous. A more serious effect is leucodenna, a group of diseases in which large areas of skin lose their melanin and appear pink. An extreme effect is albinism, a condition in which tyrosinase enzyme is entirely dysfunctional and no pigmentation of skin (or eyes or hair) occurs.
If on the other hand tyrosinase activity is accelerated, as in sun-tanning or in some pathological conditions, the amount of melanin formed increases and skin color darkens. When the distribution of the new melanin is even and controlled, the result is a “glorious bronzed body”; but if the new melanin is patchy or produced uncontrollably, the result is pathological. Skin melanomas are sites of localized hyperactivity by tyrosinase; they are often associated with cancerous cell modification. The causal relationship of tyrosinase action to skin pigmentation was established many years ago (Mason, H. S. (1948) J. Biol. Chem. 172, 83-86; Balin, A. K. and Kligman, A. M. (1989) Aging and the Skin 372pp, Raven Press, N.Y.) and is now well-understood.
Materials which suppress the action of tyrosine oxidase are presumed to slow the build-up of skin spots over time, and this presumption is vindicated by scientific evidence. Thus, the correlation between tyrosinase inhibition and protection of skin against unwanted pigmentation is accepted by the medical profession and by the cosmetic industry.
In addition to its skin functions, tyrosinase is active in other types of living tissue in the turnover metabolism of tyrosine and in the production of pigmented materials in those tissues.
With respect to cosmetics, skin lightening and skin darkening have been practiced since earliest times, and today these are mainstays of some sectors of the world cosmetics industry. Skin lightening has traditionally been accomplished by rigorously excluding sunlight from skin, or by the use of chemical lightening agents. One such agent is synthetic hydroquinone (1,4-dihydroxybenzene). This substance is considered the cosmetic industry standard for tyrosinase inhibition potency.
SUMMARY OF THE INVENTION
Prior to the present invention, the possibility of finding effective tyrosinase inhibitors in dicotyledonous plant species indigenous to Canada had not been appreciated.
Accordingly, the present invention provides a product comprising an extract derived from a dicotyledonous plant species indigenous to Canada, wherein the extract inhibits tyrosinase. Preferably, the extract is derived from a plant species selected from Polygonaceae, Rosaceae and Onagraceae. The extract is preferably derived from one or more parts of the plant selected from leaves, twigs, flowers, flowering aerials, fruiting aerials, seeding aerials, roots and fruits.
Preferably, the extract is derived from the group consisting of:
flowering aerials of
Artemisia campestris
(plains wormwood);
flowering aerials of
Aster ericoides
(white prairie aster);
flowering aerials of
Aster hesperius
(willow aster);
leaves, twigs and flowers of
Cornus stolonifera
(red-osier dogwood);
leaves and twigs of
Cotoneaster acutifolia
(cotoneaster);
flowering aerials of
Epilobium angustifolium
(fireweed);
seeding aerials of
Euphorbia esula
(leafy spurge);
fruiting aerials of
Fragaria americana
(wild strawberry);
fruiting aerials of
Fragaria glauca
(Wild strawberry);
flowering aerials of
Geranium bicknelli
(Bicknell's geranium);
flowering aerials of
Geum aleppicum
(yellow avens);
flowering aerials of
Geum triflorum (
3-flowered avens);
flowering aerials of
Glycyrrhiza lepidota
(wild licorice);
flowering aerials of
Hedysarum americanum (American hedysarum);
roots of
Heuchera richardsonii
(alumroot);
flowering aerials of
Oenothera biennis
(yellow evening-primrose); flowering aerials of
Polygonum persicaria
(lady's-thumb);
flowering aerials of
Potentilla fruticosa
(shrubby cinquefoil);
flowering aerials of
Potentilla norvegica
(rough cinquefoil);
flowering aerials of
Rosa acicularis
(prairie rose);
fruiting aerials of
Rosa arkansana
(low rose);
fruiting aerials of
Rumex maritimus
(golden dock);
fruiting aerials and flowering aerials of
Rumex occidentalis
(western field dock);
fruiting aerials and fruits of
Rumex pseudonatronatus
(field dock); and
fruits of
Rumex stenophyllus
(narrow-leaved dock).
The present invention also provides a composition comprising the product as defined herein, together with a cosmetically or pharmaceutically acceptable, or edible, diluent or carrier. The composition is preferably for cosmetic treatment of skin or for inhibiting browning of edible products. The composition is more preferably for skin lightening, even more preferably to reduce melanin and/or melanogenesis. The at least one plant extract in the composition is preferably selected from the group consisting of:
fruiting aerials of
Rumex maritimus
(golden dock);
fruiting aerials of
Rumex occidentalis
(western field dock);
flowering aerials of
Rumex occidentalis
(western field dock);
fruiting aerials of
Rumex pseudonatronatus
(field dock);
fruits of
Rumex pseudonatronatus
(field dock); and
fruits of
Rumex stenophyllus
(narrow-leaved dock).
The present invention also provides a method for detecting tyrosinase inhibiting activity in an extract derived from a dicotyledonous plant species indigenous to Canada. This method comprises:
a) preparing a first solution comprising an amount of tyrosinase and a suitable substrate;
b) preparing a second solution comprising the same amount of tyrosinase and the suitable substrate and further comprising an amount of the extract;
c) measuring tyrosinase activities of the first and second solutions by suitable methods;
d) comparing the tyrosinase activities of the first and second solutions; and
e) detecting tyrosinase inhibiting activity, present when the tyrosinase activity of the second solution is less than the tyrosinase activity of the first solution.
It is preferable that the tyrosinase inhibiting activity is comparable to, or greater than, that of hydroquinone.


REFERENCES:
patent: 5980904 (1999-11-01), Leverett et al.
patent: 6068834 (2000-05-01), Kvalnes et al.
patent: 6174533 (2001-01-01), SaNoguira et al.
patent: 57-163307 (1982-10-01), None
patent: 60-214721 (1985-10-01), None
patent: 62-029528 (1987-02-01),

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