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Publisher Summary This chapter describes the alkaloids of calycanthaceae. The family Calycanthaceae is represented by only two genera, Calycanthus L., with about four species in the United States, and Chimonanthus Lindl. ( Meratia Loisel. ) with two Asiatic species. Its relation to other plant families is uncertain, and the nature of its chemical constituents has not shed any light on possible affinities. The belief in the presence of an indole nucleus in calycanthine was so firmly rooted that the first structures that bear some resemblance to the true one still retained the indole nucleus, even though they are largely based on the then-known structure of calycanine. There are few examples in the history of organic chemistry where deductions of structure based on identified fragments have been as wide of the mark as in the work on calycanthine. Reactions, that because of their mildness could be presumed to proceed without molecular rearrangements, yielded products that only served to confuse the real structure.

Publisher Summary Indole has been isolated from the flowers of many Jasminium and Citrus species, from Robinia pseudacacia L., Cheirunthus cheiri L., Narcissus jonquilla L., and Chimonanthus fragrans Lindl.; it appears to be an essential constituent of the perfumes of these flowers. Reports have also been made of the isolation of indole from nonfloral material, for example, Celtis reticulosa Miq. and Thlaspi arvense L., but these have been criticized on the grounds that the indole was probably the result of bacterial action on a labile indole precursor. Numerous other claims for the presence of indole in plants have been based solely on the color reactions given either by the plant extracts or by the volatile constituents of the oils obtained from the blossoms by enfleurage. In some plants, at least, the reverse may be true, and indole may be converted into tryptophan by combination with serine. Whether this is the principal mode of biosynthesis of tryptophan remains to be determined; it is perhaps more likely that indole and tryptophan are products of alternative pathways of metabolism of indole-3-glycerol phosphate, and that conversion of the last-named into tryptophan does not proceed by way of indole.