Related to : White Henbane (Hyoscamus Albus) and Hyoscamus Aureus, neither of which seem to have been seen in the UK for several decades. Henbane too is quickly disappearing from the UK.
Uniquely identifiable characteristics
Distinguishing Feature : Large euphonium-shaped flowers coloured a creamy yellow netted with dark purple veins.
No relation to :
Wolf's-bane, Leopard's-Bane, or any of the
Fleabanes [plants with similar names]
Henbane is deadly poisonous, its black berries even more so. It is a biennial that grows near the seaside on sand or shingle, or inland on disturbed ground. It is a rare plant that is rather common on Walney Island (or perhaps once was for Henbane is in decline in the UK). The plant was the one used by Dr Crippen to poison his wife. The fruit is a green capsule nestled within the five broad green sepals, turning into a large glossy black berry. Its leaves are sticky and the plant has an unpleasant odour.
The specimen found in Nottinghamshire was found on a site recently underwent an archaeological dug by the Time Team, which was helped by Nottingham University. It just so happens that Nottingham University Pharmaceutical Sciences Department were growing Henbane (and other more exotic species of Datura) for research purposes in their grounds, several of which have since escaped and 'gone native'.
As a member of the Nightshade Family, along with Deadly Nightshade and other deadly poisonous plants, some more poisonous than others, it has a repertoire of interesting poisonous compounds. Many of the Nightshade family, like Bittersweet, Potato and
Tomato, contain deadly poisonous steroidal glycoalkaloids such as Solanine, Chaconine and Tomatine. Henbane, Thorn-Apple (which Americans call 'Jimsonweed'), Apple-of-Peru and Deadly Nightshade go a step above those poisons. Henbane contains toxic tropane alkaloids such as Scopolamine, Hyoscine and Atropine but seems not to possess any solanines, or if it does, they are not mentioned.
Atropine is a toxic tropane alkaloid which is also present in Deadly Nightshade and Thorn-apple, both members of the same Nightshade Family to which Henbane belongs. Atropine is a pharmaceutical used to dampen the parasympathetic nervous system. It is also used in the eye, both as a mydriatic to dilate the pupils and as a cycloplegic to stop bright lights from constricting the iris via the accommodation reflex. It accomplishes this by paralysing the dilatory muscles in the eye. Because its effects are very slow to wear off, it is not used for short ophthalmic examinations where the drug Tropicamide is preferred. Atropine is also used to treat extremely low pulse rates, which it accomplices by paralysing the vagus nerve which otherwise acts to slow the heart-rate, thus an increase in heart rate results. It is also given to counteract some of the effects of organophosphate (nerve gas and some insecticides) poisoning. Sarin is one such oraganophoshate, which also contains an atom of fluorine, and is a nerve-gas poison of the utmost severity. Atropine is a racemic mixture of the optically rotating isomers dextro-hyoscamine and laevo-hyoscamine, the latter of which is the most active pharmacologically. Atropine is used pharmaceutically as an anti-cholinergic drug, obtained from Deadly Nightshade.
Scopolamine, somewhat confusingly also known as Hyoscine or Laevo-Duboisine, is a tropane alkaloid related to Hyoscamine. The racemic mixture of Laevo-Hyoscamine and Dextro-Hyoscine is known as Atroscine. Scopolamine has one extra oxygen atom and it too is a dangerously poisonous pharmaceutical found in Henbane, Deadly Nightshade, Thorn-apple and related species, some not native to the UK. It is an anti-cholinergic drug, used in minute quantities as a skin-patch (not taken orally!) to relieve travel sickness. Scopolamine is one of the three components of Belladonna tinctures, which obtains its name from Deadly Nightshade (Atropa Belladonna) which also lends its name to Atropine. Belladonna (which in Italian means a beautiful wide-eyed maiden), is the reason (Atropa Belladonna), which contains Atropine which dilates the pupils making them wide, is so named.
Eserine - which should not be confused with
Eseroline, a metabolite of Physostigmine) which does NOT occur in Thorn-apple, but rather in Calabar beans and in the Manchineel Tree (which are both found in Africa).
Physostigmine has two endocyclic nitrogen atoms, making it an alkaloid, plus another nitrogen atom on a side-branch. It is a highly toxic parasympathomimetic alkaloid and indeed was used as a poison after its discovery in 1846. A mere 20 or so years later it was being used medicinally to treat glaucoma.
Because it can also cross the blood-brain barrier (most other drugs cannot do this) and enhances the transmission of acetylcholine signals within the brain it is also used to treat poisoning by
Scopalamine (which are anti-cholinergic toxic substances contained within Henbane and some other Solanaceae). [Anti-cholinergic substances like Atropine and Scopolamine interfere with the transmission of acetylcholine signalling].
Physostigmine is used as the antidote of choice for poisoning by Thorn-Apple (Datura stramonium). It can also be used to treat poisoning by Deadly Nightshade (Atropa belladona).
Physostigmine is also toxic; the LD50 in mice is 3mg/kg.
MORE TROPANE ALKALOIDS
Cocaine, another tropane alkaloid and naturally occurring substance found in Coco plants (non-indigenous to the UK) has a similar structure to both Hyoscamine and Scopolamine, but is not present in Henbane. The Coca-Cola company ceased putting this poison into their Coca-cola drinks some decades ago, which is just as well really, since it too is toxic. Cocaine no longer has any medicinal uses, but might still be used as a local anaesthetic.
Cocaine is very similar to the naturally occurring
Cochlearine that occurs in some members of the Scurvygrass Genus (Cochearia.
Both Meteloidine and Littorine are Tropane Alkaloids found in Henbane and a few other plants. They are not as well known as the above. Littorine is an intermediate of the other Tropane Alkaloids, which are all derived from Tropane, which is itself probably absent from the plants.
Tropane Alkaloids such as nearly all of the above are found in the non-native Mandrake and Coco plants, plus Deadly Nightshade Japanese Lantern, Cock's-Eggs, Thorn-Apple which all belong to the Nightshade Family. But they are also found in some Bindweeds, some Orchids, some Spurges and some Brassicas which do not belong to the Nightshade Family.
A PYRROLIDINE ALKALOID
Hygrine is a Pyrrolidine Alkaloid rather than a Tropane Alkaloid. Nevertheless, if the reader studies the molecule of Tropane above he will discern the same 5-membered Pyrrolidine ring (on the left). Hygrine is found mainly in the leaves of the Coca plant from which Cocaine is obtained but also occurs in some members of the Nightshade Family. It is a thick yellow liquid rather than a solid and has a strong taste and pungent odour.
SARIN and MODUS OPERANDII of ORGANOPHOSPHATES
and the role of Atropine as Antidote
Organophosphates are esters of Phosphoric Acid. Some occur naturally, such as those within RNA and DNA and in the co-factors that are essential for the functioning of life.
Sarin is a man-made organophosphate nerve-gas having no natural occurrence. First and foremost, it is not a gas, but a liquid, although it does vaporize easily. It also contains one atom of fluorine which adds to its toxicity. Even tiny amounts are sufficient to cause permanent harm if untreated; it is estimated to be 500 times more poisonous than cyanide. The Gulf-war syndrome experienced by soldiers within 600 km of the bombing of Iraqs' stockpiles of Sarin during the Gulf War of 1990-91 is attributed to the effects of Sarin. Impaired attention, impaired memory and altered brain structure are typical symptoms of Gulf-War syndrome. Those exposed to intermediate levels of Sarin have less grey matter in regions of the brain associated with cognition and memory. Sarin kills mammals by blocking the normal breakdown of acetylcholine, the neurotransmitter which transmits nerve impulses to muscles. The muscles, including those of the respiratory system, go into spasm. Death follows convulsions. The pupils contract to pin-points and the pallor of the skin becomes red and blue due to asphyxiation.
Sarin chemically reacts with acetylcholine forming a stable phosphoester with
Acetylcholine, which persists unless treated. The fluorine part of the Sarin departs and forms no part in the resulting phosphoester. The phosphoester makes the acetylcholine permanently biologically ineffective. Atropine, being an antagonist to the muscarinic acetylcholine receptors, is an antidote to Sarin poisoning but needs to be taken within minutes or hours of an otherwise fatal exposure. Atropine treatment can also be effective in less severe cases even when taken weeks later.
Another but synthetic antidote serving a differing purpose is
Pralidoxime which can regenerate acetylcholinesterase (AChE) if taken within 5 hours. Pralidoxime binds to acetylcholine which has been inactivated by organophospates (such as Sarin) and removes the phosphate group from it, thus regenerating the acetylcholinesterase. The two antidotes are generally used together, but care must be taken especially if the dose of Atropine has been large. An injection of the sedative and anti-epileptic pharmaceutical
Diazepan is also used.
There are many other synthetic organophosphates, many used as insecticides, herbicides and nerve-gases. Phosphoric Acid, being a triprotic acid, can form tri-esters (as well as di-esters and mono-esters). The organophosphates used in agriculture all act on acetylcholinesterase, permanently inactivating it. This kills those insects which brush up against this pesticide in the field. It can also adversely affect humans and any other mammals. Although no organophosphate used by agriculture is as potent as sarin, many have the potential to cause permanent damage (as detailed above for Sarin) to the nervous system of humans mammals who are in contact with them. They are absorbed through the skin on contact, absorbed through the lungs if breathed or ingested on food. Since 2001 organophosphates have been banned in the European Union for home-use, but many are licensed for use by farmers. These include
Tetrachlorvinphos with Malathion being widely used. There are dozens more that are licensed for use agriculturally. All (except a few mentioned below) are potential nerve-agents, acting in much the same way on acetylcholineesterase as does Sarin, permanently inactivating it. Because effects are cumulative, even very low but repeated exposure (including from residues on the skin of vegetables and fruit) to these agents can cause permanent chronic health effects, which include impaired memory and concentration, irritability, confusion, disorientation, headache, delayed reaction times, speech difficulties, nightmares, sleepwalking, drowsiness, insomnia and severe depression. They also increase the likelihood of developing Alzheimers disease. There are often and repeated calls for the banning of many, if not all, organophosphate pesticides.
Although some types of organophosphates are harmless when first ingested, the metabolites of those types are poisonous (which is how those types kill insects).
Nerve agents are agents that have specifically been developed and produced for use during war. DFP (DiIsoPropylFluoroPhosphate) was one of the first. This was followed by
Soman culminating in
VX nerve agent.