3,5-Dimethylorsellinic Acid Derived Meroterpenoids from Penicillium chrysogenum MT-12, an Endophytic Fungus Isolated from Huperzia serrata

Abstract

Eight new chrysogenolides (A-H (1-8)) and seven known (9-15) 3,5-dimethylorsellinic acid derived meroterpenoids were isolated from the solid substrate fermentation cultures of a Huperzia serrata endophytic fungus, Penicillium chrysogenum MT-12. The structures of the new compounds were elucidated by interpretation of spectroscopic and spectrometric data (1D and 2D NMR, IR, and HRESIMS). The absolute configurations of 1-4 were determined by single-crystal X-ray crystallographic analysis, and those of 5-8 were assigned on the basis of experimental and calculated electronic circular dichroism spectra. Compounds 3, 4, 6, 11, and 12 showed inhibition of nitric oxide production in lipopolysaccharide-activated RAW 264.7 macrophage cells with IC values in the range of 4.3-78.2 μM (positive control, indomethacin, IC = 33.6 ± 1.4 μM).

3,5‐Dimethylorsellinic Acid Derived Meroterpenoids from Eupenicillium sp. 6A‐9, a Fungus Isolated from the Marine Sponge Plakortis simplex

“…Using this methodology, the computed chemical shift for C-12 is δ C = 36.9 ppm, with only a deviation of 3.6 ppm from the experimental value (δ C = 33.3 ppm). Moreover, this 13 C chemical shift investigation not only confirmed the elucidated constitution of 1, but also supported the relative stereochemistry assignment of 2. Table S1 and Figure S4 in the Supporting Information).…”

“…[16] The calculated 13 C NMR spectroscopic data show good agreement with the experimental values, with average absolute deviations of 1.8 ppm ( Figure 5 and Table S11). Using this methodology, the computed chemical shift for C-12 is δ C = 36.9 ppm, with only a deviation of 3.6 ppm from the experimental value (δ C = 33.3 ppm).…”

“…These groups account for seven oxygen atoms, which leaves one oxygen atom unassigned, and six degrees of unsaturation, which suggests that 2 is a tetracyclic compound. The COSY and HMBC data associated with the D and E rings of 1 are present in the NMR spectra of 2 ( Figure 2), and the 1 H and 13 C NMR spectroscopic data of these two rings of 2 are comparable to those of 1 (Table 1), which provides ample evi- dence of the D and E rings and discloses the location of the last oxygen atom. Besides, much of the NMR spectroscopic data associated with the B ring and its isopropenyl and propionic acid side-chains of berkeleyone C (8) [10] are also present in the Figure 2).…”

“…We than resorted to modern quantum mechanical methods to explore this 13 C chemical shift (see the Supporting Information for details). [16] The calculated 13 C NMR spectroscopic data show good agreement with the experimental values, with average absolute deviations of 1.8 ppm ( Figure 5 and Table S11).…”

“…Interestingly, 22-deoxy-10-oxominiolutelide B (5) and 22-deoxyminiolutelide B (6) were isolated as an inseparable mixture of two ketone/hemiketal isomers in equilibrium. Furthermore, 1 and 2 have the very rare 6(D)/5(E) fused ring system [13] instead of the 5(D)/6(E) fused rings present in 5, 6, and 9 with the C-11-positioned methoxycarbonyl group in 5, 6, and 9 moved to C-9 in 1 and 2, [13] which suggests that a special shunt path is present in the biosynthetic pathway for meroterpenoids in Eupenicillium sp. 6A-9.…”