Process for fractioning and refining natural products obtainable from waste vegetal material and particularly from artichoke (Cynara scolymus) production or from other plants of the Cynara genus such as the cultivated or wild cardoon. The process is based on the use of membrane separation technologies envisaging a tangential microfiltration (MF) phase on the raw decoction, followed by tangential ultrafiltration (UF) on the previous MF permeate and reverse osmosis (RO) on the UF permeate, in order to obtain a retentate rich in concentrated active ingredients and a permeate consisting of ultrapure water that is recycled for the preparation of the decoction. The process enables obtaining purified extracts of high biological valence to be used in the pharmaceutical industry, in the nutraceutic sector, in the cosmetics industry and for innovative products in the food industry.