The Effect of pH and Solvent Addition on Curcumin Solubility and its Impact on DNA Integrity in Escherichia coli strain HB101
By Divya Vattikonda, Bharat Raj, and Sophia Diep | Valley Christian High School, San Jose, California, United States
I. Abstract
Cancer’s rapid growth and unique mutations make targeted therapies challenging. Curcumin inhibits cell proliferation, induces apoptosis, and causes DNA damage, but its low solubility limits therapeutic potential. Using E. coli as a model for cancer cells, we hypothesized that increasing curcumin solubility with acetone would enhance its ability to damage DNA because lowering the pH may lead to crystallization, reducing solubility. Curcumin was dissolved in ethanol, with citrate (acidic) and tris (basic) buffers to adjust pH, and acetone tested as a solvent. Spectrophotometric analysis found the highest solubility at a pH of 3.5 (13.103 mg/mL) and the lowest at a pH of 8.0 (1.000 mg/mL). No crystallization occurred. Acetone had minimal impact on curcumin solubility. The E. coli exposed to curcumin grew 24 hours slower than controls, with acidic curcumin (pH 3-4) showing the least growth. We quantified DNA damage through gel electrophoresis. The E. coli exposed to curcumin had smears instead of a clear band with lower band intensity suggesting higher DNA degradation. The E. coli exposed to curcumin at a pH of 4 had the lowest band intensity, despite not having the lowest solubility. This may be due to increased protonation at lower pH, reducing reactive oxygen species production and DNA damage. These results indicate that higher curcumin solubility enhances its ability to damage DNA. We learned the importance of the mode of solubility in cancer drug development, though further experimentation on human cancer cells is required to accurately determine curcumin’s impact.
II. Research Poster
The research poster published, “The Effect of pH and Solvent Addition on Curcumin Solubility and its Impact on DNA Integrity in Escherichia coli strain HB101,” was received on June 10, 2025, and was reviewed and accepted on July 21, 2025. To contact editors and reviewers please click here.
