Toxic Plants PDF

Non-Medicinal Toxic Plants Toxic plant Plant toxins are substances produced as secondary metabolites that show both useful and harmful effects in human beings and animals. They show a wide range of side effects from minor itching, nausea, vomiting to adverse effects like psychosis, paralysis, tera...

Non-Medicinal Toxic Plants Toxic plant Plant toxins are substances produced as secondary metabolites that show both useful and harmful effects in human beings and animals. They show a wide range of side effects from minor itching, nausea, vomiting to adverse effects like psychosis, paralysis, teratogenicity, arrhythmias. Toxins may enter into the body either by inhalation, swallowing and contact. In some species of plants, the poisonous constituents occur throughout the whole plant. In others they are concentrated in one or more parts. The degree of toxicity also depends on the location, climatic factors including the local microclimate (light, warmth, humidity), the growing season, type of soil, fertilization, plant variety and age. Plant toxins are described according to the organ system in the human body which they affect, e.g. cardiotoxins, neurotoxins etc. 1- Hallucinogens Most cultures of man. from earliest times. have had recourse to some form of narcotic. often hallucinogenic drug. These hallucinogens often derived from plants, have frequently been used within a religious context. With the exception of cannabis, the principal known hallucinogenic plants contain alkaloids related to the neurophysiological transmitters noradrenaline and 5- hydroxytryptamine (serotonin). A- Fungi: Some of the poisonous fungi when taken orally produce hallucinations; these include toadstools of the genera Amanita, Psilocybe and Conocybe. Amanitas: A number of Amanita species, in addition to promoting hallucinogenic effects, are extremely toxic. The appearance of the serious symptoms is considerably delayed (particularly with amatoxins formula) after ingestion, by which time effective treatment becomes difficult. Three classes of toxins are recognized in this genus: tryptamines (e.g. bufotenine). cyclic peptides (phallotoxins and amatoxins). Isoxazole alkaloids (e.g. ibotenic acid). The three classes of compound appear to be restricted to certain specific sections of the genus. The fly agaric. The fly agaric (Amanita muscaria) is readily distinguished by its red or orange cap, often covered with white flecks. -It contains a mixture of isoxazole alkaloids, ibotenic acid and muscimol. Polysaccharides and a carboxymethylated derivative of the fungus have been shown to possess antitumor activity. -The pigments (betalains) of the fungus, also found in the Caryophyllales, are formed from tyrosine. and the rapid development of pigments formation in Amanita muscaria has given an ideal system for isolating the enzymes involved. The pharmacological effects appear within an hour or so of ingestion, with an initial period of excitation followed by muscular twitches, a slowed pulse rate, impaired breathing, delirium and coma; however, ingestion of the fungus is rarely fatal. Hallucinogenic Mexican mushrooms. A number of small toad stools particularly species of Psilocybe (P. mexicana), Conocybe(C. cyanopus) and Stropharia— constitute the Mexican hallucinogenic mushrooms. The onset of symptoms after ingestion of the fungi is rapid, and includes inability to concentrate and the occurrence of hallucinations. The active constituents are the tryptamine derivatives psilocybin and psilocin, compounds related to serotonin. the highest proportion of psilocin contained in any mushroom (3.3%, dry weight) was reported in Psilocybe cubensi. Puffballs. Species of Lycoperda contain constituents which produce auditory hallucinations and a state of half-sleep about half an hour after consumption. The effects are distinct from those caused by the mushrooms. B- Lysergic Acid Derivatives: The hallucinogenic properties of lysergic acid, and, in particular, the diethylamide derivative, are well-known. This acid forms the non-peptide portion of a number of ergot alkaloids and can also be produced by suitable cultivation of the fungus in liquid culture. Morning Glory seeds In the sixteenth century the Spaniards in Mexico reported the use of sacred hallucinogenic seeds known as 'ololiuqui' The climbing plant from which they were obtained was subsequently identified as Rivea corymbosa. The seeds of Ipomoea tricolor and those of various species of Argyreia are closely related in constituents and action. The trade names of species of Ipomoea are endlessly mixed. The seeds of the Peyote Certain cacti are of pharmaceutical and pharmacological interest, as they contain protoalkaloids, some of which have marked hallucinogenic properties. One of these is the cactus Lophophora williamsii which has long been used by Mexican Indians. The chief active constituent is the alkaloid mescaline. By 1973 some 56 alkaloids had been characterized from the cactus and these could be classified as: (1) Mono-, di- and tri oxygenated phenethylamines and their amides. (2) Tetrahydro isoquinoline alkaloids and their amides. (3) Phenethylamine conjugates with Kreb’s cycle acids. (4) Pyrrole derivatives. Examples of these groups : Indian Hemp The Indian hemp plant was originally considered as a distinct species but came to be regarded as a variety of Cannabis sativa, the common European hemp. which thus exhibited a variety of ecotypes giving rise to differing cannabinoid mixtures. Subsequently(in 1974),a case was presented by American taxonomists for the recognition of three distinct species C. sativta, C. indica and C. ruderalls. Intemperate climates large quantities of hemp are grown for the stem fiber and for the seeds, which yield 30–35% of a drying oil. Hemp products: Three main type of narcotic product are produced. 1. The Indian hemp or ganja: This is the flat- or Bombay-ganja, which was formerly official in many pharmacopoeias. 2. Bhang (Hindustani) or Hashish (Arabic): consists of the larger leaves and twigs of both male and female plants. It is used in India for smoking, either with or without tobacco and drugs such as opium or Datura, or is taken in the form of an electuary made by digestion with melted butter. 3. Charas or churrus is the crude resin. This is obtained by rubbing the tops between the hands, beating them on cloths or carpets, or by natives who wear leather aprons walking among the growing plants. The medicinal uses of cannabis 1.It was used in the treatment of hysteria. 2.used to in the treatment of movement disorders in patients with Parkinson disease. 3.Anti-tumor effects against lung, skin, uterine and several other carcinomas. 4.Cannabis products are used as aphrodisiacs It has been demonstrated recently that the main effects are attributable to Δ9-tetra hydrocannabinol (THC) The tetrahydrocannabinols, which form an oily mixture of several isomers, are non- nitrogenous organic compounds derived from terpenes. They are not alkaloids effects of cannabis even more than of other hallucinogens, are highly variable from person to person and from one plant strain to another. OTHER HIGHER PTANTS Nutmeg and mace Nutmeg has received attention as a psychotropic agent and this action may possible arise from the miristicin and elemicin components Virola spp. Virola spp. are also of the family Myristicaceae. They yield a blood-red, bark resin which is used by Indian tribes of the Amazon region for the preparation of hallucinogenic snuffs They contain Various tryptamines. Leguminosae. The beans of Anadenanthera peregrina are used in Northern South America for the preparation of snuff. A root decoction of Mimoso hostilis is used in east Brazil. Both contain tryptamine. 2- Natural Allergens: A large number of plant and animal materials give rise to allergic reactions in certain individuals. The allergenic material is transmitted by direct skin contact, by airborne pollens, smoke and dried plant particles, and on the coats of domestic animals. Once a person has been sensitized to a particular allergen, subsequent exposure to the materials produces an antigen–antibody reaction which results in the liberation of histamine or histamine-like compounds which in turn cause the allergic symptoms. The following allergens are well-known. 1- Pollens. Responsible for seasonal hay fever, which may progress to chronic asthma. 2- Spores. A number of common moulds produce spores which cause rhinitis and asthma in sensitive individuals. In the UK the spores of Cladosporium herbarum and Sporobolomyces roseus cause the most trouble. Exposure to lycopodium spores has caused allergic reactions varying from dermatitis to severe asthma attacks. A- Rhus (Toxicodendron) spp. Rhus radicans (poison ivy), R. toxicodendron (poison oak), and R. vernix (poison sumach, poison elder) (Anacardiaceae) contain contactant allergens which produce severe dermatitis associated with watery blisters which burst and quickly spread across the skin. B- Sesquiterpene lactones. These compounds obtained from members of the Compositae, Lauraceae and Magnoliaceae and from the liverwort Frullania (Jubulaceae), are a major class of substances causing allergic contact dermatitis in man. Two other plant species which can give rise to allergic reactions are the common rue (Ruta graveolens) and the indoor ornamental ‘dumb cane’ (Dieffenbachia seguine, Araceae). In the latter instance it would appear that the irritant substances are introduced into the body tissues by abrasion, through punctures caused by acicular crystals of calcium oxalate contained in idioblasts. C- Miscellaneous. Hair, feathers and house dust can all act as allergenic material; house dust often includes mites. Numerous other materials, not of natural origin (e.g. detergents, dyes, cosmetics), may also act as contact allergens. 3- Teratogens of Higher Plants Teratogenic substances, when ingested by the mother, can cause abnormalities in the developing fetus; thalidomide represents the tragic example of a synthetic drug having such undetected properties at the time of its use. Teratogens usually, but not invariably, act during a short, relatively early period of the gestation cycle. The range of plant constituents known to have teratogenic effects, includes 14 different groups of alkaloids, coumarins, lignans, macrolides, nitriles, terpenoids, toxic amino acids and unidentified compounds of many plants. As with the hallucinogens, the majority of teratogens contain nitrogen. Other Toxic Plants Such plants are generally of local importance and it is desirable that the pharmacist should have some knowledge of those found in his own locality. be familiar with those characters by which the plant can be- identified and be aware of the antidotes required for the treatment of poisoning. Cases of poisoning of humans by higher plants are most likely to occur with children and to involve those plants that produce attractive berries (e.g. belladonna,), seeds (e.g. laburnum) eaten for green peas, and those which may be introduced into the mouth for other reasons (e.g. the hollow stem of hemlock used as pea-shooters). Mistaken identity occasionally leads to fatalities and this is particularly so in the case of members of the umbelliferae. The poisoning of livestock by plants is relatively common, particularly in extensive grazing areas where there is no attempt to control weeds. Some widespread poisonous plants owe their properties to the presence of hepatotoxic pyrrolizidine alkaloids. Another group of compounds which has been shown to promote liver cancer in rats is that containing safrole and other alkenylbenzene derivatives. Fungi have a geographically universal potential as toxic agents, and the significance of their active constituents, mycotoxins, is only now coming to be fully appreciated. The mycotoxins produced by various Aspergillus spp. (e.g. A. flavus, A. parasiticus) are termed aflatoxins, all having a coumarin nucleus fused to a bifuran unit and possessing in addition a pentenone ring (B series) or a six-membered lactone (G series).