Effects of cryoprotectants on the viability and activity of freeze dried recombinant yeasts as novel oral drug delivery systems assessed by an artificial digestive system

Eur J Pharm Biopharm. 2005 Sep;61(1-2):32-9. doi: 10.1016/j.ejpb.2005.03.009.

Abstract

The aim of this study was to investigate, in a gastric-small intestinal system TIM-1, the effect of cryoprotectants on the survival of freeze-dried Saccharomyces cerevisiae expressing the heterologous P450 73A1 and their ability to convert trans-cinnamic acid into p-coumaric acid. Yeasts were lyophilized in suspensions of trehalose, maltose, lactose, or a milk proteins/trehalose mix. Freeze-dried or native yeasts and trans-cinnamic acid were introduced simultaneously into TIM-1 at the beginning of digestion. Yeast survival rate was evaluated by cell counting in the ileal effluents. P450 73A1 activity was followed by HPLC assay of p-coumaric acid. Freeze-dried yeasts showed high tolerance to digestive conditions. Nevertheless, their survival rate was lower than that of non-dried cells (around 80% whatever the protective agent vs. 96%). The ability of recombinant freeze-dried S. cerevisiae to perform a bioconversion reaction in the digestive tract was shown with all the protectants. The highest trans-cinnamic acid conversion rate (24 vs. 41% for native yeasts) was obtained with the milk proteins/trehalose mix. These results show that freeze-drying might be considered for the pharmaceutical formulation of new drug delivery systems based on orally administered recombinant yeasts and that TIM-1 could be a helpful tool for the pre-screening of oral dosage forms.

MeSH terms

  • Cryoprotective Agents / pharmacology*
  • Cytochrome P-450 Enzyme System / biosynthesis*
  • Drug Delivery Systems / methods*
  • Freeze Drying
  • Gastrointestinal Tract / metabolism*
  • Genetic Engineering
  • Helianthus / enzymology
  • Helianthus / genetics
  • Humans
  • Mixed Function Oxygenases / biosynthesis*
  • Models, Biological*
  • Saccharomyces cerevisiae / drug effects*
  • Saccharomyces cerevisiae / genetics
  • Trans-Cinnamate 4-Monooxygenase

Substances

  • Cryoprotective Agents
  • Cytochrome P-450 Enzyme System
  • Mixed Function Oxygenases
  • Trans-Cinnamate 4-Monooxygenase