Abstract: Six compounds (1-6) were obtained by using Diaion HP-20 column,silica gel column,Sephadex LH-20 column and semi-preparative HPLC during the further investigation on the chemical constituents of the soil fungus Curvularia affinis HS-FG-196.Their structures were determined on the basis of spectroscopic analysis,including ¹H NMR,¹³C NMR,¹H-¹HCOSY,HMQC and HMBC,as well as HR-TOF-MS and compared with the data reported in the literature.Pyrenocine S (1) was a new compound and the 5 known compounds were identified to be pyrenocine B (2),pyrenocine E (3),pyrenocine I (4),pyrenochaetic acid B (5) and pyrenochaetic acid C (6).The cytotoxicity of these compounds was assayed in vitro against the human tumor cells A549,HCT-116,ACHN,K562 and HepG2.As a result,compounds 1,2,3 showed strong cytotoxic activity and the remaining three compounds showed weak activity.

Key words: soil fungus, secondary metabolites, pyrenocines, pyrenochaetic acids, cytotoxic activity