Flavonoids of Tripodanthus acutifolius inhibit TNF-α production in LPS-activated THP-1 and B16-F10 cells

Ethnopharmacological relevance: T. acutifolius is an endemic species from South America which has been used in traditional medicine since ancient times due to its biological properties, including its anti-inflammatory effects. Aim of the study: The aim of the article is to investigate the inhibitory activity of T. acutifolius over TNF-alpha production in THP-1 and B16-F10 cells. To achieve this, phytochemical analysis has been used to determine the compounds present in the species with anti-inflammatory effects. Materials and methods: Leaves and stems of T. acutifolius were extracted with n-heptane, dichloromethane, methanol and water. The resulting extracts were analysed in THP-1 and B16-F10 cells by measuring their inhibitory capacity over the production of TNF-alpha stimulated with LPS. Results: The guided-bioassay led to the isolation of 6,2',4'-trimethoxyflavone (1), 5,3',4'-trihydroxy-6,7,8 trimethoxyflavone (2), (E)-2',4'-dihydroxy-6'-methoxy-chalcone (3) and 5,4'-dihydroxy-6,7,8-trimethoxyflavone (4) from the dichloromethanic extract. Compounds showed an inhibitory activity of TNF-alpha production in THP-1 cells, with IC50 of 2.38 +/- 0.02 mu M, 12.36 +/- 0.17 mu M, 1.12 +/- 0.01 mu M and 8.09 +/- 0.04 mu M, respectively. In addition, the compounds showed an inhibitory activity of TNF-alpha production in B16-F10 cells with IC50 of 1.32 +/- 0.03 mu M, 5.63 +/- 0.09 mu M, 0.60 +/- 0.02 mu M and 3.77 +/- 0.15 mu M, respectively. Conclusions: We identified 3 flavones (6,2',4'-trimethoxyflavone, 5,3',4'-trihydroxy-6,7,8-trimethoxyflavone, 5,4'-dihydroxy-6,7,8-trimethoxyflavone) and a chalcone ((E)-2',4'-dihydroxy-6'-methoxy-chalcone) present in the leaves and stems of T. acutifolius. These compounds are an alternative for the treatment of immune-mediated inflammatory disorders, acting as negative modulators over the TNF-alpha production.