The promising role of natural products in Alzheimer's disease

Experimental studies support the discussion of the use of bioactive products of natural products as novel antioxidants sources of neuroprotection against neurodegeneration. Natural antioxidants, such as polyphenols, vitamins, Ginkgo biloba, curcumin, and herbal formulations are thought to reduce oxidative stress and to have preventive or therapeutic potential in Alzheimer's disease (AD). Extensive oxidative stress and a dysfunctional antioxidant system have predominant implications in the pathogenesis of AD. To date, treatment of AD attenuates symptoms rather than fighting the root cause of the disease. Several natural antioxidants have revealed potential in animal models of AD. However, clinical trials using antioxidant bioactive molecules for AD treatment are not yet conclusive. It has become apparent that modified strategies that enhance the bioavailability and brain permeability of bioactive molecules designed to target free radicals are prospective therapeutic options against AD. The present review summarizes the effectiveness of several bioactive molecules, traditional herbal formulations, and natural products from Brazilian Caatinga as sources of antioxidants activity for attenuating the neuropathology of AD reported in various animal models, preclinical and clinical trials. On the whole, setbacks and future perspectives on the therapeutic use of these molecules regarding bioavailability, formulation, and clinical trials status will also be discussed.