Sweet Potatoes: Uber Tubers Packing an Antioxidant, Antimicrobial Punch


Earlier this year, researchers published a study in the Merit Research Journal of Agricultural Science and Soil Sciences on sweet potato (Ipomoea batatas (L.) and its multiple benefits—particularly as an antioxidant and antimicrobial.

According to the article abstract, the β-carotene-rich orange flesh and anthocyanin-rich purple flesh of sweet potatoes have gained attention as a cheap source of food antioxidants. Furthermore, some freshly harvested tubers and leaf extracts of purple, orange and white flesh sweet potatoes exhibit antimicrobial activity against Escherichia coli and Staphylococcus aureus

To test these effects, tubers and leaves were freeze-dried, milled and extracted using 90% ethanol in a 1:5 w/v ratio in a shaker incubator for 24 hr. The extracts were centrifuged at 2,000 rpm for 20 min and filtered. The solvents were then evaporated and the extracts obtained were stored at 4°C.

The details of the Disk Diffusion test method used can be found in the full paper. Results showed the tuber extracts, in particular, of specific varieties had significant inhibitory effects against E. coli and S. aureus. On the contrary, ethanolic leaf extracts of sweet potato were ineffective against E. coli and S. aureus. The authors noted that the antimicrobial properties of these extracts could be due to the presence of polyphenols such as β-carotene and anthocyanin in the extracts at different levels.

These findings could lead to the development of potent antibiotic drugs to combat multi-drug resistant and sensitive bacteria. Further, antioxidant activities have several implications in delaying the process of aging and protecting against food spoilage. The authors note these results are encouraging for future work on edible therapeutics, food and other traits of purple and orange flesh sweet potato.

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