This study aimed to investigate the metabolic fate of bioactive components in watermelon and explore their effect on endothelial function. Six healthy overweight/obese (BMI: 28.7 ± 1.6 kg/m2) adults received 100 kcal of watermelon flesh (WF), rind (WR), seeds (WS), or control meal. l-Citrulline, arginine, and (poly)phenolic metabolites were characterized in plasma over 24 h using UHPLC-MS. Endothelial function was assessed using a flow mediated dilation (FMD) technique over 7 h. Maximum concentration (Cmax) and area under the curve (AUC0-8h) of l-citrulline were significantly higher after WF- and WR-containing test meals compared to control (p < 0.05). Likewise, several individual phenolic metabolites in plasma had significantly higher Cmax after WR, WF, or WS intake compared to control. FMD responses were not different among test meals. Our results provide insights on circulating metabolites from watermelon flesh, seed, and rind and lay the foundation for future clinical trials on vascular benefits of watermelon.
Keywords: arginine; endothelial function; l-citrulline; polyphenols; watermelon.