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TropicalBotanic Gardenand Research Institute, Palode
Thiruvananthapuram - 695 562, India



Snakes are remarkable animals, successful on land, in the sea, in forests, in grasslands, in lakes, and in deserts. Most snake bites are caused by non-venomous snakes. Of the roughly 3,000 known species of snake found worldwide, only 15 percent are considered dangerous to humans (Russell, 1990). Snakes are found on every continent except Antarctica. The most diverse and widely distributed snake family, the Colubrids, has only a few members which are harmful to humans. Of the 120 known indigenous snake species in North America , only 20 are venomous to human beings, all belonging to the families Viperidae and Elapidae (John Henkel, 1995). However, in the United States, every state except Maine, Alaska, and Hawaii is home to at least one of 20 venomous snake species (John Henkel, 1995).

Consequently, no accurate study has ever been conducted to determine the frequency of snakebites on the international level. However, some estimates put the number at 2.5 million bites per year, resulting in perhaps 125,000 deaths. Worldwide, snake bites occur most frequently in the summer season when snakes are active and humans are outdoors (Wingert and Chan, 1988). Agricultural and tropical regions report more snake bites than anywhere else (Russell, 1990). Snakes are most likely to bite when they feel threatened, are startled, provoked, and/or have no means of escape when cornered. Encountering a snake is always considered dangerous and it is recommended to leave the vicinity.

As far as Indian snakes are concerned, it's not the only way either. A variety of poisonous snakes kill 50,000 Indians a year. In fact as many people die of snakebites in India as the rest of the world put together (John Sudworth, 2006).

Snakes have no limbs, yet all are meat eaters. They catch prey that includes insects, birds, small mammals, and other reptiles, sometimes including other snakes. Only about 400 of 3000 snake species worldwide inject venom (a poison). Many snakes catch their prey by constriction. In constriction, a snake suffocates its prey by tightening its hold around the chest, preventing breathing or causing direct cardiac arrest. Snakes do not kill by crushing prey. Some snakes grab prey with their teeth and then swallow it whole. Snakes are cold-blooded. Thus, they are unable to increase their body temperature and stay active when it is cold outside. They are most active at 25-32°C (77-90°F).

Based on their morphological characteristics including arrangement of scales, dentition, osteology, myology, sensory organs etc., snakes are categorized into families. The families of venomous snakes are Atractaspididae, Elapidae, Hydrophidae and Viperidae.
The major families in the Indian subcontinent are, Elapidae which includes common cobra, king cobra and krait, Viperidae which includes Russell's viper, pit viper and saw-scaled viper and Hydrophidae, the sea snakes( Philip,1994).
Of the 52 poisonous species in India , majority of bites and consequent mortality is attributable to 5 species viz. Ophiophagus hannah (king cobra), Naja Naja (common cobra), Daboia rusellii (Russell's viper), Bungarus caeruleus (krait) and Echis carinatae (saw-scaled viper).

How snakes bite

Snakes that inject venom use modified salivary glands. Venom is a modified form of saliva and probably evolved to aid in chemical digestion. Varying degrees of toxicity also make it useful in killing prey. During envenomation (the bite that injects venom or poison), the venom passes from the venom gland through a duct into the snake's fangs, and finally into its prey. Snake venom is a combination of numerous substances with varying effects.



The most common symptoms of all snake bites are panic, fear and emotional instability, which may cause symptoms such as nausea and vomiting, diarrhea, vertigo, fainting, tachycardia, and cold, clammy skin (Kitchens and Van Mierop, 1987).

The time onset of poisoning is similar in different species. Cobra produces symptoms as early as 5 minutes (Paul, 1993) or as late as 10 hours (Reid, 1979) after the bite. Vipers take slightly longer - the mean duration of onset being 20 minutes (Paul, 1993). However, symptoms may be delayed for several hours. Sea snake bites almost always produce myotoxic features within 2 hours so that they are reliably excluded if no symptoms are evident within this period (Paul, 1993).

Based on the predominant constituents of venom of a particular species, snakes were loosely classified as neurotoxic (notably cobras and kraits), hemorrhagic (vipers) (Bhetwal et al., 1998) and myotoxic (sea snakes).

Since the act of delivering venom is completely voluntary, all venomous snakes are capable of biting without injecting venom into their victim. Such snakes will often deliver such a "dry bite” rather than waste their venom on a creature too large for them to eat. Dry snake bites, and those inflicted by a non-venomous species, are still able to cause severe injury to the victim. There are several reasons for this, a snake bite which is not treated properly may become infected (as is often reported by the victims of viper bites whose fangs are capable of inflicting deep puncture wounds), the bite may cause anaphylaxis in certain people, and the saliva and fangs of the snake may harbor many dangerous microbial contaminants, including Clostridium tetani. If neglected, an infection may spread and potentially even kill the victim.

Most snake bites, whether by a venomous snake or not, will have some type of local effect. Usually there is minor pain and redness, but this varies depending on the site. Bites by vipers and some cobras may be extremely painful, with the local tissue sometimes becoming tender and severely swollen within 5 minutes. This area may also

Healing tradition of Kerala

Healing tradition of Kerala includes both Codified and non codified systems, which are strongly interrelated and based on principles of Ayurveda. It involves classical methods of diagnostics and treatment like Sushrutha Samhitha and Ashtanga Hridaya. Visha Vaidya is one component of the healing tradition of Kerala.

Visha Vaidya

Visha Vaidya is one branch of traditional healing, popular in Kerala, mostly in Palakad and Trichur, involving treatment of poisonous bites like that from snake, dog and stings of scorpion, spider etc. Visha Vaidya deals with management of poisonous bites, poisonous substances and their action, Antidotes and Understanding of poisonous creatures. Treatment include herbals, administered as nasal drops, eye drops and oral medicine, strict food regulations, Abstaining from alcohol and non vegetarian foods. Treatment also includes rituals and offerings to God.

Tribal Information from Kerala

The Kani tribe of the Western Ghats of Kerala apply ‘Vishakallu’, a medicated stone with anti - poisoning properties to the affected area (snake bite). The ingredients that go into the making of ‘Vishakallu’ are, Pebbles from the river, Tulsi or Holy Basil leaves (Ocimum sanctum - Lamiaceae), Leaves of Perumthumba (Anisomeles malabarica - Lamiaceae), Heartwood of Chandanam (Santalum album - Santalaceae).

Mode of preparation of ‘Vishakallu’

Pebbles are ground, mixed with the other ingredients and made into paste and wrapped with 7 leaves of Aristolochia tagala. It is baked on fire made by burning wood of Chuvannakil (Chukrasia tabularis – Meliaceae; native to India and Sri Lanka ) or Dysoxylum malabaricum (Vella Akil; Meliaceae), sandalwood, holy basil and camphor. This baked cake is covered with paste of termite mount soil and again baked on low fire. The soil coat is removed and the cake is soaked in water for an hour, covered with paste of Pittosporum neelgherrense - Analivegam ( Pittosporaceae) stem bark . The whole thing is baked again and covered with stem bark of Kunstelaria keralensis (Fabaceae). And sun dried. This ‘stone’ is stored in burnt cow dung ash and Nicotiana tabacum - Pukayila (Solanaceae) leaves (Tobacco).

Mode of administration of ‘Vishakallu’

It is administered only by experienced tribal healers. The stone is directly applied to the bitten part. It sticks there and absorbs the venom from the wound. During this operation, Lord Siva is propitiated by chanting mantras. When all the venom is absorbed the stone falls away automatically. The stone is immersed in cow’s milk for detoxification for 2 hours.It is again dried and stored in cow dung ash. It is believed from experience that it can be used 20 times.

Plants for snake bite

Plants and their extracts have been used for the treatment of snake bite in most areas where venomous species are endemic (Houghton and Osibogun, 1993). In spite of this wealth of ethnopharmacological information only a relatively few species have been tested scientifically for anti – venom activity and the species where an active compound has been isolated are very few in number.This report lists the plants used by the traditional healers against snakes and snake bite in India.

Plants used against snake bite in India .

Although many plants may not neutralize the venom itself, they may be used to treat snake bite because they alleviate some of the symptoms (fear and panic) by tranquilising compounds eg: Rauwolfia serpentina – ‘Sarpagandhi’ (Apocynaceae) since this plant containing the tranquilising alkaloid, Reserpine.

Some species are grown around houses or their extracts sprinkled on the floor to repel snakes. e.g., Garlic (Vellulli - Allium sativum ; Liliaceae) and Garlic vine (Pseudocalyma alliceaum, Bignoniaceae).

Some plants may stimulate the immune system thus having beneficial effects, helping in removal of the venom. In this context, Aristolochia species (Aristolochiaceae) is noteworthy. It contains Aristolochic acid which is an immune stimulant.

Plants with analgesic and anti - inflammatory effects may lessen the inflammation and pain caused by snake bites. e.g., Rhapidophora pertusa - Anathipali’ (Araceae).

Aristolochia indica and A. tagala of Aristolochiaceae are two plants, used by the Kanis to treat snake bite (krait & cobra).They call them ‘Cheriya arayan’ and ‘Veliya arayan’ respectively. According to them, A. tagala is more potent than A. indica. A. indica was used as antidote to snake bite by ancient Ayurvedic physicians also. It is an excellent blood purifier, used as diuretic, heart stimulant and against skin diseases. Paste of fresh leaves or roots of A. indica or A. tagala is applied externally over the bitten part. 10 – 15 ml fresh juice from leaf/ root with a pinch of black pepper is administered orally 6 times a day.

The whole plant of A. indica or A. tagala (1 part), bark of Ficus religiosa – arayal (Moraceae), 1 part and powder of black pepper (1 part) are mixed together and used as nasal inhaler to recover from the coma caused by snake bite.

The leaves of Cipadessa baccifera (Kattuveppu; Meliaceae) are mixed with pepper and taken orally against snake bite by Malapandaram tribe of Wayanad, Kerala.

Other major plants for snake bites



Local name

Part used

Tribe used


Strychnos nux vomica



Seeds and Roots

in Orissa

Helecteres isora


Edampiri valampiri

Root and Seeds


Calycopteris floribunda






Cyperus rotundus




in Rajasthan

Pittosporum neelgherrense




Stem bark

Kani and Malapandaram

Rhinacanthus nasuta


Nagamulla ;

Leaves and Roots

traditional healers of Kerala

Celastrus paniculatus




Crushed stem bark

in Rajasthan

Oxalis corniculata




Whole plant

in Orissa

Plumbago zeylanica





in Orissa

Tragia involucrata





in Orissa

Boerhavia diffusa






Costus speciosus






Hedyotis corymbosa




Whole plant.



Major phytocompounds responsible for anti venom activity

Aristolochic acid from Aristolochia species (Aristolochiaceae) is reported to inactivate venom and reduce hemorrhage from snake bite.It inhibits phospholipases. It produce non - specific increase in immune response (Wagner and Proksch, 1985)

Gymnemic acids (triterpenoid glycosides) from Gymnema sylvestre (Chakkarakolli; Asclepiadaceae) is used as a remedy for snake bite in India . It inhibits ATP ase in snake venom (Kini and Gowda, 1982)

Eclipta prostrata (Kaiyonni; Asteraceae) extracts inhibit effects of South American rattle snake bite. Three active compounds, coumestan, wedelolactone stigmasterol and sitosterol have been isolated from the crude extract this plant (Mors et al., 1989).

Phenolic compounds like tannins are well – known for their ability to bind with proteins. The tannin from Diospyros perigrina (Panichi; Ebenaceae) inhibits swelling in feet of mice caused by sea snake venom and improved survival rate of mice injected with snake venom (Okonogi et al., 1979).

The phenolic pterocarpans from a Brazilian root Cabeca – de – negro used in Amazon to treat snake bite. Negro reverses the effect of Bothrops atrox venom in dogs (Nakagawa et al., 1982). Unfortunately the botanical identity of this plant is not known.

Curcuma longa rhizomes (Manjal; Zingiberaceae) are used to treat snake bite. Turmerone from C. longa afforded protection against the lethal effect of the venom of Bothrops jararaca when it was injected into mice (Ferreira et al., 1992).

Atropine, from Atropa belladona, the deadly nightshade (Solanaceae) protects against the toxins from the green and black mamba. These venoms increase transmitter release from cholinergic nerve terminals. Therefore it was suspected that a cholinergic blocker like atropine reduces its effect. This was proved by in vivo tests in mice (Lee et al., 1982).


Tests to determine anti – venom activity

The testing of plant extracts for anti - venom activity illustrates the traditional use of plants in treatment of snake bite.

The variety of activity displayed by different snake venom systems requires different test systems to investigate inhibitory effects of plant extracts. Workers studying a particular plant species have to devise and use a range of experiments or concentrate on the most venomous snakes in the area where the plant is used. A few studies were carried out where the extracts were given prior to injection of venom or after administration of venom, which is most analogous to the case of snake bite.

In vivo tests to determine anti venom activity

The tests should reproduce the conditions and effects of envenomization but also be economic, socially acceptable and suitable for a high throughput of samples.

In vivo animal testing

The protection of whole animals against a dose of venom by the plant extracts approximates the field situation closely. This method is impractical now-a-days because of ethical considerations. Recently mice have been used for the testing of crude extracts. In most cases, a lethal dose of the venom was mixed with the varying doses of the plant extract and injected into the animal. Later the survival rate with and without extracts was determined and any significant decrease in mortality was taken to imply protection due to deactivation of the venom by compounds present in the plant. A few studies were carried out where the plant extract was given prior to injection of the venom or after administration of the venom, which is most analogous to case of snake bite.

Testing using isolated organ preparations

The use of isolated tissue for testing of biological activity does not require large doses or long periods of experiments using whole animals. If the effects produced can be removed by washing out, the preparation can be re – used. The tests consists of measurements on nerve – muscle preparations, isolated muscles and studies on blood - clotting procedures. The cobra venoms that impair neuromuscular transmission is experimentally studied using nerve - muscle preparations from neck of chick (biventer cervicis) and abdomen of the rat (phrenic nerve hemidiaphragm). Indirect stimulation of these preparations is inhibited by the venoms. Plant extracts containing anti – venom activity may consequently reverse these inhibitory effects. This was demonstrated with Curcuma longa extract against the neurotoxin from Naja naja siamensis (Cherdchu et al., 1978; Cherdchu and Karlsson, 1983). The isolated rat uterus was used to demonstrate the decrease in response to bradykinin released by the venom of Bothrops in the presence of Mandevilla velutina (an African plant) extract (Apocynaceae).

Another use of isolated tissue was described in a test for agents protective against the myotoxins of crotalid venom (Mors et al., 1989). The rate of release of creatinine kinase enzyme from superfused limb muscles was measured. The venom causes loss of the enzyme due to damage to the sarcoplasmic membrane and therefore, a high rate of release. This was considerably reduced by incorporating an aqueous extract of Eclipta prostrate (Asteraceae) in to the superfusion medium (Mors et al., 1989).

The in vitro systems were devised to study the inhibition of clotting mechanism of blood by plant extracts. Bothrops species cause haemorrhage at the point of injection due to inhibition of the clotting mechanism. The haemorrhagic effect was quantified by measuring the change in optical density of the skin at the site of injection in mice and found that E. prostrata neutralized the effects of Bothrops venom.

Envenomization by the Carpet viper, Echis carinatus causes rapid intra - arterial clotting of blood, resulting in internal haemorrhage due to depletion of fibrinogen. Mucuna pruriens (Naikurana; Leguminosae) increased the clotting time of blood induced by E. carinatus venom.

Tests using Enzymes

The enzyme – based assays were used for enzyme – inhibition or enzyme ctivation of large numbers of plant extracts.The potasium salt of gymnemic acid isolated from Gymnema sylvestre (Asclepiadaceae) inhibits ATPase from cobra and viper venom (Kini and Gowda, 1982). Inhibition occurs due to competitive binding between gymnemate and ATP. Aristolochic acid from Aristolochia species inhibits the action of phospholipase – A2 enzyme from viper venom responsible for edema formation. It occurs due to complexation of phospholipase with aristolochic acid (Vishwanath et al., 1987). Similarly hypolaetin–8–glucoside, a flavanoid from soyabean inhibited phospholipase A2 enzyme from snake venom (Alcaraz and Hoult, 1985).


In view of the number of deaths caused by snake bite, particularly where anti venom is not readily accessible, the development of thermostable cheap remedies suitable for emergency treatment is important. Scientific investigation into plants traditionally used to treat snake bite are showing results which indicate the plants may provide the source for individual compound or standardized extract which could be of benefit in many places where snake bite is a serious public health hazard.


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2.      John Henkel, 1995. For Goodness Snakes! Treating and Preventing Venomous Bites. FDA Consumer magazine

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