Meroterpenoid Pigments from Albatrellus flettii (Basidiomycetes)

Abstract

Keywords: Natural products / Meroterpenoids / Mushrooms / Quinones / FuransThe pigments responsible for the blue colour of the North American polypore Albatrellus flettii have been isolated and their structures elucidated by spectroscopic methods. Albatrellin, a dimeric meroterpenoid with a furylbenzoquinone chromophore, is accompanied by its 16-hydroxy and 16-oxo derivatives. The latter has recently been described as grifolone B from a Japanese collection of A. caeruleoporus.

Cristatomentin, a Green Pigment of Mixed Biogenetic Origin from Albatrellus cristatus (Basidiomycetes)

“…Since the NMR spectroscopic data exclude a connection of partial structure A with the aromatic part of the molecule through one of the 4‐hydroxyphenyl rings, the second half of cristatomentin is represented by structure B (Figure 1). A combination of both partial structures yields constitution 5 for cristatomentin, which is supported by the agreement of the chemical shift values for the carbon atoms connecting both moieties in cristatomentin ( 5 ) (C‐6: δ C = 134.3 ppm; C‐21′: δ C = 141.3 ppm) and albatrellin ( 6 ) (C‐6: δ C = 135.5 ppm; C‐21′: δ C = 140.3 ppm) 6a…”

“…The EI‐MS of cristatomentin ( 5 ) shows that the compound suffers thermal decarboxylation2a,6a and yields a pseudo molecular ion peak at m / z (%) = 646 (4) in additionto a more intense peak at m / z (%) = 648 (16); [M + 2] ions are characteristic for benzoquinones and arise by reduction of the quinone in the inlet system 8. Two fragment ions at m / z (%) = 340 (10) [C 22 H 28 O 3 ] and 310 (100) [C 18 H 14 O 5 ] correspond to the molecular compositions of cristatin ( 2 ) and 2‐deoxyleucoatromentin ( 10 ), respectively, and indicate thermal cleavage of decarboxyleucocristatomentin ( 7 ; m / z = 648) in the inlet system (Scheme ).…”

“…We have recently shown that albatrellin ( 6 ) is formed by addition of cristatin ( 2 ) to 2‐farnesyl‐3‐hydroxy‐5‐methyl‐1,4‐benzoquinone 6a. An analogous reaction between cristatic acid ( 1 ) and 2‐ O ‐acetylatromentin ( 4 ) would afford adduct 11 , which could subsequently lose acetic acid to form the furylbenzoquinone 5 (Scheme ) 10.…”

Meroterpenoid Pigments from the Basidiomycete Albatrellus ovinus

“…An intensive [M + H] + ion peak in the EIMS spectrum, a strong IR absorption at 1647 cm −1 , and two downfield carbon signals at δ C 184.1 and 186.9 were characteristic for a quinone moiety. 9 Further, The HMBC cross-peaks from H-7′ (δ H 3.17) to C-2′, C-6′, and C-1′ and from OH-2′ to C-1′, C-3′, and C-2′ revealed that 5a was a pbenzoquinone with a farnesyl group at position 1′. Me-22′ was located at position 4′ based on the HMBC cross-peaks from Me-22′ to C-3′, C-4′, and C-5′ ( Figure 3).…”

Meroterpenoids produced by fungi

“…142 The pigments albatrelin 288 and 16hydroxyalbatrelin 289, responsible for the blue color of A. flettii, have been isolated and their structure elucidated by spectroscopic methods. 143 288 is a dimeric meroterpenoid with a furylbenzoquinone chromophore. In addition, grifolinone C 290, which displays an alternative mode of dimerisation through the aromatic moieties, was obtained from the fruiting bodies of A. confluens, accompanied by 274, 275, 287, and 288.…”