PHARMACOGNOSY—A BRIEF HISTORY
‘Pharmacognosy’—has been coined by the merger of two Greek words Pharmakon (drug) and Gnosis (knowledge) i.e., the knowledge of drugs. The nomenclature ‘Pharmacognosy’ was usedfirst and foremost by C.A. Seydler, a medical student in Halle/Saale, Germany, who emphatically employed Analetica Pharmacognostica as the main title of his thesis in the year 1815. Besides, further investigations have revealed that. Schmidt has made use of the terminology ‘Pharmacognosis’ in the monograph entitled Lehrbuch der Materia Medica (i.e., Lecture Notes on Medical Matter)which dates back to 1811, in Vienna. This compilation exclusively deals with the medicinal plants and their corresponding characteristics. It is indeed quite interesting to observe that our ancients were duly equipped with a vast, indepth and elaborated knowledge of plethora of drugs from the vegetable origin but unfortunately they possessed a scanty knowledge with regard to the presence of chemically pure compounds in most of them. Camphor found its enormous use in the treatment and cure of many ailments, for instance: internally as—a stimulant and carminative; externally as—an antipruritic, counterirritant and antiseptic by the ancient Egyptians, Chinese, Indians, Greeks and Romans. Earlier it was obtained by mere cooling of volatile oils from—ssasafras, rosemery, lavender, sage; while the Ancient Greeks and Romans derived it as a by product in the manufacture of wine. Nowadays, camphor is obtained on a large-scale synthetically (racemic mixture) from the α-pinene present in the terpentine oil (Chapter 5).
African natives used plant extracts in their ritual ceremonies whereby the subject would lose his/her complete body movements but shall remain mentally alert for 2 or 3 days. Later on, the earlier civilization also discovered a number of fermented drinks solely derived from carbohydrate—rich plant substances invariably containing alcohols and vinegar. With the passage of time they also recognised certain plant products exclusively used for poisoning their spears and
arrows in killing their preys and enemies as well. Interestingly, they found that some plant extracts have the unique property of keeping the new meat fresh and also to mask its unpleasant taste and flavour. The human beings belonging to the ancient era in different parts of the globe independently discovered the inherent stimulating characteristics of a wide variety of drinks exclusively prepared from the vegetative source as stated below in Table 1.1.
Table 1.1 Stimulating Characteristics from Vegetative Sources
Figure 1 shows the basic nucleus of ‘Xanthine’ and ‘Purine’; besides the three well-known members of the Xanthine family viz., Caffeine, Theophylline and Theobromine.
Figure 1.2, illustrates the mode of synthesis of caffiene essentially from the same precursors present in Caffea arabica as the three purine alkaloids (see Fig 1.1) found in order biological systems which have been studied so far at length, either from a compound which may afford an active 1-carbon fragment (e.g., serine, methanol, glycine and formalin) or from formic acid.
Methionine along with the said four compounds act as active precursors of the three ‘Methyl
Groups’ at N1, N3 and N7 positions respectively.
*Glycine is responsible for the contribution of C-4, C-5 and C-7,
*Carbon dioxide contributes C-6,
*N-1 is provided from aspartate, and
*N-3 and N-9 are derived from the amide nitrogen of glutamate.
Such elaborated and intensive studies of chemical constituents present in ‘Natural Products’
could only be feasible with the advent of various advancement in the field of ‘Phytochemistry’.
However, it is pertinent to mention here that the scientific reasonings for the various age-old
established characteristic medicinal properties have been adequately ascertained and determined in the past two centuries. A critical survey of literatures would reveal that a few chemical entities were not only identified but also known to the therapeutic armamentarium between the said era. A few typical examples are enumerated below in a chronological order, as stated in Table 1.2.
Considerable progress has been made in the nineteenth century when chemists seriously took up
the challenge of synthesizing a plethora of organic compounds based or ‘biologically-activeprototypes’. Some of these purely ‘synthesized compounds’ essentially possessed structures of ever increasing complexity; and later on, after systematic pharmacological and microbiological evaluations proved to be yielding excellent useful therapeutic results. Evidently, as most of these ‘tailor-made’ compounds having marked and pronounced therapeutic indices were found to be existing beyond the realm of ‘pharmacognosy’ or more specifically ‘phytochemistry’—an altogether new discipline under the banner of ‘medicinal chemistry’ came into existence. However, this particular discipline almost remained dormant since the era of Parcelsus. But now, the ‘medicinal chemistry’ has acclaimed deserving wide recognition across the globe due to its own legitimate merit and advantages.
In short, three major basic disciplines became largely prevalent with regard to the development
of drugs, namely:
* Pharmacognosy: embracing relevant information(s) with regard to medicines exclusively derived
from natural sources, for instance: plants, animals and microorganisms,
* Medicinal Chemistry: covering entirely the specific knowledge not only confined to the science
of ‘synthetic drugs’ but also the basic fundamentals of ‘drug-design’, and
* Pharmacology: dealing particularly the actions of ‘drugs’ and their respective effects on the
cardiovascular system and the CNS-activities.
Over the years, with the tremendous growth of scientific knowledge and valuable informations
the three aforesaid disciplines have fully-emerged as ‘complete sciences’ within their own
spheres.
Though copious volumes of ancient literatures in Chinese, Egyptian, Greek, Unani and Indian
(Ayurvedic) systems of herbal medicines were found to contain factual and invariably exaggerated claims of their therapeutic efficacies, yet when they are evaluated intensively on a scientific basis with the advent of latest analytical techniques, such as: FT-IR, NMR, MS, GLS, HPLC, HPTLC, X-Ray Diffraction, ORD, CD and UV-spectroscopy—it has adequately and promptly provided an elaborated structure of various complex chemical constituents. A few select typical examples of known compounds are given in Table 1.3.
