Abstract
Flavonoids are present naturally in many fruits and vegetables including onions, apples, tea, cabbage, cauliflower, berries and nuts which provide us with quercetin, a powerful natural antioxidant and cytotoxic compound. Due to antioxidant property, many nutraceuticals and cosmeceuticals products contain quercetin as a major ingredient nowadays. Current review enlightened sources and quercetin's role as an antioxidant, antimicrobial, antidiabetic, anticancerous and anti-inflammatory agent in medical field during last 5 to 6 years. Literature search was systematically done using scientific for the published articles of quercetin. A total of 345 articles were reviewed, and it was observed that more than 40% of articles were about quercetin's use as an antioxidant agent, more than 25% of studies were about its use as an anticancer agent, and articles on antimicrobial activity were more than 15%. 10% of the articles showed anti-inflamamatory effects of quercetin. Literature search also revealed that quercetin alone and its complexes with chitosan, metal ions and polymers possessed good antidiabetic properties. Thus, the review focuses on new therapeutic interventions and drug delivery system of quercetin in medical field for the benefit of mankind.