Researchers have discovered that combining green tea extract and xyloglucan (Xylo) can create adhesive films that help alleviate oral inflammation.

Previous studies have found that green tea has anti-inflammatory properties, which can relieve oral mucositis (inflammation of the mouth lining.

This inflammation is often caused by damage to rapidly dividing mucosal cells during chemotherapy and radiation. The condition causes significant discomfort and interference with vital activities, such as eating and sleeping.

A research team from the Tokyo University of Science (TUS), led by Takehisa Hanawa, explored the potential of tea catechins in developing a novel treatment for oral mucositis to minimise patient discomfort.

Green tea is known for its natural antioxidants, with catechins leading the charge among its polyphenols, which protect cells from oxidative stress. These powerful compounds neutralise harmful free radicals generated during cancer treatment.

Takehisa said, "Our goal was to create a formulation for oral mucositis that patients could use easily and comfortably, helping to prevent the decline in quality of life and difficulties with eating caused by cancer treatments."

The research team designed a thin mucoadhesive film enriched with tea catechins, which can be applied directly to affected areas for prolonged relief. The film is a thin, flexible material that adheres to the inside of the mouth to deliver active ingredients, like medications, directly to the affected area. It offers a more convenient, inexpensive, and user-friendly alternative to mucoadhesive tablets, which often have limited usability.

The research

The films were prepared by combining Xylo, a water-soluble polymer extracted from tamarind seeds, with green tea extract which contains over 75 per cent catechins, including more than 40 per cent epigallocatechin gallate (EGCG). Xylo is a natural gelling agent, commonly used as a food thickener. It forms a structure similar to the mucin network in the mouth, giving the film its mucoadhesive properties.

Given the availability, usage as a food additive, and low cost of green tea extract, which contains EGCG as well as various catechins, it was selected as a gelling agent for Xylo.

The researchers examined how Xylo and green tea extract gelled together and explored the physical and chemical properties of the gels and films they produced.

The team developed two types of films:

  • Hydrogels: prepared by drying Xylo/green tea extract solutions at 4 °C for 24 hours
  • Xerogels: dried for seven days, resulting in firmer, drier films

The hydrogel transitioned into a liquid-like state at skin surface temperatures (35 to 37 °C) and became weak, breaking with just a small amount of pressure. In contrast, the xerogel films demonstrated better mucoadhesive properties, withstanding up to 10 times more force and performing similarly to commercially available oral mucoadhesive films.

To test the adhesive strength of the xerogel, the researchers simulated oral conditions using mucin disks coated with artificial saliva.

The film was pressed onto the disk with a plunger, and the force required to detach it was measured. The films adhered well, with detachment forces matching or exceeding those of over-the-counter products.

The team also examined the release of EGCG by soaking the films in water, discovering that higher concentrations of Xylo facilitated greater EGCG release over time, highlighting their potential as mucoadhesive films.

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