RESUMEN
Medicinal plants are long been used for pharmaceutical and cosmetic industry. Among medicinal plants, Polygonum amplexicaule of family polygonaceae has traditional use in medicines and skin care. P. amplexicaule belongs to genus Polygonum that contains several important phytochemicals and considered as a rich source of antioxidants. The present study was designed to formulate herbal gel containing P. amplexicaule extract and evaluate its different physical properties as well as antioxidants and antityrosinase activities. Chitosan gel base was used as gelling agent and different gel formulations were prepared by different concentrations of extracts and polymers. Physical properties like pH, colour, odour, appearance and homogeneity, spreadability, extrudability and stability were optimized and analysed. A stable gel formulation containing 1% chitosan gel base and 5% plant extract was prepared that showed good appearance and homogeneity, easily spread ability and excellent extrudability. This gel formulation was tested for antioxidant and skin whitening properties by DPPH free radical scavenging assay and tyrosinase inhibition assay respectively and ascorbic acid was used as reference standard. DPPH scavenging activity with an IC50 value of 0.446 mg/mL and tyrosinase inhibition activity with an IC50 value of 0.805 mg/mL was observed and results indicated that this herbal gel formulation has a good potential for cosmetic use.