Changes in amino acid pool and utilization during apoptosis in HL-60 cellsinduced by epigallocatechin gallate or gallic acid

Recent studies have demonstrated the apoptosis-inducing potential of epigal locatechin gallate (EGCG), a major component of green tea, against various cultured cell lines. By using an amino acid analyzer, we investigated here the possible changes in the amino acid pool and utilization during the apop tosis of HL-60 cells induced by EGCG or gallic acid, a structural unit of t annin. Sublethal concentrations of EGCG initially elevated and then reduced the intracellular concentrations of most of amino acids except for glutami c acid and aspartic acid, whereas lethal concentrations of EGCG continuousl y reduced these amino acid pools during 6 hours. Both sublethal and lethal concentrations of gallic acid initially elevated and then reduced these ami no acid pools. Both inducers elevated the intracellular accumulation and pr oduction of arginine and extensively reduced the utilization of other amino acids. These data demonstrate that EGCG showed more severe effects on the amino acid pool and utilization than gallic acid, which may explain, at lea st in part, the difference in apoptosis-inducing potential between these in ducers.