**3.3 Statistical analysis**

In our study, for the first time, a correlation was calculated between the content of phenolic compounds in the faba bean extracts and their antioxidant activity. The

**Figure 1.** *Correlation between the total phenolic contents and the results of ABTS and FRAP assays.*

**47**

**Figure 2.**

*Correlation between the content of tannins and the results of ABTS and FRAP assays.*

*Antioxidant Activity of Faba Bean Extracts DOI: http://dx.doi.org/10.5772/intechopen.85534*

lentil, and green lentil [44].

coefficients of correlation between the total phenolic content and the results of the ABTS and FRAP assays were 0.864 and 0.862, respectively (**Figure 1**). The correlations between the content of condensed tannins and results of ABTS and FRAP assays were weaker and characterized by r = 0.543 and r = 0.528 (**Figure 2**). A correlation was also observed between the results of both assays (r = 0.795) (**Figure 3**). In our previous study, we noted a correlation between the total phenolic content and ABTS and FRAP results determined for red bean (r = 0.997 and 0.997, respectively) [35], white (r = 0.480 and 0.850, respectively) [29], and grass pea (r = 0.881 and 0.781, respectively) [32]. Statistically significant correlations between the content of total phenolics and TEAC as well as between the content of condensed tannins and TEAC (r = 0.857 and 0.787, respectively) were reported for extracts obtained from seeds of faba bean, broad bean, adzuki bean, red bean, pea, red

In the principal component analysis (PCA) (**Figure 4**), the two first components accounted for 93.6% of the total variability between the faba bean cultivars. The analysis includes the content of total phenolic compounds and condensed tannins

*Antioxidant Activity of Faba Bean Extracts DOI: http://dx.doi.org/10.5772/intechopen.85534*

*Plant Extracts*

to 7.90 mmol Fe2+/100 g seeds (FAB 187).

Fe2+/g) [29], and lupin 0.046–0.064 [31].

**3.3 Statistical analysis**

seeds (FAB 187). Ferric-reducing antioxidant power (FRAP) values varied from 0.595 (FAB 443) to 0.908 mmol Fe2+/g extract (FAB 5023) and from 4.61 (FAB 297)

The results of ABTS assay obtained in this study for faba bean extracts were much higher than those reported before for extracts of grass pea (0.017–0.037 mmol Trolox/g) [32], cow pea (0.285–0.665 mmol Trolox/g) [43], white bean (0.0270– 0.043 mmol Trolox/g) [29], mung bean (0.021–0.031 mmol Trolox/g) [35], and lupin (0.260–0.620 mmol Trolox/g) [31]. The results of FRAP assay were also much higher than those reported for extracts of grass pea (0.045–0.120 mmol Fe2+/g), [32], cow pea (0.487–1.566 mmol Fe2+/g) [43], white bean (0.066–0.089 mmol

In our study, for the first time, a correlation was calculated between the content of phenolic compounds in the faba bean extracts and their antioxidant activity. The

**46**

**Figure 1.**

*Correlation between the total phenolic contents and the results of ABTS and FRAP assays.*

coefficients of correlation between the total phenolic content and the results of the ABTS and FRAP assays were 0.864 and 0.862, respectively (**Figure 1**). The correlations between the content of condensed tannins and results of ABTS and FRAP assays were weaker and characterized by r = 0.543 and r = 0.528 (**Figure 2**). A correlation was also observed between the results of both assays (r = 0.795) (**Figure 3**).

In our previous study, we noted a correlation between the total phenolic content and ABTS and FRAP results determined for red bean (r = 0.997 and 0.997, respectively) [35], white (r = 0.480 and 0.850, respectively) [29], and grass pea (r = 0.881 and 0.781, respectively) [32]. Statistically significant correlations between the content of total phenolics and TEAC as well as between the content of condensed tannins and TEAC (r = 0.857 and 0.787, respectively) were reported for extracts obtained from seeds of faba bean, broad bean, adzuki bean, red bean, pea, red lentil, and green lentil [44].

In the principal component analysis (PCA) (**Figure 4**), the two first components accounted for 93.6% of the total variability between the faba bean cultivars. The analysis includes the content of total phenolic compounds and condensed tannins

**Figure 2.** *Correlation between the content of tannins and the results of ABTS and FRAP assays.*

**Figure 3.** *Correlation between the results of FRAP and ABTS assays.*

**Figure 4.** *Results of the principal component analysis (PCA).*

in seeds as well as their antioxidant potential determined using ABTS and FRAP methods. A considerable variability in terms of the analyzed traits expressed jointly with the grates Mahalanobis distance was recorded for sample 18 from Afghanistan (FAB 187) and samples 8, 10, and 11 from Sudan (FAB 297), Yemen (FAB 219), and Israel (FAB 6318). The close clustering was observed for seeds from Sudan, Yemen, and Afghanistan and for seeds from Morocco, Sudan, and Tajikistan (sample 4, 7, and 15; FAB 5019, FAB 225, and FAB 354).

The hierarchical cluster analysis (**Figure 5**) showed several pairs of faba bean accessions (e.g., FAB 337 and FAB 202, FAB 5023 and FAB 604). Two main clusters were observed. The first contained 16 accessions, whereas the second contained only 6. The presence of similar pairs of faba bean accessions from different countries confirms the limitation of the hierarchical cluster analysis in the discrimination of the geographical origin of samples.

**49**

*Antioxidant Activity of Faba Bean Extracts DOI: http://dx.doi.org/10.5772/intechopen.85534*

**4. Conclusions**

*The hierarchical cluster analysis.*

**Acknowledgements**

**Conflict of interest**

assays.

**Figure 5.**

The extracts obtained from faba bean were characterized by a high content of phenolic compounds and condensed tannins. Their antioxidant potential was higher than that reported previously for the extracts of other legume seeds. The content of total phenolics and condensed tannins in the faba bean extracts strongly influenced the antioxidant activity of extracts determined using ABTS and FRAP

The technical assistance of Kamila Penkacik is acknowledged.

The authors declare no conflict of interest.

### *Antioxidant Activity of Faba Bean Extracts DOI: http://dx.doi.org/10.5772/intechopen.85534*

*Plant Extracts*

**Figure 3.**

**Figure 4.**

**48**

in seeds as well as their antioxidant potential determined using ABTS and FRAP methods. A considerable variability in terms of the analyzed traits expressed jointly with the grates Mahalanobis distance was recorded for sample 18 from Afghanistan (FAB 187) and samples 8, 10, and 11 from Sudan (FAB 297), Yemen (FAB 219), and Israel (FAB 6318). The close clustering was observed for seeds from Sudan, Yemen, and Afghanistan and for seeds from Morocco, Sudan, and Tajikistan (sample 4, 7,

The hierarchical cluster analysis (**Figure 5**) showed several pairs of faba bean accessions (e.g., FAB 337 and FAB 202, FAB 5023 and FAB 604). Two main clusters were observed. The first contained 16 accessions, whereas the second contained only 6. The presence of similar pairs of faba bean accessions from different countries confirms the limitation of the hierarchical cluster analysis in the discrimina-

and 15; FAB 5019, FAB 225, and FAB 354).

*Results of the principal component analysis (PCA).*

*Correlation between the results of FRAP and ABTS assays.*

tion of the geographical origin of samples.

**Figure 5.** *The hierarchical cluster analysis.*
