Secondary metabolites such as mycotoxins can be produced by fungi on agricultural commodities in the field. These fungi can colonize medicinal plants, such as Catharanthus roseus. On the PDA medium, 18 isolates of exophytic and endophytic fungi isolated from C. roseus, including Aspergillus, Penicillium, and Talaromyces species, were tested for mycotoxin production. Thin layer chromatography indicated the formation of six mycotoxins from six isolates, including aflatoxin G1, aflatoxin B1, sterigmatocystin, citrinin, aflatoxin B2, and penicillic acid. To measure the impact of C. roseus leaf extract on the generation of fungal mycotoxin, toxic isolates were cultivated on a PDA medium supplemented with the leaf extract. It was discovered that enriched PDA media could enhance the formation of certain mycotoxins. Toxicity tests were performed on brine shrimp larvae Artemia salina for fungal mycotoxin extraction and C. roseus leaf extraction. Selected fungal extracts at 10 μg/ml were also harmful to brine shrimp larvae, while leaf extracts at 6.25-200 μg/ml were very toxic.