Bioactive Substances

The use of natural products as source of drugs is as old as mankind itself. However, since man is largely land-based, he has concentrated on and became familiar with those sources which immediately surround him; mainly, the terrestrial plants and animals. A search through Pharmacopoeias reveals that crude plant and animal products and some inorganics were used as drugs. As medical science progressed, these were slowly replaced by purified extracted principles, and more recently by pure synthetic organic compounds. The latter is mainly due to the fact that it is usually easier to synthesize a drug than to collect it from natural source though in many cases nature makes many compounds cheaper and more efficiently than man. Alkaloids like quinine, an antimalarial drug obtained from fever tree Cinchona officinalis bark; reserpine, sedative from the roots of Rauwolfia serpentina, the analgesic codeine and morphine from opium-poppy, Papaver somniferum, and antibiotics such as penicillins, tetracyclines and cephalosporins, which are produced by microbial fermentation are well known examples of this.