Journal of Wilderness Medicine, 5,451-452 (1994)
Letter to the editors Treatment of Snakebite with Plants To the Editors:
Snakebites are responsible for many deaths each year; one estimate puts the total at 40000 . Many more cases of snakebite cause serious incapacity, although, of course, there are many nonvenomous species of snakes, and trauma is often more psychological than physical. The successful treatment of snakebite in a wilderness situation is influenced by several factors, such as species of snake involved, availability of conventional treatment, and correct first aid procedure to be adopted. Different families of venomous snakes produce toxins consisting mainly of mixtures of peptides. These toxins exert a variety of effects. The venoms of the Elapidae (which includes the cobras, Naja species) act on the synaptic membranes of nerves and muscles, while the Viperidae (vipers) and Crotalidae (rattlesnakes, moccasins) produce venoms that, among many other actions, interfere with the blood-clotting process, causing either rapid clotting or prevention of clotting. This may lead to death by hemorrhage. Thus, different effects necessitate different treatments, both as first aid and with an antidote(s). In many cases of envenomation, it may be difficult or impossible to determine the identity of the species of snake, since it may have slid away soon after the envenomation. Although modern Western medicine treats envenomation by snakes with antivenom, supplies of these antidotes usually have to be held in a refrigerator. The implications of difficulty of availability to casualties in a wilderness situation are obvious. Persons in many places where venomous snakes exist have traditions of using plants to treat snakebite. Knowledge of such plants growing in an area could be of benefit as an alternative first-aid treatment in a wilderness situation. However, the relevant information about the identity of the plant, the way to apply it, and the types of snake against which it is supposed to be effective are by no means complete as far as the scientific literature is concerned. Scientific proof of the efficacy of most of these plants is lacking, but a recent review  lists over 700 species of plant with a reputation for use against snakebite. These names were obtained from a wide variety of literature sources dealing with most parts of the world. Of particular interest was the occurrence of plants of the same genus or family, but from different geographical regions, such asAristolochia, where 22 species are listed. Examination of the list showed that the reputed activity of some of the plants might be explained, at least in part, by biological activities of relevance to the symptoms of snakebite rather than direct antagonism to the venom. Thus, the panic that follows snakebite in many people could be alleviated by plants which have tranquilizing properties. Rauvolfia serpentina is a wellknown Indian anti-snake plant, which contains the tranquilizing compound reserpine. The list also contained plants with analgesic activity, such as the opium poppy Papaver somniferum, as well as plants that have recently been shown to contain compounds giving an overall nonspecific boost to the immune system, such as aristolochic acid from Aristolochia spp. The list also summarizes the plants where some type of biological test has given tentative 0953-9859 © 1994 Chapman & Hall
Letter to the editors
support to the traditional use. The most valid of these tests are those where survival of envenomed animals treated with the extract was statistically better than that in an untreated group . Such tests raise practical, financial, and ethical problems if screening on a large scale or bioassay-guided fractionation is considered. Simpler tests have been developed that do not use whole animals, but rather, isolated organs, tissues, and even cells and enzymes . Some of the plants listed have shown activity against various venoms in such tests, but it is always important to stress the difference between showing activity in a test system and protection against venom in vivo. The chemical agents isolated from these plants that have been shown to be responsible for antivenom activity is very small. This is chiefly due to the problems of bioassay-guided fractionation outlined above. Several of the plants listed are known to have a high tannin content; thus, any antivenom effect may be due to the well-known reaction that occurs between tannins and some peptides. At first glance, this list of plants might be thought useful for wilderness medicine, but the lack of experimental evidence for efficacy in most of the plants mentioned pre-empts the use of this list as a manual for wilderness travelers. It does, however, raise the possibility of the local flora providing first aid in snake envenomation. It is to be hoped that studies of these plants will result in a clearer picture of which species are safe and effective and can eventually be adopted for this purpose. References 1. Habermehl, G.G., Venomous Animals and Their Toxins. Berlin: Springer, 1981. 2. Houghton, P.J. and Osibogun, I.M., Flowering plants used against snakebite. J Ethnopharmacology 1993; 39, 1-29. 3. Pereira, N.A., Ruppelt, B.M., do Nascimento, M.e., Parente, J.P., and Mors, W.B., An update on plants used against snakebite, Brasilianisch-Deutsches Symposium fUr Naturstoffchemie, Hanover, . 1991, pp. 48-51. . PETER J. HOUGHTON,
Pharmacognosy Research Laboratories, Department of Pharmacy, King's College London, Manresa Road, LONDON SW3 6LX, U.K.