Abstract: In this study, the cell-free excretory supernatants (CFS) and cell-free extracts (CFE) of 13 Lactobacillus strains deposited in the laboratory were evaluated for α-glucosidase and dipeptidyl peptidase IV inhibitory activities. Then probiotic characteristics of the strains with higher enzyme inhibitory activities were assessed. The results showed that the CFS of the 13 strains had different α-glucosidase inhibitory activities, with inhibition rates of 0%–12.13%, while none of the CFE possessed α-glucosidase inhibitory activities. The inhibition rates of DPP-IV with the CFS and CFE of all strains were 0%–7.13% and 0%–55.42%, respectively. L. acidophilus KLDS1.1003, KLDS1.0901 and KLDS1.0902, with higher enzyme inhibitory activities, were selected to determine their probiotic properties. Among them, L. acidophilus KLDS1.0901 showed the highest acid tolerance, and L. acidophilus KLDS1.1003 showed the highest bile salt tolerance and hydrophobicity. Principal component analysis (PCA) showed that L. acidophilus KLDS1.1003 had the best comprehensive performance: its α-glucosidase inhibitory activity was 10.29%; DPP-IV inhibitory activity was 7.13% and 50.14% for its CFS and CFE, respectively; the survival rate was 51.55% after incubation for 1 h at pH 2.0; under 0.3% bile salt conditions, the lag time was 2.26 h; the hydrophobicity rates in xylene, ethyl acetate and chloroform were 134.33%, 20.51% and 344.08% respectively. Overall, L. acidophilus KLDS1.1003 had high enzyme inhibitory activity and good probiotic properties.

Key words: Lactobacillus, α-glucosidase, dipeptidyl peptidase IV, inhibition, diabetes