New sulphated flavonoids from Tamarix africana and biological activities of its polar extract

The phytochemical investigation of Tamarix africana Poir. (Tamaricaceae) shoot polar extract afforded three new sulphated flavonoids, (2S,4R)-5,7,4’-trihydroxyflavan-4-ol 5,7-disulphate (1), (2S)-5,7,4’-trihydroxyflavan 7-O-sulphate (2), and (2S)-naringenin 4’-O-sulphate (3), together with ten known compounds. Their structures were determined by spectroscopic methods including 1D and 2D NMR analysis and high resolution mass spectrometry. Biological activities of the polar extract of T. africana shoots related to its phenolic content were also investigated. A high total phenolic content (151.1 mg GAE/g) was found in the methanol shoot extract, which exhibits strong antioxidant activities using the ORAC method and in a skin cell based-assay. Moreover, the shoot extract showed significant anti-inflammatory activity, reducing NO release by 53.5 % at 160 µg/mL in LPS stimulated RAW 264.7 macrophages. Finally, T. africana shoot extract inhibited the growth of A-549 lung carcinoma cells, with an IC50 value of 34 µg/mL.