Quercetin nanoformulations: recent advancements and therapeutic applications

Quercetin is a natural bioflavonoid and is an inevitable part of a person’s daily diet. It exhibits anti-inflammatory, anti-oxidant, anti-cancer, anti-microbial effects and is used for the treatment of several diseases like cancer, cardiovascular ailments, and microbial infections. The major limitations of quercetin are low water solubility, less chemical stability, low bioavailability, and short biological half-life. All these major drawbacks can be overcome by its encapsulation in various nanocarriers (nanoparticles, nanoliposomes, nanocrystals, nanomicelles, etc). Such quercetin encapsulated nanoformulations displayed enhanced solubility, stability, bioavailability, high encapsulation efficiency, controlled drug release and extended systemic circulation time period. Quercetin loaded nanocarriers can easily pass across different barriers like blood brain barrier (BBB), skin barriers, mucosal membrane, hence providing target site specific delivery. They also exhibited improved therapeutic effects such as enhanced anti-cancer, anti-diabetic, anti-microbial, anti-inflammatory, anti-psoriasis, anti-oxidant, anti-asthmatic, anti-acne, skin-whitening, hepatoprotective, photoprotective, neuroprotective, nephroprotective and cardioprotective actions. Major health issues associated with nanoformulations are risk of cytotoxicity, oxidative stress, DNA damage, and mutations that can be minimised with continual advancements in nanotechniques. The present review discusses quercetin, its historical background, pharmacokinetics, mechanism of action, and therapeutic applications with major emphasis on the quercetin nanoformulations such as nanoparticles, nanoemulsions, nanoliposomes, nanocrystals, nanosuspensions and nanomicelles that enhances its physicochemical stability, solubility, and therapeutic applications. Also this review includes different quercetin nanoformulations developed for colon cancer and colorectal cancer treatment, brief description of pre-clinical & clinical studies, toxicological concerns, challenges & opportunities, future aspects, patents and marketed quercetin products.