Terphenyls polyporic acid

The dimethoxy derivative of polyporic acid, betulinan A (4), is another of the few known />-terphenyls with unsubstituted side rings. It has recently been isolated from fruiting bodies of Lenzites betulina, together with the related betulinan B (113, see Section 4.1) [27], Betulinan A and B are potent inhibitors of lipid peroxidation in rat liver microsomes (thiobarbituric acid method), and 4 showed the highest activity (IC50 = 0.46 pg/mL). 

The isolation of polyporic acid (11) [Stahlschmidt, 1877 (597, 592)], atromentin (13) [Thorner, 1878 (653)] and thelephoric acid (16) [ZOPF, 1889 (730)] marked the start of the chemical investigation of fungal pigments. The structure elucidation and chemistry of these compounds has been amply covered in Thomson s book (655) and does not need to be repeated here. In recent years several papers dealing with ultraviolet (311), infrared (208) and mass spectra (304, 465) and with the chromatography (267) and detection (274) of simple terphenyl-quinones have been published. Details of their known distribution in fungi are given in Table 3 and their physical properties are summarised in Table 4. 

From mycelial mats of Phlebiopsis gigantea ( = Peniophora gigantea) the colourless 2, 3, 5-trimethoxy-p-terphenyl (27) has been isolated 134) which appears to be biogenetically related to polyporic acid. 

Mosbach, K., H. Guilford, and M. Lindberg The Terphenyl Quinone Polyporic Acid Production, Isolation and Characterisation. Tetrahedron Letters 1974, 1645. 

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