''Strychnos usambarensis'' is a shrub or small tree up to 15m tall or a 70m long liane of

Sub-Saharan Africa Sub-Saharan Africa is, geographically, the area and regions of the continent of Africa that lies south of the Sahara. These include West Africa, East Africa, Central Africa, and Southern Africa. Geopolitically, in addition to the List of sov ...

, occurring in forest and woodland, mountain ravines and coastal bush, often on rocky slopes and named for the

Usambara Mountains The Usambara Mountains of northeastern Tanzania in tropical East Africa, comprise the easternmost ranges of the Eastern Arc Mountains. The ranges of approximately long and about half that wide, are situated in the Lushoto District of the Tang ...

Tanzania Tanzania (; ), officially the United Republic of Tanzania ( sw, Jamhuri ya Muungano wa Tanzania), is a country in East Africa within the African Great Lakes region. It borders Uganda to the north; Kenya to the northeast; Comoro Islands and ...

. The species is found from

Guinea Guinea ( ),, fuf, 𞤘𞤭𞤲𞤫, italic=no, Gine, wo, Gine, nqo, ߖߌ߬ߣߍ߫, bm, Gine officially the Republic of Guinea (french: République de Guinée), is a coastal country in West Africa. It borders the Atlantic Ocean to the we ...

east to

Nigeria Nigeria ( ), , ig, Naìjíríyà, yo, Nàìjíríà, pcm, Naijá , ff, Naajeeriya, kcg, Naijeriya officially the Federal Republic of Nigeria, is a country in West Africa. It is situated between the Sahel to the north and the Gulf o ...

, from Congo east to

Kenya ) , national_anthem = "Ee Mungu Nguvu Yetu"() , image_map = , map_caption = , image_map2 = , capital = Nairobi , coordinates = , largest_city = Nairobi , ...

and south to kloofs of the

Magaliesberg The Magaliesberg (historically also known as ''Macalisberg'' or ''Cashan Mountains'') of northern South Africa, is a modest but well-defined mountain range composed mainly of quartzites. It rises at a point south of the Pilanesberg (and the Pil ...

South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring countri ...

. Bantu tribes from

Rwanda Rwanda (; rw, u Rwanda ), officially the Republic of Rwanda, is a landlocked country in the Great Rift Valley of Central Africa, where the African Great Lakes region and Southeast Africa converge. Located a few degrees south of the Equator ...

and

produce an arrow poison from the root bark and leaves of this species, sometimes combining it with extracts from other plants. (see

Toxalbumin Toxalbumins are toxic plant proteins that disable ribosomes and thereby inhibit protein synthesis, producing severe cytotoxic effects in multiple organ systems. They are dimers held together by a disulfide bond and comprise a lectin (carbohyd ...

) The leaves are opposite, held in a horizontal plane, ovate to elliptic in shape with a characteristic drip-tip, and glossy dark green above. Flowers are small, in axillary clusters, whitish to yellowish-green, and fragrant. Fruits are soft-shelled and small, 1-1.5 cm in diameter, yellow when ripe, tapering to a collar at peduncle. The genus ''Strychnos'' is represented by some 300 species of lianes, shrubs and small trees, fairly evenly divided among Asia, America, and Africa. Prota Database
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Chemical composition

''Strychnos usambarensis'' has been thoroughly investigated for potential pharmacological drugs and some 60

indole Indole is an aromatic heterocyclic organic compound with the formula C8 H7 N. It has a bicyclic structure, consisting of a six-membered benzene ring fused to a five-membered pyrrole ring. Indole is widely distributed in the natural environmen ...

alkaloids Alkaloids are a class of basic, naturally occurring organic compounds that contain at least one nitrogen atom. This group also includes some related compounds with neutral and even weakly acidic properties. Some synthetic compounds of similar st ...

have been isolated, mostly dimeric terpenoid in structure. Root bark holds tertiary alkaloids and several quaternary alkaloids and some anhydronium bases. Among these are the retuline class alkaloids C-dihydrotoxiferine, C-curarine and C-calebassine and the monomeric C-fluorocurarine, which are also the active principles of calabash curare obtained from South American ''Strychnos'' spp. The use of

curare Curare ( /kʊˈrɑːri/ or /kjʊˈrɑːri/; ''koo-rah-ree'' or ''kyoo-rah-ree'') is a common name for various alkaloid arrow poisons originating from plant extracts. Used as a paralyzing agent by indigenous peoples in Central and South ...

alkaloids reduces the risks of anaesthesia, as smaller amounts of anaesthetic are needed to achieve the same effect. ''S. usambarensis'' root bark also holds the less active afrocurarine, the monomeric tetracyclic alkaloid akagerine, the non-terpenoid alkaloids

harmane Harmane (harman) is a heterocyclic amine found in a variety of foods including coffee, sauces, and cooked meat. It is also present in tobacco smoke. Chemistry Harmane is a methylated derivative of β-carboline with the molecular formula C12H10N ...

and melinonine F and the monoquaternary alkaloids malindine and Isomalindine, which belong to the group of trinitrogenated alkaloids. Four root alkaloids, the dimeric usambarensines, are of the

corynanthine Corynanthine, also known as rauhimbine, is an alkaloid found in the ''Rauvolfia'' and '' Corynanthe'' (including ''Pausinystalia'') genera of plants. It is one of the two diastereoisomers of yohimbine, the other being rauwolscine. It is also rela ...

class. Several of the alkaloids in ''S. usambarensis'' have promising anticancer or antimalarial properties, justifying further research.

References

External links

Image of foliage and fruits
{{Taxonbar, from=Q15312094 usambarensis Taxa named by Adolf Engler