NIDULAL, A NOVEL INDUCER OF DIFFERENTIATION OF HUMAN PROMYELOCYTIC LEUKEMIA-CELLS FROM NIDULA-CANDIDA

Nidulal (1), a novel inducer of differentiation of human HL-60 promyel ocytic leukemia cells, was isolated from fermentations of the basidiom ycete Nidula candida together with low amounts of niduloic acid (2). B oth compounds are bisabolane sesquiterpenes. Their structures were elu cidated by spectroscopic methods. In reporter gene assays nidulal (1) preferentially activated the transcription factor complex AP-1-mediate d expression of secreted alkaline phosphatase in COS-7 cells. In addit ion nidulal (1) and niduloic acid (2) exhibited weak cytotoxic and ant ibiotic activities.