Securinega alkaloid

The securinega alkaloids occur in several species of the Securinega and Phyllan-thus genera (150). Securinine was first isolated from the leaves and stems of Securinega suffruticosa (Euphorbiaceae). Securinine nitrate is a central nervous system stimulant similar to strychnine but less toxic. It was found to be useful in treatment of paresis and paralysis following infectious diseases and psychic disorders. The related alkaloids were obtained from Securinega suffruticosa allose-curinine, dihydrosecurinine, securinol A, and securinol B from the leaves, and securitinine from the roots. 

Virosecurinine and viroallosecurinine obtained from the leaves of Securinega virosa were found to be the enantiomers of securine and allosecurinine, respectively. Securinega alkaloids obtained from the roots of Phyllanthus discoides are securinine, allosecurinine, and phyllantine. These alkaloids are biogenetically produced from lysine and a C6-C3 unit derived from tyrosine (Fig. 5.2.6). 

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Senecio alkaloids, see Pyirolizidine alkaloids Secoisoquinoline alkaloids, 33, 231 (1988) Securinega alkaloids, 14, 425 (1973) Sinomenine, 2, 219 (1952)... 

Senecio alkaloids, see Pyrrolizidine alkaloids Securinega alkaloids, 14, 425 (1973)... 

The synthesis of fused butenolides via the reaction of a-ketols with lithium ethoxyacetylide had been previously developed in connection with the synthesis of Securinega alkaloids.22 This synthesis has now been generalized... 

Aside from securinine, allosecurinine is the only other Securinega alkaloid whose structure and relative stereochemistry has been confirmed by X-ray analysis. Although Nakano s stereochemical investigations (Section II, G) pointed to a trans A/B ring junction (103) for allosecurinine, the X-ray determination on allosecurinine methiodide showed a cis A/B arrangement (104) (41). This is almost certainly a... 

Thus allosecurinine (96) is a C-2 epimer of securinine (27). Further stereochemical interrelationships of allosecurinine with other Securinega alkaloids which establish its absolute configuration as represented by formulation 96 are described in Section II, G. 

Indollzidine alkaloids. A group of alkaloids from various classes based on the bicyclic ring system of in-dolizidine. They differ in structure, biogenesis, and occurrence thus, the indolizidine ring system has very little value as a characterizing structural. The I. a. include the pumiliotoxins (Dendrobates alkaloids), poly hydroxy alkaloids such as swainsonineand cas-tanospermine, Elaeocarpus alkaloids, Securinega alkaloids, Tylophora alkaloids, and the Ipom(o)ea alkaloids. 

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