The present invention relates to a cosmetic skin care method to prevent and/or treat at least one sign of skin ageing, comprising the topical application to the skin of a composition comprising at least one active ingredient selected from cassumunarin and/or an arylbutenoid and/or a botanical extract containing them, such as an extract from Zingiber cassumunar Roxb. It also pertains to an extract from Zingiber cassumunar Roxb, which is obtainable by extracting rhizomes thereof with at least one apolar solvent having a polarity index of less than 1, optionally mixed with at least one polar solvent having a polarity index of more than 3.5.