Long acting hyaluronate--exendin 4 conjugate for the treatment of type 2 diabetes.

Despite clinical exploitation of exendin 4 for the treatment of type 2 diabetes, the significantly short half-life requiring twice a day injection has limited the wide applications. In this work, a protocol for the synthesis of long acting hyaluronate (HA) - exendin 4 conjugate was successfully developed using Michael addition chemistry between vinyl sulfone modified HA (HA-VS) and thiolated exendin 4. The exendin 4 content could be controlled in the range of 5-30 molecules per single HA chain with a bioconjugation efficiency higher than 90%. The conjugation of exendin 4 with HA resulted in about 20 times improved in vitro serum stability maintaining the hypoglycemic and gluco-regulatory bioactivities of exendin 4. HA - exendin 4 conjugates showed excellent glucose-lowering capabilities in type 2 db/db mice demonstrating protracted hypoglycemic effect up to 3 days after a single subcutaneous injection. Furthermore, insulin immunohistochemical analysis of islets in db/db mice confirmed the improved insulinotropic activity of HA - exendin 4 conjugates. The HA - exendin 4 conjugates will be investigated further as a twice a week injection dosage form for clinical applications.

Target specific and long-acting delivery of protein, peptide, and nucleotide therapeutics using hyaluronic acid derivatives.

Hyaluronic acid (HA) is a biodegradable, biocompatible, non-toxic, non-immunogenic and non-inflammatory linear polysaccharide, which has been used for various medical applications such as arthritis treatment, ocular surgery, tissue augmentation, and so on. In this review, the effect of chemical modification of HA on its distribution throughout the body was reported for target specific and long-acting delivery applications of protein, peptide, and nucleotide therapeutics. According to the real-time bio-imaging of HA derivatives using quantum dots (QDot), HA-QDot conjugates with 35mol% HA modification maintaining enough binding sites for HA receptors were mainly accumulated in the liver, while those with 68mol% HA modification losing much of HA characteristics were evenly distributed to the tissues in the body. The results are well matched with the fact that HA receptors are abundantly present in the liver with a high specificity to HA molecules. Accordingly, slightly modified HA derivatives were used for target specific intracellular delivery of nucleotide therapeutics and highly modified HA derivatives were used for long-acting conjugation of peptide and protein therapeutics. HA has been also used as a novel depot system in the forms of physically and chemically crosslinked hydrogels for various protein drug delivery. This review will give you a peer overview on novel HA derivatives and the latest advances in HA-based drug delivery systems of various biopharmaceuticals for further clinical development.

Signal transduction of hyaluronic acid-peptide conjugate for formyl peptide receptor like 1 receptor.

Agonistic and antagonistic peptides for formyl peptide receptor like 1 (FPRL1) receptor have been investigated as novel drug candidates for inflammatory diseases such as sepsis, asthma, and rheumatoid arthritis. In this work, a novel protocol for the synthesis of hyaluronic acid (HA)-peptide (CWRYMVm) conjugate for FPRL1 receptor was successfully developed for further clinical applications of peptide drugs. Aminoethyl methacrylated HA (HAAEMA) was synthesized by the coupling reaction of tetrabutyl ammonium salt of HA (HA-TBA) and AEMA using benzotriazol-1-yloxy-tris(dimethylamino) phosphonium hexafluorophosphate (BOP) in dimethyl sulfoxide (DMSO). Then, HA-AEMA was conjugated with CWRYMVm in water via Michael addition reaction between methacrylate group of HA-AEMA and thiol group in cysteine. The formation of HA-peptide conjugate was confirmed by 1H NMR and gel permeation chromatography (GPC). The average number of conjugated peptide molecules could be controlled from 5 to 23 per single HA chain. The HA-peptide conjugate showed serum stability longer than four days. In Vitro signal transduction activity of the HA-peptide conjugate for FPRL1 receptor was confirmed from the elevated levels of phospho-extracellular signal-regulated kinase (pERK) and calcium ion in FPRL1 overexpressing RBL-2H3 cells. The partially decreased biological activity of HA-peptide conjugates by the steric hindrance of HA was recovered after its degradation by hyaluronidase treatment.