Two new hydronaphthoquinones from Sinningia aggregata (Gesneriaceae) and cytotoxic activity of aggregatin D

Two new hydronaphthoquinones, aggregatins E and F (1 and 2, resp.) were isolated from the tubers of Sinningia aggregata (Ker-Gawl.) Wiehler (Gesneriaceae), along with twelve known compounds aggregatin D (3), tectoquinone (4), 1-hydroxy-2-methylanthraquinone (5), icosyl ferulate (6), pustuline (7), 1,6-dihydroxy-2-methylanthranquinone (8), 6-hydroxy-2-methylanthraquinone (9), 7-hydroxy-2-methylanthraquinone (10), tyrosol (11), halleridone (12), calceolarioside B (13), and cornoside (14). All compounds were identified by analysis of spectroscopic and spectrometric data. Compounds 3, 4, and 10 had already been reported in this species. Compounds 2 and 3 were evaluated against several tumor cell lines, but only 3 exhibited activities against UACC-62, 786-0 and OVCAR-3 cell lines, with IC50 values of 12.3, 12.8 and 0.3 μg/ml, respectively, without toxic effects on non-cancer cell line HaCat (human keratinocyte).