A recent study revealed that polyphenols found in peanut skins may inhibit the growth and proliferation of childhood leukemia cells. 

In the study, published in Current Developments in Nutrition, researchers from the University of Wisconsin–Madison utilized a polyphenol-rich peanut skin extract (PSE) prepared using an acetone/water/acetic acid solution (70:29.5:0.5 v/v/v). The researchers evaluated the cytotoxic properties of PSE on Jurkat cells, a model established from a patient with acute T-cell leukemia. The researchers demonstrated that PSE reduced the proliferation of cultured Jurkat leukemia cells for up to 72 hours after application, though the findings remain preliminary.

The researchers employed multiple methods to assess the efficacy and nutritional relevance of peanut polyphenols:

• Cell viability assays: RealTime-Glo MT Cell Viability Assay and XTT Assay were used to evaluate cytotoxic properties of PSE at different concentrations and time points.
• Bioaccessibility analysis: Caco-2 cells were used to examine intestinal absorption and metabolism of PSE phenolics. PSE was applied to the apical chamber at 1,000 ng/μL and incubated for 4 hours at 37°C.
• UHPLC-MS/MS analysis: Phenolics in PSE, media from both sides of Caco-2 membranes, and those interacting with Jurkat cells were analyzed using this technique.
• Data processing: Freestyle 1.8 SP2 and Compound Discover 3.3 Software were utilized for data analysis.

Among the key findings included:

• PSE inhibited Jurkat cell viability at 24, 48, and 72 hours postapplication, as determined by RealTime-Glo Assay.
• Cell proliferation rates were significantly reduced at 72 hours, measured by XTT assay.
• Procyanidin A2 was identified as the most abundant phenolic compound extracted from Jurkat cells treated with PSE and was found in the basolateral compartment, supporting its bioaccessibility.

Peanut skins contain various polyphenolic compounds, including resveratrol, phenolic acids, flavonoids, flavonols, and isoflavones, which are believed to act synergistically to inhibit cancer cell development. Specifically, procyanidins, phytosterols, and resveratrol have shown cancer-preventative qualities in earlier research:

• Phytosterols: May prevent cancer cell growth and spread, potentially inhibiting lung, gastric, ovarian, prostate, colorectal, and breast cancers.
• Resveratrol: Has shown promise in preventing cancer cell invasion and cutting off the blood supply to growing tumors in cancers like breast, lung, colorectal, prostate, brain, and bladder.
• Procyanidins: Appear to reduce inflammation and kill cancer cells by preventing their growth and division.

The paper-thin skins of peanuts were also noted to contain bioactive compounds, including antioxidants that can help neutralize free radicals, along with nutrients such as protein, fiber, carbohydrates, fats, vitamins, and minerals. The researchers emphasized that while this study is promising, further investigation is needed to fully understand the role of peanut polyphenols in cancer prevention and treatment.

The study was funded by The Peanut Institute.