Proceedings Volume 2010 (format .pdf) - SimpBTH

Antioxidant activityDPPH- Free radical-scavenger activityThe free radical-scavenger activity was determined by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay, as described in [23, 26] .The antiradical activity of each fraction was evaluated using a dilutions series, inorder to obtain a large spectrum of sample concentrations.The reduction of DPPH absorption is indicative of the capacity of the flavonoidicvegetal pigments to scavenge free radicals, independently of any enzymaticactivity. The extraction methods resulted in different flavonoidic vegetal pigments,with diverse compositions, either in qualitative or quantitative terms (Table 1). Allfractions promoted the reduction of DPPH (Figure 2). The best free radicalscavengeractivity was reported for the PVH5 and fractions PVA1 and PVH4,respectively (Figure 2). The lowest activity was observed for fraction PVH7. It isinteresting to note that all these flavonoidic vegetal pigments possessed highreactivity and had an important flavonoid component (namely fractions PVH5 andPVA1). Fraction PVH7 exhibited the weakest reactivity, significantly differentfrom any other extract, in spite of having a considerable proportion of flavonoidsand caffeoylquinic-type acids.This low reactivity could be related to the presence of other compounds (e.g.sugars, amino acids) that could somehow interfere in the total reactivity of thefraction.Scavenging activity on DPPH free radicalScavenging activity (%)8280787674727080.3478.9777.878.21 78.3773.82 74.14PVA1 PVA2 PVA3 PVH4 PVH5 PVH6 PVH7Fig 2. Scavenging activity on DPPH free radicalChemiluminescence testsTaking into account the importance and therapeutical role of vegetal antioxidants,the flavonoidic extracts have been tested by chemiluminescence using luminol andhydrogen peroxide at pH = 8.6 in presence of TRIS + HCl, following the proceduredescribed in [25]. The data are reported in table 3.235