You certainly have seen kleci potatoes. The thumbed black-skinned potato is found in many traditional markets. In our life, this small tuber is usually steamed for consumption or sometimes mixed in the vegetables. This black potato’s flavor is similar to other potatoes. But, do you know the content in it?
Kleci potatoes (Coleus tuberosus) apart from becoming source of carbohydrates, also contain antioxidant compounds and anti-proliferation of cancer cells triterpenic acid group. This has attracted Mutiara Nugraheni, a student of S-3 Program of Food Science Faculty of Agricultural Technology, Universitas Gadjah Mada, to conduct a series of studies associated with functional compound of black potatoes. From her research, it is found that the dominant triterpenic acid compounds in black potatoes are ursolic acid (UA) and oleanolic acid (OA).
From Mutiara’s research, it is noted that the content of compounds in the skin is higher (about 4 times) compared with the tuber. "After antioxidant activity test using FTC and TBA methods, these compounds and extracts of black potato tubers positively show high activity," Prof. Dr. Ir. Umar Santoso, M.Sc said at UGM, Tuesday (13/9).
As the promoter of Mutiara Nugraheni in gaining doctorate of UGM, Umar Santoso said that Mutiara has conducted anti-proliferating activity test on extracts of black potato’s (skin and tuber) using breast cancer cells MCF-7 (Michigan Cancer Foundation-7) and MTT Assay method. Briefly, cancer cells placed in wells on the plate are then given treatment with the extracts of black potato tubers in various concentrations.
After being incubated for 72 hours and given additional MTT reagent, a measurement of cell viability using ELISA Reader, the results showed either ursolic acid, oleanolic acid, or tuber extract significantly inhibited the proliferation of cancer cells. "And apparently proliferating activity of extracts of the skin is higher than the tuber. This is because the content of ursolic acid and oleanolic acid is higher in the skin," Umar Santoso explained.
Umar Santoso explained that to know the mechanism of anti-proliferation, Mutiara Nugraheni as the researcher conducted a microscopic observation after providing color (staining) using acridine orange/ ethidium bromide. This gives evidence that cancer cells treated with potato tuber extracts undergo apoptosis, the morphological damage, DNA fragmentation, and death of the cancer cells.
"The team assessed that research result of Mutiara Nugraheni becomes an interesting finding, because it proves scientifically that the tubers that have been practically unknown, in fact, contain potent functional components of health. This finding has also been published in three international journals, namely the International Food Research Journal, African Journal of Food Science, and Journal of Medicinal Plants Research. With her dissertation, Mutiara Nugraheni, a lecturer of UNY, has passed cum laude and is now awaiting inauguration of graduate program UGM in November 2011," Umar who is also proud of this finding said.