Phenolic bioactive-linked antioxidant, anti-hyperglycemic, and antihypertensive properties of sweet potato cultivars with different flesh color

Sweet potato is a rich source of antioxidant phytohemicals, like β-carotene, vitamin C, anthocyanins, xanthophylls, and phenolics, which are relevant for providing dietary protections against chronic oxidative stress-associated diseases, like type 2 diabetes. However, the health protective phytochemical profiles and associated antioxidant and anti-diabetic properties of sweet potatoes vary widely between different flesh color and among cultivars. Therefore, the aim of this study was to screen aqueous and ethanol (12%) extracts of seven sweet potato cultivars with different flesh colors (white–yellow, orange, and purple) for their phenolic phytochemical-linked functional qualities. Total soluble phenolic (TSP) content, phenolic profile, protein content, total antioxidant activity, anti-hyperglycemic function relevant α-amylase, α-glucosidase, and anti-hypertensive function related angiotensin-I-converting enzyme (ACE) inhibitory activities of sweet potato cultivars were determined using rapid in vitro assay models. The purple flesh cv. NIC-413 had significantly higher phenolic content (2.8 mg GAE 100 g −1 FW) and associated high antioxidant activity. Catechin, gallic, and dihydroxybenzoic acids were found in all cultivars, while chlorogenic acid was present only in purple-flesh cultivar. Anti-hyperglycemic property relevant α-amylase (74–84%), and α-glucosidase (21–60%) enzyme inhibitory activities were present in all sweet potato cultivars. Additionally, anti-hypertensive property relevant ACE (10–88%) enzyme inhibitory activity were present across all sweet potato cultivars. The results of this in vitro screening study suggested that sweet potato cultivars like NIC-413, Murasaki, Evangeline, and Covington are good dietary source of phenolic antioxidants and can be relevant for anti-hyperglycemic and anti-hypertensive benefits to target type 2 diabetes associated health risks.