Exploring Major Flavonoid Phytochemicals from Nelumbo nucifera Gaertn. as Potential Skin Anti-Aging Agents: In Silico and In Vitro Evaluations

Nelumbo nucifera Gaertn., an aquatic medicinal plant (Nelumbonaceae family), has a history of use in traditional medicine across various regions. Our previous study demonstrated the skin anti-aging potential of its stamen ethanolic extract by effectively inhibiting collagenase and tyrosinase enzymes. While the major constituents of this extract are well documented, there is a lack of research on the individual compounds' abilities to inhibit skin aging enzymes. Therefore, this study aimed to evaluate the anti-aging potential of the primary flavonoids found in N. nucifera using both in silico and in vitro approaches. Our initial step involved molecular docking to identify compounds with the potential to inhibit collagenase, elastase, and tyrosinase. Among the seven flavonoids studied, kaempferol-3-O-robinobioside (Kae-3-Rob) emerged as the most promising candidate, exhibiting the highest docking scores for three skin aging-related enzymes. Subsequent enzyme-based inhibition assays confirmed that Kae-3-Rob displayed robust inhibitory activity against collagenase (58.24 +/- 8.27%), elastase (26.29 +/- 7.16%), and tyrosinase (69.84 +/- 6.07%). Furthermore, we conducted extensive 200-ns molecular dynamics (MD) simulations, revealing the stability of the complexes formed between Kae-3-Rob and each enzyme along the MD simulation time. MM/PBSA-based binding free energy calculations indicated the considerably stronger binding affinity of Kae-3-Rob for collagenase and tyrosinase compared to elastase, which was related to the greater percentage of hydrogen bond occupations. These computational findings were consistent with the relatively high inhibitory activity of Kae-3-Rob against collagenase and tyrosinase observed in our in vitro experiment. In conclusion, the results obtained from this comprehensive study suggest that Kae-3-Rob, a key flavonoid from N. nucifera, holds significant potential as a source of bioactive compounds for anti-aging cosmeceutical and other phytopharmaceutical application.