# Portuguese Grapevine Leaves: A Neglected By-Product with High Potential
## 3 How Can Portuguese Grapevine Leaves Contribute to Meeting the Goals of the 2023 Agenda?
These leaves are rich in antioxidants, phenolic compounds, fibers, and essential fatty acids, making them suitable for a broad range of uses that align with sustainability and the principles of circular economics [6; 15; 25; 26; 27; 28; 29; 30; 31]. In the food industry, grapevine leaves have been traditionally employed in Mediterranean cuisine [10]. However, their potential extends significantly beyond this conventional use. Due to their high content of quercetin, kaempfer, and other bioactive compounds, they can be transformed into functional ingredients that enhance cardiovascular health and reduce inflammation [5]. Good practices include employing preservation techniques, such as drying or freeze-drying, to maintain their bioactive properties [8]. These leaves can then be incorporated into products like teas, snacks, and dietary supplements. For instance, grapevine leaf powder has been successfully utilized in gluten-free products to enhance their nutritional value [15; 26; 77]. In pharmaceuticals, the therapeutic properties of bioactive compounds in grapevine leaves are gaining considerable attention. Flavonoids derived from these leaves exhibit anti-inflammatory, antimicrobial, and anti-cancer activities, making them a promising resource for natural supplements and medicinal formulations [45; 46; 47; 48]. These compounds have also demonstrated potential in regulating blood glucose levels, offering opportunities for developing novel anti-diabetic treatments [14; 61; 71]. Recent advancements in green extraction methods, such as ultrasound-assisted extraction, enable efficient recovery of these bioactive molecules while ensuring high yields and environmental sustainability [6; 182]. The nutraceuticalal industry is also well-positioned to benefit from grapevine leaves. Their rich antioxidant, anti-inflammatory, and cardio-protective properties make them suitable for inclusion in dietary supplements and functional beverages [10; 11; 12; 13; 14]. The incorporation of these bioactive compounds can help mitigate oxidative stress and support overall metabolic health, addressing the growing consumer demand for natural health products [15; 136; 179]. In the cosmetic sector, grapevine leaves have been recognized for their antioxidant-rich composition, particularly resveratrol and flavonoids. These compounds provide protection against UV radiation and help reduce signs of aging, making them valuable in formulations for sunscreens and anti-aging skincare products [24; 36]. Research has confirmed that grapevine leaf extracts possess skin-whitening and anti-inflammatory properties, which can be beneficial in products targeting pigmentation issues and enhancing overall skin health. Utilizing encapsulation technologies can ensure the stability and bioavailability of these compounds in cosmetic applications [23; 186]. Beyond these industries, grapevine leaves show promise in agriculture. They can be repurposed as natural fertilizers or soil conditioners, contributing their high phenolic and fiber contents to improve soil health, promote plant growth, and provide sustainable alternatives to chemical fertilizers [15]. Furthermore, the bioactive compounds in these leaves may function as natural bio-pesticides, contributing to more eco-friendly farming practices [21]. The integration of grapevine leaves into these diverse industries not only aligns with the principles of circular economy and zero-waste production, but also opens innovative pathways for creating high-value eco-friendly products [6; 15]. By adopting green extraction methods and multi-product strategies, this previously undervalued by-product can be transformed into functional foods, pharmaceuticals, nutraceuticalals, cosmetics, and agricultural inputs, thereby enhancing public health while promoting environmental sustainability.