Chemical synthesis of glycosaminoglycan mimetics for targeting endoglycosidase activity

Wootton, Hannah Sophie

Abstract

Glycosaminoglycans are a family of extraordinary, long-chain polysaccharides that are highly abundant on the mammalian cell surface and in the extracellular matrix. These linear chains exist as proteoglycans which perform critical roles in many biological functions as well as being involved in many disease processes. Chondroitin sulfate (CS) is a glycosaminoglycan comprised of repeating disaccharide units but an unpredictable heterogeneous structure consisting of various CS subtypes due to differing sulfation patterns. Previous research has focused on deciphering the relationship between the complex structure of CS and its functions, but this remains challenging due to a limited access to homogenous CS oligosaccharides for biological studies. Access to reliable synthetic routes targeting CS oligosaccharides is desirable to build large and diverse GAG libraries. There are few dependable synthetic routes towards CS-D mimetics, a rare subtype employing a 2',6-O sulfation pattern. CS-D has been shown to be preferentially cleaved by an endogalactosaminidase, Hyaluronidase-4 (HYAL-4) which is upregulated in several cancer types. However, the biological relevance of this is yet to be determined as detection and quantification of HYAL-4 is challenging due to the absence of a structurally defined synthetic target.

The work presented herein describes the synthesis of a novel CS-D fluorescent probe. A multistep synthetic route was developed with carefully planned protecting group manipulations to allow diversification and a robust glycosylation methodology was established. Furthermore, a general method for the late-stage attachment of coumarin derivatives to a CS disaccharide was optimised, followed by deprotections to facilitate the synthesis of a specific CS-D probe. This could provide much-needed insight into the role of HYAL-4 in human disease and give access to novel diagnostic opportunities and potential for drug discovery platforms targeting HYAL-4.

Citation

Wootton, H. S. (2025). Chemical synthesis of glycosaminoglycan mimetics for targeting endoglycosidase activity. (Thesis). Keele University. https://keele-repository.worktribe.com/output/1279726

• Thesis Type: Thesis
• Online Publication Date: Jun 26, 2025
• Deposit Date: Jun 17, 2025
• Public URL: https://keele-repository.worktribe.com/output/1279726
• Additional Information: Embargo on access until 1 June 2026 - The thesis is due for publication, or the author is actively seeking to publish this material.
• Award Date: 2025-06