Abstract
Annona muricata, commonly known as Graviola, has been utilized as a traditional medicine to treat various human diseases. The aim of this study was to examine the immune-enhancing activity of Graviola leaf extracts in RAW 264.7 macrophage cells. Active ingredients in Graviola leaf extracts (GE) were identified as kaempferol-3-O-rutinoside and quercetin-3-O-rutinoside by LC-MS/MS. When treated with steam or 50% ethanol GE, cell morphology was altered due to initiation of cell differentiation. While the cell viability was not altered by the steam GE, it was reduced by the ethanol GE. Both steam and ethanol GE induced the transcriptional expression of cytokines, including tumor necrosis factor-α (TNF-α) and interleukin-1β, but only the steam extract upregulated inducible nitric oxide synthase (iNOS). In consistence with mRNA expression, the production of TNF-α and nitrite was elevated by both steam and ethanol extracts of Graviola leaves. This is mainly due to activation of mitogen-activated protein (MAP) kinase signaling pathways. These results suggest that Graviola leaves enhance immunity by activation of the MAP kinase pathways. These bioactive properties of Graviola indicate its potential as a health-promoting ingredient to boost the immune system.