Attitudes toward the use of plants in medical treatments have taken a cyclical swing over the past two hundred years. Prior to the 19th century herbal remedies were commonplace, effective and subject to neither ridicule nor skepticism. No one queried their efficacy, as the evidence upon which their use was based was consistent, globally, over time and place, since the beginning of recorded history. Then, in the early part of the nineteenth century extraction of active plant constituents that proved to be therapeutically effective in the treatment of specific diseases heralded the birth of modern pharmacology.



The Herb Spiral probes some of the history of this scientific process, how it evolved from the pursuit of a magical cure for every malaise, the rise of the drug industry whose vested interests demand the discrediting of the very medicine that was in fact its precursor, its beginning, to a growing appreciation that the effectiveness of medicinal plants cannot always be reduced to that of a single extracted constituent.

Early experiments in what has become the science of pharmacology were carried out by a number of French scientists, and in 1803 a French scientist extracted a mixture of 2 alkaloids from opium. The first individual alkaloid, morphine, was isolated in 1804 from poppy. About that time quinine, which would become the antimalarial drug that would provide profound and lasting benefits to the health of African and other tropical populations was isolated from the South American cinchona tree,

These successes led to the process of isolating principles from plants being actively, almost obsessively, pursued and in 1821 the renowned French scientist François Magendie published a pocket book with the somewhat lengthy title of “Formulary for the preparation and use of several new drugs, such as nux vomica, morphine, prussic acid, strychnine, veratrine, the cinchona alkaloids, emetine, iodine”. This work became an essential guide to the use of isolated alkaloids in clinical medicine

Thus, the foundations of pharmacology were laid as the isolation and purification of constituents from plant medicines, which had already been used for centuries in non-purified forms. In fact, about half of the pharmaceutical medicines at the beginning of the 20 th century were still “impure” multi-constituent plant medicines. Many of the 19 th century and early 20 th century medical journals documented case studies substantiating the effectiveness of plant medicines in their crude, non-refined form.

Nonetheless, successes from the isolation and purification of active plant constituents are undeniable, and it is argued that these products provide the benefit of measured dosing and diminishes possible adverse events induced by other unwanted plant constituents. However these compounds clearly carry their own risks.

A 2006 report of the Institute of Medicine puts the number of medication errors causing injury to Americans at 1.5 million per year. Furthermore, the British Medical Journal noted that adverse events from herbal remedies are “a tiny fraction of adverse events associated with conventional drugs,” and risks

Moreover, the notion that “therapeutic reproducibility” is better because of its ability to offer more precise dosing of an isolated chemical totally ignores the wide variation in drug metabolism in individuals which can vary many-fold in healthy subjects. Thus, if an individual with a slow metabolism is exposed to a concentrated chemical, severe toxicity may occur whereas the probability of this occurring with a medicinal plant, which is inherently a dilute mixture of chemicals, is, relatively speaking, much less.

Another argument regularly heard is that the low concentration of any one constituent in a plant creates a mixture of compounds too dilute to have any beneficial effect. In fact, it has been shown that even very low concentrations of any one chemical will contribute to the chemical mixture's activity, even if that chemical does not show activity when isolated. As early as 1928 it was demonstrated that the effectiveness of combinations of constituents was different to that which might predicted by the activity of the isolated constituents. That is to say that the therapeutic benefit of a medicinal plant often cannot be reduced to that of any single constituent.

In fact, the strategy of using multiple compounds in clinical medicine is already in use. Drug cocktails have had success in the treatment of other complex diseases. For example, treatments for cancer, infectious diseases and hypertension, and psychiatric treatment protocols are achieving maximum benefit by targeting several biochemical pathways simultaneously; exploiting synergy, and minimizing toxicity. Drug cocktails are being used to compensate for resistance in tuberculosis found in the inner cities. Also, drug cocktail therapies are having successful outcomes in the treatment of AIDS and bacterial, fungal, and viral infections.

The position of the recent United Nations Convention on Biological Diversity is that evolution has been selecting and perfecting diverse bioactive molecules for millions of years. Hopefully, then, workers in the science of pharmacology will also recognize this premise in their choices of the directions that their research will take them in future years. Research may best be targeted, not at expensively extracted, manufactured and marketed “silver bullets” hitting a single target, but toward understanding the workings of the multi-component, broad-spectrum, molecular cocktails found in natural plants.

Ian Finlayson

(The original, longer version of this article, with references, can be viewed by clicking here )