Dereplication of depsides from the lichen Pseudevernia furfuracea by centrifugal partition chromatography combined to 13C nuclear magnetic resonance pattern recognition

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

“…By applying exactly the same approach, cluster 2 was identified as isovitexin (7). Its structure matched as the first hit over 10 proposals from the database and was confirmed by finding all 13 C chemical shifts in raw NMR data of fractions F9 and F10 [16]. Astragalin (1) matched as the first to hit over 25 proposals for cluster 3 [18].…”

“…As summarized in Table 1, only compounds 5, 6, 8, and 11 exhibited EC50 values ranging from 8.0 to 20.2 μg/mL whereas the 50% DPPH inhibition was not reached even at 200 μg/mL for the other compounds. The purification of fraction F7 that exhibited an EC50 value of 28.7 ± 0.9 μg/mL (Table 1 and Figure 1) yielded isoquercitrin (5) which was already identified by dereplication, hyperoside (6), as well as two minor compounds coronillin (16), and coronarian (15). The activity of F7 was thus attributed to both 5 and 6 since compounds 15 and 16 were not active at 200 μg/mL ( Table 1).…”

“…As a result, one new compound (13) and twelve known flavonoid glycosides together with three nitropropanoylglucopyranoses were isolated including four flavonoids already identified by dereplication (1, 5, 7, and 8), in addition to kaempferol- (14), coronillin (16) and coronarian (15) [10,26] (Figure 3 Figure 3. Structures of compounds 1-16 isolated from the aerial parts of Securigera varia.…”

“…The other fractions were significantly less active than the positive reference ascorbic acid. In parallel to DPPH scavenging assays, fractions F1-F16 were all analyzed by 13 C-NMR for dereplication [16]. Automatic peak picking and binning of 13 C signals across spectra resulted in a table with 16 columns (one per fraction) and 267 rows (one per chemical shift bin containing at least one 13 C signal in at least one fraction).…”

“…This dereplication approach was completed by further semi-preparative high performance liquid chromatography purification experiments in order to identify unknown or minor active compounds. As a result, one new (13) and twelve known flavonoid glycosides (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12) together with three nitropropanoylglucopyranoses (14)(15)(16) were isolated from the aerial parts of Securigera varia. The structures were established by NMR and mass spectrometry as well as by comparison to their spectral data (MS, 1 H-and 13 C-NMR) found in the literature.…”