Tyrosinase inhibitors from plants

Abstract

The present invention provides tyrosinase inhibiting extracts from dictotyledonous plant species indigenous to Canada and compositions containing the extracts for the treatment of skin, particularly skin lightening. The present invention also provides a method of detecting tyrosinase activity in an extract of a dicotyledonous plant species indigenous to Canada.

1 . A product comprising an extract derived from a dicotyledonous plant species indigenous to Canada, wherein the extract inhibits tyrosinase.  
     
     
         2 . The product according to  claim 1 , wherein the extract is derived from a plant species selected from Polygonaceae, Rosaceae and Onagraceae.  
     
     
         3 . The product according to  claim 1 , wherein the extract is derived from one or more parts of the plant selected from leaves, twigs, flowers, flowering aerials, fruiting aerials, seeding aerials, roots and fruits.  
     
     
         4 . The product according to  claim 1 , wherein 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 or 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).    
     
     
         5 . A composition comprising the product as defined in  claim 1 , together with a cosmetically or pharmaceutically acceptable, or edible, diluent or carrier.  
     
     
         6 . A composition comprising the product as defined in  claim 4 , together with a cosmetically or pharmaceutically acceptable, or edible, diluent or carrier.  
     
     
         7 . The composition according to  claim 5 , wherein the diluent or carrier is cosmetically acceptable and the composition is for cosmetic treatment of skin.  
     
     
         8 . The composition according to  claim 7 , wherein the extract is derived 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).    
     
     
         9 . The composition according to  claim 8 , which further comprises ascorbic acid.  
     
     
         10 . Use of the composition according to  claim 7  as a skin lightener.  
     
     
         11 . Use of the composition according to  claim 7  to reduce melanin and/or melanogenesis in skin.  
     
     
         12 . The composition according to  claim 5 , wherein the diluent or carrier is edible and the composition is for treating edible products to inhibit browning.  
     
     
         13 . A method for detecting tyrosinase inhibiting activity in an extract derived from a dicotyledonous plant species indigenous to Canada, which 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 a tyrosinase activity of each of the first and second solutions;    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.    
     
     
         14 . The method according to  claim 13 , wherein tyrosinase activity is measured spectrophotometrically.  
     
     
         15 . The method according to  claim 13 , wherein the substrate is L-DOPA.  
     
     
         16 . The method according to  claim 13 , wherein the tyrosinase inhibiting activity is equal to, or greater than, that of hydroquinone (1,4-dihydroxybenzene).  
     
     
         17 . The method according to  claim 13 , wherein 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 or 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).    
     
     
         18 . The method according to  claim 17 , wherein the extract is derived 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).    
     
     
         19 . A tyrosinase inhibiting plant extract having tyrosinase inhibiting potency at least equal to hydroquinone.