Towards the scientific validation of the medicinal properties of herbs

RESUMO

The theraputic use of herbs spans at least three thousand years and dates from ancient civilizations such [as] those in Sumeria and China. The scientific investigation and evaluation of the medicinal properties of herbs however, began comparatively recently with the activities of the physicians/botanists such as William Withering (1741-1799) who first described the benefit of foxglove in treating "dropsy". This led directly to the identification of digitalis as the active drug in increasing the force of contraction of cardiac muscle in congestive heart failure. In truth the birth of pharmacology concurs with scientific investigations of plant-derived drugs on living organisms and systems. Plant alkaloids such as atropine, nicotine, and curare enabled physiologists to unravel the mysteries of the autonomic nervous system and neuromuscular junction. From such studies the concept of receptors (originally proposed by Paul Ehrlich, 1854-1915) and the importance of precise chemical molecular structure of drugs to produce a biological effect was confirmed unequivocally ...... With regulation, comes the requirement for scientific validation of appropriate biological activity of a preparation, the standardization of the preparation by assay to ensure uniform purity and also evaluation of the toxicity and potential for adverse events and interaction with other drugs. This validation of the activity of existing medicinal plants as well as the search for new drugs in plant extracts requires bioassay techniques with studies in vivo (whole animal) exploring lethality, convulsions, vomitting, changes in blood pressure, urine flow or levels of metabolites (e.g. blood glucose) and also their actions in animal models of disease. Other studies, use in vitro bioassay techniques such as survival rates of cultures of microorganisms, isolated pieces of living organisms (e.g. muscle, heart, an endocrine gland, receptor binding assays) and cultures of normal and diseased human cells (e.g. cancer cell lines)