A systematic determination of polyphenols constituents and cytotoxic ability in fruit parts of pomegranates derived from five Chinese cultivars

Rui Li, Xiang Gui Chen, Kun Jia, Zhen Ping Liu, Hai Yan Peng

Plant polyphenols derived from pomegranates are natural health-promoting components, and their bioactivities are well proved. However, the systematic studies of polyphenols constituents and cytotoxic ability in fruit parts of pomegranates derived from different Chinese cultivars have not been studied yet. In this report, a validated and sensitive HPLC-DAD method and fluorescence spectrophotometric method was established for quantitative analysis of four polyphenols and total phenolic content (TPC) in fruit parts of pomegranates (including peels, flesh, seeds, juices and leaves) derived from five Chinese cultivars, respectively. HPLC analysis was performed on the YMC ODS-A C18 column with gradient elution of MeOH and 0.1 % TFA. Four polyphenols including gallic acid, ellagic acid, punicalagin A&B and punicalin A&B exhibited satisfactory linearity in the concentration ranges of 20-320, 39-624, 74-1184 and 38-608 μg/mL, respectively. The results demonstrated that the amounts of TPC and four polyphenols in different fruit parts of pomegranates varied significantly. Peels of Sour-YRP possessed the highest content of punicalagin A&B (125.23 mg/g), whereas other three polyphenols exhibited only trace. Among the five Chinese cultivars, Sour-YRP contained the highest content of TPC (688.61 mg/g) and could be considered as the desirable botanical source to obtain polyphenols. It is also discovered that low-maturity pomegranate might possessed much higher TPC than high-maturity pomegranate. The optimized HPLC-DAD method could be used for quality control of different pomegranates by identification and quantification of its main polyphenolic components. Furthermore, the in vitro cytotoxicity of different pomegranates fruit parts to cancer cells was evaluated. We discovered that peels and flesh extract of Sour-YRP significantly inhibited the proliferation of HepG2 and Hela cancer cells lines. The results of this work are promising for further investigation and development of pomegranates as therapeutic agent for the treatment of cancer.