Bees collect propolis to seal their hives.
A bee product from New Zealand has been shown to suppress tumours in mice, says a study presented to a scientific conference in the United States.
The researchers at a German hospital tested propolis against tumours that can occur in the nervous system and on skin in a
condition called neurofibromatosis.
Propolis is a resin found in young tree buds. Bees collect the substance, mix it with their own enzymes and beeswax, and use this to seal the hive.
About half of cases of neurofibromatosis are inherited, while the rest arise from spontaneous gene mutation. The condition has two types. The German experiment involved the more-common type 1, which occurs in about 1 in 3000 people.
The type 1 condition's effects range from mild to severe. The tumours only rarely become malignant, although they can still cause potentially serious problems, including seizures, learning disabilities and bone deformities.
The German study found that using propolis supplied by Te Awamutu company Manuka Health suppressed growth of type 1 neurofibromatosis tumours in mice by over 90 per cent.
"Caffeic acid phenethyl ester is the first identified anti-cancer ingredient in propolis, an extract from beehives ... ," the scientists said in their paper for a conference in Utah.
It was the most potent natural derivative of caffeic acid yet identified that was involved in the chemical signalling pathway that controlled the growth of the tumours. It had not been tested alone in clinical trials because it was not easily absorbed. Propolis, however, contained other substances which made it more easily absorbed, as well as other anti-cancer substances.
Caffeic acid phenethyl ester appeared to work better in the presence of the other polyphenols found in propolis to suppress growth of the tumours, in test-tube and animal experiments.
The lead researcher, Dr Hiroshi Maruta, is now using propolis in a group of 15 sufferers of type 1 neurofibromatosis in Japan.
Propolis is sold as a complementary remedy said by its suppliers to have various health benefits.
