Evaluation of Culture Media for Butyrolactone I Production by Aspergillus terreus LS07 as Antidiabetic

Butyrolactone I (BL-I) has been reported as inhibitor of α-glucosidase and antioxidant compound isolated from culture broth of Aspergillus terreus. The purpose of this study was to determine the effect of various liquid media compositions on production of BL-I from A. terreus LS07. Fermentation was conducted in four liquid medium: potato dextrose broth (PDB), potato malt peptone (PMP), malt extract (ME), and Czapek-Dox broth (CDB), which were incubated for seven days at room temperature, with agitation of 70 rpm. Ethyl acetate (EtOAc) was used to extract the active metabolite from each broth. Glucosidase inhibitory activity was measured by the inhibition of yeast α-glucosidase, while antioxidants measured by testing the total phenol and DPPH free radical scavenger activity. The results showed that the EtOAc extract on CDB had strong inhibition activity against the enzyme α-glucosidase and strong antioxidant with IC50 values 6.45 and 24.05 μg/mL, respectively. The CDB extract also showed the highest content of total phenols (349.66 mg Gallic Acid Equivalent (GAE)/g extract) and BL-I (58.5% w/w). Based on these results, among the four kinds of medium used, Czapek-Dox broth is an ideal culture medium of A. terreus LS07 that could be applied for increase production of BL-I as natural antidiabetic source from terestrial fungi