LD50 (rat) > 2.5 g/kg

Human plasma cell lines (LP1, KMS11, OPM2, H929) were used for activity evaluation. Plasma cells were cultured in 96-well plates at a density of 1.5 Ч 104 cells per well and treated with 0, 0.39, 0.78, 1.56, 3.12, 6.25, 12.5, and 25 μM of DHR (Dihydrorotenone). After 72-h incubation, tetrazolium (MTT) was added to each well to a final concentration of 5.0 mg/mL and incubated for 4 h. Formazan crystals resulting from MTT reduction were dissolved in 100 μL of sodium dodecyl sulfate (SDS) buffer (containing 10% SDS and 0.01 M HCl). The absorbance was detected at 570 and 650 nm using a plate reader (SpectraMax M5; Molecular Devices, Sunnyvale, CA). Relative viable cells were calculated from the difference of OD570 and OD650.