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Cannabis Campaigners' Guide News Database result:
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Herbalists Say Their Extracts Are More Potent Than Purified Drugs.
New Scientist
Saturday 26 May 2001 Swallow it Whole Herbalists say their extracts are more potent than purified drugs. Now scientists find they may be right. HERBAL remedies are more popular than ever. Estimates vary, but the global market has grown rapidly in the past decade, and according to the European Herbal Practitioners Association, the European Union market is worth E6.8 billion a year. No one doubts that herbs are full of medicinal chemicals--after all, plants are the source of half the pharmaceuticals in our modern medicine cabinet. Most of the top seven sellers seem to have something going for them (see Table, right and p 40). But why take a risk by swallowing something as unpredictable as plant material when modern science can isolate the active ingredient and serve it to you straight? Herbalists claim it is because mixtures are better than pure chemicals. They say the dozens of biologically active compounds in a plant work together to produce a greater effect than any one chemical on its own. It sounds like New Age hokum. But scientists are finding that the herbalists are sometimes right. In fact, herbs could point us towards a whole new generation of drugs. Modern medicine is hooked on the idea of the "magic bullet" --the pure drug molecule, like aspirin or penicillin. Even multi-drug approaches such as combination therapy for HIV are just more of the same. Each ingredient in the cocktail is a magic bullet in its own right. Revolutionary though modern medicine has been, there are a host of illnesses, from depression to multiple sclerosis, for which there is no magic bullet. Some respond better to the kind of mixtures found in herbs. Is it time for a rethink? The first hints that herbalists were onto something came in the early 1990s, when Raphael Mechoulam, head of pharmacology at the Hebrew University in Jerusalem, discovered human receptors that bind tetrahydrocannabinol or THC, the main active ingredient in cannabis. Although the function of these receptors remains obscure, Mechoulam also discovered that we make our own signalling molecules that bind to them. One, 2-AG, is produced alongside two companion compounds. Though closely related to 2-AG, neither has a biological effect on its own. But they do enhance the potency of 2-AG by making it bind to its receptor more strongly. In other words, the chemicals act in synergy--the mixture has an effect greater than the sum of its parts. "I have no idea how they do that," admits Mechoulam. But he suspects similar chemical partnerships explain why whole herbs can work better than their single purified ingredients. Hundreds of MS sufferers who use cannabis as a remedy swear the whole plant works better than pure THC. Could it be that other chemicals in cannabis work like 2-AG's companions, enhancing THC's affinity for cannabinoid receptors? There is certainly evidence that cannabis taken whole works better than isolated extracts. At a symposium at the Royal Pharmaceutical Society in London in April, pharmacologist Elizabeth Williamson of the University of London School of Pharmacy reported that in a mouse model of MS, an extract of whole cannabis relieved muscle spasms much more effectively than pure THC. Williamson says this shows chemicals other than THC enhance the effect, but not whether the action of these is synergistic or merely additive. Some herbal derivatives seem to show true synergy. Hildebert Wagner and colleagues at the University of Munich have shown that a mixture of two anti-clotting chemicals found in ginkgo leaves is more powerful than the sum of their individual effects. Similarly, the six most active chemicals in the herbal sedative kava kava seem to act synergistically. Williamson says additive or synergistic effects may make for better therapies because you can achieve the medicinal effect with smaller doses of each ingredient. That means you can avoid the side effects that tend to kick in with higher doses. There's anecdotal evidence that this is true: the herbal stimulant ephedra, for example, is said to have fewer side effects than ephedrine, one of its ingredients. But no one has done any research to find out why. The mainstream pharmaceuticals industry isn't really interested in herbs because they're unpatentable. To market herbal derivatives with full patent protection, they would have to do clinical trials on the active ingredients, separately and together. Compared with testing a single magic bullet, this is prohibitively expensive. And there is a downside to these complex interactions. The better brands of the herbal antidepressant St John's Wort, for example, contain specific quantities of one of the active ingredients, hypericin. But since there are a dozen or more active compounds in the herb, two batches with the same hypericin content might have very different potencies. In any case, most herbal preparations are marketed with little testing, even to make sure they contain the plants they claim to. European manufacturers try to ensure that at least the safety, if not the efficacy, of their products is tested, but they are under pressure from the US industry to weaken even these controls. Without the support of the pharmaceuticals industry, herbs are likely to remain mired in uncertainty. What a waste.
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