Compounds found in green tea block Bortezomib

(15 February 2010: VIDYYA MEDICAL NEWS SERVICE) -- Bortezomib (Velcade), a drug approved to treat multiple myeloma and being tested in clinical trials to treat several other cancer types, works by interfering with the activity of proteasomes, cellular structures that break down unneeded proteins. Based on laboratory data, scientists have proposed that compounds found in green tea, including epigallocatechin gallate (EGCG), may increase the effectiveness of bortezomib when given concurrently.

However, in a study published online February 3 in Blood, Dr. Axel Schönthal and colleagues from the University of Southern California found exactly the opposite—EGCG completely blocked the activity of bortezomib in multiple myeloma and glioblastoma cells lines, in tissue cultures from patients with multiple myeloma, and in mice implanted with multiple myeloma cells. In one set of experiments, the EGCG was supplied by a dietary supplement currently available over the counter. A second supplement containing complete green tea extract (GTE), as well as several other individual compounds found in green tea, also interfered with bortezomib-induced cell death.

The researchers found that EGCG directly bound to a chemical group (boronic acid) found in bortezomib. This prevented bortezomib from binding to and blocking the activity of the proteosomes, which would normally cause cell stress and cell death.

“We…would strongly urge patients undergoing [bortezomib] therapy to abstain from consuming green tea products,” stated the authors, “in particular those widely available, highly concentrated GTEs that are sold in liquid or capsule form.”

Return to Vidyya Medical News Service for 15 February 2010

© RAmEx Ars Medica,Inc. All rights reserved.

Information appearing on the Vidyya Medical News Service is not intended as a substitute for professional medical care. Seek professional medical help and follow your health care provider's advice.

Interested in subscribing to our daily e-mail newsletter? Send an email to Vidyya@Ramex.com with the word subscribe in the subject field.