Investigation of the antifungal effects of algal extracts on apple-infecting fungi.

It is known that cell extracts of various algae have antifungal activity against microorganisms in vitro. Antifungal activities of Ulva lactuca, Chlorella vulgaris, Chlorella minutissima, and Chlorella protothecoides were investigated against: Aspergillus niger, Alternaria alternata, and Penicillium expansum fungi to present their fungicide potentials. Aspergillus niger, Alternaria sp., and Penicillium expansum are typical soft-rotting fungi and cause important loss of apple fruit in the storage. In vitro antifungal activity was evaluated by agar disc diffusion assay against pathogenic apple rot fungi. As a result, almost all of the extracts obtained from algae species were revealed to have antifungal activity against selected fungal pathogens. Free radical-scavenging activity of the extracts was determined with 1,1-diphenyl-2 picryl hydrazyl (DPPH) free radical-scavenging method. Extract of C. protothecoides was determined to have a stronger antioxidant activity than other algae extracts. This study reveals that the potential of algae should be investigated for the production of natural fungicide for pharmaceutical and food industries.