The anti-inflammatory and anticancer properties of eight meroterpenoids isolated from the brown seaweed Cystoseira usneoides have been evaluated. The algal meroterpenoids (AMTs) 1-8 were tested for their inhibitory effects on the production of the pro-inflammatory cytokines tumor necrosis factor (TNF-α), interleukin-6 (IL-6), and interleukin-1β (IL-1β), and the expression of cyclooxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS) in LPS-stimulated THP-1 human macrophages. The anticancer effects were assessed by cytotoxicity assays against human lung adenocarcinoma A549 cells and normal lung fibroblastic MRC-5 cells, together with flow cytometry analysis of the effects of these AMTs on different phases of the cell cycle. The AMTs 1-8 significantly reduced the production of TNF-α, IL-6, and IL-1β, and suppressed the COX-2 and iNOS expression, in LPS-stimulated cells (p < 0.05). The AMTs 1-8 displayed higher cytotoxic activities against A549 cancer cells than against MRC-5 normal lung cells. Cell cycle analyses indicated that most of the AMTs caused the arrest of A549 cells at the G2/M and S phases. The AMTs 2 and 5 stand out by combining significant anti-inflammatory and anticancer activities, while 3 and 4 showed interesting selective anticancer effects. These findings suggest that the AMTs produced by C. usneoides may have therapeutic potential in inflammatory diseases and lung cancer.
Keywords: Cystoseira usneoides; cell cycle; cytokines; inflammation; lung cancer; meroterpenoids.