Total anthocyanin, flavonoid, polyphenol and tannin contents of seven pomegranate cultivars grown in Iran

Background. Pomegranates are healthy fruits rich in bioactive phytochemicals and widely consumed in the human diet. This study was designed to assess their physico-chemical properties and total polyphenolic compounds, along with antioxidant and ascorbic acid concentrations of the skin and juice of seven unstudied pomegranate cultivars grown in Iran. Materials and methods. Ten fruits of each of seven selected cultivars were picked. Methanolic extracts from the fruit skins as well as juices were subjected to an evaluation of their physico-chemical properties and phenolic content. Results. From the pomegranate cultivars studied, the highest juice concentration was measured in 'Zagh- -e-Zabol' (72.9 ±2.55%). The highest total soluble solids (18.79 ±1.06 °Brix) of juice, as well as the highest ascorbic acid (16.54 ±2.09 mg/100 g) and total anthocyanin content of skin [11.20 ±2.4 mg CyE (cyanidin- -3-glucoside equivalent)/L] were measured in 'Bajestan'. Total flavonoids were more concentrated in the skin of 'Siah-e-Zabol' [930 ±16 mg QuE (quercetin equivalent)/L]. In the juice of 'Rabab-e-Pust Ghermez' and 'Malas-e-Saveh' the highest concentrations of phenolic compounds were recorded [1082 ±12.8 mg GaE (gallic acid equivalent)/L] and tannins [6.55 ±0.5 mg TaE (tannic acid equivalent)/L], respectively. Conclusion. Significant differences were assessed between the skin and juice of the cultivars in terms of their physico-chemical properties and polyphenolic contents. The results showed higher levels of total tannins, phenolics and antioxidant activity in juice of pomegranate, whereas the skins possessed higher total flavonoid, anthocyanin and ascorbic acid content. Further phytochemical analysis are therefore needed to identify the most representative phenylpropanoids by LC-MS (liquid chromatography coupled to mass spectrometry) and to develop novel and promising dietary supplements.