Nanoemulsion Strategy for Ursolic and Oleanic Acids Isolates from Plumeria Obtusa Improves Antioxidant and Cytotoxic Activity in Melanoma Cells

Background: Triterpenoids are an important class of natural bioactive products present in many medicinal plants. Objective: The aim of present study is to investigate the antioxidant and anticarcinogenic potential of Oleanolic Acid (OA) and Ursolic Acid (UA) on B16 murine melanoma cell line isolated from Plumeria obtusa, free and loaded in a nanoemulsion (NEm) system. Methods: The nanoemulsion was characterized by dynamic light scattering, transmission electron microscopy. The viscosity was also evaluated. The antioxidant activity was determined by the reduction of 2,2-diphenyl-2- picrylhydrazyl (DPPH) free radical. In vitro proliferation studies were determined using the sulforhodamine-B method. Results: OA/UA natural mixture exhibited high percentage of inhibition of DPPH (86.06% and 85.12%, with and without irradiation). Percentages of inhibition higher than 85% in samples with and without ultraviolet irradiation were recorded when loaded in the NEm system. The natural mixture incorporated into the NEm showed cytotoxic activity from 2.9 μM, whereas the free compounds from 17.4 μM. Conclusion: We conclude that these pentacyclic triterpenes loaded in a NEm system could be considered as a new potential tool for further investigation as anticancer agents.