Three new 4-quinolinone metabolites were isolated from Pseudomonas cepacia PC II, along with the known 2-(2-heptenyl)-3-methyl-4-quinolinone (HMQ) and 3-methyl-2-(2-nonenyl)-4-quinolinone, and their structures were established as 3-methyl-2-pentyl-4-quinolinone, 2-heptyl-3-methyl-4-quinolinone and 3-methyl-2-nonyl-4-quinolinone. HMQ showed antifungal and red pepper growth promoting activities.