A group of Taiwanese researchers led by Yu-Jen Chen have been investigating the anti-cancer properties of Honey Fungus Armillaria mellea, the common parasitic fungus feared by gardeners and foresters the world over but also a delicious edible mushroom. Their research shows that extracts of Honey Fungus, Armillarikin and Armillaridin are cytotoxic and induce apoptosis (cell death) in cancer cells of Leukemia and Malignant Hepatoma. You can read their recent paper here
Honey Fungus can form some of the biggest organisms in the world covering many square miles of forest in North America. They are chiefly regarded as parasitic on trees but can also live as saprophytes growing on dead wood and probably also as mycorrhizal partners with some trees. They are themselves parasitised by orchid species such as the the Lady Orchid in the UK.
See my Wild Mushroom Guide http://www.mushroomtable.com/wild-mushrooms/honey-fungus/
They are rarely a problem in native woodland, where there is a healthy mycorrhizal community of fungi, only affecting very weak or stressed trees. In gardens however, where most of the shrubs and trees are non-native, the mycorrhizal fungi are less well established and the plants are looking for mycorrhizal partners. This is where Honey Fungus can take hold before other mycorrhizal fungi can partner with the new plants and protect them.
Honey Fungus are a delicious edible mushroom which can be harvested in prolific quantities. In the UK they are usually in season in mid-October. They are an excellent choice for preserving and pickling, as well as cooking and eating. http://www.mushroomtable.com/recipes-2/honey-fungus-and-potato-pancake/