Many plants have devised methods of protecting themselves; one of such methods is the use of endophytic fungi. The antagonistic mechanism by endophytic fungi has rarely been revealed. This study investigated Chaetomium cupreum from Macleaya cordata (Willd.) R.Br Herb, which was identified by analysis of morphological characteristics and 28S rDNA sequence. The crystal isolated from culture broth of C. cupreum was identified by X-ray single crystal diffraction as 3,3',6,6'-tetrahydroxy-4,4'- dimethyl-1,1'-bi(cyclohexa-3,6-diene)-2,2',5,5'-tetraone (abbreviated as oosporein). We demonstrated that oosporein had antifungal activity against Rhizoctonia solani, Botrytis cinerea, Pytium ultimum, and antitumor activities against HL-60 and A549. It is toxic to Artemia salina.Keywords: Chaetomium cupreum, toxicity, antifungal activity, oosporein, antitumorAfrican Journal of Biotechnology Vol. 9(36), pp. 5955-5961, 6 September, 201
