Sweet potato (SP) has long been used as food and in traditional medicine. For the first time, total antioxidant activity (TAA), reducing power (RP), ferric-reducing antioxidant power (FRAP) and 1,1-diphenyl-2-picryl-hydrazyl (DPPH) antioxidant activities from European sweet potato vines holding a Protected Geographic Indication (PGI) were studied through a factorial design. Plant part was the main influential factor followed by solvent acidification. Principal component analysis revealed total phenolic content, total flavonoid content, FRAP and RP assays more related to sample differences (stems or leaves) and DPPH to extraction conditions, namely solvent acidification. The in vitro antioxidant activities of leaves were 1.25 g AAE/100 g dw for TAA and 50.8 g GAE/100 g dw for RP. DPPH scavenging activity was higher than FRAP (i.e., 58.6 and 29.3 and μM Trolox/g dw, respectively). Stems results were 1.3 to 9.2 times lower than leaves. These outcomes confirmed SP leaves a potential resource of antioxidants in the human diet that may add supplementary value to PGI agriculture products.
Vines, especially leaves, from PGI sweet potatoes could be advantageously used as a natural source of antioxidants, with potential to be used as a food in the diet. Focus on sweet potato of European origin may contribute to increase interest on its cultivation and consumption. In addition, insights on the potential added value present in Protected Geographic Indication (PGI) agriculture products may enhance protected demonization turnover for producers. Industries that pursuit food with functional applications may consider sweet potato vines in their new product development processes, aiming for health benefits.