Antioxidant Impact of Soft Knotwood Extracts on Human Keratinocytes Shown by NMR Metabolomic Analysis

The Pinophyta family
has long
been used to protect the skin from oxidation, thanks to the action
of molecules such as stilbenes, flavonoids, and lignans, which are
particularly concentrated in knotwood. These molecules are of interest
from a cosmetic perspective. The present study focuses on four species
from larch (Larix decidua Mill.), silver
fir (Abies alba Mill.), Norway spruce
(Picea abies (L.) H.Karst), and Douglas
fir (Pseudotsuga menziesii (Mirb.)
Franco) knotwood, recovered from byproducts of the wood industry.
The molecules are extracted from knotwood and used in vitro on human keratinocytes (HaCaT). Studies quantifying reactive oxygen
species (ROS) have demonstrated its ability to eliminate hydroxyl
radicals and superoxides. Metabolomic analyses using proton nuclear
magnetic resonance (1H NMR) and multivariate statistics
(PLS-DA) demonstrated that keratinocytes modulate metabolite expression
after treatment with knot extracts. Indeed, our findings indicate
an increase in metabolites such as glutathione, glycine, glutamate,
sarcosine, taurine, and proline, which are known to reduce intracellular
oxidative stress and validate the effect on ROS levels. They also
indicate that knotwood extracts may affect membrane balance, collagen
formation, and oxidative stress levels. This study highlights the
value of metabolomic analysis in the cosmetic industry for a detailed
understanding of the mechanisms implemented in a whole cell.