Anthocyanins from a new hybrid sweet potato peel cultivated in Northern Thailand mitigate LPS-induced inflammation and RANKL-induced osteoporosis by regulating ROS-mediated pathways

Abstract

Maejo 341 Sweet potato (MSP) is a new purple sweet potato variety cultivated in Northern Thailand, but its health benefits are unknown. This study aimed to investigate its antioxidant, anti-inflammatory, and anti-osteoporotic activities, as well as its anthocyanin content. The peel and flesh of MSP were extracted with ethanol and water. Compared with the flesh extracts, the peel extracts presented greater antioxidant capacity and were rich in phenolics, flavonoids, and anthocyanins, namely, cyanidin-3-O-glucoside, peonidin-3-O-glucoside, pelargonidin-3-O-glucoside, cyanidin, and peonidin. The peel extracts suppressed lipopolysaccharide-induced inflammation by inhibiting the secretion of proinflammatory cytokines and enzymes, including TNF-α, IL-1β, IL-6, COX-2, and iNOS, as well as reducing nitric oxide and matrix metalloproteinase-9 secretion. The extracts inhibited the RANKL-induced NF-κB and MAPK pathways and downregulated osteoclastogenic marker expression. Under LPS and RANKL treatment, the peel extracts notably reduced reactive oxygen species production while increasing antioxidant gene expression. Furthermore, they increased osteoblast viability and slightly raise alkaline phosphatase activity. These findings suggest that MSP peel could be used as a functional food to alleviate oxidative stress and inflammation-related osteoporosis.