## 1 Introduction  
The agri-food sector is heavily reliant on grape production as a significant economic activity worldwide. In 2020, over 83 million tons of grapes were produced, with a significant proportion of these grapes used for wine production. However, the high volume of grape by-products results in considerable economic and environmental costs [1].  
To address this issue and mitigate excessive seasonal by-product production, the circular economy concept proposes reducing the food waste by repurposing it as feedstock for the creation of new products and applications [2]. Moreover, this approach supports alternative recycling flows in the food system [3]. The circular economy is associated with social tendencies towards developing a restorative/regenerative structure that promotes innovation, adding value to by-products that were previously considered end-of-life materials once the compounds that hindered their initial reuse have been removed [4].  
The generation of these residues is significantly higher during the harvest compared to post-grape harvesting, with production being concentrated within a short time frame [5,6]. Some of these same wine residues, such as stems [7, 8, 9], grape seeds, skins, and pulps [10, 11, 12], have been studied regarding their phenolic composition and biological activity.  
However, there is a notable scarcity of research on the phenolic composition and biological activity of pruning firewood and lees, despite their significance as important by-products within the agricultural sector. Interestingly, the Dao Region, despite being the country's oldest demarcated wine region, remains relatively unexplored and understudied concerning the by-products of the wine industry. In 2021/2022, the year of the present study, 286,821 hL of wine has been produced in the Region ([[https://www.ivv.gov.pt/np4](https://www.ivv.gov.pt/np4)]([https://www.ivv.gov.pt/np4](https://www.ivv.gov.pt/np4)) /home.html, accessed on 2 September 2023)  
Given this backdrop, the primary objective of our work is to quantify the phenolic compounds present in the aforementioned by-products, assess the antioxidant activity of each, and evaluate the antibacterial effects of the extracts derived from pruning firewood and stems across the three studied varieties. Specifically, the study focused on their impact on relevant pathogenic bacteria species associated with diabetic foot infections. Remarkably, the global prevalence of diabetes has been steadily increasing over the years. In fact, according to the International Diabetes Federation, approximately 537 million people had diabetes in 2021, and this number is projected to rise to 643 million by 2030 ([[https://diabetesatlas.org/](https://diabetesatlas.org/)]([https://diabetesatlas.org/](https://diabetesatlas.org/)), accessed on 2 September 2023).  
Our research aimed to shed light on a relatively uncharted area, contributing valuable insights to this underrepresented facet of the wine industry, particularly in the historically significant but underexplored Dao Region.  
This preliminary study opens the door to an array of exciting research opportunities that span pharmaceuticals, food science, cosmetics, and sustainability. It underscores the importance of harnessing the inherent value of by-products for innovative solutions to pressing global challenges. We look forward to seeing how future research endeavors will build upon these foundations and drive advancements in multiple fields.