Can green tea lower your blood sugar? If so, it seems that health benefit might be primarily due to a natural compound in green tea called deoxysappanone. Here's the story:
A research team led by Harvard Medical School assistant professor and Broad Institute associate member Vamsi Mootha has developed a toolkit that isolates five primary aspects of mitochondrial function and analyzes how individual drugs affect each of these areas. These results are published online February 24, 2008 in Nature Biotechnology.
Over the last few decades, mitochondria have increasingly been understood as a key determinant of cellular health. On the other hand, mitochondrial dysfunction can lead to many neurodegenerative conditions as well as metabolic diseases such as diabetes. Since mitochondria are responsible for turning the food we eat into the energy that drives our bodies, these and other connections are logical. Nevertheless, there has not yet been a systematic method for thoroughly interrogating all facets of mitochondrial activity.
In order to thoroughly analyze these organelles, Mootha and his team zeroed in on five basic features of mitochondria activity, looking at how a library of 2,500 chemical compounds affected mitochondrial toxic byproducts (like all “chemical factories” mitochondria produce their own toxic waste), energy levels, speed with which substances pass through these organelles, membrane voltage, and expression of key mitochondrial and nuclear genes. (Mitochondria contain their own genome, consisting of approximately 37 genes in humans.)
Probably the most clinically relevant finding builds on a paper Mootha coauthored in 2003, a paper that demonstrated how type 2 diabetes was linked to a decrease in the expression of mitochondrial genes. A subsequent and unrelated paper showed a relationship between type 2 diabetes and an increase in mitochondrial toxic byproducts. Mootha’s group decided to query their toolkit and see if there were any drugs that affected both of these functions, drugs that could boost gene expression while reducing mitochondrial waste.
Indeed, they found six compounds that did just that, five of which were known to perturb the cell’s cytoskeleton, that is, the scaffolding that gives a cell its structure.
“Our data shows that when we disrupt the cytoskeleton of the cell, that sends a message to boost the mitochondria, turning on gene expression and dropping the toxic byproducts,” says Mootha. “The connection between the cytoskeleton and mitochondrial gene expression has never been shown before and could be very important to basic cell biology.”
Of the five drugs that did this, one, called deoxysappanone, is found in green tea and is known to have anti-diabetic effects. Another, called Mebendazole, is used for treating intestinal worm infections. This connection gives a rationale to case reports in which diabetics treated with Mebendazole have described improvements in their glucose levels while on the drug.
The researchers intend to further investigate some of the basic biological questions that this study has raised, foremost being the relationship between the cytoskeleton and mitochondria. They also plan on using this toolkit to develop strategies for restoring normal mitochondrial function in certain metabolic and neurodegenerative conditions where it has broken down (Newswise).