Inhibition of Proinflammatory Cytokine Release by Flavones and Flavanones from the Leaves of Dracaena steudneri Engl.
Vaderament-A Nchiozem-Ngnitedem,Leonidah Kerubo Omosa , Kibrom Gebreheiwot Bedane, Solomon Derese
Abstract
The leaves of Dracaena steudneri yielded 6 new flavonoids–3,5,7-trihydroxy-6-methyl-3′,4′-methylenedioxyflavone (1), 5,7-dihydroxy-3-methoxy-6-methyl-3′,4′-methylenedioxyflavone (2), 3,5,7-trihydroxy-6-methoxy-3′,4′-methylenedioxyflavone (3), (2S,3S)-3,7-dihydroxy-6-methoxy-3′,4′-methylenedioxyflavanone (4), 4′,5,7-trihydroxy-3,3′,8-trimethoxy-6-methylflavone (5), (2R) 7-hydroxy-2′,8-dimethoxyflavanone (6)–together with 13 known congeners. Their structures were established using spectroscopic and spectrometric methods including NMR, CD, and HRMSn measurements. The compounds were evaluated for their anti-inflammatory potential through measurement of the levels of cytokines IL-1β, IL-2, GM-CSF, and TNF-α in the supernatant of human peripheral blood mononuclear cells stimulated by lipopolysaccharide. Flavones derivatives 1–4 with a C-3′/4′ methylenedioxy substituent led to a substantial increase in the production of IL-1β and GM-CSF out of 4 pro-inflammatory cytokines relative to LPS control. Quercetin derivatives 5, 11, and 13 with a hydroxyl group at C-4′ inhibited the production of IL-2, GM-CSF, and TNF-α. The presence of a C-2/C-3 double bond in 14 was pivotal to the significantly stronger (0.4 to 27.5% of LPS control) inhibitory effect compared to its dihydro derivative 8 (36.2 to 262.7% of LPS control) against all tested cytokines. It is important to note that the inhibitory activity of 14 was substantially higher than that of the standard drug used, ibuprofen.
Key words
Dracaena steudneri - Asparagaceae - flavonoids - anti-inflammatory effects - flavones - flavanones