ISOLATION, IDENTIFICATION, ANTIMICROBIAL AND ANTIOXIDANT ACTIVITY OF PUNICALAGIN FROM POMEGRANATE PEEL

Pomegranate (Punica granatum L.) has antioxidant, antimicrobial and antifungal properties. Pomegranate peel is rich in polyphenols such as ellagitannins, especially punicalagin which are the most abundant compound with high bioavailability. This study aimed to extract, isolate and identify punicalagin from pomegranate peel and analyze the antimicrobial activity against Escherichia coli, Staphylococcus aureus, Salmonella choleraesuis, Bacillus cereus and 8 strain isolated from bovine mastitis and the determination of antioxidant activity of purified punicalagin (PN) and pomegranate peel extract (PP). The pomegranate peel was separated from the fruit and dried in an oven at 40°C for 48 h. For the extraction of punicalagin and obtention of pomegranate crude extract, methanol and ethanol were used, respectively. After solvent removal, the crude extract was introduced in a Flash Chromatography (FC) system for isolation of punicalagin. All fractions were analyzed by High Performance Liquid Chromatography using a punicalagin commercial standard for quantification. The microdilution method determined the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC). The antioxidant activity was analyzed by the DPPH method. The results showed a suitable punicalagin isolation by FC by the presence of α and β-punicalagin in the isomers mixture. The DPPH values were 2023.51 and 2379.4 μmol of TE. g-1 of PN and the extract (PP), respectively. The experimental results revealed that PN present in pomegranate peel at 85%, is responsible for the antioxidant activity. The MIC of punicalagin was active at 200 - 750 µg.mL-1 optimal values. The MBC is between 200 and 1500 µg.mL-1 with a bactericidal effect. The results of the antimicrobial assay revealed that PN was more active against bovine mastitis strains, S. aureus and E. coli when compared to S. choleraesuis. The literature on the MIC of punicalagin against bovine mastitis isolates has not been reported until today. In conclusion, we can confirm the effectiveness of punicalagin as an important natural product with both antimicrobial and antioxidant properties, giving importance to the use of pomegranate peel disposal with potential in many areas such as food and pharmaceutical.