Plants have the special faculty to produce their own nutrients, proteins, carbohydrates, and fats, which we use every day in the human diet. These plants must adapt to their ecosystem and defend themselves against external stress. Since they cannot move or flee from attacks, they have slowly evolved molecular systems and responses to survive them. They thus produce numerous non-energetic substances called "secondary metabolites" which are involved in their interactions with the environment.
These molecules enable plants to communicate with each other, attract pollinators or repel attackers... Some secondary metabolites protect the aerial parts of the plant against UV rays, which generate free radicals, others repel insect attacks and others protect them against bacterial or fungal infections. It turns out that these protective plant molecules are often polyphenols that also have bioactive properties that are of interest to humans. We are also subject to the damaging factors of our environment.
Our skin, just like plants, is directly subjected to damage from the sun, air pollution, including cigarette smoke, and the stress of our modern lives. Indirectly, it is also subject to the harmful effects of our sometimes-unbalanced diets and is a vector of pollutants. These regular attacks lead to the weakening and premature ageing of skin tissue.