Pharmacological profile of γ-oryzanol: Its antioxidant mechanisms and its effects in age-related diseases

Abstract γ-Oryzanol is the most potent natural antioxidant in rice (Oryza sativa L.), and its pharmacological profile has been intensively investigated. A growing body of evidence demonstrated that γ-oryzanol exerts its antioxidant activity at least through three mechanisms: (1) acting as a free radical scavenger, (2) boosting endogenous antioxidant enzyme activities, and (3) modulating the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway. In fact, its beneficial health effects have been demonstrated in a series of pathological conditions where oxidative stress is a main feature, such as hyperlipidemia, hyperglycemia, inflammation, and cognitive impairment. Additionally, different pharmacokinetic studies of γ-oryzanol have illustrated that it is absorbed in the intact form via the intestine into the blood circulation in a dose-dependent manner and highly distributed throughout the body, particularly in the brain. Its safety with no observed adverse effect makes γ-oryzanol as a natural dietary supplement for humans, and it is approved in Japan as a prescription medicine.