Neobaicalein, a flavonoid from the Scutellaria litwinowii Bornm. & Sint. ex Bornm. induced apoptosis in human leukemic cell lines

Objective(s): Neobaicalein is one of the rich plant flavonoids isolated from the roots of Scutellaria spp. In this study, we evaluated and compared cytotoxic activity and the related apoptosis mechanisms of neobaicalein from Scutellaria litwinowii Bornm. & Sint. ex Bornm on apoptosis-proficient HL-۶۰ cells and apoptosis-resistant K۵۶۲ cells. Materials and Methods: Cell viability, cell apoptosis, caspase activity, and apoptosis-related protein expression were measured using MTS assay, propidium iodide (PI) staining and flow cytometry, caspase activity assay, and western blot analysis, respectively. Results: Neobaicalein significantly reduced cell viability in a dose-dependent manner using the MTS assay (P<۰.۰۵). The IC۵۰ values (µM) against HL-۶۰ and K۵۶۲ cells after ۴۸ hr treatment were ۴۰.۵ and ۸۴.۸, respectively. Incubation of HL-۶۰ and K۵۶۲ cells with ۲۵, ۵۰, and ۱۰۰ µM neobaicalein for ۴۸ hr, significantly increased the number of apoptotic cells and showed cytotoxic effects compared with the control group. Treatment with neobaicalein significantly increased Fas (P<۰.۰۵) and the cleaved form of PARP (P<۰.۰۵), and decreased the Bcl-۲ levels (P<۰.۰۵) in HL-۶۰ cells, whereas neobaicalein significantly increased Bax (P<۰.۰۵) and the cleaved form of PARP (P<۰.۰۵), and the caspases of the extrinsic and intrinsic pathways including caspases-۸ (P<۰.۰۰۰۱), -۹ (P<۰.۰۱), and effector caspase-۳ (P<۰.۰۰۰۱) levels in K۵۶۲ cells compared with the control group.Conclusion: It seems neobaicalein might cause cytotoxicity and cell apoptosis through interaction with the different apoptosis-related proteins of apoptotic pathways in HL-۶۰ and K۵۶۲ cells. Neobaicalein may exert a beneficial protective effect in slowing the progression of hematological malignancies.

Keywords:

Apoptosis , Caspase , Neobaicalein , Poly (ADP-ribose) polymerase , Scutellaria litwinowii