Dereplication of Wrightia dubia and Wrightia pubescens by UPLC-ESI- Orbitrap-MS/MS

Wrightia pubescens R.Br. subsp. laniti (Blanco) Ngan and Wrightia dubia (Sims) Spreng. belong to the Apocynaceae family. Several metabolites were identified from W. pubescens, and none reported from W. dubia. The limited knowledge about their metabolites hinders further pharmacological investigation of the plants. To address this issue, a dereplication approach was proposed to identify the known metabolites and guide the isolation work towards potential new metabolites. W. pubescens and W. dubia were collected in Pulau Tuba, Langkawi, Malaysia in November 2019. The plant materials were air-dried and extracted successively using hexane, dichloromethane and methanol. The dichloromethane extracts were pre-treated with a C-18 SPE and profiled using UHPLC, followed by UPLC-MS/MS analysis. Tryptanthrin was isolated from W. dubia stem bark following exhaustive purification using recycling preparative HPLC. Metabolite databases from the Apocynaceae family, genus Wrightia, Wrightia pubescens and Wrightia dubia were created using the Sirius software. The annotated metabolites were identified using molecular formula identification, zodiac, fingerprint prediction, structure database search and compound class prediction. The analysis revealed 21 compounds in W. pubescens twig and 20 compounds in W. dubia stem bark. The compounds belong to the coumarin, lignan, alkaloid, fatty acid, peptide and lactone classes. Both plants were found to contain tryptanthrin, an indole quinazoline alkaloid, and dipeptides namely asperphenamate, asperglaucide and aurantiamide. The dereplication strategy was validated using tryptanthrin. Future isolation studies will be directed towards unknown compounds and selected alkaloids for further pharmacological assessments ([Fig. 1]).

Fig. 1 Total Ion Chromatogram of the twig extract of Wrightia pubescens (a) and stem bark extract of Wrightia dubia (b).

 

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Conflict of Interest

The authors declare no conflict of interest.

Publikationsverlauf

Artikel online veröffentlicht:
16. November 2023