Stability of the glucuronides of aliphatic alcohols [Zur stabilität der glucuronide aliphatischer alkohole]

The non-enzymatic and enzymatic hydrolysis of glucuronides of aliphatic alcohols (C-1 up to C-5) have been investigated. For the non-enzymatic hydrolysis sulfuric acid or sodium hydroxide solution was used and for the enzymatic hydrolysis β-glucuronidase from E. coli. In the investigation of the nonenzymatic hydrolysis only small amounts of the glucuronides were released as free alcohols even in strong alkaline medium (5 M NaOH) at 70°C. The influence of the branching of the alkylic chain in this process was noticable, but not of the chain length. The glucuronides of primary alcohols, except for methylglucuronide, were the most stable. In strong acid medium the glucuronides were less stable. In this case the chain length had a considerable influence whereby the longer the alkylic chain was, the better the glucuronides were hydrolysed. Glucuronides of secondary alcohols were better hydrolysed than glucuronides of primary alcohols. The enzymatic cleavage with β-glucuronidase from E. coli resulted in a pH optimum of 5.7 and a temperature maximum at 47°C. The rate of hydrolysis increased with increasing chain length of the alcohols. Branching of the alkylic chain only played a role in the comparison of the glucuronides of isopropanol and n-propanol. The comparison of the other glucuronides showed that the MichaelisMenten constants of the glucuronides with branching of the alkylic chain were barely higher than the constants of the glucuronides without chain branching.