Oligo-polyethene glycol (PEG)-modified 14-deoxy-11,12-didehydroandrographolide derivatives: synthesis, solubility and anti-bacterial activity

A class of 14-deoxy-11,12-didehydroandrographolide (DA) derivatives with oligo-polyethylene glycol (PEG) substituents has been synthesized. It is found that small degree of polymerization of PEG favors the synthesis of dual-PEGylated DA derivatives, whereas large degree of polymerization is good for the preparation of mono-PEGylated DA derivatives. As compared to the prototype compound DA, the PEGylated DA derivatives show enhanced water solubility which is beneficial to drug's bioavailability. Preliminary study finds that the PEGylated DA derivatives exhibit better anti-bacterial activity than that of DA.

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