Waste tea leaf extract offers hope of lung cancer treatment after ‘accidental’ discovery

'It is still not clear what really happens and how the cancer cells are killed'

An Indian tea plantation worker picks leaves in a tea garden in Kaziranga, east of Guwahati (AFP/Getty)

Extract from waste tea leaves could provide the key to a breakthrough treatment for lung cancer, following an “accidental” discovery by a team of scientists.

Researchers from Swansea University and two Indian universities were creating microscopic biomarkers called “quantum dots” to improve the detection and imaging of tumours.

In an effort to increase the luminosity of the quantum dots the team introduced tea leaf extract to the particles, but instead of increased fluorescence the team found the plant had unexpectedly reduced the size of the quantum dots considerably, and also that they destroyed 80 per cent of the lung cancer cells they were exposed to.

“It was very surprising for us,” lead researcher Dr Sudhagar Pitchaimuthu told The Independent. “We made a systematic laboratory-based analysis with lung cancer cells, and we got an impressive result. And when we increased the quantum dot concentration we saw a corresponding fall in cancer cells.”

“It was very surprising and it is still unclear how it works,” he added, though he said the team “got a good repeatable result.”

Describing how the discovery came about, Dr Pichaimutu said: “First we started with a nanoparticle synthesiser that reduced [the size of the quantum dots] and we got it to a 100 – 200 nanometre size.

“Then we added the tea leaf extract. Previous research showed that the [plant’s] chlorophyll helps with the chlorophyll fluorescence effect – light emitting behaviour. What we were expecting was that by adding the tea leaves we would help the quantum dots emit more light.

“But instead we found we had very tiny particles of 3-5 nanometres. It was unbelievable. The particle size was reduced by about 30 times.”

The use of tea leaf extract in the production of quantum dots makes the process cheaper and less poisonous to healthy cells surrounding cancerous cells. In addition, the use of waste tea from the crop to produce the extract means the research could have beneficial environmental implications.

Dr Pitchaimuthu said: “The issue with normal quantum dots is that they are prepared in high temperatures, they require chemicals and they are very expensive. One milligram is about £200-£500 grams. They also contain cadmium which is very highly toxic.”

“We got our very small quantum dots by the help of tea leaf extract, and it is cheap – we get it from waste tea leaves – a third of the tea leaf crop is unsuitable for drinking. It normally goes to landfill. So we collect these waste tea leaves for this useful technology.”

Lung cancer is the world’s most common form of cancer and has one of the worst survival rates among common cancers. According to the Welsh Cancer Intelligence and Surveillance Unit just 6.5 per cent of people diagnosed with the disease in Wales survive for five years or more.

But a useable cancer treatment is not imminent. Dr Pichaimutu’s team first have to understand more about the process before human trials can start.

He said: “Over the next two years we would like to repeat the experiments with different concentrations of tea leaf extract.

“It is still not clear what really happens and how the cancer cells are killed. We need to investigate the underlying mechanism in laboratory conditions.

“Hopefully after two years we can move all this technology to clinical trials in India.”

Even if the trials are successful a widely available treatment based on the discovery could be at least 10 years away.