Direct amination of naphthopurpurin and mompain, sea urchin pigments, and their O-methyl ethers by the reaction with ammonia

Hydroanthraquinones from Nigrospora sphaerica and Their Anti-inflammatory Activity Uncovered by Transcriptome Analysis

“…Nigroquinone J (10) was obtained as a yellow powder with a molecular formula of C 16 H 17 NO 6 . Its 13 13 C NMR spectra of 10 were similar to those of 10deoxybostrycin. 12 A comparison of the HMBC spectrum of 10 with that of 10-deoxybostrycin indicated the difference is the position of a hydroxy group.…”

“…The NMR spectra of 4 are similar to 3. The most obvious difference in the 13 C NMR spectra of 4 was the absence of an oxygenated methyl signal. The chemical shifts of C-9 (Δ δ = −8.8 ppm) is significantly shielded and that of C-9a (Δ δ = +3.0 ppm) is obviously deshielded, further revealing the presence of a hydroxy group instead of a methoxy group at C-9.…”

“…The coupling constant (J = 5.3 Hz) and the NOESY correlations between H-4a and H-9a as well as the small coupling constant (J = 2.6 Hz) between H-9 and H-9a combined with the NOESY correlations of H4a/H-9a indicated the relative configurations of C-4a, C-9, and C-9a in 2 are the same as those in 4a-epi-9-methoxydihydrodeoxybostrycin (Figure 2). 12 Compared with 4a-epi-9methoxydihydrodeoxybostrycin, the downfield chemical shift of C-4 (δ 74.7 in 3 versus δ 28.7 in 4a-epi-9-methoxydihydrodeoxybostrycin) in the 13 C NMR indicated a hydroxy group instead of a proton at C-4. The NOESY correlations of H-4/4a and H-4/H-9a indicated the remaining proton at C-4 is αoriented.…”

“…Nigroquinone J ( 10 ) was obtained as a yellow powder with a molecular formula of C 16 H 17 NO 6 . Its 13 C NMR spectra showed the characteristic signals of an 8-amino-5-hydroxy-6-methoxynaphthalene-1,4-dione moiety at δ 183.1 (C-9), 181.9 (C-10), 161.9 (C-5), 156.8 (C-7), 144.3 (C-9a), 140.3 (C-8), 139.9 (C-4a), 105.8 (C-10a), 105.6 (C-8a), 104.2 (C-6), and 56.8 (7-OMe), an oxygenated methine at δ 70.4 (C-2), two methylenes at δ 36.3 (C-1) and 29.4 (C-4), and a methyl group at 2-Me. The planar structure of 10 was determined as 5,6,7,10-tetrahydroxy-2-methoxy-7-methyl-5,6,7,8-tetrahydroanthracene-1,4-dione by the 1 H– 1 H COSY correlations of H-3/H-4 as well as the HMBC correlations of 2-Me/C-1, C-2, C-3, of H-1/C-9a, and of H-4/C-4a.…”

“…Subfraction J was subjected to fractionated preparative HPLC using a reversed-phase column to afford compound 9 (MeOH−H 2 O, 60:40; 3 mL/min; t R : 18.2 min; 1.0 mg). 13 C NMR data see Tables 1 and 2. 13 C NMR data see Tables 1 and 2.…”