Curare

Curare is a South American vine native to the Amazon Basin. It is found growing in Brazil, Bolivia, Peru, Guiana, Ecuador, Panama and Colombia. This woody vine, sometimes 4 inches thick at its base, climbs a considerable height up into the canopy (up to 30 meters high). Its large heart-shaped leaves have a soft silky underside made up of tiny white hairs, giving the plant the common name of velvet leaf. It has both male and female flowers which are small, greenish-white, and grow in clusters. It produces an edible bitter-sweet fruit. The names curare and woorari are Indian names which refer to the poisons they prepare to dip hunting darts and arrows into. The actual name, curare, is a corruption of two Tupi Indian terms meaning "bird" and "to kill." Chondrodendron tomentosum or the curare vine is one of the main plants used by the Indians in the Amazon to prepare these arrow poisons.

Tribal and Herbal Medicine Uses

Many different plants are used to prepare curare arrow poisons and many different recipes are used by different Indian tribes in the Amazon. Generally the Indians in Venezuela and the Guianas use Strychnos plants as the main ingredient and tribes in Peru, Ecuador and Brazil use curare vine (Chondrodendron tomentosum) as the main ingredient in their poisons. In both cases, it usually is a combination of several different plants and even snake and frog venom is sometimes added. The Sionas of Colombia, the Lamistas of Peru and the Ketchwas of Ecuador use curare vine in the preparation of their poisons; they crush and cook the stems and roots of the vine, adding other plants and venomous animals. It is boiled down (sometimes for as long as 2 days) until it becomes a dark-colored syrup or paste. The resulting substance is then used to coat the darts of their blowguns and tips of hunting arrows. These poisons are not actually true toxins - rather they are potent muscle relaxants.

Death from curare poison is caused by asphyxia (respiratory arrest) because the muscles become so relaxed that the muscles operating the diaphragm and lungs stop functioning. Interestingly, it only works if the poison gets into the bloodstream; ingesting curare poison (and even eating the meat of curare-poisoned animals) has no toxic effect since it isn't absorbed in the stomach. It works well for the Indians because oftentimes their prey is high up in the canopy - the muscle-relaxant effect of the poison prevents the animal from fleeing and releases their grip on branches in the trees so they fall to the ground. The muscle-relaxing effect begins almost immediately upon hitting the bloodstream, but death from respiratory arrest can take a few minutes for birds and small prey, and up to 20 minutes or longer for larger mammals.

Curare vine also holds a place in herbal medicine systems. In Brazil and Peru the root of the vine is used to increase urination, reduce fever and promote menstruation. It is also used to treat edema, kidney stones and testicular inflammation. Externally it is used for bruises and contusions. In Brazil the leaves are also crushed and applied externally for the treatment of poisonous snake bites. In homeopathy the plant is used for inflammation of the urinary tract and enlarged prostate. Sir Walter Raleigh and several other early explorers reported on the Indian's use of curare vine in the 1500's and the plant became known in European herbal medicine systems. Maude Grieve, British author of the book "A Modern Herbal" (first published in 1931), reported that the plant acts as an antiseptic to the bladder for chronic inflammation of the urinary passages and recommended it for stones, vaginal discharges, rheumatism, jaundice, edema and water retention, and gonorrhea.

Plant Chemicals

Curare vine is a rich source of alkaloids. The main alkaloid responsible for the muscle-relaxant actions (and why it works as an arrow poison) is called d-tubocurarine. It was first isolated in 1897 and obtained in drug form in 1935. The alkaloid works by blocking the signals in the brain which tell the muscles to move - thereby rendering the whole body immobile to the point of becoming virtually paralyzed. It's not a toxin - and the effects generally wear off in about 90 minutes. In 1942 curare and d-tubocurarine were introduced into clinical anesthesia, starting the modern era of surgery. Today it is still sold as a prescription drug which is used as a general anesthetic and muscle relaxant in various types of surgeries (during which breathing can be controlled with machines).

It is also used to treat paralysis caused by tetanus (which causes uncontrollable muscle contractions throughout the body). D-tubocurarine's chemical pathways and actions are also being evaluated for their role in blocking serotonin, reducing vomiting, alleviating drug withdrawal symptoms, and for their anti-anxiety effects. D-tubocurarine also stimulates the release of histamine. This release of histamine may cause lowered blood pressure due to relaxation of blood vessels. Intravenous administration of d-tubocurarine causes rapid muscle relaxation, first affecting the toes, ears and eyes, then the neck and limbs and finally respiration.

The main chemicals found in this rainforest vine include chondrocurarine, chondrocurine, chondodine, chondrofoline, curine, cycleanine, D-tubocurarine, isochondrodendrine, L-bebeerine, L-tubocurarine, N-benzyl-phthalimide, norcycleanine, pelonine, tomentocurine, and tubocurarine.

Biological Activities and Clinical Research

As is often the case in plant research - since scientists supposedly discovered the "main active chemical" in the plant so many years ago and turned it into a drug, further research on the natural plant wasn't forthcoming. Literally no clinical research has been conducted on the use of extracts of this natural vine as it is used in herbal medicine systems.

Current Practical Uses

Curare is yet another example of how the empirical knowledge of rainforest Indian tribes has been utilized by western science and the pharmaceutical industry. Since the strong muscle-relaxant chemicals in the plant are not absorbed in the stomach, oral extracts of the vine and root are considered 'safe' in herbal medicine systems. Its uses today, however are mainly limited to South America. A root decoction is generally prepared for persistent urinary tract infections, prostatitis, and testicular inflammation.

One U.S. manufacturer of herbal supplements does state that they use Chondrodendron tomentosum in a formula (for lowering blood sugar levels), however, they call it "abuta." Abuta and curare, are in fact, two different species of vines with very different uses in herbal medicine and different plant chemicals (and neither have been used for diabetes or blood sugar balancing). The real "abuta" vine is featured in this book as Cissampelos pareira. Even more confusing - the picture of the plant in their marketing materials is neither plant. . . but looks suspiciously like yet another rainforest vine: Abuta grandifolia (which has been used indigenously for diabetes). An experienced herbalist or botanist would wonder if this company even knew which plant they were actually using! As always; consumers should look for a reputable supplier of this plant and all medicinal plants coming from South America.

Traditional Preparation: 1 cup twice daily of a standard root decoction on an empty stomach. See Traditional Herbal Remedies Preparation Methods page if necessary for definitions.

Contraindications:

• Not to be used during pregnancy and breast-feeding.
• Curare may possibly reduce blood pressure; it should not be used in those with low blood pressure or those on medication to lower their blood pressure.

Drug Interactions: None reported.