The Antioxidant and In Vitro Wound Healing Activity of Cotyledon orbiculata Aqueous Extract and the Synthesized Biogenic Silver Nanoparticles

Abstract

The synthesis of silver nanoparticles using biogenic methods, particularly plants, has led to the discovery of several effective nanoparticles. In many instances, plant-derived silver nanoparticles have been shown to have more activity than the plant extract which was used to synthesize the nanoparticles. Silver nanoparticles have been successfully synthesized using the medicinal plant, <i>Cotyledon orbiculata.</i> This is a shrub found in the Western Cape province of South Africa. It has a long history of use in traditional medicine in the treatment of wounds and skin infections. The <i>C. orbiculata</i> synthesized silver nanoparticles (<i>Cotyledon</i>-AgNPs) were reported to have good antimicrobial and anti-inflammatory activities; however, their wound-healing properties have not been determined. This study aimed to determine the wound healing activity of <i>Cotyledon</i>-AgNPs using the scratch assay. Gene expression studies were also done to determine the nanoparticles' mechanism of action. The <i>Cotyledon</i>-AgNPs showed good antioxidant, growth-promoting and cell migration properties. Gene expression studies showed that the <i>C. orbiculata</i> water extract and <i>Cotyledon</i>-AgNPs promoted wound healing by upregulating genes involved in cell proliferation, migration and growth while downregulating pro-inflammatory genes. This confirms, for the first time that a water extract of <i>C. orbiculata</i> and silver nanoparticles synthesized from this extract are good wound-healing agents.