Aim of this study: Within the genus Scutellaria various species are used in different folk medicines throughout Asia. Traditional Chinese Medicine (TCM) uses S. baicalensis (Labiatae) to treat various inflammatory conditions. The root shows strong anticancer properties in vitro and was suggested for clinical trials against multiple myeloma. Further, S. barbata was successfully tested against metastatic breast cancer in a phase I/II trial. Therefore, we investigated the anti-cancer properties of S. orientalis L. ssp. carica Edmondson, an endemic subspecies from the traditional medicinal plant S. orientalis L. in Turkey, which is used to promote wound healing and to stop haemorrhage.
Materials and methods: Freeze-dried plant material was extracted with petroleum ether, dichloromethane, ethyl acetate, and methanol and the bioactivity of these extracts was analysed by proliferation assay, cell death determination, and by investigating protein expression profiles specific for cell cycle arrest and apoptosis.
Results: The strongest anti-leukemic activity was shown by the methanol extract, which contained apigenin, baicalein, chrysin, luteolin and wogonin, with an IpC50 of 43 microg/ml (corresponding to 1.3mg/ml of dried plant material) which correlated with cyclin D1- and Cdc25A suppression and p21 induction. At 132 microg/ml (=4 mg/ml of the drug) this extract caused genotoxic stress indicated by substantial phosphorylation of the core histone H2AX (gamma-H2AX) followed by activation of caspase 3 and signature-type cleavage of PARP resulting in a 55% apoptosis rate after 48 hours of treatment.
Conclusions: Here, we report for the first time that S. orientalis L. ssp. carica Edmondson exhibited potent anti-leukaemic properties likely through the anti-proliferative effect of baicalein and the genotoxic property of wogonin.