In Vitro Anti-Inflammatory Activity in Arthritic Synoviocytes of A. brachypoda Root Extracts and Its Unusual Dimeric Flavonoids

Abstract

<i>Arrabidaea brachypoda</i> is a plant commonly used for the treatment of kidney stones, arthritis and pain in traditional Brazilian medicine. Different in vitro and in vivo activities, ranging from antinociceptive to anti-<i>Trypanosoma cruzi</i>, have been reported for the dichloromethane root extract of <i>Arrabidaea brachypoda</i> (DCMAB) and isolated compounds. This work aimed to assess the in vitro anti-inflammatory activity in arthritic synoviocytes of the DCMAB, the hydroethanolic extract (HEAB) and three dimeric flavonoids isolated from the DCMAB. These compounds, brachydin A (<b>1</b>), B (<b>2</b>) and C (<b>3</b>), were isolated both by medium pressure liquid and high-speed counter current chromatography. Their quantification was performed by mass spectrometry on both DCMAB and HEAB. IL-1β activated human fibroblast-like synoviocytes were incubated with both extracts and isolated compounds to determine the levels of pro-inflammatory cytokine IL-6 by enzyme-linked immunosorbent assay (ELISA). DCMAB inhibited 30% of IL-6 release at 25 µg/mL, when compared with controls while HEAB was inactive. IC₅₀ values determined for <b>2</b> and <b>3</b> were 3-fold higher than <b>1</b>. The DCMAB activity seems to be linked to higher proportions of compounds <b>2</b> and <b>3</b> in this extract. These observations could thus explain the traditional use of <i>A. brachypoda</i> roots in the treatment of osteoarthritis.