Haemodorum

At first sight the title compounds characterized by the general formula 111, are rather unrelated to diarylheptanoids. At closer look, however, the two classes of compounds can be linked by a very plausible biosynthetic hypothesis first forwarded by Thomas (80) and shown in the following scheme below. 9-Phenylphenalenones were isolated from Haemodorum (74), Lachnates (75, 76), Xiphidium (77), Wachendoifia (78), and Anigozanthos (79) (Haemodoraceae) species. 

Haemocorin was isolated from Haemodorum corym-bosum in 1955 as the first P. from a higher plant. 

Haemodorum corymbosum (54, 55, 56) Lachnanthes tinctoria (57) Wachendorfia thyrsiflora (49)... 

The earliest reference to biological activity of a plant in the family Haemodoraceae seems to have been one by Darwin (73) to the toxic action of Lachnanthes on white pigs and the immunity of the black ones. This has frequently been assumed by later writers to indicate a photodynamic action. Some experimental support for this belief has been obtained by the observation that extracts of Lachnanthes tinctoria induce phototoxicity in microorganisms 74). The Australian plant Haemodorum corymbosum has also been regarded as toxic to animals (75). Haemocorin, the phenalenone pigment from this plant, was shown to have antitumor activity 76) and a wide range of antibacterial activity (77). 

Cooke, R. G., and W. Segal Colouring Matters of Australian Plants IV. Haemo-corin A Unique Glycoside from Haemodorum corymbosum. Vahl. Austral. J. Chem. 8, 107 (1955). 

Bick, I. R. C., and A. J. Blackman Haemodorin — A Phenalenone Pigment from Haemodorum distichophyllum Hook. Austral. J. Chem. 26, 1377 (1973). 

Perinaphthenones.— The biosynthesis of haemocorin aglycone, a pigment of Haemodorum corymbosum, was mentioned in last year s Report. Edwards et alV have shown that a very closely similar pigment, lachnanthoside (58), is formed in Lachnanthes tinctoria, by precisely the same general route, i.e. from phenylalanine, tyrosine, and acetic add, the acetate carboxy-group bdng... 

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