The present application relates to a process for preparing an extract of leaves of Vitis vinifera L. comprising the following steps: a) preparing a drug from leaves of Vitis vinifera L. b) extracting the drug with an eluant selected from among water and mixtures of water with alcohol, to obtain a raw extract, c) separating the raw extract from the extracted drug, d) at least partly eliminating the eluant, to obtain a thick extract, e) redissolving the thick extract in water, f) separating off any insoluble constituents, g) selectively concentrating secondary plant ingredients by i. a 2-phase extraction or ii. membrane filtration； the extract that is obtainable therefrom, pharmaceutical preparations containing this extract and the use thereof.
