Chapter XIV The Erythrina Alkaloids

Abstract

Publisher Summary This chapter describes erythrina alkaloids. The alkaloids found in numerous species of the genus Erythrina are, with the exception of hypaphorine, of wide interest, because of their remarkable physiological action. The occurrence of hypaphorine in Erythrina subumbrans has long been known. In a systematic investigation, it has been shown that out of 105 known species of Erythrina , the 50 that have been tested contain alkaloids of paralyzing activity. Besides hypaphorine that occurs in a number of species, the bases found in these plants fall into two groups. The free alkaloids isolated so far are erythramine, erythraline, erythratine, and erythroidine that occur in two isomeric forms, α - and β -erythroidine. Only two “combined” alkaloids, erysothiovine and erysothiopine, have been characterized, while the following “liberated” alkaloids have been described in the chapter: erysopine, erysovine, erysodine, and erysonine. The chapter discusses the method of extracting alkaloids from the seeds of Erythrina species. Free alkaloids are isolated directly from the extracts of the plant without the necessity of previous hydrolysis and are purified by fractional crystallization of their salts. Erysopine, on hydrogenation, gives rise to tetrahydroerysopine that still contains a tertiary nitrogen atom. The chapter also presents a table on the physical constants of the erythrina alkaloids and their products of transformation and degradation.