Antioxidant Activity of Faba Bean Extracts

*Wojciech Rybiński, Magdalena Karamać, Katarzyna Sulewska and Ryszard Amarowicz*

## **Abstract**

Phenolic compounds were extracted from seeds of 22 cultivars of faba bean (*Vicia faba* L.) by using 80% (v/v) aqueous acetone. The total phenolic compound and condensed tannins contents of the extracts and their antioxidant activity were determined using the Folin-Ciocalteu's phenol reagent, vanillin/HCl method, and ABTS and FRAP assays, respectively. The content of total phenolic compounds ranged from 40.7 to 66.1 mg/g extract and from 326 to 574 mg/100 g seeds. Contents of condensed tannins ranged from 2.40 to 49.9 mg/g extract and from 22.2 (FAB) to 365 mg/100 seeds. The extracts and seeds were characterized by Trolox equivalent antioxidant capacity (TEAC) values ranging from 0.550 (FAB 443) to 1.030 mmol Trolox/g extract (FAB 187) and from 4.85 (FAB 318) to 9.81 mmol Trolox/100 g 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) to 7.90 mmol Fe2+/100 g seeds (FAB 187). The total phenolic content of faba bean extract was correlated with the results of the ABTS (r = 0.864) and FRAP (r = 0.862) assays. The coefficients of correlations between the contents of condensed tannins and ABTS and FRAP results were 0.543 and 0.862. We also noted a correlation between results of ABTS and FRAP assays (r = 0.795).

**Keywords:** faba bean, *Vicia faba* L., phenolic compounds, antioxidant activity, ABTS assay, DPPH assay

### **1. Introduction**

Phenolic compounds of plant origin can inhibit or delay the oxidation of nutrients present in food products. In the human organism, natural antioxidants can protect lipids, proteins, and DNA against reactive oxygen and nitrogen species (ROS, RNS) [1, 2]. Results of numerous research groups demonstrate the protective effect of consuming phenolic-rich grains, legumes, oilseeds, fruits, berries, and nuts against several chronic diseases [3–7].

In human nutrition, legumes are an important source of proteins, starch, oligosaccharides (prebiotics), dietary fibers, vitamins, and minerals [8, 9]. As a rich source of natural antioxidants, legumes can play an important role in cardio and cancer protection [5, 10–15].

Faba bean (*Vicia faba*) is a species of Fabaceae family. It is native to South America, North Africa, and southwest and south Asia and is extensively cultivated elsewhere. Similar to other legumes, faba bean seeds contain phenolic compounds

[16] including condensed tannins [17–19]. The antioxidant potential of faba bean was determined using DPPH, FRAP, and ORAC assays [17, 20, 21]. Very high antioxidant capacity of *Vicia faba* sprouts was confirmed by Okumura et al. [22].
