In vivo anti-inflammatory activity of Fabaceae species extracts screened by a new ex vivo assay using human whole blood

Abstract

Introduction: Plants have been considered a promising source for discovering new compounds with pharmacological activities. The Fabaceae family comprises a large variety of species that produce substances with diverse therapeutic potential, including anti-inflammatory activity. The limitations of current anti-inflammatories generate the need to research new anti-inflammatory structures with higher efficacy as well as develop methods for screening multiple samples, reliably and ethically, to assess such therapeutic properties.

Objective: Validate and apply a quantification method for prostaglandin E₂ (PGE₂ ) production from an ex vivo assay in human blood in order to screen anti-inflammatory activity present in many Fabaceae species extracts.

Methods: Human blood was incubated with extracts from 47 Fabaceae species. After lipopolysaccharide (LPS)-induced inflammation, PGE₂ was quantified in the plasma by liquid chromatography with tandem mass spectrometry (LC-MS/MS). The extracts that presented PGE₂ production inhibition were further assessed through in vivo assay and then chemically characterised through an analysis of ultra-performance liquid chromatography electrospray ionisation quadrupole time-of-flight tandem mass spectrometry (UPLC-ESI-QTOF-MS² ) data.

Results: The new ex vivo anti-inflammatory assay showed that five out of the 47 Fabaceae species inhibited PGE₂ production. Results from an in vivo assay and the metabolic profile of the active extracts supported the anti-inflammatory potential of four species.

Conclusion: The quantification method for PGE₂ demonstrated fast, sensitive, precise, and accurate results. The new ex vivo anti-inflammatory assay comprised a great, reliable, and ethical approach for the screening of a large number of samples before an in vivo bioassay. Additionally, the four active extracts in both ex vivo and in vivo assays may be useful for the development of more efficient anti-inflammatory drugs.

Keywords: LC-MS/MS; LPS; PGE2; SPE; UPLC-ESI-QTOF-MS2; dereplication; ear edema; plants; plasma samples.