Serum gel formulations contained no extracts or no gelatin nanoparticles (F0), the extracts (F1), and the extract-loaded gelatin nanoparticles (F2), respectively. The F1 and F2 contained 100 times its IC50, respectively. Other excipients in weight percent were carbomer-940 (0.5), propylene glycol (15) (link), triethanolamine (0.5), potassium sorbate (0.1), sodium metabisulfite (0.1), green tea oil (qs), and purified water (to make 100). A step-by-step serum gel formulations were prepared using carbomer 940 (20:1), spread into pure water little by little, and left for 24 hours. The carbomer pH was set to 7 by the addition of triethanolamine. The neutral carbomer was transferred into a Beaker glass, added a small amount of water, and homogenized to form a gel base. The propylene glycol was added and mixed until homogeneous. The potassium sorbate and sodium metabisulfite in purified water were dissolved at 30 rpm for 10 minutes and added to the gel base. Each extract or the extract-loaded gelatin nanoparticles, as the actives, was added to the gel bases of F1 or F2. The actives had been dissolved previously in propylene glycol. The green tea oil was added as flavor and homogenized at 150 rpm for 15 minutes. Finally, serum gel formulations were evaluated, including organoleptic, pH, homogeneity, spreadability, viscosity, flow properties, stability, and anti-elastase activity [15, (link)16, (link)17] (link).