Growth inhibition and apoptosis induction by Scutellaria pinnatifida A. Ham. on HL-60 and K562 leukemic cell lines

• Scutellaria pinnatifida A. Ham. (Lamiaceae) is a herb that is used in traditional medicine of eastern countries.
• Wogonin and neobicalein are flavonoids that are isolated from S. pinnatifida.
• Among different extracts of the plant CH2Cl2 extract is the most cytotoxic extract on the K562 and HL-60 cell line.
• Apoptosis is a possible mechanism of plant cytotoxicity.

A rich flavonoid plant extensively used in traditional medicine is Scutellaria (Lamiaceae). In this study the cytotoxic effects of different extracts of Scutellaria pinnatifida were explored on two different cancer cell lines including K562 and HL-60 and a normal cell line. Also, the role of apoptosis on this toxicity was explored. The cell viability was quantitated by alamarBlue® assay. S. pinnatifida could effectively decrease the viability of malignant cells and the CH2Cl2 extract of S. pinnatifida had showed the most cytotoxic effects among other extracts. Apoptosis was confirmed after propidium iodide staining of DNA fragments and detection of the sub-G1 peak in the related flow cytometry histogram of cells. The results of western blot assay showed that CH2Cl2 extract has been able to increase the amount of Bax and cleavage of PARP protein after a 48 h contact with cells. Neobaicalein (skullcapflavone II) and wogonin were identified in the extract of S. pinnatifida as the active components. The result of the present study confirmed the putative role of neobaicalein (skullcapflavone II) and wogonin as cytotoxic components in the CH2Cl2 extract of S. pinnatifida.