*3.3. Antioxidant Activity*

The DPPH and ORAC values obtained are summarized in Table 3. Regarding DPPH, one-way ANOVA with a Tukey post hoc as the statistical test shows a significant difference (*p* < 0.05) between the results for polyphenolic enriched extracts of skin and flesh. For instance, skins show a higher antioxidant activity, with an average of 10.95 μg extract/mL while the flesh average is 20.15 μg extract/mL. At the individual level, T. Atkins skin presents the greater antioxidant value (IC50 = 9.97 μg extract/mL), followed by Keitt skin (IC50 = 11.93 μg extract/m). Both are higher than findings for the skin of cultivars from Chile reporting a value of IC50 = 46.39 μg extract/mL for T. Atkins cultivar and IC50 = 32.23 μg extract/mL for Pica cultivar [34]. This trend is also found when comparing flesh from these cultivars, where IC50 = 122.22 μg extract/mL and IC50 = 73.76 μg extract/mL were reported for T. Atkins and Pica mangoes [34], lower than our results for Keitt (IC50 = 17.78 μg extract/mL) and T. Atkins (IC50 = 22.51 μg extract/mL) cultivars. On the other hand, when comparing our DPPH values expressed as mmol TE/g extract (in respect to Trolox IC50 = 5.62 μg/mL) with reports in the literature, it is observed that Keitt and T. Atkins skin values fit in the range between α-tocopherol and enju extract (0.42–0.76 mmol TE/g extract), which are existing antioxidant food additives [56].



1 Values are expressed as mean ± S.D. 2 Different superscript letters in the same column indicate differences are significant at *p* < 0.05. ORAC: oxygen radical absorbance capacity; DPPH: 2,2-diphenyl-1-picrylhidrazyl method.

In respect to ORAC evaluation, the results also show significant di fferences (ANOVA, *p* < 0.05) between skin and flesh extracts. In fact, skins exhibit a higher antioxidant activity, with an average of 9.66 mmol TE/g extract, while the flesh extract average is 4.68 mmol TE/g extract. At the individual level, T. Atkins skin also shows the highest antioxidant value (11.02 mmol Trolox equivalents/g extract), followed by Keith skin (8.30 mmol TE/g extract), while the lowest value is shown by T. Atkins flesh (3.56 mmol TE/g extract). A previous study on the flesh of di fferent cultivars from Spain reported an ORAC value of 156.6 μmol TE/100 g fresh weight for T. Atkins cultivar and higher values for Francis and Ataulfo cultivars (225.8 and 326.6 μmol TE/100 g fresh weight, respectively) [8], all of which are lower than our results for Keitt flesh (357.1 μmol TE/100 g fresh weight) and T. Atkins flesh (606.4 mmol TE/100 g fresh weight).

Finally, a correlation analysis was carried out between total polyphenolic contents (TPC) values (Table 1) and the DPPH and ORAC results. The findings indicate a significant positive correlation (*p* < 0.05) between both DPPH (mmol TE/g extract) and ORAC antioxidant findings (*r* = 0.989), and between TPC and ORAC values (*r* = 0.910), and a significant negative correlation (*p* < 0.05) was found between the TPC results and DPPH values (*r* = −0.960). Therefore, our results align with previous studies reporting a correlation between the total polyphenolic contents and antioxidant activities of *Mangifera indica* cultivars [54].
