Granatin B and punicalagin from Chinese herbal medicine pomegranate peels elicit reactive oxygen species-mediated apoptosis and cell cycle arrest in colorectal cancer cells.

BACKGROUND

Colorectal cancer ranks among the most common cancers. 5-Fluorouracil (5-FU) based first-line chemotherapy for colorectal cancer treatment often leads to chemoresistance and gastrointestinal mucositis.

PURPOSE: This study aimed to find potential therapeutic agents from herbal medicine with anti-colorectal cancer and anti-mucositis activities.

METHODS

Chinese medicine theory, network pharmacology analyses, and antioxidant activity coupled with liquid chromatography tandem mass spectrometry analyses were used to identify potential bioactive compounds. HT-29 human colorectal cancer cell culture and xenograft tumor models were employed to study anti-colorectal cancer efficacy. Lipopolysaccharide-induced RAW 264.7 and 5-FU treated Dark Agouti rats were used to evaluate anti-inflammatory and anti-mucositis activities. Histological staining, immunofluorescence imaging, western blots, and flow cytometric analyses were employed to explore the underlying mechanisms.

RESULTS

Both Chinese medicine theory and network pharmacology analyses indicated pomegranate peels as a potential anti-colorectal cancer and anti-mucositis agent. Antioxidant activity coupled with liquid chromatography tandem mass spectrometry analyses revealed granatin B and punicalagin as the most potent antioxidant compounds in pomegranate peels. Granatin B and punicalagin demonstrated superior anti-colorectal cancer activities in both cell culture and xenograft tumor models. Granatin B and punicalagin also exhibited strong anti-inflammatory activities in lipopolysaccharide-induced RAW264.7 cells and anti-mucositis activities in 5-FU-treated rats. Mechanistic studies revealed that granatin B and punicalagin induced reactive oxygen species-mediated S-phase cell cycle arrest and apoptosis in HT-29 cells. Moreover, these compounds sensitized HT-29 cells to 5-FU-induced cell death and S-phase cell cycle arrest.

CONCLUSION

We report that granatin B and punicalagin exhibit superior anti-colorectal cancer and anti-mucositis activities. To the best of our knowledge, these results are novel and suggest that utilizing phenols from herbal medicine, such as granatin B and punicalagin, to target reactive oxygen species may be an innovative therapy to treat colorectal cancer and intestinal mucositis.