Induction of differentiation and anti-proliferative effects of aqueous extract from the bark of Quercus infectoria in the human promyelocytic leukemia HL-60 cells

Quercus infectoria is a widely distributed tree known for its potential use in alternative medicine. Quercus infectoria galls exhibit astringent, anti-inflammatory [1], antiviral [2], antidiabetic [3], larvicidal [4], antibacterial [5–10], antiulcerogenic and gastroprotective activities [11]. The cytotoxic activity of the aqueous extract of the Quercus infectoria bark was examined by evaluating its effect on the induction of differentiation and inhibition of proliferation of the human promyelocytic leukemia HL-60 cells. The anti-proliferative effect of the extract was evaluated by MTT-assay and mRNA expression of transforming growth factors (TGF-alpha, TGF-beta1 and TGF-beta2) using RT-PCR at 48, 72 and 96 hrs. In parallel, the differentiation effect of various doses (25–500µg/ml) of the extract was measured by NBT (nitroblue tetrazolium) reduction assay at 48, 72 and 96 hrs. The degree of differentiation was assayed by the ability of cells to reduce NBT to insoluble blue-black formazan on stimulation by PMA (phorbol 12-myristate 13 acetate). Treatment of HL-60 cells with 50µg/ml of the extract for 96 hrs caused 50% inhibition of cell proliferation, while 500µg/ml dose produced more than 95% effect. Also Quercus infectoria produced significant increase in number of differentiated HL-60 cells when treated for 96 hrs: concentrations of 50 and 200µg/ml of the extract induced the differentiation of 18 and 83% of HL-60at 72 hrs, and 101 and 196% of HL-60 after treatment for 96 hrs. The results of this study show that the Quercus infectoria bark aqueous extract possesses anti-proliferative effects and stimulates differentiation of HL-60 cells.

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