Boiling-Resistant Single-Chain Sweet Protein Monellin as a Safe and Effective Sugar Alternative for Metabolic and Glycemic Management in Mice

The global rise in obesity and metabolic disorders has intensified the demand for safe and effective sugar alternatives. Monellin, a naturally sweet protein derived from <i>Dioscoreophyllum cumminsii</i>, serves as an excellent sugar alternative, but its broader application has been constrained by poor thermal stability and limited evaluation of long-term metabolic effects. In this study, we evaluated the metabolic effects of MNEI-Mut6, a boiling-resistant single-chain monellin variant, in male C57BL/6 mice fed standard chow supplemented with either 4% sucrose or an equivalent sweetness concentration of MNEI-Mut6 for 16 weeks. Compared with sucrose, MNEI-Mut6 did not promote weight gain, preserved insulin sensitivity, and maintained glucose homeostasis. In addition, MNEI-Mut6 reduced hepatic lipid accumulation and adipocyte hypertrophy without inducing hepatotoxic or nephrotoxic effects. Collectively, these findings demonstrate that MNEI-Mut6, a thermally stable and metabolically neutral sweetener, is a promising and safer alternative to sucrose and artificial sweeteners suitable for application in food processing and product formulation.