In vitro antifungal effect of plant-based and Ulva sp. extracts on Aspergillus flavus growth and conidia germination

Mycotoxins in cereals, particularly maize, pose a significant threat to agriculture, worsened by climate change. Therefore, developing effective mitigation strategies are urgently claimed. Plant waste and seaweed extracts offer promising sources of phytochemicals for combating fungal plant pathogens. This study investigated the in vitro antifungal potential and polyphenol composition of hydroalcoholic extracts from plant waste materials and seaweed ( Ailanthus altissima (Mill.) Swingle leaves, Humulus lupulus L. trub, Olea europaea L. leaves and Ulva sp. thallus). With the exception of O. europaea , all extracts inhibited Aspergillus flavus growth, with Ulva sp. showing the highest efficacy (EC ₅₀  = 14.2 mg/mL). Analysis revealed enrichment in glycosylated flavonols and hydroxycinnamic acids across extracts, while Ulva sp. specifically contained rosmarinic acid, p -hydroxybenzoic acid, and uronic acid and sulfate groups, characteristics of ulvan polysaccharides. These results suggest Ulva biomass is a promising botanical source for Aspergillus flavus biocontrol, paving the way for its future application in agriculture and post-harvest systems.