Biosynthesis of methyl glucoside and its antibacterial activity against Staphylococcus aureus and Escherichia coli

In this study, the methyl glucosides (MGn) was synthesized using β-cyclodextrin (β-CD) and methanol through the coupling reaction of recombinant cyclodextrin glycosyltransferase (CGTase) from Bacillus circulans A11. The optimal condition for the synthesis of MGn consisted of an incubation of 1.5% (w/v) β-CD and 500 U/mL of CGTase in a water/methanol solution containing 30% (v/v) methanol at pH 6.0, 50 °C for 120 h. Upon analysis by TLC, at least three MG products were observed. The molecular weight of the main transferred product was 217.08 Da; this value was in accordance with methyl monoglucoside (MG1). MG1 was produced and prepared on a large scale and subsequently purified by preparative TLC. The combined 1H- and 13C-NMR analysis confirmed that the structure of MG1 was methyl-α-d-glucopyranoside. In addition, MG1 showed emulsification activity and stability in its formation in water and n-hexadecane. The antibacterial activity of MG1 was also determined by agar disc diffusion method. The results found that the MG1 (1, 5 and 10 mg/disc) showed antibacterial activity against E. coli ATCC 25922 only, with inhibition zones of 28, 38 and 40 mm, respectively. The MIC values (mg/mL) of MG1 against S. aureus ATCC 25923 and E. coli ATCC 25922 were found to be 20.00 and 0.63, while MBC values (mg/mL) were 40.00 and 0.63, respectively.Graphical abstract
Source: Bioactive Carbohydrates and Dietary Fibre - Category: Food Science Source Type: research