Plants have the unique ability to manufacture their own nutrient substances, such as proteins, carbohydrates, and lipids, which we use every day in human nutrition. These plants must adapt to their ecosystem and defend themselves against external stress. Unable to move or flee from attacks, they have developed molecular systems and defenses over the course of evolution to survive. They produce numerous non-energy substances known as "secondary metabolites" that are involved in their interactions with the environment.
These molecules allow plants to communicate with each other, attract pollinators, or repel aggressors. Some secondary metabolites protect the plant's aerial parts against UV radiation, which can generate free radicals, while others repel insect attacks, and still others protect against bacterial or fungal infections. It turns out that these protective molecules in plants are often polyphenols, which also have interesting bioactive properties for humans. We also experience aggressions from our environment.
Just like plants, our skin is directly subjected to the aggressions of the sun, air pollution - including cigarette smoke - and the stress of our modern life. Indirectly, it also experiences the harmful effects of our sometimes unbalanced diet and exposure to pollutants. These regular attacks lead to a weakening and premature aging of the skin tissue.