Chaetoviridin A, an azaphilone isolated from Chaetomium globosum, is characterized as 6H-furo[2,3-h]isochromene-6,8(6aH)-dione with substitutions including a chloro group at position 5, a 3-hydroxy-2-methylbutanoyl group at position 9, a methyl group at position 6a, and a 3-methylpent-1-en-1yl group at position 3. It exhibits antifungal activity against plant pathogenic fungi.