The Indian system of medicine, Ayurveda, makes use of plant kingdom very effectively and has stood the test of time. Synthetic chemicals in the form of drugs, pesticides, etc. have been successful in combating diseases of man, his domestic animals and plant crops. However, their side effects are of major concern in the modern world. Moreover many of the microbes and insects have become resistant to most of these chemicals. Hence we look to nature as an ally and resource in finding new strategies to combat diseases. In this respect, plants serve as a vast reservoir of biodegradable chemicals, many of which may have evolved in the defense of predators.