Medicinal plants are a rich source of bioactive phytochemicals or bionutrients. Studies carried out during the past 2–
3 decades have shown that these phytochemicals have an important role in preventing chronic diseases like cancer,
diabetes and coronary heart disease. The major classes of phytochemicals with disease-preventing functions are
dietary fibre, antioxidants, anticancer, detoxifying agents, immunity-potentiating agents and neuropharmacological
agents. Each class of these functional agents consists of a wide range of chemicals with differing potency. Some of
these phytochemicals have more than one function. There is, however, much scope for further systematic research in
screening Indian medicinal plants for these phytochemicals and assessing their potential in protecting against
different types of diseases