Identification of a Novel Antibiotic from Myxobacterium Stigmatella Eracta WXNXJ-B and Evaluation of its Antitumor Effects I n - vitro.

This work was to isolate and identify the bioactive secondary metabolite which was produced by myxobacterium Stigmatella eracta WXNXJ-B, and to evaluate its antitumor and apoptosis-inducing effects. The results showed that one novel compound (molecular formula C29H25NO3) was isolated, purified by Sephadex LH-20 column chromatography and preparative RP-HPLC, and identified as 5-(6-benzyl-quinolin-3-ylmethyl)-6- phenyl-3,7-dioxa- bicycle [4.1.0] heptan-3-one (named as quinoxalone) according to its UV, IR, HRMS and NMR spectra. The compound showed strong antitumor activity on B16, HepG2, MCF-7, SGC-7901, MDA-MB231 and CT-26 six tumor cell lines in-vitro. Nevertheless, it showed less cytotoxic to the mouse normal spleen cells (IC50 was 836.27 ± 13.02 µg mL(-1)). The cytotoxic study on HepG2 cells in-vitro showed that quinoxalone could induce the change of cell nuclear and arrested the cell division in the S and G2/M phase. Our results suggest that quinoxalone could be a potential anti-cancer agent.