Physarorubinic acid

The plasmodia of the wild type of Physarum polycephalum are bright yellow and produce an orange-red pigment that is also present in a white mutant [120]. This compound, named physarorubinic acid (64), binds calcium and other metals very well and this made acquisition of the H-NMR spectrum difficult (line broadening) unless the sample was washed with aq. EDTA solution. The structure contains a decapentaene system and signals at 5 102.4 (C-3), 172.6 (C-7), 174.5 (C-2) and 194.0 (C-4) are characteristic of C-3 acylated tetramic acid unit. 

Steffan et al. studied the difference in the pigments of the suspension cultured plasmodia of P. polycephalum under dark and light conditions. On the basis of HPLC analyses, physarorubinic acids A (66) and B (68) were contained in both cultures under dark and light conditions. Apparently it was revealed that light stimulated the... 

Synthesis of physarorubinic acid, which is a polyenoyltetramic acid plasmodial pigment, is another example. The synthesis uses a Lacey-Dieckmann cyclization starting with ester 51, followed by deprotection to give physarorubinic acid (52) in 78% yield for the two steps. ... 

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