Strychnos plants

Azayohimbine-Type Alkaloids. Recently, some new types of alkaloids nauclefine (29), naucletine (210), angustidine (213), and angustoline (215), were isolated (71,120-122) from the Nauclea and Strychnos plants, which... 

There have already appeared many chapters on Strychnos alkaloids, including those of calabash curare, in previous volumes (7-6) of this treatise. Although extensive studies on Strychnos alkaloids were carried out and many of the main structural classes of alkaloids were determined by the mid-1960s, various types of new alkaloids have since been found and efficiently characterized, sometimes even from small pieces, of herbarium specimens of Strychnos plants. 

Strychnos alkaloids. A group of monoterpenoid indole alkaloids that are not exclusively isolated from Strychnos plants and do not exclusively belong to the strychnidine type. The most well-known members of this group of alkaloids are strychnine, its methoxy-lated derivative brucine, the toxiferines, and curare, as well as vomicine which all have structures derived from the strychnidine skeleton. 

As described previously, the origins of the three types of curare are the extracts of Chondodendron (Menispermaceae) and/or Strychnos (Loganiaceae) plants. Among them, the toxic components of Strychnos plants are C-curarine and C-toxiferine I, etc.These constituents are alkaloids derived from tryptophan and are described in the next (Section 2.15).The C- is the initial of calabash. On the other hand, the toxic principle of tubocu-rare is d-tubocurarine, an alkaloid derived from phenylalanine. The alkaloid was first isolated as a hydrochloride from tubocurare and is preserved in the Museum of the British Society of Pharmacy [1]. The chemical structure of d-tubocurarine was first proposed as a bisbenzylisoquinoline with two quaternary ammonium moieties. This was revised in 1970 to be the structure with one tertiary and one quaternary amine after X-ray crystallographic analysis [2]. 

Aqueous extracts of S. toxifera and other various species of Strychnos plants indigenous to the Amazon-Orinoco basins are called curare (calabash curare) and are used by natives for hunting (105) (Sect. S.2.2.5.2). 

Two Strychnos plants reported to be curare ingredients were described by Planchon from incomplete (sterile) material, viz S. gubleri and S. yapurensis, and they have never been satisfactorily identified. Such material as exists was not seen by Krukoff during his studies of South American Strychnos, so that renewed investigation is required in both cases. 

In the 1950s, investigation of Strychnos plant materials led to the isolation of very small amounts of many, often colored, alkaloidal products, which... 

This association of sempervirine with yohimbine is of biological interest since the former alkaloid is derived from a plant of the Loganiaceas in which alkaloids of the strychnos group seemed to be characteristic, whereas the yohimbine group of alkaloids have so far only been found in the Apocynaceae and Rubiace c. 

Strychnine is a complex lipophilic alkaloid from the plant Strychnos mx-vomica, which acts as a neurotoxin. It has been used to control vertebrate pests, including moles. The acute oral LDjq to the rat is 2 mg/kg. 

Fig. 62. Strychnos minor Dennst. From Plants of South India, C.E. Ridsdale 395. date 7/12/1976. Geographical localization Walaiyar Estate, Papanasam, Tamil Nadu. In evergreen forest. Distributed by the Rijskherbarium, Leiden. 

Fig. 63. Strychnos axillaris Colebr. Department of Wildlife and National Parks. Plants of Krau. Wildlife Reserve, Malaysia. Field collectors Hanne Christensen and Rozidan M. Geographical localization 3° 36 North-1020 8 East. In mature forest on level ground. 

Initially, neuromnscnlar jnnction blockers were isolated from curare, the extract of which is produced from South American plants Strychnos and Chondodendron. Today, synthetic compounds as well as tnbocnrarine, an alkaloid isolated from curare, are used as antidepolarizing or cnrare-like drags, which are called antidepolarizing or competitive blockers. 

ANTAGONIZING ACETYLCHOLINE Curare, found in a resinous extract of the plants Chondrodendrott tomentosum and Strychnos toxifera from the Orinoco and Amazon basins in South America, is an antagonist at nicotinic acetylcholine receptors. Curare does not cross the blood—brain barrier, and therefore its actions are expressed only outside of the brain at the neuromuscular junction where neurons control muscles. Curare is extremely lethal for one simple reason—it blocks the nicotinic receptors located on the diaphragm therefore, death from curare results from asphyxiation. Imagine you ve been shot by a curare-tipped arrow you d be awake, fully aware of having been shot, yet completely unable to move, speak, or, ultimately, breathe. 

It is a toxic plant and has properties similar to strychnine, which is obtained from Strychnos nux vomica. Once recommended as a remedy for cholera, the plant is used to treat fever and acute emotional and mental afflictions such as hysteria, insomnia, and depression. In toxic doses, it causes muscle spasms, painful convulsions, and even death by asphyxiation (see Chapter 62). 

Curare (Woorara) is a vegetable extract obtained from various members of the Strychnos family, as well as from Paullinia curare and other plants. In South America, it is known by the names Caroval and Vao. Its active principle is the very poisonous alkaloid curarine, c18h35n. 

Pauridiantha appears, therefore, to be a genus in which the biosynthetic pathways are limited in number and are stopped at primitive alkaloids. It follows a lack of structural specificity, permitting chemotaxonomic correlations with other plants characterized by the same features. From this point of view, the genus Pauridiantha resembles not only many Nauclea, but also a number of Strychnos. 

The root and stem bark of Strychnos decussata (Pappe) Gilg. contain akagerine, 17-O-methylakagerine, and three new alkaloids, i.e. 10-hydroxy-21-O-methylkribine (79a) and its 21-epimer (79b) and 10-hydroxy-O-methyl-akagerine (80) 56 these alkaloids may be responsible for the muscle-relaxant properties of extracts of the bark of this plant. 

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