New flavanone glycoside from the leaves of Faramea marambaiae (Rubiaceae)

The species Faramea marambaiae M. Gomes (Rubiaceae) is endemic in the city of Rio de Janeiro, Brazil, and there are no reports about its chemical composition or therapeutic potential. From the methanol extract of its leaves were isolated, among other compounds, by liquid-liquid partition followed by reverse phase (C18) column chromatography (CC) and semi-preparative reverse-phase (C18) high performance liquid chromatography coupled to a diode array detector (HPLC-DAD) the novel flavanone glycoside: 5-hydroxy-4'-methoxy-flavanone-7-O-s-D-apiofuranosyl-(1 – 6)-s-D-glucopyranoside. Structural determination was made by nuclear magnetic resonance (NMR) techniques in one and two dimensions (1H NMR, 13C NMR, COSY, HSQC and HMBC), ultraviolet spectroscopy (UV) and optical rotation. Preliminary test for in vitro cytotoxicity of the methanol extract towards a human breast cancer tumor cell line (MCF-7) showed no cytotoxicity. Tests for antioxidant activity with DPPH and phototoxic activity (photosensitizer action to produce singlet oxygen – 1O2) of the flavonoid rich methanol:water 9:1 fraction, obtained by partition of the methanol extract, showed moderate antioxidant activity (IC50= 174.96 µg/mL) and absence of phototoxicity. Acknowledgments: CNPq and FAPERJ (Brazil), Oswaldo Cruz Foundation NMR Lab.