Evaluating the advantages and disadvantages of natural ingredients in comparison to synthetic was a central theme of the Cosmetic Science Symposium held in the UK in May.
The majority of speakers and delegates were against the idea that natural is inherently safer or more effective, arguing for a palette containing both.
However, Professor Peter Houghton, from Kings College London, explained why in some cases the complexity of natural extracts might make them more effective than isolated compounds.
Synergy and polyvalence were described by Houghton as the two ways in which an extract made up of different component parts could have a stronger effect than a single active compound.
Two plus two is seven
“Synergy is when compounds with similar actions give stronger effects than would be expected, a sort of two plus two equals seven effect,” explained Houghton.
According to Houghton, synergy is very difficult to prove scientifically and polyvalence, where different compounds with different activities all contribute to an overall effect, is more frequent.
This can be particularly useful if the problem you wish to tackle is a complex process involving many different pathways, for example wound healing or skin lightening, he said.
Houghton outlined South African research that focused on plants traditionally used for skin lightening.
“The work showed many of the plants had tyrosinase [an enzyme involved in the production of melanin] inhibiting factors but also strong antioxidant properties which may also contribute to the melanin inhibiting effect,” he said.
However, in the pharmaceutical world, the polyvalence of an extract is a problematic concept and the drug regulatory system is geared to single chemical entity drugs, which means extracts are not always accepted by the establishment, Houghton argued.
This message was echoed by perfumer George Dodd, who works both with natural and synthetic fragrance materials.
According to Dodd the molecular complexity of natural fragrances is what sets them apart from their synthetic counterparts, as creating that in a laboratory can be both time consuming and costly.
But this complexity brings with it regulatory issues, argued Tony Burfield of CropWatch UK, an NGO that campaigns against what it claims to be the over restrictive regulation regarding natural fragrances.
“Under existing legislation natural ingredients are treated as a mix of chemicals. Essential oils often contain more than one of the known allergens that have to be included on cosmetic labels,” he said.
Burfield argued that such a reputation is undeserved and the over cautious regulation is damaging the trade in natural fragrances.
Mathias Vey, from industry body IFRA, argued that natural fragrances were not discriminated against by the regulatory bodies, rather the scientific data was considered regardless of their origin.