Hydrophilic and lipophilic antioxidant activities of guava fruits

The objectives of this study were to evaluate the hydrophilic antioxidant activity (AOAH) and the lipophilic antioxidant activity (AOAL); and their correlations with vitamin C, and total phenolic and beta-carotene contents in fresh guava fruits of one white flesh clone ('Allahabad Safeda') and three pink flesh clones ('Fan Retief', 'Ruby Supreme,' and an advanced selection). A ferric reducing antioxidant power assay was used to estimate both AOAH and AOAL from methanol and dichloromethane extracts, respectively. The white flesh clone, 'Allahabad Safeda,' showed higher levels of both AOAH [33.3 microM Trolox equivalents (TE)/g fresh weight (FW)] and AOAL (0.25 microM TE/g FW) than the pink flesh clones that ranged from 15.5 to 30.4 and from 0.12 to 0.13 microM TE/g FW for AOAH and AOAL, respectively. The AOAH was positively correlated with vitamin C (r = 0.92, p < 0.01) and total phenolic (r = 0.97, p < 0.01) but was negatively correlated with beta-carotene (r = -0.73, p = 0.03). The AOAL was not correlated with these antioxidants.