Isolation of streptonigrin and its novel derivative from Micromonospora as inducing agents of p53-dependent cell apoptosis

Streptonigrin (1) and its novel natural derivative 7-(1-methyl-2-oxopropyl)streptonigrin (2) were isolated from an actinomycete strain, Micromonospora sp. IM 2670. The inductions for 1 and 2 are more potent in the human neuroblastoma SH-SY5Y cells that contain wild-type p53 than in SH-SY5Y-5.6 cells that overexpress a dominant negative mutant of p53, thus suggesting that they induce apoptosis through a p53-dependent pathway.