Anti-Inflammatory Meroterpenoids of Cordia glazioviana (Boraginaceae)

Abstract

The phytochemical reinvestigation from the heartwood of the extracts of Cordia glazioviana led to the isolation of four still undescribed hydroquinones derivatives designated as cordiaquinol D (1), cordiaquinol E (2), (10R)-10,11-dihydrofuran-1,4-dihydroxy-globiferin (3) and 2-[(1’E,6’E)-3’,8’‑dihydroxy-3’,7’-dimethylocta-1’,6’-dienyl]-benzene-1,4-diol (4), along with the naphthoquinone 6-[(2’R)-2’-hydroxy-3’,6’-dihydro-2H-pyran-5’-yl]-2‑methoxy- 7‑methylnaphthalene-1,4-dione (5). Additionally, six previously known compounds were also isolated: rel-1,4-dihydroxy-8α,11α;9α,11α-diepoxy-2-methoxy-8aβ-methyl- 5,6,7,8,8a,9,10,10a‑octahydro-10-antracenone (6), didehydroconicol (7), 1β,6β-dihydroxy-7-epieudesm-3-ene (8), 1β,6β-dihydroxy-7-epi-eudesm-4(15)-ene (9), 10,11-dihydroxybisabolol (10), and hamanasal-A (11). The structures of the new compounds were assigned by high-resolution mass spectrometry (HRMS) and nuclear magnetic resonance (NMR) analyses. The relative stereochemistry of 3, 4, and 5 was improved by quantum mechanical calculations. Eight, out of the eleven isolated compounds (2-9), were tested through cellular viability and lipopolysaccharide (LPS)-induced inflammation assays against RAW 264.7 macrophage-like cells. Compounds 3-5 exhibited a stronger effect on LPS-induced NO production (half-maximal inhibitory concentration (IC50) 50.34, 105.83, and 66.73 μM, respectively).

Selenate—An internal chemical shift standard for aqueous 77Se NMR spectroscopy

“…Despite the long-standing use of this technique, a reliable and robust chemical shift standard is still an unmet need, as seen in a systematic error between separately reported 77 Se chemical shifts in the literature. [12] In the 77 Se NMR literature, chemical shift data are referenced to a relatively large number of compounds(seleninyl chloride, [13] dimethyl selenide, [14,15] selenophene, [16][17][18][19] diphenyl diselenide, [20][21][22][23][24] 4,4 0dimethyldiphenyl diselenide, [25] selenium oxide, [26] sodium selenite, [27] selenous acid). [13,[28][29][30][31] In addition, indication of the measurement parameters (concentration, ionic strength, temperature) is rather the exception than the case.…”