Butyrolactone II is a butenolide fungal metabolite that has been found in A. terreus.1 It scavenges 2,2-diphenyl-1-picrylhydrazyl and ABTS free radicals (EC50s = 11.5 and 68.5 μM, respectively). It inhibits 5-lipoxygenase (5-LO; IC50 = 21.43 μg/ml) and α-glucosidase (IC50 = 0.126 mM).2,3

|1. Kang, H.-S., and Kim, J.-P. Butenolide derivatives from the fungus Aspergillus terreus and their radical scavenging activity and protective activity against glutamate-induced excitotoxicity. J. Appl. Biol. Chem. 62:43, (2019).|2. Wang, F.-S., Ke, A.-B., Zhu, J.-T., et al. Butyrolactones, inhibitors of 5-lipoxygenase from fungal metabolites. J. Chin. Pharma. Sci. 19(4), 251-255 (2010).|3. Zhang, L.-H., Feng, B.-M., Zhao, Y.-Q., et al. Polyketide butenolide, diphenyl ether, and benzophenone derivatives from the fungus Aspergillus flavipes PJ03-11. Bioorg. Med. Chem. Lett. 26(2), 346-350 (2016).