New research reveals that sweet potato leaves and stems, often discarded, contain powerful compounds that can slow cancer cell growth—offering a natural alternative in the fight against cancer.
Study: Antiproliferative potential of sweetpotato in breast (BT549) and lung (A549) cancer cell lines. Image Credit: Martina Sappe
A study led by researchers from Tennessee State University, USA, has found that methanolic extracts of sweet potato leaves and stems can inhibit the growth of breast and lung cancer cells. The findings are published in the journal BMC Complementary Medicine and Therapies.
Background
Sweet potato is a highly nutritious vegetable belonging to the Convolvulaceae family. The plant is found in more than 100 countries, with developing countries yielding approximately 95% of the global output.
The large tuberous root is the most widely consumed part of the sweet potato plant. Leaves are mainly consumed in the Pacific Ocean, Africa, Asia, China, Taiwan, the Caribbean, and Southern and Central America.
Sweet potato leaves, stems, stalks, peel, and flesh are rich sources of bioactive flavonoids, proteins, phenolic acids, carbohydrates, lipids, carotenoids, and anthocyanins, which are associated with antioxidant, antidiabetic, anticancer, hepatoprotective, antimicrobial, antiulcer, and immunostimulant activities.
Evidence suggests that sweet potato leaf extracts can reduce oxidative stress and prevent the risk of developing various health conditions, including allergies, aging, cardiovascular disorders, viral infections, age-related macular degeneration, cataracts, and cancer.
The majority of studies on sweet potato have focused on its antioxidant properties. Among studies on anticancer properties, most have tested the effect of sweet potato roots from different cultivated varieties (cultivars) on the viability of cancer cells.
Although the entire sweet potato plant, including tuberous roots, leafy greens, and stems, has been used as traditional medicine for centuries, these parts are often discarded or used as animal feed. This study highlights the potential of utilizing these underused plant parts for health benefits.
In this study, researchers investigated the effects of sweet potato leaves and a combination of leaves and stems on the viability of human breast and lung cancer cells.
The Study
The study investigated the anti-proliferative (cytotoxic) effects of methanolic extracts of sweet potato leaves and stems collected from Tennessee State University’s Organic Research Farm. Two types of sweet potato strains, including purple-fleshed and orange-fleshed strains, were tested.
The extracts were used to treat human breast and lung cancer cell lines, and a cell viability assay was carried out to determine the cytotoxic effects of the extracts. Tamoxifen, a drug for treating breast cancer, was also used for treatment as a positive control.
Study Findings
The study found that the leaf extracts from the All-Purple sweet potato cultivar (purple-fleshed) and the stem and leaf extracts from the Carolina Ruby sweet potato cultivar (orange-fleshed) significantly inhibited the viability of lung and breast cancer cells in a dose-dependent manner.
The cell viability assay findings showed that the half-maximal effective concentration (EC50) values of All-Purple sweet potato leaf extracts were 0.013 µg/µl for lung cancer (A549) and 0.002 µg/µl for breast cancer (BT549), confirming its stronger effect on breast cancer cells.
At a concentration of 0.003 µg/µl, All-Purple sweet potato leaf extracts inhibited the growth of lung and breast cancer cells by 37% and 76%, respectively.
Unlike All-Purple sweet potato leaf extracts, which exhibited a lower EC50 value for the breast cancer cell line, Carolina Ruby sweet potato leaf and stem extracts exhibited a lower EC50 value for the lung cancer cell line (0.0014 µg/µl) compared to its effect on breast cancer (EC50 = 0.007 µg/µl).
In lung cancer cells, Carolina Ruby sweet potato leaf and stem extracts caused 96% growth inhibition at a concentration of 0.0056 µg/µl.
These findings suggest that the magnitude of natural products' anti-proliferative effects is cancer-type specific, meaning that extracts may affect different cancer types in distinct ways.
Interestingly, the Carolina Ruby leaf and stem extract at 0.0056 µg/µl showed an inhibitory effect on lung cancer cells that was approximately 1% higher than that of tamoxifen, highlighting its potential as a potent natural alternative.
Overall, the study found that the sweet potato extracts (both leaf extract and the combination of leaf and stem extracts) had minimal cytotoxic effects at lower concentrations but exhibited significant inhibitory effects at higher concentrations.
Study Significance
The study highlights the cytotoxic effects of sweet potato leaves and stems on human cancer cells. Among the two cultivated varieties tested, All-Purple sweet potato leaf extracts had the strongest effect on breast cancer cells, while Carolina Ruby leaf and stem extracts were more effective against lung cancer cells.
The anticancer activity of sweet potato extracts is believed to be driven by their high levels of bioactive compounds, particularly polyphenols and anthocyanins. These compounds are known to induce cell cycle arrest and promote apoptosis (programmed cell death) in cancer cells.
The observed anti-proliferative effects of sweet potato align with previous research, indicating that bioactive components in sweet potato leaves, such as phenolic acids and flavonoids, can inhibit cancer cell growth.
While the current study confirms the cytotoxic effects of sweet potato extracts, future research should focus on identifying specific bioactive compounds, understanding their molecular mechanisms, and evaluating their effects on gene expression and cancer progression.
Overall, the study findings emphasize the importance of incorporating sweet potato leaves and stems into regular diets, not only for their nutritional benefits but also for their potential role in cancer prevention.
Future Directions
For a deeper understanding of the anticancer mechanisms, future studies should characterize and identify the key bioactive compounds responsible for sweet potato's anti-proliferative effects, explore their impact on gene regulation, and investigate their role in cancer cell cycle progression and apoptosis.