Alterations in antioxidant activity and free radical scavenging capacity in seeds of lentil (Lens culinaris Medik.) genotypes under arsenate exposure

Lentil (Lens culinaris Medik.), being one of the first crops to be domesticated and cultivated by man, have been and continue to be an important food source for over 8000 years [1]. The high protein content of lentil has made them a nutritious substitute for meat. In fact, 100 grams of lentil has as much protein as 130 grams of meat in addition to beneficial dietary fiber [2]. The low phytate content of lentil makes micronutrients like iron and zinc easily available to human nutrition. Lentil and lentil-based food items are excellent to lower rates of cardiovascular disease, angina and type-II diabetes and hypertension. The balance of about 1⁄4 protein and 3⁄4 carbohydrate and fiber is ideal for regulating blood sugar–a low glycemic index [3, 4]. Thus, lentil has become more important to the diets of people in the Middle East, West Asia, parts of Europe and South Asia where they are placed on the table in some forms for nearly every meal [3-9]. Arsenic (As) is a wide-spread toxic metalloid. Groundwater contamination by As and its entry into crops through water-soil-plant system has caused great environmental concern. The bioaccumulation of As in crop plants has huge negative impact for public health issues [10], and this is of great environmental concern because As is known to be a carcinogen and a powerful co-mutagen [11, 12]. Alarmingly, as is gradually entering into pulse food system through its accumulation in major legumes like chickpea, pea, lentil, beans and grasspea [13-18]. Negative impact of as on nodulation and nitrogen-fixation capacity has been reported in Indian genotypes of black gram (Vigna mungo) [19]. As can induce severe oxidative stress in legume plants through alteration in cellular and metabolic system, severely jeopardizing plant growth and inflicting damage to yield and nutritional quality of grain, and may also render the Abstract Arsenic (As) is a wide-spread carcinogenic and toxic metalloid. Seeds of lentil (Lens culinaris Medik.) genotypes are rich in proteins, antioxidants (flavonoids, phenolics) and free radical-scavenging capacity. Despite grown in As-contaminated soil in vast areas of south and south-east Asia and sensitivity of lentil genotypes to Asinduced oxidative stress, effects of As exposure to seed nutritional composition in this important food legume is still unknown. Present study was endeavored to investigate effects of arsenate (As V) on antioxidant and free radical scavenging activity on seeds of three lentil genotypes in laboratory conditions. Plants were grown in pot soil spiked with 100 mg As kg −1 , added as Sodium arsenate, in a completely randomized block design till maturity. As exposure significantly reduced antioxidant activity and free radical scavenging capacity of IPL406 and WBL58 seeds but alteration was not significant in case of B256 genotype. Total phenolics and flavonoid contents, potential FRAP test, DPPH free radical scavenging capacity, and hydroxyl and superoxide scavenging capacity was decreased in Astreated IPL406 and WBL58 seeds compared to control. Total seed protein content, however, did not show any significant alterations in As-treated three genotypes in relation to control. The results suggested genotypic differences of lentil varieties in seed phytochemical constituents under As exposure and seeds of B256 was found superior in antioxidant and free radical scavenging capacity. Obviously, a focused germplasm strategy is required to identify genotype/s of lentil which is relatively safe to consume in Ascontaminated regions.