Elicitation under salinity stress increases flavonoid content and antioxidant activity in cowpea (Vigna unguiculata) sprouts

Legumes are often used as a source of natural antioxidant. Elicitation is a promising alternative way of improving antioxidant compounds in legumes sprouts, such as flavonoid compound. NaCl stress can be used as one of abiotic elicitation that induced non-enzymatic defense in a plant, thus increases secondary metabolites which enhance the antioxidant capacity. However, its effects on cowpea (Vigna unguiculata) germination need to be more studied. In this study, we germinated cowpea under increasing salinity (0, 50, 100, 150mM NaCl) to investigate its effect on the total flavonoid content and antioxidant activity (radical scavenging activity and reducing power). Total flavonoid content and radical scavenging activity of cowpea sprouts increase along with increasing NaCl concentration. Meanwhile, only 150mM NaCl showed significantly higher reducing power among other concentrations. Total flavonoid content have a high correlation with radical scavenging activity (r=0,962; p<0,01) but not correlated with reducing power (r=0,137; p>0,05). This research results proved that elicitation using 150mM NaCl could be used as one of the strategies to enhance bioactive compound and antioxidant activity in legumes, thus increasing its potential to be developed as an antioxidant-based functional food.