Novel antifungal and antibacterial activities of newly synthesized phytochemical coumarin [H 2 L 1 , HL 2 and H 2 L 3 ] and their copper (II) complexes [L 1 Cu], [L 2 Cu(OAc)] and [(L 3 )Cu 2 (H 2 O) 4 (OAc) 2 ] were evaluated against nine pathogenic fungal species (Alternaria alternata, Aspergillus flavus, Botrytis cinerea, Cladosporium herbarum, Fusarium moniliforme, Helminthosporium tetramera, Penicillium expansum, Rhizopus stolonifer and Verticillium albo-atrum) and eight pathogenic bacterial species, four Gram-positive bacteria (Staphylococcus citrus, Streptococcus pneumoniae, Bacillus subtilis and Micrococcus luteus) and four Gram-negative bacteria (Enterobacter aerogenes, Escherichia coli, Pseudomonas aeruginosa and Salmonella typhi). The phytochemical copper (II) complex [L 2 Cu(OAc)] was the most effective derivative, where it reaches to 90 and 100% inhibition in the most sensitive pathogens (B. subtilis and A. flavus), respectively, accompanied with a significant reduction in pectinolytic and cellulytic enzyme activities in all tested pathogenic species. Addition of [L 2 Cu(OAc)] complex leading to leakage of sugars and electrolytes from the most sensitive microbial cells accompanied with collapsed hyphae of A. flavus and membrane blobbing of B. subtilis. The production of mycotoxins decreased with the extension exposure to [L 2 Cu(OAc)] complex reaching to a minimum values for the mycelium originating from the inoculum exposed to the minimum inhibitory concentration (2%). Both aflatoxin (AFB 1 ) and citrinin were the most sensitive toxins.