K-State's Soyoung Lim, doctoral student in human nutrition, Manhattan has revealed that purple sweet potatoes have high contents of anthocyanin, which is a pigment that presents the purple colour in the vegetable.
The pigment can produce red, blue and purple colours depending on the source's chemical structure, such as in foods like blueberries, red grapes and red cabbage.
According to Lim, anthocyanins have been epidemiologically associated with a reduced cancer risk, but the anti-cancer ability of the purple sweet potato has not been well investigated.
During the study, the researchers analysed three different purple sweet potatoes that had varying amounts of anthocyanin.
To quantify the amount in each potato, Lim extracted pigments from the vegetables and injected them into an HPLC-MS Analysis, which she said is a method that separates components.
The potatoes were segregated by multiple traits based on flesh pigmentation and fibre contents.
The study showed that Kansas-bred potato had significantly higher anthocyanin contents compared to the other potatoes.
The researchers also found two derivatives of anthocyanin that were dominant: cyanidin and peonidin.
The specially bred purple sweet potato had a much higher total phenolic content and antioxidant capacity than the other regularly occurring purple sweet potatoes.
Phenols are chemical compounds that have been found to have anti-aging and antioxidant components.
For further study, Lim treated human colon cancer cells with low concentrations of the pigment derivatives cyanidin and peonidin and found that the treatment led to significant cell growth inhibition for the cancer cells.
The findings were presented at Experimental Biology Meeting.