Apoptosis-inducing activity of galloylglucoses from Juglans mandshurica in human promyeloid leukemic HL-60 cells

Abstract

Two galloyl monosaccharides, 1,2,6-trigalloylglucose (1, TRgG) and 1,2,3,6-tetragalloylglucose (2, TEgG), were isolated from the stem-bark of Juglans mandshurica. Two galloylglucoses showed cytotoxic effects on human promyelocytic leukemia HL-60 cells. In order to elucidate their mechanism of action, we have investigated the flow cytometric analysis after Annexin V-FITC and PI staining, caspase-3 activity, and internucleosomal DNA fragmentation in HL-60 cells. HL-60 cells treated with both compounds 1 and 2 at 150 and 100 μM, respectively, led to a morphological features of apoptosis, such as plasma membrane blebbing and cell shrinkage. TRgG (1) and TEgG (2) increased the percentage of FITC+ and FITC+PI+ cells in flow cytometry after Annexin V-FITC and PI staining. The increase of apoptotic cells was preceded by the activation of caspase-3 reported to play a central role in apoptotic process and inducing internucleosomal DNA fragmentation. TEgG (2) showed to have stronger apoptosis inducing activity in HL-60 cell lines as compared with TRgG (1).