Search National Agricultural Library Digital Collections
Back to Search
NALDC Record Details:
Thielavins A, J and K: alpha-glucosidase inhibitors from MEXU 27095, an endophytic fungus from Hintonia latiflora
Bioassay-guided fractionation of the bio-active organic extract obtained from solid-media culture of MEXU 27095, an endophytic fungus isolated from the Mexican medicinal plant Hintonia latiflora (Rubiaceae), led to separation of three tridepsides which were identified as thielavins A, J and K. All three compounds inhibited Saccharomyces cerevisieae a-glucosidase (aGHY) in a concentration-dependent manner with IC50 values of 23.8, 15.8, and 22.1 lM, respectively. Their inhibitory action was higher than that of acarbose (IC50 = 545 lM), used as a positive control. Kinetic analysis established that the three compounds acted as non-competitive inhibitors with ki values of 27.8, 66.2 and 55.4 lM, respectively (a = 1.0, 1.2, 0.7, respectively); acarbose behaved as competitive inhibitor with a ki value of 156.1 lM. Thielavin J inhibited the activity of a-glucosidase from Bacillus stearothermophilus (aGHBs) with an IC50 of 30.5 lM, being less active than acarbose (IC50 = 0. 015 lM); in this case, compound (2) (ki = 20.0 lM and a = 2.9) and acarbose (ki = 0.008 lM and a = 1.9) behaved as non-competitive inhibitors. Docking analysis predicted that all three thielavins and acarbose bind to homologated aGHBs and to aGHY (PDB: 3A4A) in a pocket close to the catalytic site for maltose and isomaltose, respectively. The a-glucosidase inhibitory properties of thielavin K (3) were corroborated in vivo since it induced a noted antihyperglycemic action during an oral sucrose tolerance test (3.1, 10.0 and 31.6 mg/kg) in normal and nicotinamide–streptozotocin diabetic mice. In addition, at a dose of 10 mg/kg, it provoked a moderate hypoglycemic activity in diabetic mice.
Anthony E Glenn
inhibitory concentration 50
Phytochemistry 2013 v.94
Journal Articles, USDA Authors, Peer-Reviewed
Download [PDF File]
Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.
Agricultural Research Service
Web Policies and Important Links