General Plants of Nigerian Origin PDF

General Plants of Nigerian Origin By
Dr. Saifullahi Umar
DEPARTMENT OF PHARMACOGNOSY & HERBAL MEDICINE




25th April,...

General Plants of Nigerian Origin By
Dr. Saifullahi Umar
DEPARTMENT OF PHARMACOGNOSY & HERBAL MEDICINE




25th April, 2024 1  OUTLINE General introduction (classification, significance in relation to community health, etc) Local examples of poisonous plants 2  General introduction (classification, significance in relation to community health, etc) Man has always been faced with challenges of illness and responded appropriately within their abilities in order to remain alive. Their actions often blended with the tradition and culture of the people. The commonest item in this practice is the use of plants. Hunters especially in Africa, Nigeria inclusive, have been reported as the original custodians of some effective traditional recipes. Such knowledge could have been acquired when, for example, a hunter studies the behaviour of a wounded animal. 3  Cont’d If the animal ran away, chewed leaves from a specific plant and did not die, it was believed the hunter noted the plant as possessing an antidote for poison or a pain-relieving property. Ruminants (goats, sheep and cows) while looking for plants for food will always avoid some plants. This was taken as first indication of poisonous plants. However, there is a thin line between medicinal plants and ordeal plants. A medicinal plant can become ordeal if wrongly used similarly an ordeal plant can become useful if selectively used, in many cases. 4  Cont’d For example, Physostigma venenosum (Calabar bean) was formally used to detect guilt as it can kill but it also has a very useful alkaloid, physostigmine (eserine) which is used as ophthalmic agent. It’s important to note that plants contain chemical constituents also called phytochemicals. These phytochemicals are responsible for their biological and pharmacological activities. Plants have been the most important source of medicines for human health. Many modern medicines are derived from plants, either extracted from the plants themselves or artificially synthesized from to copy plant chemical compounds. 5  Cont’d Medicinal plants form an integral part of world economy and millions are used for medicines. The medicinal properties of plants can be from any of the morphological parts of the plants. Active compounds can be derived from over-ground (aerial) parts like leaves, flowers, fruits, seeds, bark and woods or from underground (subterranean) parts like tubers, bulbs, corms, roots, rhizomes etc. World health organisation (WHO) estimates that up to 80% of the world’s people rely on plants for their primary healthcare. Western pharmaceuticals are often expensive, 6 inaccessible and often unaffordable for the rural  Cont’d It is estimated that 74% of plant-based prescription drugs in the market today have the same or related use in western medicine as originally practiced by the native healers. Plants have contributed more than 7000 different compounds in use today as heart drugs, anticancer agents, hormones, contraceptives, diuretics, antibiotics, decongestants, analgesics, anesthetics, ulcer treatments and anti-parasitic compounds. Worldwide, screening of plants to identify chemical compounds that may provide new treatment for human diseases has produced many drugs and is still on-going. 7  Cont’d Similarly, records of responses from individuals (including animals) from consumption of plants with deleterious effects were also indication of poisonous plants. A poisonous or an ordeal plant is a plant that have deleterious (harmful) effects on the body while a medicinal plant is any plant which, in one or more of its organs, contains substances that can be used for therapeutic purposes or as a precursor for the synthesis of useful drugs. Some have been used for hunting poisons (e.g strychnine) and for insecticides (e.g. pyrethrum). Some plants are poisonous in part and harmless otherwise (the leaf blades, not the stalks, of rhubarb are poisonous) or poisonous at one season and not at another season (the very young poke, or pokeweed, shoot is sometimes 8  Cont’d Certain plants contain psychotropic chemicals, which are extracted and ingested or smoked, including tobacco, cannabis (marijuana), cocaine and opium, causing damage to health or even death. Both illegal and legal drugs derived from plants have negative effects on the economy, effecting workers productivity and law enforcement costs. Some plants causes allergic reactions in people and animals when ingested, while other plants cause food intolerances that negatively affect health. The laws governing use of poisonous plants varies from country to country although there are international and regional agreements and protocols which are binding on individual member nations that are signatories to such accords. 9  Calabar Bean Calabar Bean 10  Calabar Bean Scientific Name(s): Physostigma venenosum Balf. Family: Fabaceae Common Name(s): Calabar bean, ordeal bean, chop nut, esere nut, faba calabarica History: This plant is native to an area of Africa around Nigeria once known as Calabar. The plant is widely known in Africa because the seeds had been used as an “ordeal poison” to determine if a person was a witch or possessed by evil spirits. 11  Cont’d When used for this purpose, the victim was made to ingest several beans; if the person regurgitated the beans and survived the “ordeal,” his innocence was proclaimed. Western settlers who were captured by native tribes and who underwent the “ordeal” soon learned not to chew the bean, but to swallow the kidney-shaped bean intact, thereby not permitting the release of the toxic constituents. The plant has been long recognized as a commercial source of the alkaloid physostigmine, first isolated in 1864. 12  Chemistry The seeds contain the alkaloid physostigmine (eserine) in a concentration of about 0.15%, along with the related alkaloids eseramine, physovenine, calabatine, and geneserine, among others. These alkaloids are derived from a tryptophan precursor. On exposure to air, physostigmine oxidizes to a reddish compound, rubreserine, and therefore should be protected from air and light. 13  Botany The calabar bean is the dried ripe seed of P. venenosum, a perennial woody climbing plant found on the banks of streams in West Africa. Vines of the plant extend more than 6 metres or more long by 1 centimetre diameter climbing among the trees in forest canopies (Flora of West Tropical Africa, 2014). The plant bears showy purple flowers and seed pods that grow to about 6 inches in length. Each pod contains from 2 to 3 seeds. The dark brown seeds are about 1 inch wide and thick and have an extremely hard shell. 14  Uses and Pharmacology Physostigmine (usually as the stable salicylate salt) (Antilirium) is an acetylcholinesterase inhibitor and, therefore, prolongs the neuronal activity of acetylcholine. It is used clinically to contract the pupil of the eye, often to counter the dilating effects of mydriatic drugs, reverse the CNS toxicity of anticholinergic drugs, including tricyclic antidepressants, and to manage intraocular pressure in patients with glaucoma. Physostigmine and related drugs have been investigated for their ability to increase cognition, particularly in demented patients, but these therapies have met with minimal success. Physostigmine and the related synthetic agent neostigmine (eg, Prostigmin) have been used for the diagnosis and treatment of myasthenia gravis. 15  Cont’d Dosage Calabar bean has been widely studied as the pure alkaloid physostigmine. A typical dose for the pure alkaloid is 2 mg. There is no clinical evidence relating to the crude plant material or to an extract. In African pharmacopoiea the seed is used as a vermifuge for fleas and in eye treatment (Useful Plants of West Tropical Africa, 2014) Pregnancy/Lactation Documented adverse effects. Avoid use. 16  Cont’d Interactions: None well documented. Adverse Reactions: There are few reports on adverse reactions, as Calabar bean is toxic to humans. Toxicology: Physostigmine is extremely toxic, with an oral LD50 of 4.5 mg/kg in mice. The maximum reported number of beans eaten followed by survival of a human is 35. Physostigmine kills by affecting heart contractility and inducing respiratory paralysis. 17 18  Indian hemp Scientific Name(s): Cannabis sativa Linn. Family: Cannabibaceae Common Name(s): Cannabis, Marijuana, hemp, grass, hashish, bhang, charas, ganja, Igbo, It consists of the dried flowering and fruiting tops of the plant. The plants are known for their resin production by glandular trichomes. Potency of the resin, varies greatly depending on the genetic strains and growing conditions. C. sativa is believed to have originated in central Asia; but now widely cultivated worldwide, Three distinct species are now recognized namely; Cannabis sativa, Cannabis indica and Cannabis ruderalis 19  Cont’d Early history in China and India Use of Cannabis can be traced back about 5000 years to ancient China where the hemp plant was valued for its fibres (for cloth, paper, and rope) and medicinal properties. Earliest documented records of marijuana’s use as a hallucinogen can be traced to the Scythians, ancient nomadic horsemen from central Asia, about 500 BC. Marijuana use spread from central Asia to Asia minor, northern Africa, India, and elsewhere. The first written mention in Indian around 600 BC. Marijuana use in Indian was associated largely with religious ceremonies and achieving a contemplative state. Description Indian hemp occurs in agglutinated masses of dull-green or greenish brown colour. The odour is heavy and characteristic in the fresh drug but faint in the dried specimen. The taste is slightly bitter. 20  Microscopy Numerous glandular hairs, sessile or with unicellular or multiseriated stalk and an 8- celled head, conical, curved, unicellular clothing trichomes along with cystoliths of calcium carbonate in the enlarged bases. Clusters of calcium oxalates are also present. 21  Constituents Marijuana use is popular, but it competes with a host of other readily available drugs. The active principles of the drug are contained in the resin (15-20%). Cannabis contains a large number of phenolic compounds known as cannabinoids, but the main psychoactive component is delta-9- tetrahydrocannbinol (THC). The concentration of THC in the plant varies considerably, depending on the genetic strain, sex of the plant, climate, and growing conditions 22  Other cannabinoids believed to be isomers of THC includes cannabinol, cannabidiol, cannabidiolic acid, cannabigerol, etc. The effects of Cannabis include a sense of euphoria and calmness. According to studies, even moderate use of marijuana impairs learning, short term memory, and reaction time. Because THC is fat soluble, it accumulates in body tissues, and measurable amounts may remain in the body for days after inhalation. 23  Effects of marijuana on males include a decrease in sperm production and decreased testosterone levels. In pregnant women, THC can cross the placenta and possibly damage the foetus. Other constituents found in the plant include volatile oils, an alkaloid (cannabisativine), flavonoid-o-glycosides, trigonelline and spermidine, and calcium oxalates. 24  Medicinal uses In contemporary medicine, marijuana is used mainly to treat glaucoma and as an aid to chemotherapy. Patients undergoing chemotherapy for cancer often experience side effects of nausea, vomiting, and loss of appetite. These side effects can be reduced by using marijuana or marinol, a synthetic form of tetra- hydrocarnabinnol (THC). Marijuana has also been used to counteract weight lost associated with the AIDS wasting syndrome, and to reduce spasmodic movement in patients with multiple sclerosis and Parkinson's disease. 25  Identification of cannabis Microscopy: The trichomes stain deep- reddish-purple with vanillin in ethanolic sulphuric acid. Chemical Tests Beam’s test: The extract the drug with petroleum ether, evaporate to dryness and treat residue with N/10 alcoholic potasium hydroxide(KOH), a purple or red colour is obtained. The reaction is very specific. 26  Cont’d Distinguishing test Spray a spot of the drug with bis-diazotizes-di-o-anisidine in 0.1N Sodium Hydroxide (NaOH); THC gives red colour, cannabidiol gives violet colour, cannabigerol gives orange colour. To the light petroleum ether extract of the drug add 15% Hydrochloric acid (HCl) in dehydrated alcohol. A red colour develops at the junction of the two liquids. After shaking, the upper layer becomes colourless while the lower layer acquires an orange pink colour which disappears on the addition of water. 27  Dependence on Cannabis Repeated administration of cannabis and cannabis substances on a periodic or continuous basis leads to drug dependence. This is characterized by a desire or need to continous taking the drug including a feeling of enhanced capabilities, by a psychic dependence on the effects of the drug without physical dependence. There is little or no development of tolerance and consequently little or no tendency to increase the dose. It has been reported that cannabis users do not experience difficulty in discontinuing its use. 28  Toxic effects of cannabis Unusual sensations induced in man by cannabis use are common and are more from smoking cannabis than from oral administration. Nausea and vomiting may be the first effects of oral ingestion of cannabis and appear about 3 hours after ingestion. The effects of smoking cannabis appear within a few minutes as anxiety and restlessness. The full effects of cannabis are largely dependent on the personality of the user and on the environment as well as the dose taken. Small doses may be followed by a mildly pleasant effect but larger doses may give rise to variety of physical and psychological effects imposed upon a frequent pattern of anxiety and restlessness, disturbed auditory and visual perception, depression and then sleep. 29  Cont’d Physical effects of cannabis intoxication include heart rate and blood pressure, cold extremities, dilated pupils and injected conjunctiva vessels, ataxia and deep reflexes, hypoglycaemia, diarrhea, and frequency of micturation, bronchitis and asthma. Respiratory depression may occur in severe intoxication. Psychological effects include elation, distortion of time and space, irritability and disturbances of memory and judgment. 30  Cont’d Psychotic episodes of an acute type are often characterized by paranoid delusions of ability. Schizophrenic-like reactions have been reported as have been teratogenic effects in animals. Smokers of excessive doses of cannabis are emaciated and suffer from chronic laryngitis, bronchitis, dyspepsia and alternating bouts of diarrhea and constipation. 31 Tobacco 32  Tobacco Scientific Name(s): Nicotiana tabacum Linn (Family Solanaceae) Common Name(s): Tobacco Nicotiana tabacum Contain the ingredient, nicotine among others. Richest in leaves, followed by stalk, roots and flowers. The seeds do not contain nicotine. The total alkaloid of the leaves varies from 0.5-10% according to the specie, habitat, cultural conditions, etc. 33  Cont’d Other constituents of Nicotiana are nornicotine, anabasine, nocityrine, nicotelline and anatabine. Small traces of amino acids, harmane, terpenes, etc Nicotine has both peripheral and central activities. In these sites nicotine has initial stimulation and depression phases of actions The excitation of respiration is a particularly prominent action of nicotine. Death results from respiratory arrest due to both central paralysis and peripheral blockade of muscles of respiration. 34  Cont’d Nicotine is not used therapeutically but it has proved a useful tool in experimental pharmacology. Nicotine is very poisonous, from protozoa to man. 35 Datura metel 36  Datura metel Common Name: Thorn Apple, Angel's Trumpet, Hindu Datura, Horn of Plenty, Downy Thorn Apple Botancal Source: Datura metel Family: Solanaceae Local name: Zakami Synonms: D. alba. Nees., D. fastuosa. L All members of this genus contain narcotics and are very poisonous, even in small doses Waste places, river sands etc in sunny positions E. Asia - S. China, India. Naturalized in the Mediterranean. 37  The plant is an annual or short-lived shrubby perennial herb (lacking the fleshy, perennial roots found in perennial species such as Datura innoxia (from which it has been found to have been created by selective breeding) and Datura wrightii) growing up to 6 ft (1.8 m) high. It is slightly pubescent, with green to dark violet shoots and oval to broad oval leaves that are often dark violet as well. The pleasantly-scented 6–8 in (15–20 cm) flowers are immensely varied, and can be single or double. Corolla colour can range from white to cream, yellow, red, and violet. 38  The seed capsule is covered with numerous conical warts or short, sparse spines. It is similar, in its above-ground parts, to Datura innoxia, but, while D. metel has almost glabrous leaves and fruits that can be nodding or erect and are warty, rather than spiny; D. innoxia is pilose (softly hairy) all over and has a markedly spiny, nodding fruit with a more prominently frilled and reflexed persistent calyx. 39  The leaves and roots are bruised, mixed with water and left to stand for several hours. The liquid is then drawn off and drunk. This is a highly narcotic drink, producing a stupefying effect that it is not easy to remove 40  The whole plant, but especially the leaves and seed, is anaesthetic, anodyne, antiasthmatic, antispasmodic, antitussive, bronchodilator, hallucinogenic, hypnotic and mydriatic It has a wide range of applications in India, including in the treatment of epilepsy, hysteria, insanity, heart diseases, fever with catarrh, diarrhoea, skin diseases etc A poultice of the crushed leaves is used to relieve pain In China, the plant is used in the treatment of asthma In Vietnam, the dried flowers and leaves are cut into small chips and used in antiasthmatic cigarettes 41  Great caution is advised in the use of this plant since excess doses cause hallucinations, severe intoxication and death. The toxic dose is very close to the medicinal dose so this plant should only be used under the guidance of a qualified practitioner. The plant contains the alkaloids hyoscyamine, hyoscine and atropine Atropine dilates the pupils and is used in eye surgery 42  Total alkaloid content of the leaves is 0.426%, which is mainly atropine The seeds contain 0.426% alkaloids, which is mainly hyoscyamine The roots contain 0.35% hyoscyamine An extract of the flowers is used as an anaesthetic – 3 – 5 g applied orally produces a general anaesthesia within 5 minutes and lasting 5 - 6 hours 43