A composition including an extract of buckwheat seed and a fractionation product of the extract of buckwheat seed useful for the prevention and therapy of aging is disclosed. The composition prevents, treats and improves aging phenomena such as the symptoms of Alzheimer's syndrome and pathological lesions of the brain. Further, the composition activates and improves the function of a brain including the ability to learn, memorize, and think, as well as providing other physiological benefits.