Session 3 . Application of natural products in human and ani - mal nutrition , pharmacy and cosmetic industries

The antioxidant capacity of 80% methanolic extracts from stems, leaves, flowers and mature seeds of common and tartary buckwheat during growth period was determined against ABTS·+ (TEAC assay) and O2 radicals (PCL assay). The antioxidant capacity of aerial parts of buckwheat was highly differentiate during growth period. The highest antioxidant capacity was noted in flowers of common buckwheat during growth period and in leaves of tartary buckwheat during flowering. It was concluded that both applied assay can be used as a tool for the selection of high utility material from buckwheat. Introduction: Buckwheat is an important crop in some areas of the world which refers to any member of Fagopyrum family (Polygonaceae). There are many species of buckwheat and mainly nine species have agricultural meaning. Among them, only common buckwheat (F. esculentum) and tartary buckwheat (F. tartaricum) are of increasing concern (Jiang et al., 2007). The genus Fagopyrum is an important native source of flavonoids and good source for rutin extraction (Fabjan et al., 2003; Kalinova & Dadakova, 2004). These compounds, mainly responsible for the antioxidant potential of buckwheat-derived material, have recently been shown to be potent antioxidants in cultured cells (Wolf et al., 2008), an excellent metal ion chelators and can prevent copper-catalysed peroxidation of low density lipoproteins (Scalbert et al., 2005). Human studies of flavonoids have also demonstrated effects that can in part be attributed to their antioxidant action (Williamson & Manach, 2005). Nowadays, healthiness is considered as one of the key drivers in food business, and both agricultural and pharmaceutical industry look for the natural material of high antioxidant capacity as a potentially a new source of flavonoids. Therefore, the intention of the present work was to find out whether antioxidant capacity assays can serve as a tool for selection of high antioxidant material from aerial parts of buckwheat. Materials and Methods: In the year 2008 common buckwheat variety Volma and tartary buckwheat were sown on an experimental fields in Bałcyny near Ostróda in Production-Experimental Station of the University of Warmia and Mazury in Olsztyn. During vegetation period there was no mechanical or chemical treatment of the growths. The material for analysis was harvested in three stages (early flowering, flowering and seed formation, and seed ripening) and divided into the parts for analysis (leaves, stems, and flowers). About five randomly selected plants per each stage were collected to obtain enough aerial parts of both type of buckwheat. This material was immediately frozen and freeze-dried. The seeds were harvested in optimum maturity and were also freeze-dried. Material was milled into dust and it was stored at –40°C in polyethylene bags. About 100 mg of pulverized buckwheat material was extracted with 1 mL of 80% methanol at room temperature. Next, the mixture was vortexed for 30 s, sonicated for 30 s and centrifuged for 5 min (13200 × g at 4oC). That step was repeated five times and supernatants were collected in 5 mL flask. Finally, all extracts were kept at –40oC prior to further analysis. The AC of the extracts was evaluated against stable, non-biological radicals such as ABTS·+ radical cation (TEAC assay) using a spectrophotometer UV-160 1PC with CPS-Controller (Shimadzu, Japan), and against the key reactive oxygen intermediate — O2 radical by photochemiluminescence (PCL) assay using Photochem® apparatus (Analytik Jena, Leipzig, Germany) as it was reported previously (Zielińska et al., 2007). The AC was presented independently of the techTable 1. The antioxidant capacity of aerial parts of common (CB) and tartary buckwheat (TB) provided by TEAC assay (μmol