Abstract
From the rhizomes of Begonia heracleifolia six known cucurbitacins (1-6) were isolated. Based on spectral data (1D and 2D1H-, 13C-NMR, ESI- and CI-MS) the structures were established as cucurbitacin B (1), cucurbitacin D (2), 23,24-dihydrocucurbitacin D (3), 23,24-dihydrocucurbitacin F (4), 2-O-β-glucopyranosyl-cucurbitacin B (5), and 2-O-β-glucopyranosyl-cucurbitacin D (6). Four of them (3-6) were so far not reported as constituents of Begonia spp. Varyingly strong antiproliferative activity towards tumor and immune cells was observed for three compounds (1 -3), due to different structural features.
