What are the benefits and limitations of the extractions of drugs from plants?

The active ingredients for 25% of the world's prescription drugs are substances extracted from plants. Once the active component is isolated and identified, it can be synthesized for use, often at a lower cost than extracting it from harvested plants. Then the natural compound can be modified to produce an array of related chemicals, many of which are useful drugs. This process had led to compounds used in contraceptive pills, tranquilizers, muscle relaxers, and life-saving drugs for treating malaria, leukemia and Hodgkin's diesease, testicular and lung cancers, heart disease, high blood pressure, multiple sclerosis and many other diseases. Most of the original strains of rice, wheat and corn that supply the world's food were developed from wild tropical plants. Drug and biotech companies are chemical prospecting to find new material before it is lost forever but often the countries of origin receive little or none of the immense profit from the drugs. Problems arise with the patenting of intellectual property.