Epigallocatechin-3-gallate inhibits lactase but is alleviated by salivary proline-rich proteins

Shahina Naz, Rahmanullah Siddiqi, Tristan P. Dew, Gary Williamson

Research output: Contribution to journalArticleResearchpeer-review

32 Citations (Scopus)


Lactase phlorizin hydrolase is a small intestinal brush border enzyme that catalyzes the hydrolysis of the milk sugar, lactose, and also many flavonoid glucosides. We demonstrate that epigallocatechin-3-gallate (EGCG), the principal flavonoid from green tea, inhibits in vitro hydrolysis of lactose by intestinal lactase. We then tested the hypothesis that salivary proline-rich proteins (PRPs) could modulate this inhibition and stabilize EGCG. Inhibition by EGCG of digestive enzymes (α-amylase > chymotrypsin > trypsin > lactase ≫ pepsin) was alleviated ∼2-6-fold by PRPs. Furthermore, PRPs appeared stable to proteolysis and also stabilized EGCG under digestive conditions in vitro. This is the first report on EGCG inhibition of lactase, and it quantifies the protective role of PRPs against EGCG inhibition of digestive enzymes.

Original languageEnglish
Pages (from-to)2734-2738
Number of pages5
JournalJournal of Agricultural and Food Chemistry
Issue number6
Publication statusPublished - 23 Mar 2011
Externally publishedYes


  • amylase
  • enzyme inhibition
  • epigallocatechin gallate
  • lactase
  • protease
  • Salivary proline-rich proteins

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