The invention concerns a method for preparing an extract comprising a mixture of madecassoside, terminoloside and optionally asiaticoside, an extract of Centella asiatica comprising more than 75 wt % of a mixture of madecassoside, terminoloside and asiaticoside, relative to the extract total weight, an extract of Centella asiatica comprising more than 95 wt. % of a mixture of madecassoside and terminoloside relative to the extract total weight and their use for regulating inflammatory mechanisms.