STUDY OF IRIDACEAE PLANTS WITH THE CAPABILITY TO INDUCE DIFFERENTIATION OF HL-60 PROMYELOCYTIC LEUKEMIA-CELLS

Thirteen species of Iridaceae plants were studied with the capability to induce HL-60 promyelocytic leukemia cells into macrophages. The neutrophil stimulating activity in these plants was also examined by measuring superoxide production. Both activities are known to be possessed by tumor promoters such as 12-O-tetradecanoylphorbol-13-acetate (TPA). Dried parts of Iridaceae plants were extracted with methanol. Then, each extract was added to a culture medium of HL-60 cells and cultured for two days. A morphological change of the cells from suspended to adherent state, which was reported to occur in the process of differentiation, was observed. Nine species, most of which belong to the Iris genus, had the activity to cause cell adhesion. Each of the cell adhesion-positive extract was applied to a silica gel column and eluted with chloroform, ethyl acetate and methanol in order. The activity was recovered only in the ethyl acetate eluate in all the cases. Those partially purified fractions also activated superoxide generation of neutrophils. When ethyl acetate fractions of Iris tectorum and Iris japonica were analyzed by HPLC, three active peaks different from TPA and teleocidins in UV spectra were detected. From these results, it was suggested that several plants of Iridaceae may contain TPA-type and yet structurally-different tumor promoters.