Pomegranate peel-derived punicalagin: Ultrasonic-assisted extraction, purification, and its α-glucosidase inhibitory mechanism

The pomegranate peel is a by-product of pomegranate fruit rich in polyphenols. In this study, pomegranate peel polyphenols were explored using LC-MS/MS, and punicalagin was the most abundant compound. The highest yield (505.89 +/- 1.73 mg/g DW) of punicalagin was obtained by ultrasonic-assisted extraction (UAE) with the ethanol concentration of 53%, sample-to-liquid ratio of 1:25 w/v, ultrasonic power of 757 W, and extraction time of 25 min. Punicalagin was further purified by the macroporous resin D101 and prep-HPLC, reaching the purity of 92.15%. The purified punicalagin had the IC50 of 82 +/- 0.02 mu g/mL against alpha-glucosidase, similar to the punicalagin standard with IC50 of 58 +/- 0.014 mu g/mL, both exhibiting a mixed inhibitory mechanism. Molecular docking further revealed that a steric hindrance with the intermolecular energy of - 7.99 kcal/mol was formed between punicalagin and alpha-glucosidase. Overall, pomegranate peel is a promising source of punicalagin to develop anti-diabetic functional foods.

Automated summary

Punicalagin, the main compound in pomegranate peel, has the potential to develop anti-diabetic functional foods. Ultrasonic-assisted extraction can obtain the highest yield of punicalagin, and the purified punicalagin shows significant inhibitory activity against alpha-glucosidase.