Bioactive dihydroagarofuran sesquiterpenes from the twigs of Tripterygium hypoglaucum

Thirteen undescribed dihydroagarofuran sesquiterpenes, hypogricins A-M, were isolated from the twigs of Tripterygium hypoglaucum. Extensive spectroscopic techniques were used for the structural elucidation of these compounds. All the compounds showed no significant cytotoxicity against adriamycin-sensitive HepG-2 and adriamycin-resistant HepG-2/Adr cell lines. When HepG-2/Adr cell line was co-treated with those compounds plus adriamycin, hypogricins A and B showed potent activity to reverse multidrug resistance (MDR) of HepG2/Adr cells to adriamycin (reversal fold: RF = 102 and 200, respectively). In addition, hypogricins E, H, and L showed moderate activity to inhibit NO production in LPS-stimulated RAW264.7 cells with the IC50 of 22.3, 17.8, and 19.8 μM, respectively.