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Fungi are a good source for lead molecules in drug discovery and development. However, many compounds derived from fungi were not evaluated for their bioactivity against economic, agricultural, and public health pests. Twelve fungal secondary metabolites (1-12) were evaluated for herbicidal activity against Silybum marianum and insecticidal activity against Culex pipiens larvae. Among the tested metabolites, brefeldin A (6) and 6-eopxy-4-hydroxy-3-methoxy-5-methyl-cyclohex-2-en-1-one (11) showed potent herbicidal activity against S. marianum with complete inhibition of seed germination at 500 mg L-1. Compound 6 revealed an exceptional herbicidal activity as it caused complete inhibition of root growth and strong reduction in shoot growth (I = 74.5%) and germination (10.0%) at 25 mg L-1. In addition, dehydroaustin (9), phomaxanthone A (4) and deacetylphomaxanthone A (5) displayed a potent toxicity against fourth larval instar of C. pipiens with LC50 values of 3.27, 57.03 and 63.50 mg L-1, respectively. Based on the results of this study, compounds 4-6, 9 and 11 should be developed as natural pesticides. [ABSTRACT FROM AUTHOR]