Inhibition of proliferation of human carcinoma cell lines by phenolic compounds from a bearberry-leaf crude extract and its fractions

► We examine the effect of bearberry-leaf phytochemicals against human cancer cell lines. ► Bearberry-leaf phenolics can inhibit tumor cell proliferation. ► The tannin fraction of the bearberry-leaf extract seems most potent. ► Gallotannins were isolated from the bearberry-leaf extract and their structures elucidated.