Development of stable emulsified formulations of Terminalia arjuna for topical application: evaluation of antioxidant activity of final product and molecular docking study.

Objective: The aim of this work was to develop stable emulsified formulations containing Terminalia arjuna (T. arjuna) extract and to assess antioxidant potential of the final product with in silico molecular screening. Methods:Terminalia arjuna emulsified formulations were prepared by application of ternary phase diagram design and were evaluated for phytochemical screening, solubility studies, ex vivo permeation study, DPPH free radical scavenging assay, anti-tyrosinase activity, skin irritation, stability studies, molecular docking study, and pharmacophore modeling. Results: Phytochemical screening resulted in the presence of secondary metabolites. The result of the solubility study exhibited that olive oil, tween 80, and PEG 400 could be the most appropriate combination for preparation of the emulsified system. The ex vivo study showed adequate release from its emulsified formulation. Globule size determination and Zeta potential analysis indicate the stability of the emulsified system. The result of DPPH free radical scavenging activity and anti-tyrosinase activity of the final product were satisfactory. Skin irritation test on albino rats resulted in no allergic dermal effects. All the prepared formulations were found to be stable upon storage for 3 months. Molecular docking resulted in antioxidant potential via tyrosinase inhibitory mechanism mainly by hydrogen bonding interaction with His60B, Glu158B, His208B, Asn205B, Met215B, His42B, and Asn57B whereas ionic interactions by Arg209B and Val218B of tyrosinase. Pharmacophore modeling describes the similarity features with the standard. Conclusions: The results suggest that developed emulsified formulations with T. arjuna extract for topical application demonstrate interesting attributes to be explored as potential pharmaceutical products.