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 α-glucosidase inhibitory activity in vitro. Only compound 1 exhibited IC