Haemocorin

Diketide products of this super family of plant polyketide synthases probably include acridones and also phenylphenalenones such as the aglycone of haemocorin (69), which may be formed from one malonyl-CoA and two phenylpropanyl-CoA units (Figure 8). The proposed derivation of 69 via a diarylheptanoid related to curcumin (70) was... 

Haemocorin aglycone see phenalenones. Haemofluorone A see phenalenones. Haemoventosin. 

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

P. are toxic towards microorganisms and animals. Haemocorin has tumor-inhibiting and antibacterial activities. ... 

Haemocorin aglycone purple-red plates or almost black needles 277—278° (230—232°)... 

Subsequent to the investigation of haemocorin other phenalenones and phenalenone derivatives were isolated from other plants. Their structures were determined partly by conversion to known derivatives but largely by spectroscopic methods, using as models the many phenalenone derivatives prepared during the study of haemocorin. 

Dihydroxy-5-methoxy-9-phenyl-l H-phenalen-1-one (Haemocorin aglycone)... 

The most generally useful data for structure elucidation have been provided by very comprehensive studies of the proton magnetic resonance spectra of the natural arylphenalenones and the related metabolites, together with a large number of synthetic model compounds. As shown for structures (54) and (55) the H-NMR spectra (6 values in CDCI3) easily distinguish between the dimethyl ethers obtained from 2,6-di-hydroxy-5-methoxy-9-phenyl-1 H-phenalen-1 -one (haemocorin aglycone). 

The application of the above reactions is illustrated in Scheme VIII by the synthesis of 2,6-dihydroxy-5-methoxy-9-phenyl-IH-phenalen-I-one (haemocorin aglycone) (59). 

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). 

Colouring Matters of Australian Plants V. Haemocorin The Chemistry of the... 

Laundon, B., and G. A. Morrison Naturally Occurring Compounds Related to Phenalenone II. The Synthesis of Haemocorin Aglycone. J. Chem. Soc. (London) C. 1694 (1971). 

Cooke, R. G., and I. J. Rainbow Colouring Matters of Australian Plants XIX. Haemocorin Unequivocal Synthesis of the Aglycone and Some Derivatives. Austral. J. Chem. 30, 2241 (1977). 

Thomas, R. The Biosynthesis of the Plant Phenalenone Haemocorin. Chem. Commun. 739 (1971). 

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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