Inhibition of pro-inflammatory cytokines by homalolide A and homalomenol A isolated from rhizomes of Homalomena pendula .

Inflammation, a natural process of the innate immune system, involves elevated levels of various proinflammatory mediators, such as, nitric oxide (NO) and prostaglandin (PGE ₂ ), cytokines such as interleukin 6 (IL-6), interleukin 10 (IL-10) and tumor necrosis factor alpha (TNF-α), and enzymes including inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). This study investigated the anti-inflammatory effects of homalolide A ( 1 ) and homalomenol A ( 2 ), two sesquiterpenoids isolated from the rhizome of Homalomena pendula , on lipopolysaccharide (LPS)- stimulated macrophage cells. The results demonstrated that both 1 and 2 dose-dependently inhibited the production of PGE ₂ , TNF-α and IL-6 in RAW 264.7 macrophages. Furthermore, 2 also stimulated IL-10 production in RAW 264.7 cells. Consistent with these findings, these compounds suppressed the LPS-stimulated protein levels of iNOS and COX-2 in RAW 264.7 cells. These results suggested that 1 and 2 could be effective candidates for ameliorating inflammatory-associated complications.
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