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DOI: 10.1055/s-0035-1565693
Isolation of anti-inflammatory compounds from Sambucus ebulus leaves through in vitro activity-guided fractionation
The in vitro anti-inflammatory effects of subextracts (n-hexane, chloroform, ethyl acetate, n-butanol, remaining water) of the methanol extract of the leaves of Sambucus ebulus L. (Adoxaceae) were investigated for their inhibitory activities on the activation of Nuclear factor kappa B (NF-κB) on lipopolysaccharide induced Raw 264.7 cells. The n-hexane, chloroform and ethyl acetate subextracts inhibited NF-κB activation at 50, 100 and 100 µg/mL concentrations, respectively. Two flavonoid mixtures [quercetin-3-O-β-D-glucopyranoside, quercetin-3-O-β-D-galactopyranoside], two flavonoids [isorhamnetin-3-O-β-D-glucopyranoside (1), isorhamnetin-3-O-rutinoside (2)] were isolated from ethyl acetate subextract. 10-O-acetylpatrinoside (3) and a new iridoid [Sambulin B (4)] was obtained from chloroform and n-hexane subextracts respectively. Structures were elucidated by NMR and MS. The compounds exerted inhibitions between 30 – 80% on NF-κB. Flavonoids were applied to cells at 25, 50, 75 and 100 µg/mL concentrations. Sambulin B was applied at 6,25, 12,5, 25 and Sambulin A applied at 12,5, 25 and 50 µg/mL concentrations. The effects on nitric oxide (NO), prostaglandine E2 (PGE2), tumor necrosis factor (TNFα) and interleukins (IL-1α, IL-1β, IL-2, IL-6) were investigated by Griess and ELISA. The effects on iNOS, COX-2 protein levels and phosphorylation levels of mitogen activated protein kinases and I kappa B alpha (IκBα) were examined by Western Blotting. 1, 2, 3 and 4 inhibited NO productions (between 59 – 84%), iNOS levels were decreased. 2, 3 and 4 exerted inhibitions on PGE2 between 39 – 84%, COX-2 protein levels were decreased. 1 and 2 prevented p38/IκBα phosphorylations while 3 inhibited JNK/p38. Compound 4 inhibited JNK phosphorylation. All compounds (except mixtures) inhibited TNFα more than 29% and only 4 inhibited IL-6.
Acknowledgements: This study is supported by TUBITAK-SBAG (Project no: 110S197) research grant.