Paenibacillin A, a new 2(1H)-pyrazinone ring-containing natural product from the endophytic bacterium Paenibacillus sp. Xy-2.

A new 2(1H)-pyrazinone ring-containing natural product, paenibacillin A (1), together with five known diketopiperazine derivatives 2-6 and two known isoflavones 7-8, was isolated from the culture of an endophytic bacterium Paenibacillus sp. Xy-2. The structure of compound 1 was elucidated by extensive spectral methods, including UV, IR, HR-ESI-MS, 1D and 2D NMR and ECD experiments. Compound 1 exhibited moderate cytotoxicity against HL-60 cell line with IC50 value of 50.48 μM.