Meroterpenoids from the Fungus Ganoderma sinensis and First Absolute Configuration Clarification of Zizhine H

Abstract

Five new meroterpenoids, zizhines P-S and U (1−4,7), together with two known meroterpenoids (5 and 6) were isolated from Ganoderma sinensis. Their structures including absolute configurations were assigned by using spectroscopic, computational, and chemical methods. Racemics zizhines P and Q were purified by HPLC on chiral phase. Biological evaluation found that 4, 5 and 6 are cytotoxic toward human cancer cells (A549, BGC-823, Kyse30) with IC50 values in the range of 63.43–80.83 μM towards A549, 59.2 ± 2.73 μM and 64.25 ± 0.37 μM towards BGC-823, 76.28 ± 1.93 μM and 85.42 ± 2.82 μM towards Kyse30.

Isolation and Characterization of trans‐p‐Hydroxycinnamoyl Meroterpenoids from Ganoderma sinensis

“…The 13 C‐NMR and DEPT spectra of 1 ( Table 1) reveal 30 carbons ascribed to one methyl, six sp 3 methylene groups (two oxygenated), eleven sp 2 methine groups, and twelve nonprotonated carbons (one ketone, two carbonyls, four oxygenated). The NMR data of 1 resemble those of zizhine R, [7] differing in that the presence of 5‐OH, 7‐ketone, and the Δ 9(11) double bond in 1 , which is supported by the 1 H− 1 H COSY correlations of H‐11 ( δ H 7.01)/H 2 ‐12/H‐13 ( δ H 5.31), HMBCs of H‐3/C‐5 ( δ C 155.8), C‐7 ( δ C 202.1), H‐8 ( δ H 3.99)/C‐7, C‐9, C‐10 ( δ C 170.6), C‐11 ( δ C 145.2), and the HMBCs of H‐3 ( δ H 7.31), H‐6 ( δ H 6.30)/C‐2 ( δ C 112.5), C‐5, C‐7 ( Figure 2). Thus the planar structure of 1 was assigned and named zizhine V.…”

“…The 13 C-NMR and DEPT spectra of 1 (Table 1) reveal 30 carbons ascribed to one methyl, six sp 3 methylene groups (two oxygenated), eleven sp 2 methine groups, and twelve nonprotonated carbons (one ketone, two carbonyls, four oxygenated). The NMR data of 1 resemble those of zizhine R, [7] differing in that the presence of 5-OH, 7-ketone, and the Δ 9 (11) 2). Thus the planar structure of 1 was assigned and named zizhine V.…”

“…Compound 6 , obtained as a yellow gum, was found to have the molecular formula of C 30 H 30 O 9 from its HR‐ESI‐MS, 13 C‐NMR, and DEPT spectra with 16 degrees of unsaturation. The NMR data of 6 resemble those of zizhine H, [7] differing in that C‐15 in zizhine H is oxidized to a carboxylic acid and the oxygenated C‐15 is reduced to an sp 3 −CH 2 . These alterations are supported by the HMBCs of H‐13/C‐14, C‐15 ( δ C 171.0), C‐16, and 1 H− 1 H COSY correlations of H 2 ‐16 ( δ H 2.38)/H 2 ‐17/H‐18 ( Figure 2).…”

“…The NMR characteristics indicate that 3 is also an analog of 1 or 2 . A comparison of the NMR data with those of zizhine S [7] found that 3 differs zizhine S in that one methoxy group and one hydroxymethylene group in zizhine S disappears instead of the presence of oxygenated C‐16. These alterations are supported by the absence of HMBCs of −OC H 3 /C‐10, H 3 ‐15/C‐13, C‐14, C‐16 ( Figure 2).…”

“…�)-Zizhine Z2(7): Yellow gum; UV (MeOH) λ max (logɛ) 379 (3.28), 311 (4.11), 258 (3.78), 225 (4.15) nm; {[α] D 25 + 8.6 (c = 0.01, MeOH); (+)-7}; {[α] D 25 À 15.0 (c = 0.02, MeOH); (À )-7}; HR-ESI-MS m/z 509.2184 [MÀ H] À , (calc. for C 29 H 33 O 8 , 509.2181).…”