Inhibition of Sucrose-Dependent Biofilm Formation by α-Glucosidase Inhibitors

Introduction: Acarbose, an α-glucosidase inhibitor, used to treat type II diabetes, has been shown to inhibit glucosytransferase activity and sucrose-dependent biofilm formation by mutans streptococci (MS). Therefore, it has potential as a “mutans-specific” anti-plaque anti-caries agent. Other, α-glucosidase inhibitors, including proprietary drugs and herbal extracts used to treat type II diabetes, may also be potent inhibitors of glucosyltransfrease activity and sucrose-dependent biofilm formation by MS. Voglibose (Basen™) has an inhibitory concentration fifty (_IC50) for intestinal sucrase that is ~100X lower than acarbose. Extracts of Salacia oblonga and S. reticulata, woody shrubs, have been used for centuries in Ayurvedic medicine for treatment of type II diabetes. Recently these extracts have been found to contain, salacinol and kotalanol, two novel compounds that inhibit intestinal α-glucosidase activity.

Objective: To determine if voglibose and Salacia extract (tea) inhibit sucrose-dependent biofilm formation by MS in a manner similar to that reported for acarbose.

Methods: S. mutans ATCC 25175 biofilms were formed on polystyrene tubes by culture in BHI-0.3% sucrose broth with and without the test compounds. Biofilm formation was quantified by crystal violet staining. In brief, non-adherent bacteria were removed by pouring and washing the tubes with distilled water, biofilms adhered to the sides of the tubes, were stained with crystal violet, dried, and decolorized by addition of ethanol containing 3% hydrochloric acid. The absorbance (OD₅₆₀) of the decolorization solution was then measured to determined biofilm mass.

Results: Voglibose (100 mM) inhibited MS sucrose-dependent biofilm formation by ~93%, but 25 mM and 50 mM voglibose had no effect. Salacia extract (1/100) inhibited MS sucrose-dependent biofilm formation by ~71%, but 1/250 and 1/500 dilutions had no effect.

Conclusion: Voglibose and Salacia extract inhibit sucrose-dependent biofilm formation by MS, similar to acarbose, and have potential as anti-plaque anti-caries agents.

Supported by: COHORT Training Grant NIH-NIDCR T32 DE07306