Stimulating plant extracts HAS2.

Stimulating plant extracts HAS2. The invention relates to plant extracts stimulators of the synthesis of hyaluronan synthase, in particular the synthesis of hyaluronan synthase 2 (HAS2). The invention relates in particular to the use of an effective amount of at least one extract of a plant selected from Guarana The invention is aimed in particular increase the firmness and / or elasticity and / or tissue hydration and / or increase the effect of skin barrier and / or increasing the resilience of tissue and / or modulate angiogenesis or neocreacion of blood capillaries and / or improve healing and / or proliferation, migration or differentiation and / or skin atrophy, and / or intended to combat the effects of aging on the skin, and in particular against loss of skin firmness observed in the course of aging and / or atrophic scars.