Medicinal Plants, Phytomedicines, and Phytotherapy

Abstract

From a historical perspective, the production of medicines and the pharmacologic treatment of diseases began with the use of herbs. In fact, the very word drug used to denote a medicinal preparation is derived from the old Dutch word droog meaning“ to dry”, as plants were dried to be used as medicines. Methods of folk healing practiced by the peoples of the Mediterranean region and Asia found expression in the first European herbal, De Materia Medica, written by the Greek physician Pedanios Dioscorides in the first century C.E. During the Renaissance, this classical text was revised to bring it more in line with humanistic doctrines. The plants named by Dioscorides were identified and illustrated with woodcuts, and some locally grown medicinal herbs were added. Herbals were still based on classical humoral pathology, which taught that health and disease were determined by the four bodily humors — blood, phlegm, black bile, and yellow bile. The humors, in turn, were associated with the elemental principles of antiquity: air, water, earth, and fire. The elements could be mixed in varying ratios and proportions to produce the qualities of cold, moist, dry, or warm — properties that also were associated with various proportions of the four bodily humors. Thus, if a particular disease was classified as moist, warm, or dry, it was treated by administering an herb having the opposite property (Jüttner, 1983). Plant medicines were categorized by stating their property and grading their potency on a four-point scale as “imperceptible,” “perceptible,” “powerful,” of “very powerful.” For example, opium, the classic drug derived from the opium poppy (Papaver somniferum), was classified as grade 4/cold. A line of association that linked sedation with “cooling” allowed the empirically known sedative and narcotic actions of opium to be fitted into the humoral system. Pepper (the black pepper of the historical spice trade, i.e., Piper nigrum, not to be confused with the red pepper of the genus Capsicum, which as introduced to medicine after the discovery of the New World, was classified as grade 4/dry and warming. The goal of all treatment, according to Hippocrates, was to balance the humors by removing that which is excessive and augmenting that which is deficient” (Haas, 1956). Humoral pathology obviously developed into one of the basic principles of conventional medicine.