Variability of the polyphenolic content and antioxidant capacity of methanolic extracts of pomegranate peel

Pomegranate is a popular food due to its high polyphenolic content and antioxidant capacities. Pomegranate peel is used in traditional medicine and has greater antioxidant capacity compared with other parts of pomegranate. This study elucidated the differences in the polyphenolic content and antioxidant capacities of the methanolic extracts of pomegranate peel from different geographical localities including Australia, China and USA. The results showed that pomegranate peel from China generally had higher polyphenolic contents and antioxidant capacities than those from Australia and USA. The total contents of polyphenols and flavonoids, but not condensed tannins, were closely correlated with their total antioxidant activities. Differentiation of extracts from Chinese pomegranate peel to those extracts originating from Australia and USA were achieved by multivariate analyses based on their polyphenolic content and antioxidant capacities. The results indicate that polyphenols are useful indicators to differentiate the geographical localities of pomegranate peel and to predict their antioxidant activities. Overall, geographical localities should be taken into consideration when evaluating the polyphenolic content and antioxidant activity of pomegranate peel.