Secondary metabolites from Scutellaria brevibracteata subsp. subvelutina and their in vitro anti-inflammatory activities

Abstract

From the MeOH extract of the aerial parts of Scutellaria brevibracteata subsp. subvelutina 12 secondary metabolites including eight iridoid glycosides (1-8), three flavonoids (9-11) and one phenylethanoid glycoside (12) were isolated. Their structures were elucidated as catalpol (1), globularin (2), scutellarioside II (3), picroside III (4), pensteminoside (5), 8-epiloganic acid (6), albidoside (7), agnucastoside B (8), hispidulin (9), luteolin 7-O-glucuronide (10), hispidulin 7-O-glucuronide (11) and martynoside (12) by using extensive NMR and HR-MS analysis. All compounds are being reported for the first time from S. brevibracteata subsp. subvelutina while compound 5 is new for Lamiaceae family. The chemotaxonomic importance of the isolates was discussed in the detail. All the isolates were evaluated for their in vitro anti-inflammatory activities via their inhibitory actions on the release of nitrite oxide and IL-6 from LPS-induced RAW 264.7 macrophage cells. Compounds 9 and 11 exhibited significant NO reducing capacity at 100 μM concentration comparable to the positive controls, indomethacin and L-NAME. Moreover, 2, 9 and 10 significantly suppressed the release of IL-6 at the same concentration better than the positive controls.