Optimization, purification and characterization of α-glucosidase inhibitors from Streptomyces costaricanus EBL.HB6 isolated in Vietnam

Abstract BackgroundDiabetes, a disease that has been a great burden of the treatment cost for patients and society. There are many drugs have been used to cure this disease available on the pharmaceutical market. One of the most prevalent source to produce these compounds are microorganism. Among them, Streptomyces sp. are popular microorganisms used for the production of α-glucosidase inhibitors (AGIs). Methods and ResultsIn this study, different cultivation conditions were optimized to enhance the production of AGIs. Purification and evaluation of AGIs from S. costaricanus EBL.HB6 were also performed. Our results demonstrated that Streptomyces costaricanus EBL.HB6 had the highest α-glucosidase inhibitory activity among 6 Streptomyces sp. strains were isolated in Vietnam. The 16S rRNA sequencing of isolating HBC6-2 indicated 99% identity to the corresponding sequence of Streptomyces costaricanus, and was registered on GenBank with the code MT 453944.1. Streptomyces costaricanus EBL.HB6 was able to produce melanin yellow pigment, and its aerial and substrate mycelia have brown and yellow-grey pigment on ISP2 cultivating medium, respectively. The α-glucosidase inhibitory activity of the supernatant was increased by a factor of 1.2 under optimal conditions (media containing 1.5% glucose, 1.2% yeast extract at 28°C, initial pH of 6.5, and culture time for 120 h) in comparison with the initial media and condition. The purified efficacy of a-glucosidase inhibitors was 5% with a retention factor of 0.71 on thin-layer chromatography and IC50 value of 9.59 mg/mL.ConclusionsStreptomyces costaricanus EBL.HB6 strain was selected, purified and evaluated for its highly producible of α-glucosidase inhibitors.