22/08/2025
What is the 'Golden Eye' of Heparin Sodium Structure Analysis and Quality Control?
Heparin, as the most widely used anticoagulant drug globally, has a direct impact on the quality and safety of patients' lives and health. However, the production and supply chain of heparin is complex, with diverse sources of raw materials (such as pig, cow, sheep and other animal intestines or lung tissues). During the production process, other glycosaminoglycans (such as dermatan sulfate and chondroitin sulfate) or non target components (such as DNA/RNA) may be mixed in, and even global crises have been triggered by pollution events (such as the "OSCS pollution incident" in 2008). How to control the quality of heparin from the source? Nuclear magnetic resonance (NMR) technology, with its high resolution, non-destructive and multidimensional analysis capabilities, has become a key tool for solving this problem.
Further Pharma in china focuses on the research and quality control of heparin drugs, including one-stop pharmaceutical technical services such as structural analysis, process optimization, impurity preparation, and quality research.
1、 How does NMR "see through" the complex structure of heparin sodium?
It utilizes the behavior characteristics of atomic nuclei in a magnetic field, especially their spin and magnetic moment, to reveal the connection and spatial arrangement between atoms inside the molecule by applying radio frequency pulses and detecting their response. For heparin sodium, a biomacromolecule with a complex sugar chain structure, NMR technology can accurately analyze its primary structure (i.e. the sequence of the sugar chain), secondary structure (such as the conformation of the sugar ring), and even tertiary structure (overall spatial configuration), providing detailed structural information for quality control.
Specifically, NMR technology can determine the chemical environment of hydrogen and carbon atoms at different positions in heparin sodium molecules through experiments such as 1H NMR and 13C NMR, and then infer the connection mode and sequence of sugar chains. In addition, the application of two-dimensional NMR techniques such as COSY, TOCSY, HSQC, and HMBC greatly enhances the ability of NMR technology in complex structure analysis, enabling researchers to gain a deeper understanding of the fine structure of heparin sodium molecules.
Heparin is a highly sulfated glycosaminoglycan (GAG) composed of alternating units of glucosamine and glucuronic acid. The sulfation sites and degree of acetylation vary depending on the source. These subtle structural differences directly affect the activity and safety of drugs. Although traditional detection methods such as high-performance liquid chromatography can separate impurities, they are difficult to fully analyze the molecular structure. NMR technology achieves precise analysis at the molecular level through the following methods:
Signal fingerprint recognition
NMR can capture unique signals of different functional groups in heparin molecules. For example:
1. Acetyl region (2.0-2.1 ppm)
Distinguish between heparin (2.05 ppm), dermatan sulfate (2.08 ppm), and chondroitin sulfate (2.02 ppm).
2. Heteromeric proton region (4.9-5.7 ppm)
Identify sugar units with different sulfation modes (such as IdoA2S, GlcNS6S). By comparing the NMR spectra of 88 crude heparin samples, researchers found significant differences in impurity content and sulfation modes among different samples (Figure 1.).
