Synergistic Cotreatment Potential of Soursop (<i>Annona muricata</i> L.) Leaves Extract with Doxorubicin on 4T1 Cells with Antisenescence and Anti-reactive-oxygen-species Properties

Annona muricata L. extract (AME) exhibits cytotoxic activities on various types of cancer cells. This study aims to unveil the anticancer activity of AME as a cotreatment agent with doxorubicin (dox) on 4T1 cells and AME's relation to senescence. AME was obtained by maceration using 96% ethanol. AME was then subjected to qualitative analysis using TLC compared to quercetin (hRf = 75). Spectrophotometry analysis of AME resulted in a total flavonoid content of 2.3% +/- 0.05%. Cytotoxic evaluation using the MTT assay revealed that AME showed an IC50 value of 63 mu g/mL, while its combination (25 mu g/mL) with dox (10 nM) decreased the viability of 4T1 cells to 58 % (CI = 0.15). Flowcytometry using propidium iodide staining confirmed that AME (13 and 25 mu g/mL) caused cell cycle arrest in the G1 phase as a single treatment and G2/M arrest in combination with dox. However, by using the dichloro dihydrofluorescein diacetate staining assay, it turned out that AME at concentrations of 13 and 25 mu g/mL decreased intracellular reactive oxygen species (ROS) levels both as a single treatment and in combination with dox. Senescence-associated beta-galactosidase assay showed that AME decreased dox-induced senescence. AME alone and in combination with dox (cotreatment) showed cytotoxic effect synergistically on 4T1 cells, but this was not caused by an increase in intracellular ROS levels as well as senescence induction. Therefore, AME showed its potential to be a cotreatment agent with antioxidant property on triple-negative breast cancer cells.