Anti-inflammatory activity of compounds from Boesenbergia longiflora rhizomes

The rhizomes of Boesenbergia longiflora (Wall.) Kuntze have been traditionally used in treatment of inflammatory bowel disease, ulcerative colitis, aphthous ulcer and abscess. Our previous study indicated that CHCl3 fractions of Boesenbergia longiflora had potential on anti-inflammatory properties. In the present study, we investigated the active constituents of this plant for anti-inflammatory activity in order to support its traditional use.

The CHCl3 fraction was isolated using chromatographic techniques. Isolated compounds were tested using relevant in vitro anti-inflammatory assays against LPS-induced NO and TNF-α releases as well as their mechanisms in transcription levels in murine macrophage RAW264.7 cells.

The isolation of the CHCl3 fraction from Boesenbergia longiflora rhizomes led to the isolation of three new daucane sesquiterpenes, which were identified as 8-hydroxy-dauca-9, 11-diene-7-one (longiferone A; 1), dauca-8, 11-diene-7-one (longiferone B; 2) and dauca-8, 11-diene-7, 10-dione (longiferone C; 3); together with four known flavonoids, six known diarylheptanoids as well as one sterol. The longiferone B (2) and longiferone C (3) showed anti-inflammatory activity against NO release with IC50 values of 21.0 and 31.3µM, respectively. Longiferone B (2) also suppressed the iNOS and COX-2 mRNA expression. Moreover, the flavonoids and diarylheptanoids inhibited NO and TNF-α production in a dose dependent manner.

This study demonstrated that sesquiterpenes, diarylheptanoids and some methoxyflavonoids found in Boesenbergia longiflora are responsible for anti-inflammatory activity.