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Abstract: This work aimed to improve the clinical application of Radix Ophiopogonis polysaccharide (ROP), a natural anti-myocardial ischemic fructan with Mw of 4.80kDa, by mono-PEGylation. Three mono-PEGylated ROPs were prepared by a moderate coupling reaction between amino-terminated methoxy-PEG (20-, 30-, or 40-kDa) and excessive hydroxyl-activated ROP. After being fully characterized by proton nuclear magnetic resonance as well as high-performance gel permeation chromatography and anthrone–sulfuric acid colorimetry coupled assay, they were evaluated for pharmacokinetics and anti-myocardial ischemic activities in rats with coronary artery ligation. The results showed that mono-PEGylated ROPs were successfully and effectively prepared. Compared with ROP, the three mono-PEGylated ROPs showed approximately 32-, 85-, and 100-fold prolonged retention in systemic circulation with plasma half-lives reaching 16.1, 42.4, and 49.8h, respectively. Studies on anti-myocardial ischemic effects of the conjugates showed that administrated at the same molar dose of 4μmol/kg per injection as ROP, they could achieve comparable or even better therapeutic effects although their administration intervals were 2- to 6-fold longer than that of ROP. These findings confirm that PEGylation would be a promising approach to markedly reducing the injection-administered frequency of ROP and hence patient compliance without sacrifice of the therapeutic efficacy by significantly improving its pharmacokinetics. [Copyright &y& Elsevier]