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The antioxidant activity and identification of phenolic compounds of seven edible guava ( Psidium guajava ) cultivars that varied in colour from white to pink were examined. In the DPPH assay all four pink-pulp guavas (Barbie Pink, Homestead, Sardina 1, Sardina 2) included in the study showed higher activity than the white pulp cultivars (Yen 2 and Sayla) and less than the red pulp guava cultivar (Thai Maroon). In the ABTS + assay this trend was the same up to 20 min, but from 20 to 40 min Barbie Pink showed lower activity than the white guavas. Twenty-one compounds were characterised in the cultivars, and ten of them are reported for the first time in this fruit. Principle component analysis was performed to identify differences in chemistry among these cultivars. Our results suggest that the antioxidant activity and phytochemical composition of P . guajava vary significantly according to the cultivar and pulp colour. [ABSTRACT FROM AUTHOR]

Abstract: Many species of Myrtaceae are cultivated in home gardens throughout the tropics for their edible fruit, and have been used in traditional medicine to treat several inflammatory conditions. Fruit phenolics are important dietary antioxidant and anti-inflammatory constituents. We have investigated the antiradical activity, total phenolic content (TPC), and total anthocyanin content (TAC) of 14 underutilized Myrtaceae fruits, namely Eugenia aggregata, E. brasiliensis, E. luschnathiana, E. reinwardtiana, Myrciaria cauliflora, M. dubia, M. vexator, Syzygium cumini, S. curranii, S. jambos, S. javanicum, S. malaccense, S. samarangense, and S. samarangense var. Taiwan pink. An HPLC-PDA method was developed to quantify the amounts of cyanidin 3-glucoside (1), delphinidin 3-glucoside (2), ellagic acid (3), kaempferol (4), myricetin (5), quercetin (6), quercitrin (7), and rutin (8) present in MeOH extracts of the fruit. TPC ranged from 3.57 to 101mg/g, TAC ranged from undetectable to 12.1mg/g, and antiradical activity, measured as DPPH˙ IC50, ranged from very active (19.4μg/ml) to inactive (389μg/ml). [Copyright &y& Elsevier]