Antioxidant Activity of Pandanus amaryllifolius Leaf and Root Extract and its Application in Topical Emulsion

Purpose: To develop Thai pandan ( Pandanus amaryllifolius ) as an antioxidant ingredient for topical emulsion. Methods: Dried leaf and root of P. amaryllifolius ( Pandanceae ) were extracted separately by maceration with either ethanol or propylene glycol. Antioxidant capacity was investigated by 2,2-diphenyl-1-picry hydrazyl radical (DPPH) and linoleic acid peroxidation method. The total phenolic content was measured by Folin-Ciocalteau assay. Oil-in-water topical emulsions containing the individual extracts were prepared and tested for stability. Results: Propylene glycol extract exhibited higher DPPH activity and total phenolic content than the ethanol extract while the DPPH activity of the leaf extract was higher than that of the root. The 50 % inhibition concentration (IC50) value of leaf and root extracts was 0.810 and 2.340 mg/ml, respectively. Although the antioxidant activity of the crude extracts was lower than that of standard vitamin C and butylated hydroxytoluene (BHT), the ethanol/propylene glycol solution extract (ethanol was reduced to 50 % extract volume) showed higher inhibition (90.1 %) of linoleic acid peroxidation than 200 ppm of vitamin C (57.1 %) and BHT (71.1 %). An oil-in-water emulsion containing 3 % of the ethanol and propylene glycol extract showed creamy texture with medium viscosity and demonstrated good stability under accelerated aging test. Conclusion: The results indicate a potential for the development of P. amaryllifolius leaf extract as an antioxidant ingredient in topically applied formulations