Tzu Hsuan Chen

Antitumor Agents. 280. Multidrug Resistance-Selective Desmosdumotin B Analogues

6,6,8-Triethyldesmosdumotin B (2) was discovered as a MDR-selective flavonoid with significant in vitro anticancer activity against a multidrug resistant (MDR) cell line (KB-VIN) but without activity against the parent cells (KB). Additional 2 analogues were synthesized and evaluated to determine the effect of B-ring modifications on MDR-selectivity. Analogues with a B-ring Me (3) or Et (4) group had substantially increased MDR selectivity. Three new disubstituted analogues, 35, 37, and 49, also had high collateral sensitivity (CS) indices of 273, 250, and 100, respectively. Furthermore, 2-4 also displayed MDR selectivity in an MDR hepatoma-cell system. While 2-4 showed either no or very weak inhibition of cellular P-glycoprotein (P-gp) activity, they either activated or inhibited the actions of the first generation P-gp inhibitors verapamil or cyclosporin, respectively.

Altaicalarins A-D, cytotoxic bisabolane sesquiterpenes from Ligularia altaica.

Four new bisabolane sesquiterpenes, altaicalarins A-D (1-4), and three known analogues (5-7) were isolated from the roots and rhizomes of Ligularia altaica. The structures were elucidated by spectroscopic methods including 2D NMR techniques, and the structure of 1 was confirmed by single-crystal X-ray diffraction. The isolated compounds were also evaluated for cytotoxic activity against human lung carcinoma (A-549), human breast adenocarcinoma (MCF-7), epidermoid carcinoma of the nasopharynx (KB), and vincristine-resistant nasopharyngeal (KBVIN) cell lines, and 1 was found to show significant cytotoxicity, with EC(50) values of 3.4, 0.8, 1.0, and 0.9 microg/mL, respectively.

Songaricalarins A–E, Cytotoxic Oplopane Sesquiterpenes from Ligularia songarica

Five new highly oxygenated oplopane sesquiterpenes, songaricalarins A-E (1-5), and two known analogues (6 and 7) were isolated from the roots and rhizomes of Ligularia songarica. Their structures and configurations were elucidated by spectroscopic methods, including 2D-NMR techniques, and the structure of 1 was confirmed by single-crystal X-ray diffraction. All compounds were evaluated for in vitro cytotoxic activity against cultured A-549, MCF-7, KB, and KBVIN cells, and 4 exhibited cytotoxicity with EC50 values of 4.9, 0.8, 3.4, and 3.2 μg/mL, respectively.