GREEN TEA: Epigallocatechin gallate to deliver therapy to cell interiors

 It is again EGCG or epigallocatechin gallate, an anti-oxidant in green tea, which is in the spotlight with this Chinese study and thus adds to the health benefits of tea, ranging from the prevention of cardiovascular disease to weight loss. The action of EGCG, described here in the journal ACS Central Science, is surprising: again due to its antioxidant and anti-inflammatory properties, it makes it possible to deliver therapeutic RNAs inside cells.

 

These small interfering RNAs (siRNA: Small interfering RNAs) have great therapeutic potentialbecause they can deal with the expression of disease-related genes. However, “inserting” siRNAs into cells where they can act remains complex. Relatively large in size and negatively charged, siRNAs cannot easily cross the cell membrane and are susceptible to degradation by enzymes. To overcome these problems, some researchers have tried to coat these siRNAs with different polymers. However, most small polymers fail to deliver siRNAs into cells, whereas larger polymers can be effective but are usually toxic. Researchers from East China Normal University (Shanghai) and South China University of Technology wondered if they could use EGCG, which binds strongly to RNA,

 

Therapeutic nanoparticles combining EGCG and siRNAs: The team made their nanoparticles by first combining EGCG and siRNA, which self-assemble into a negatively charged nucleus. Next, the researchers coated this core with a shell made of a small positively charged polymer. These nanoparticles effectively reduced the expression of several target genes in cultured cells, showing that the particles could cross the cell membrane well. Next, the researchers tested the nanoparticles in a model of intestinal injury in mice, using an siRNA targeting a pro-inflammatory enzyme. The nanoparticles improved symptoms such as weight loss, colon shortening and intestinal inflammation.

 

Thanks to its antioxidant and anti-inflammatory properties, EGCG in green tea can thus contribute to the effectiveness of these therapeutic nanoparticles.