Nanomaterials loaded with Quercetin as an advanced tool for cancer treatment

Cancer is a major global problem ranking as the second/third cause of death, irrespective of the region or the socio-economic situation. Quercetin (QCT), a flavonoid compound almost omnipresent in fruits and vegetables, has been shown to exhibit anticancer effects by regulating important molecular pathways, such as cyclins, PI3K/ Akt, and mitogen-activated protein kinase (MAPK). More importantly, QCT has shown synergetic effects in the treatment of multidrug resistance tumors via inhibiting drug efflux mediated by transporter proteins. However, QCT is characterized by a very poor solubility in water, which leads to reduced blood circulation times and, therefore, low therapeutic efficacy when administered directly without any delivery system. Fortunately, the rapidly growing field of nanotechnology applied to health research has opened new avenues for the development of smart carriers for controlled drug delivery. This review focuses on nanoformulations for QCT loading and delivery, with special emphasis on the co-delivery of QCT with other drugs, which has demonstrated relevant results against various types of cancer, including breast, colon, lung, and gastric.