Tuesday, February 7, 2012
Essential oils: Lemongrass - assorted effects
I thought this was a really interesting study on rats and spatial memory and citral! "Although some central effects of citral have been reported, cognitive effects on spatial memory have not been investigated. The evidence showed that citral can regulate the synthesis of retinoic acid (RA), which exerts a vital function in the development and maintenance of spatial memory...The low dose (0.1 mg/kg) of citral improved the spatial learning capability, and enhanced the spatial reference memory of rats, whereas the high dose (1.0 mg/kg) was like to produce the opposite effects. Meanwhile, the low dose of citral increased the hippocampal retinoic acid concentration, while the high dose decreased it. Due to the quick elimination and non-bioaccumulation in the body, effects of citral on spatial memory in this study seemed to be indirect actions. The change in hippocampal retinoic acid concentration induced by different doses of citral might be responsible for the biphasic effect of citral on spatial learning and memory." So it does work on rats at lower levels, but not at higher levels? Considering how much citral is used in flavouring and fragrancing products, I wonder if more work shouldn't be done to see how much we can handle in our products? It might quite interesting...
CITRAL AS A SENSITIZER AND POTENTIAL ALLERGEN
From this paper: "Citral is one of 26 fragrance materials identified as a suspected cause of allergic contact dermatitis by the European Commissions advisory committee...the directive requires that citral be listed on the ingredient label of consumer products when present at greater than 10 ppm for leave-on cosmetic products and 100 ppm for rinse-off cosmetics." From the conclusions: "The chemical structure and properties of citral suggest that it would have the potential to act as a contact sensitizer...the data reported here show by a weight of evidence that the human NOEL for induction of sensitization to citral is 1400 μg/cm2." (This was tested in alcohol. It's higher when it's used in petroleum, 2759 μg/cm2.)
What does this mean? I think...and I could be wrong here...that we don't want to use more than 5.7% citral in our products. If 1414 μg/cm2 is equal to about 5.7%, then 1400 μg/cm2 is in the same ballpark. Considering that lemongrass is up to 85% citral, I wouldn't use more than 6.5% lemongrass essential oil in a product. I don't think you're going to do that - I wouldn't go over 1% for most essential oils without doing some serious research first - but it's good advice.
Join me tomorrow for a few ideas on how we can use lemongrass essential oil in our products!