The “Prunus mume Sieb. et Zucc” (Ume) is a rich natural source of novel anti-cancer substance

The apricot variety in Japan is “Prunus mume Sieb. et Zucc” (Ume). The Japanese have been growing Ume tree for more than 2000 years because of its health enhancing effects, and through cultivation, they have improved the Ume tree to produce healthier fruits. The purpose of this study was to investigate presence of anti-cancer substances in Ume. One kg Ume was squeezed to separate the soft fruit from the seed capsules. The soft Ume fraction was boiled at 90°C to 100°C to obtain 20 g of semi-solid Ume (misatol). The condensed fruit was dissolved in a water-diethylether. The fraction in diethylether was dried and further fractionated for experiments. The anti-cancer effects of the Ume were investigated on 2 established cancer cells—the Kato-III stomach cancer and the HL-60 promyelocytic leukaemia cell lines. Kato-III and HL-60 cells were grown in RPMI-1640 medium containing 10% foetal calf serum. The Ume extract in dimethyl sulphoxide was added to the cancer cell cultures at 1-10 μL/mL test (1 μL contained 20 μg extract). Without Ume, the cancer cells grew and formed colonies. When the Ume extract was added, cancer cells were dose dependently eliminated and at < 5 μL/mL, no cancer cell survived. Similarly, the condensed Ume showed strong anti-tumour effects on human pancreatic cancer and dog fibrosarcoma. The Ume preparation showed no toxic effect on normal human blood cells. In conclusion, this is the first study showing unequivocally presence of an anti-cancer agent in Ume fruit with both suppressive effect on the growth of cancer cells and lethal action on the already formed cancer cell colonies. As an abundant source of natural anti-cancer substance, Ume should have therapeutic benefit in tumour-bearing patients. Further, regular intake of Ume juice should suppress cancer initiation in healthy individuals.