###### Abstract
In fact, the identification of good practices for the efficient use of resources and the recovery of waste and agri-food by-products constitutes one of the main objectives of a sustainable economy [3; 4; 5], and it is necessary that production and consumption change to a \"circular economy\" model, which defends the idea of reducing waste and reusing waste, recycling it, reducing economic expenses, and reducing environmental damage [4; 6]. Products obtained from different parts of the vine, namely stems, leaves, skin, seeds, and pomace, have been the subject of studies that demonstrate the importance of their use and beneficial effects on health, mainly in the prevention of cardiovascular diseases, cancer, diabetes, intestinal disorders, inflammatory diseases, and hemorrhages [7; 8; 9]. The main phytochemical compounds present in grapevine by-products are stillbenoids, phenolic compounds (gallic acid, catechin, myricetin, and kaempfer-3-O-rutinoside), aromatic acids (hydroxycinnamic and hydroxybenzoic acids), flavonoids, and proanthocyanidins [10; 11]. These compounds have the potential to delay or promote the inhibition of substrate oxidation [12]. Grapevine stems are made up of around 30% cellulose, 21% hemicellulose, around 17% lignin, 15-16% tannins, and approximately 6% proteins [13], also presenting a high content of essential minerals [14]. The stem, which corresponds to almost 25% of the total by-products, is the least valued of all the by-products generated but the richest in phenolic compounds [9; 15]. Grape seeds have a very rich nutritional profile, consisting of around 40% dietary fiber, 16% essential oils, 11% proteins, and 7% phenolic compounds [16]. The main phenolic compounds present in seeds are flavan-3-ols [17]. The composition of minerals [14] and phenolic compounds in vineyard by-products is influenced by growing conditions, climatic factors, geographic location, cultivation practices, and the stage of maturation [17; 18]. Phenolic compounds are known for their antioxidant, anti-inflammatory, and antimicrobial potential [16; 19], and are abundant in grapes. Due to these beneficial properties, extracts obtained from grape residues, which are rich in phenolic compounds, can help reduce the growth of pathogenic microorganisms that cause degradation and diseases, in addition to inhibiting lipid oxidation [16], enhancing their use in the development of various products, like medical, cosmetic, and food applications [16; 19; 20]. Flavonoids have antioxidant, anti-inflammatory, antiviral, antibacterial, antidiabetic, neuroprotective, cardioprotective, and anticancer properties [21; 22; 23], being capable of inhibiting virulence factors of microorganisms and presenting a synergistic effect with conventional antibiotics [16]. The stems have biological activities such as antimicrobial, antioxidant, and even anti-inflammatory [15; 18]. Due to the high content of phenolic compounds, the seeds have antioxidant and antimicrobial activity [16]. Portugal, which comprises 14 wine regions and 31 protected denominations of origin, is one of the countries with the largest number of national grape varieties [24]. In this work, three red wine varieties (Touriga Franca, Touriga Nacional, and Tinta Roriz) and a white wine variety (Viosinho) were studied. Seed oils from the Touriga Franca and Touriga Nacional varieties are rich in derivatives of the vitamin E family and fatty acids, presenting antioxidant activity [25]. These two varieties, as well as Tinta Roriz, being a red wine, have a higher concentration of resveratrol than white wine varieties [26]. According to [PERSON] et al. [27], Tinta Roriz stems are richer in phenolic compounds than those of Touriga Franca, showing higher values of TPC, TFC, and antioxidant capacity. The stem of the Viosinho variety has high antioxidant activity and bioactivity against Gram-positive bacteria; these properties are associated with its composition of monomeric proanthocyanidins, catechins, flavonoids, and derivatives of hydroxycinnamic acids and anthocyanins [24; 28].