Gabosines P and Q, new carbasugars from Streptomyces sp and their α-glucosidase inhibitory activity

Two new polyoxygenated cyclohexenone 'ketocarbasugars', named gabosines P and Q (1 and 2), were isolated from the culture of the actinomycete Streptomycetes strain no. 8, along with two known cyclic dipeptides. The structures and absolute configurations of the new metabolites were determined by spectroscopic data (1D- and 2D-NMR, HR-ESI-MS, and IR), chemical transformation, and electronic circular dichroism (ECD). These compounds were evaluated for a-glucosidase inhibitory activity in vitro. Only compound 1 exhibited IC50 values of 9.07 mu M, with potency higher than that of the control acarbose. Molecular docking studies revealed the existence of hydrogen bonding and hydrophobic interaction between the enzyme and gabosine P. The results will be useful in designing new anti-diabetes control agents. (C) 2016 Elsevier Ltd. All rights reserved.