Biosynthesis of manganese oxide nanoparticles using Urginea sanguinea and their effects on cytotoxicity and antioxidant activity

Urginea sanguinea, a detoxifier utilised in African herbal medicine, contains toxic cardiac glycosides that are considered to have anticancer properties. In this study, manganese oxide nanoparticles (MnO x NPs) were synthesised using Urginea sanguinea and its isolates, a homoisoflavone (urgineanin E) and a mixture of bufadienolides (proscillaridin A, scillaren A and 5 α -4,5-dihydroscillaren A), and their cytotoxic effects and antioxidant activities were investigated. The presence of absorption peaks between 262 nm and 272 nm using ultraviolet-visible spectroscopy, and Mn-O-Mn vibrations in the infrared spectrum confirmed the formation of MnO x NPs. Images from high-resolution transmission electron microscopy and scanning electron microscopy revealed interconnected spheroidal shapes with nanorods for MnO x NPs (extract), and ultrathin nanosheets assembled as nanoflowers for MnO x NPs (urgineanin E) and MnO x NPs (bufadienolides). The synthesised nanoparticles were evaluated for their anticancer properties using the MTT assay. The cytotoxic effects of MnO x NPs against A549 and HepG2 cancer cell lines increased with increasing concentration with no significant cytotoxicity towards HEK293 normal cells. MnO x NPs were found to exhibit moderate free radical scavenging activity. This warrants further research into the use of manganese oxide nanoparticles synthesised with medicinal plants and active compounds as anticancer agents.