Performance of Strobilanthes crispus Leaves Extract as Potential Antioxidant Compound in Oil-in-water Emulsion

Excess of free radicals accelerates the degradation of oil-in-water (O/W) emulsion due to oxidative damage resulting in low emulsion quality such as in lotion formulation. The blend of antioxidants in O/W emulsion could reduce the damage caused by the radical compounds. The crude extract of Strobilanthes crispus (S. crispus) leaves was screened for assessing bioactive phytochemical constituents. By using various chemical assays, the extract of S. crispus leaves revealed the presence of tannins, steroids, flavonoids, terpenoids and glycosides. Besides that, the antioxidant activity of the leaf extract, spray-dried extract, a lotion containing extract and other local and abroad commercial lotions were determined as references using standard methods such as total phenolic content (TPC), total flavonoid content (TFC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and reducing power assay. In terms of TFC, the highest, 10.591±0.01 mg QE/g was recorded in crude extract along with the highest reducing power and percentage inhibition, 25.40±0.02 mg GAE/g and 88.89 % respectively. The result from TPC value can be a good indicator for a longer shelf life of the O/W emulsion if compared to other results from TPF, reducing power and DPPH value. From this study, it can be concluded that S. crispus has potential as a good natural antioxidant ingredient for the emulsion of O/W formulation.