In recent years much has been published highlighting the potential of certain plant polyphenols to protect against UV-induced skin damage; and a number of new studies are investigating the possibilities of combining the plant-based ingredients with the more traditional inorganic and organic sunscreens.
Combining plant ingredients with traditional sunscreens
Recent work from researchers in Brazil investigated combining the polyphenols found in the Passiflora incarnate L. (a climbing vine) and Plantago lanceolata (a perennial herb) and the flavonoid rutin with organic and inorganic filters.
Formulations that contained the methoxycinnamate, benzophenone-3, titanium dioxide and the plant-based ingredients performed better in terms of both SPF and the UVA protection, according to the researchers.
Although there were complications – combining some ingredients seemed to have negative effects on the protection – the work shows definite promise particularly as calls for improved protection, especially at the UVA end of the spectrum, are increasing.
Furthermore, new compounds that might have significant protective potential are being discovered.
Work from L’Oréal scientists, published in a recent issue of the Journal of Cosmetic Dermatology, highlighted phloretin, found in the skin and flesh of apples.
According to the researchers, phloretin is a new addition to the antioxidant sun protection portfolio and holds particular promise due to its superior bioavailability. As getting through the skin barrier is a major problem for many cosmetic ingredients, this could make the ingredient particularly attractive to formulators.
The L’Oréal researchers found that a cocktail of three ingredients; ferulic acid, phloretin and vitamin C, provided significant protection against the UV-induced damage to the skin.
Green tea without side effects
In addition, recent work on green tea, well known for its protective qualities, suggests the compound may be used to protect against UV damage without its staining side effect that has so far made it unpopular as a cosmetic ingredient.
Research from scientists in Switzerland looked at the effects of applying low concentrations of green tea extracts, which will not stain, over a sustained period of time.
According to the study, led by Dr Christian D. Mnich from the University Hospital of Zurich, topical application of the green tea extract at 0.4 per cent over a five week period exhibited significant photochemoprotective effects.
When commenting on the work being done in this area, Dr David Gems a researcher in the biology of ageing at University College London, said these plant-based compounds that stimulate the antioxidant defence systems hold great promise.
In comparison to substances that themselves have antioxidant properties, such as vitamin E, the compounds that stimulate a broad range of enzymes involved in antioxidant defence are much more effective, he said.
“This is a whole arsenal of defences against molecular damage, [in comparing antioxidants like vitamin E to those substances that stimulate antioxidant defence like green tea] we are comparing a pea shooter to an artillery battle,” said Gems.