Polysaccharides from Annona muricata leaves protect against cisplatin-induced cytotoxicity in macrophages by alleviating mitochondrial dysfunction

Cisplatin is a prominent chemotherapeutic agent that can induce significant damage to normal cells. Therefore, it is important to develop agents that protect normal cells without influencing the chemotherapeutic effect of cisplatin. The present study was conducted to explore the protective effects of Annona muricata leaf polysaccharides (ALPS) against cisplatin-induced toxicity in macrophages. Apoptosis was assessed in macrophages and lung cancer cells to investigate the cytoprotective effect of ALPS, their effect on the production of cisplatin-induced reactive oxygen species (ROS) and the loss of the mitochondrial transmembrane potential (MTP). Cisplatin, when used alone or in combination with ALPS, showed significant toxicity against A549 and H460 lung cancer cells. However, cisplatin-induced cytotoxicity was suppressed by cotreatment of RAW 264.7 macrophages with ALPS. ALPS significantly inhibited the upregulation of BAX, cytosolic cytochrome c and caspases-3, −8 and −9. Moreover, ALPS resulted in the cleavage of PARP and downregulation of Bcl-2 levels in a concentration-dependent manner, which ultimately led to a reduction in the apoptotic and necrotic populations of cisplatin-treated RAW 264.7 macrophages. The suppression of the apoptotic signaling pathways was mediated through the reduction of ROS and MTP loss in cisplatin-treated RAW 264.7 macrophages. In addition, ALPS alleviated cell damage by suppressing the mitochondrial apoptotic pathways in cisplatin-treated bone marrow-derived macrophages. Together, these findings suggested that ALPS may alleviate the toxic side effects of chemotherapeutic agents and act as a potential candidate for use as an effective adjuvant therapy.