Notes: Isolation of the New (- )-(3 R,4S)-4-Hydroxymellein from the Fungus Septoria nodorum Berk

Abstract

The new (-)-(3 R,4 S)-4-hydroxymellein (6) is isolated from the fungus Septoria (Phaeosphaeria) nodorum Berk, together with the previously reported isomer 5. The results so far obtained in this series of metabolites are discussed in relationship with biosynthetic considerations.

Occurrence, isolation and biological activity of phytotoxic metabolites produced in vitro by Sphaeropsis sapinea, pathogenic fungus of Pinus radiata

“…(3R,4S)-())-4-Hydroxymellein (3) Compound 3 had: [a] 25 D )24.6 (c 0.16); IR: m max (cm )1 ) 3400 (OH), 1653 (C=O), 1618, 1583, 1485, 1466 (Ph); UV: k max (log e) 245 (3.91), 313 (3.80). 1 H-NMR spectrum was very similar to that reported in literature(Devys and Barbier, 1992), while the 13 C-NMR spectrum was very similar to that reported for the cis-diastereomer (3R,4R) except for the chemical shift of the Me-11 at d (ppm) 17.9(Cole and Cox, 1981). ESI-MS (+): m/z 236 [M+K] + , 217 [M+Na] + , 195 [M+H] + ; ESI-MS ()): m/z 193 [M)H] ) .…”

Dinemasones A, B and C – New Bioactive Metabolites from the Endophytic Fungus Dinemasporium strigosum

“…The crude mass of the column fraction of petroleum ether/75 % CH 2 Cl 2 after crystallization from CH 2 Cl 2 /acetone gave white fine needles of ergosterol [4] (8.0 mg). The column fraction of petroleum ether/55 % CH 2 Cl 2 was subjected to preparative TLC on silica gel (CH 2 Cl 2 /MeOH/AcOH, 100:0.6:0.2) to obtain 2.3 mg of the cis and trans isomers of 4-hydroxymellein [5][6][7][8][9] as a mixture of two diastereomers. Chromatography of a polar fraction (CH 2 Cl 2 /1-2 % MeOH) on preparative layer silica gel plates (CH 2 Cl 2 /acetone/ AcOH, 100:4:0.2) followed by crystallization from CH 2 Cl 2 /Et 2 O/ pentane afforded dinemasone A (1a) (14.6 mg) as white fine needles.…”

“…From these extracts, four known compounds were identified as palmitic acid, [2,3] ergosterol, [4] and the cis and trans isomers of 4-hydroxymellein. [5][6][7][8][9] In addition, two new metabolites with unusual structures, 1a and 2a, were isolated in pure form by a combination of repeated chromatography and crystallization. A polar component 3a was indirectly identified by acetylation of the polar fraction as the cis-diacetylated derivative 3b, produced from the new natural product 3a (Figure 1).…”

An In Planta -Expressed Polyketide Synthase Produces ( R )-Mellein in the Wheat Pathogen Parastagonospora nodorum

“…So far, none of the products of these secondary metabolite gene clusters have been identified, and only a few secondary metabolites have been identified in this species (7). These metabolites include (R)-mellein and derivatives (8,9), septorines (10,11), mycophenolic acid (8), alternariol (12), and (ϩ)-4=-methoxy-(2S)-methylbutyrophenone (13).…”