Kigamicin A

One new carbamothioic S-acid derivative (1) and five known kigamicin derivatives (2-6) were isolated from the fermentation extract of Amycolatopsis alba DSM 44262Δabm9 elicited by N-acetyl-D-glucosamine. HPLC-DAD-UV analyses indicated that the DSM 44262Δabm9 strain did not produce these metabolites originally and the production of 1-6 was induced by adding 25 mM N-acetyl-D-glucosamine in the culture medium. The structures of 1-6 were identified on the basis of NMR spectroscopic data and high-resolution ESIMS. These results highlight that addition of N-acetyl-D-glucosamine in the microbial culture medium could activate cryptic gene expression, induce and increase the production of new or known secondary metabolites.

The stereochemistry of kigamicins A (1), C (2) and D (3) were elucidated by a combination of X-ray crystallographic analysis and degradation studies. The absolute structures of kigamicins thus determined were depicted as shown in Fig. 2.

Background: Kigamicin (KGM) is a novel compound derived from Actinomycetes that was originally reported to induce necrosis in pancreatic cancer cells only under nutrient-starved conditions via inhibition of PI3-kinase. The effects of KGM on myeloma cells were investigated. Materials and methods: Cytotoxic activity was quantified using WST8 assay. Necrosis was determined by Annexin V/PI staining. Regulatory protein levels were assessed by Western blot. LY294002 was utilized as a PI3-kinase inhibitor. Results: KGM induced necrosis in myeloma cells in nutrient rich conditions with a CC50 of approximately 100 nM. KGM did not induce necrosis in normal lymphocytes. Cyclin D1, p21, p-AKT and p-ERK were inhibited by KGM while LY294002 did not inhibit cell death by KGM. A melphalan-resistant myeloma cell line was more susceptible to KGM than the melphalan-sensitive parental cell line. Conclusion: KGM-induced necrosis in myeloma cells even at very low concentration. The present data warrant further investigation into the use of KGM as a potential therapeutic agent for multiple myeloma.