Analysis of nutritional composition and antioxidant activity of sweet potato (Ipomoea batatas L.) leaf and petiole

Two cultivars of sweet potatoes, Pumpkin and Chestnut, were planted in the didactic field of the Faculty of Horticulture, Craiova, and biochemical determinations were carried out from the blades and petioles of the leaves. This study highlights the antioxidant properties of these species, which are not well known in Romania, to encourage consumption of the vegetative parts of the plant, as well as use of the leaves in the future to develop natural antioxidants. The chlorophyll and carotene content in the blade and petiole were determined, highlighting the large amounts of petiole, depending on the cultivar. Catalase (CAT), peroxidase (POX), and vitamin C content, as well as total dry matter (TDM), reducing sugars, phenolic compounds, and antioxidant activity, were also measured. The petioles exhibited high antioxidant activity, with 62.186 μmol TE/g FW in Pumpkin and 95.168 μmol TE/g FW in Chestnut. The cultivars also exhibited differences at the blade level, with high values recorded for the Chestnut cultivar. Positive correlations between total polyphenols and reducing sugars (r = 0.89), antioxidant activity and reducing sugars (r = 0.48), and antioxidant activity and phenolic compounds (r = 0.53) were found. This study demonstrates that sweet potato leaves are a potential, inexpensive and beneficial source of natural antioxidants.