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 HRMS. Biological activities of the polar extract of T. africana shoots related to its phenolic content were also investigated. A high total phenolic content (151.1mg GAE/g) was found in the methanol shoot extract, which exhibits strong antioxidant activities using the oxygen radical absorbance capacity method and a skin cell-based assay. Moreover, the shoot extract showed significant anti-inflammatory activity, reducing nitric oxide release by 53.5% at 160 mu g/mL in lipopolysaccharide-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 mu g/mL.