De schil van een appel tegen kanker*
In de schil van een appel zitten meer dan tien verschillende bioactieve stoffen genaamd
triterpenen, waarvan sommige tot op heden nog onbekend waren. Uit een laboratoriumstudie blijkt nu dat deze triterpenen zowel kanker kunnen tegengaan als kankercellen kunnen doden.
De tripenen werden uit de schillen van ruim 100 kg Red Delicious appels gehaald. In eerdere studies, waaronder ook met dieren blijkt dat in de appel zelf ook verschillende bioactieve stoffen zitten die kanker kunnen tegengaan. Een (hele) appel
(dan wel biologisch) per dag houdt dus niet alleen de dokter maar ook kanker weg.
An Apple Peel a Day Could Keep Cancer at Bay
An apple peel a day might help keep cancer at bay, according to Rui Hai Liu, Cornell associate professor of food science, who has identified a dozen compounds -- triterpenoids -- in apple peel that either inhibit or kill cancer cells in laboratory cultures. Three of the compounds have not previously been described in the
literature.
"We found that several compounds have potent anti-proliferative activities against human liver, colon and breast cancer cells and may be partially responsible for the anti-cancer activities of whole apples," says Liu, who is affiliated with Cornell's Institute of Comparative and Environmental Toxicology and is senior author of the study, which is online and published in the Journal of Agricultural and Food
Chemistry.
In previous Cornell studies, apples had been found not only to fight cancer cells in the laboratory but also to reduce the number and size of mammary tumors in rats. The Cornell researchers now think that the triterpenoids may be doing much of the anti-cancer work.
"Some compounds were more potent and acted differently against the various cancer cell lines, but they all show very potent anti-cancer activities and should be studied further," says Liu.
With co-author Xiangjiu He, a Cornell postdoctoral researcher, Liu analyzed the peel from 230 pounds of red delicious apples from the Cornell Orchard and isolated their individual compounds. After identifying the structures of the promising compounds in the peel, the researchers tested the pure compounds against cancer cell growth in the laboratory. In the past, Liu has also identified compounds called phytochemicals -- mainly flavonoids and phenolic acids -- in apples and other foods that appear to have anti-cancer properties as well, including inhibiting tumor growth in human breast cancer
cells.
"We believe that a recommendation for consumers to eat five to twelve servings of a wide variety of fruits and vegetables daily is appropriate to reduce the risks of chronic diseases, including cancer, and to meet nutrient requirements for optimum health," said
Liu.
Abstract:
Bioactivity-guided fractionation of apple peels was used to determine the chemical identity of bioactive constituents. Thirteen triterpenoids were isolated, and their chemical structures were identified. Antiproliferative activities of the triterpenoids against human HepG2 liver cancer cells, MCF-7 breast cancer cells, and Caco-2 colon cancer cells were evaluated. Most of the triterpenoids showed high potential anticancer activities against the three human cancer cell lines. Among the compounds isolated, 2-hydroxyursolic acid, 2-hydroxy-3-{[(2E)-3-phenyl-1-oxo-2-propenyl]oxy}olean-12-en-28-oic acid, and 3-trans-p-coumaroyloxy-2-hydroxyolean-12-en-28-oic acid showed higher antiproliferative activity toward HepG2 cancer cells. Ursolic acid, 2-hydroxyursolic acid, and 3-trans-p-coumaroyloxy-2-hydroxyolean-12-en-28-oic acid exhibited higher antiproliferative activity against MCF-7 cancer cells. All triterpenoids tested showed antiproliferative activity against Caco-2 cancer cells, especially 2-hydroxyursolic acid, maslinic acid, 2-hydroxy-3-{[(2E)-3-phenyl-1-oxo-2-propenyl]oxy}olean-12-en-28-oic acid, and 3-trans-p-coumaroyloxy-2-hydroxyolean-12-en-28-oic acid, which displayed much higher antiproliferative activities. These results showed the triterpenoids isolated from apple peels have potent antiproliferative activity and may be partially responsible for the anticancer activities of whole apples.
(Juni
2008)
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