Secondary metabolites from Scutellaria brevibracteata subsp. subvelutina and their in vitro anti-inflammatory activities
Murat Erdoğan, Rima Konya, Yağmur Özhan, Hande Si̇pahi̇, İlker Çinbilgel, Milena Masullo, Sonia Piacente, Hasan Kırmızıbekmez
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.