Conjugation of Glycine max (L.) Merrill Oligopeptide with Monosaccharides: A Novel Approach for Stability and Efficacy in Cosmeceutical Applications

<b>Background/Objectives</b>: Conjugation techniques are increasingly valued in food chemistry for enhancing sensory properties, nutritional profiles, and bioactivity, with potential applications in cosmeceuticals. This study aimed to investigate the potential of <i>Glycine max</i> (L.) Merrill oligopeptide-monosaccharide conjugates as active ingredients in cosmeceuticals, emphasizing their biological activities and stability. <b>Methods</b>: <i>G. max</i> isolate was prepared and subsequently hydrolyzed using alcalase to obtain the oligopeptide (OP). The OP was then conjugated with allulose (AL) or mannose (MN) through a controlled humid-dry heating process to produce the conjugates, OPA and OPM, respectively. Their biological activities, including antioxidant, anti-tyrosinase, anti-collagenase, anti-elastase, and anti-hyaluronidase properties, were assessed and compared to the individual components. Additionally, the irritation potential was evaluated using the hen's egg test on chorioallantoic membrane (HET-CAM). The stability was examined under varying pH levels, temperatures, and light conditions based on their biological activity profiles. <b>Results</b>: OPA demonstrated the highest antioxidant activity, showing the lowest DPPH^• IC₅₀ value of 198.6 ± 2.7 µg/mL along with a strong ferric reducing power of 1.37 ± 0.04 µg FeSO₄/g sample. Besides, OPM showed superior tyrosinase inhibition on both L-tyrosine and L-DOPA substrates, highlighting its potential for skin whitening. Both OPA and OPM significantly enhanced collagenase inhibition, supporting their anti-aging potential. All samples were non-irritating in the HET-CAM test. The conjugates (OPA and OPM) demonstrated enhanced stability against pH, heat, and light compared to OP, AL, and MN. <b>Conclusions</b>: Oligopeptide-monosaccharide conjugation not only improved bioactivity but also enhanced biological stability, suggesting their potential for use in cosmeceutical applications.