Lactiplantibacillus plantarum I-UL4 produces various postbiotic metabolites with known anticancer and antioxidant activities, but its anti-inflammatory effect remains unclear. In this study, we compared postbiotic metabolites produced by L. plantarum I-UL4 with commercial de Man, Rogosa and Sharpe (MRS) medium (PMM) and a reported refined formulation (PMF) for their volatile compound profiles, cytotoxicity, antioxidant and anti-inflammatory effects on LPS-stimulated THP-1 leukaemia cells.