As mentioned before, only a few drugs of modern medicine that are directly obtained from plants have been listed here. In addition to these natural drugs of modern medicine, plants have also contributed and are still contributing to the development of modern synthetic drugs and medicines in a number of ways as stated below
- Novel structures of biologically active chemical compounds, isolated from plant sources, often prompt the chemists to synthesise similar or biologically more potent semi-synthetic compounds.
- Synthetic drugs with similar or more potent therapeutic activity are often prepared by structural mod1ficat10n of the plant-derived compounds with known biological activity.
- Various analogues and derivatives of plant constituents with similar or better pharmacological actions and therapeutic properties are often prepared by the chemists for use as potent drugs.
Homatropine (a synthetic tropane alkaloid similar to atropine), syrosingopine (a synthetic derivative of reserpine), chloroquine (a synthetic derivative of quinine), dihydromorphinone, methyl dihydromorphinone, oxymorphine, ethylmorphine and N-allyl-normorphine (synthetic derivatives of morphine) are some of the examples of such synthetic drugs which plants have contributed indirectly. Even in this age of synthetic drugs, there are some naturally occurring drugs, such as the Digitalis glycosides used in cardiac complications and the Catharanthus alkaloids used in cancers, which have no synthetic alternatives. In such cases, plants continue to remain as their principal and only sources.
Thus it is apparent that whatever progress science might have made in the field of medicine over the years, plants still remain the primary source of many important drugs used in modern medicine.