Fresh young stems of A. flava were collected from Bogor Botanical Garden in 2008. Fresh AFKR-18 fungus grown on PDA medium was inoculated into 500 mL Erlenmeyer flasks containing 200 mL of PDB medium. After still incubation at room temperature for 3 weeks, the medium and biomass were homogenized and extracted three times with ethyl acetate-methanol (4:1) in equal volume.

Plant material was collected in Yangling, Shaanxi province, China, in April 2011. All 28 isolated fungal strains (XC1-XC28) were fermented on solid rice medium. Toxicity of the fermented culture (20 µg/mL) against brine shrimp were assayed according to our previously reported protocol. The most toxic strain XC16 was selected to be cultivated on rice medium (40 g rice and 100 mL distilled water, sterilized under 121 °C for 30 min) in 200 Erlenmeyer flasks (500 mL each). The flask cultures were incubated under 28 °C for 3 weeks.