Incorporation of ascorbic acid-2-glucoside into ulvan microneedles to enhance its permeation for anti-aging and whitening treatment

For anti-aging and whitening treatment, ascorbic acid-2-glucoside (AA2G) was incorporated into a 4.0 % (w/v) ulvan solution at three concentrations (0.5 %, 1.0 %, and 2.0 % w/v) to fabricate ulvan-based microneedles (UMNs) using a spin-casting method, aimed at enhancing AA2G permeation. The in vitro skin insertion study demonstrated that incorporating AA2G into the UMNs improved their insertion capability, increasing from 86.3 % for neat UMNs to 98 % for AA2G-UMNs. Furthermore, in vitro drug permeation profiles revealed that dissolving UMNs significantly enhanced the cumulative permeation of AA2G, achieving 80-90 % within 3 h. In addition to showing good biocompatibility with HaCaT and NIH3T3 cells, AA2G-UMNs exhibited antioxidant activity and protected HaCaT cells from H₂O₂-induced oxidative stress. Their anti-aging activity was demonstrated by their ability to inhibit elastase and collagenase activity. Moreover, whitening efficacy was confirmed through the inhibition of melanin production and tyrosinase activity. Among the formulations, 2.0 % AA2G-UMNs achieved the greatest reduction in melanin content in B16F10 cells, with a 54.2 % reduction intracellularly and a 61.3 % reduction extracellularly. Tyrosinase activity inhibition by AA2G-UMNs ranged from 42.6 % to 53.4 %. These results suggest that AA2G-UMNs hold significant promise for applications in the pharmaceutical and cosmeceutical industries.