Dereplication of natural products from complex extracts by regression analysis and molecular networking: case study of redox-active compounds from Viola alba subsp. dehnhardtii

Abstract

LC-HRMS) profiles. In parallel, redox active properties were evaluated by the capacity of the molecules to reduce 2,2-diphenyl-1-picrylhydrazyl (DPPH •) and superoxide (O 2 •−) radicals using UV-Vis and electron spin resonance spectroscopies (ESR), respectively. A spectral similarity network (molecular networking) was used to highlight clusters involved in the observed redox activities. Results Dereplication on Viola alba subsp. dehnhardtii highlighted a reproducible pool of redox active molecules. Polyphenols, particularly O-glycosylated coumarins and C-glycosylated flavonoids, were identified and de novo dereplicated through molecular networking. Confirmatory analyses were undertaken by thin layer chromatography (TLC)-DPPH-MS assays and nuclear magnetic resonance (NMR) spectra of the most active compounds. Conclusion Our dereplication strategy allowed the screening of leaf extracts to highlight new biologically active metabolites in few steps with a limited amount of crude material and reduced time-consuming manipulations.

Extending compound identification for molecular network using the LipidXplorer database independent method: A proof of concept using glycoalkaloids from Solanum pseudoquina A. St.‐Hil.

“…The latest development in structure elucidation and database matching is molecular networking, a visualisation tool designed to address structure elucidation of different compounds based on MS 2 spectra similarity. It is done online using the Global Natural Products Social Molecular Network (GNPS) web service that also provides comparison of experimental MS spectra to freely available databases for direct compound identification . The molecular networks (MNs) are generated calculating the cosine similarities between MS fragmentograms and connects precursor mass labelled nodes accordingly.…”

“…It is done online using the Global Natural Products Social Molecular Network (GNPS) web service that also provides comparison of experimental MS spectra to freely available databases for direct compound identification. [5][6][7][8][9][10] The molecular networks (MNs) are generated calculating the cosine similarities between MS fragmentograms and connects precursor mass labelled nodes accordingly. The size of the network depends on cosine threshold values settled.…”

Deciphering the phylogeny of violets based on multiplexed genetic and metabolomic approaches

“…For instance, fragments with mass differences of 162 Da and 15 Da suggest the presence of one methoxy and one O-hexose substituents for compounds 1 and 2. NMR characterizations confirmed these substitutions of a coumarin aglycone (Chervin et al 2017).…”

“…UHPLC-HRMS analyses were performed with diode array detector (DAD) on a UHPLC-LTQ Orbitrap XL instrument (Ultimate 3000, Thermo Fisher Scientific, Hemel Hempstead, UK) as previously reported (Chervin et al 2017). Briefly, the LC-MS system was run using a Acquity UPLC BEH C18 column (100 × 2.1 mm i.d., 1.7 µm, Waters, MA, USA) equipped with a guard column.…”

“…Using the OPLS-DA regression analysis results, molecular formulae and structural identification of significant features were calculated with MS-FINDER 2.22 (Tsugawa et al 2016) based on our previously described model (Chervin et al 2017). An in-house database based on Viola matches inside the Dictionary of Natural Products (DNP,CRC press,v25:2) extended to the chemical classes and of local databases within MS-FINDER (KNApSAck, PlantCyc and UNPD) were used.…”