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Antioxidant activity of Pseudolysimachion spicatum (L.) Opiz (Scrophulariaceae)
The purpose of this study was to investigate radical scavenging properties and antioxidant activity of leaf, stem, and flower of Pseudolysimachion spicatum (L.) Opiz (=Veronica spicata L.). P. spicatum is a perennial herb with erect or ascending stem up to 60cm high and blue flowers arranged in dense, many flowered terminal raceme up to 30cm long. P. spicatum was collected in Velebit Mountain and methanolic extracts of leaf, stem, and flowers were prepared by ultrasonication. Content of total phenols was determined by using Folin-Ciocalteu reagent, content of flavonols using aluminium chloride and content of phenolic acids with nitrite-molybdate reagent. Antioxidant activity was established using following methods: radical scavenging activity of 2,2-diphenyl-1-picrylhydrazyl (DPPH) free-radical, reducing power, chelating activity and β-carotene-linoleic acid assay. The extracts were rich in polyphenols (211–831mg/g), phenolic acids (2–27mg/g) and flavonoids (16–37mg/g). In all the analyses the extracts were found to possess marked antioxidant activities. The activity of extracts in β-carotene-linoleic acid assay was significantly higher than the activity of butylated hydroxyanisole (BHA) (ANOVA, p<0.05). In most of the assays, activity of stem and leaf extracts was somewhat less pronounced than the activity of flower extract. However, leaf extract demonstrated the strongest reducing properties. DPPH radical scavenging activity correlated well with content of total phenols (r 2=0.89, p<0.0001). That suggests that phenolic compounds play an important role in antiradical activity of investigated plant organs.