Multivalently presented carbohydrates can be used as drug delivery vehicles and to study protein carbohydrate interactions

Abstract

Dendrimers in general excel as drug delivery vehicles since there are many different ways they can be assembled and different ways to tailor them to the system being studied. Glycodendrimers are generally nontoxic and can be further developed to meet the needs of what is being studied. For instance, in the studies below, a quaternity ammonium compound (QAC) has been attached to a glycodendrimer to determine the antimicrobial activity of a multivalently presented QAC in studies of minimum inhibitory concentration (MIC), biofilm prevention, and bacterial resistance. Results include comparable MICs to those of established antibiotics, prevention of biofilm formation but not disruption of an established biofilm, and establishment of multivalency as a strategy to counteract bacterial resistance. Another heterogeneously functionalized dendrimer was synthesized to study drug release characteristics of a prodrug attached to a cleavable substrate. In these studies, the upregulation of several proteins during cancer progression was taken advantage of including; MMP-2, -7, -9, and galectin-3. Glycodendrimers are tools used to study protein carbohydrate interactions. Study of galectins and their corresponding Beta-galactosides have illuminated their role in several essential biological processes. Multivalency plays a crucial role in many protein-carbohydrate interactions. Galectins are known to interact multivalently with various ligands. Although the role of galectins in this process is not yet fully understood, galectins have been proposed to serve as protective proteins during periods of high oxidative stress. We describe the synthesis of GalBeta1-4Fuc functionalized poly(amidoamine) (PAMAM) dendrimers in order to test C. elegans' response to high oxidative stress. In order to test the function of GalBeta1-4Fuc in vivo, C. elegans were treated with RNAi to knockdown lec-1 or lec-10, and then treated with glycodendrimer and exposed to oxidative stress. C. elegans that were pre-treated with the glycodendrimers were less susceptible to oxidative stress than untreated controls. The glycodendrimers mainly appeared within the digestive tract of the worms, and uptake into the vulva and proximal gonads could also be observed in some instances. This study indicates that multivalently presented GalBeta1-4Fuc can protect C. elegans from oxidative stress by binding to galectins.