Fast Identification of Radical Scavengers from Securigera varia by Combining 13C-NMR-Based Dereplication to Bioactivity-Guided Fractionation

Abstract

Securigera varia (Fabaceae) is a common herbaceous perennial plant widely growing in Europe and Asia and purposely established for erosion control, roadside planting, and soil rehabilitation. The aim of this study was to determine the radical scavenging activity of a crude methanol extract of S. varia aerial parts by using the free radical DPPH (1,1-diphenyl-2-picrylhydrazyl) and to rapidly identify the compounds involved in this activity. The crude extract was initially separated in five fractions on Diaion HP20 resin and the most active part was fractionated by Centrifugal Partition Extraction (CPE). Known compounds were directly identified by a 13 C-NMR-based dereplication method. Semi-preparative high performance liquid chromatography purification experiments were further performed to identify unknown or minor active compounds. As a result, one new (13) and twelve known flavonoid glycosides together with three nitropropanoylglucopyranoses were isolated, including astragalin (1) (14), coronillin (16) and coronarian (15). 120 mg of the most active compound isoorientin against the free radical DPPH was recovered by CPE with an HPLC purity of 99%.

Two new bis-iridoids isolated from Scabiosa stellata and their antibacterial, antioxidant, anti-tyrosinase and cytotoxic activities

“…The antioxidant activity of crude extracts, fractions and purified compounds was measured in terms of hydrogen donating or radical scavenging ability using the stable radical DPPH method [33]. 5 µL of different concentrations of the samples were added to 95 µL of a DPPH solution (158 µM, dissolved in EtOH 50%).…”

Antioxidant activity-guided isolation of flavonoids from Silene gallica aerial parts

“…The 1 H and COSY NMR spectra of 2 exhibited in aglycone region an ABX system at δH 7.58 (1H, d, J= 2.0 Hz, H-2'), 7.53 (1H, dd, J= 8.3 and 2.0 Hz, H-6') and 6.93 (1H, d, J= 8.3 Hz, H-5'), due to a 3',4'-disubstituted B-ring. Full assignment of the remaining aglycone resonances in the 13 C NMR spectrum of 2 was achieved by analysis of HSQC and HMBC data, which confirmed the presence of an orientin derivative and a βglucopyranosyl unit (Sientzoff et al, 2015). Each assignment of the aglycone moiety was confirmed by 2D NMR experiments, which also revealed that the saccharide moiety of compound 2 was identical to that of compound 1 (Table 2).…”

Bio-guided Studies of Lotus maritimus Aerial Parts and Investigation of their Antioxidant, Tyrosinase and Elastase Inhibitory Activities

“…The free radical scavenging capacity was determined by using the stable 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical [19]. Hydromethanolic (HEM), dichloromethane (DCMF), ethylacetate (EAF) and nbutanolic (n-BF) extracts, fractions (n-BF3-n-BF6), and pure compounds 2-8 were tested for their DPPH radical scavenging activity using the procedure described in Schmitt et al [12].…”