CHEMICAL SWITCHING OF TAXO-DITERPENOIDS BETWEEN LOW SOLUBILITY ACTIVE FORMS AND HIGH SOLUBILITY INACTIVE FORMS

摘要

Cyclic chemical switching method is employed for solubilizing and desolubilizing taxo-diterpenoids with respect to aqueous solvents. 2-halogenated onium salts of aza-arenes are employed to derivatize taxo-diterpenoids so as to alter their solubility in aqueous solvents. The onium salt of aza-arene includes a delocalized charge which imparts polarity and aqueous solubility to taxo-diterpenoid derivatives. Solubilization is achieved in a one step derivatization with the onium salt of 2-halogenated aza-arenes. Desolubilization is achieved by contacting onium salts of taxo-diterpenoid-Cn,2-O-aza-arenes with serum protein to displace the 2-O-aza-arene and form a soluble protein:taxo-diterpenoid intermediate. This protein:taxo-diterpenoid intermediate then dissociates over time to provide a bioactive taxo-diterpenoid. Preferred taxo-diterpenoids include taxol, C-2 substituted taxol, and TaxotereTM. These same onium salts of taxo-diterpenoid-Cn,2-O-aza-arenes are employed as water soluble prodrugs. For example, taxol-2'-methylpyridinium tosylate (MPT) is characterized by an elevated aqueous solubility, rapid activation by serum protein, good stability in most other aqueous solutions, formation of a protein:taxol intermediate and good retention within the circulatory system. The toxicity of the activated form is comparable or greater than underivatized taxol. Furthermore, taxol-2'-MPT can be synthesized by a simple one step reaction between taxol and 2-fluoro-1-MPT. The invention is applicable to taxol and taxol mimetics having hydroxyls that are reactive with onium salts of 2-halogenated-aza-arenes. For example, taxol and Taxotere each have reactive hydroxyls at the 2' and 7 positions. The invention is also applicable to a wide array of 2-halogenated-aza-arenes.