Evaluation of antioxidant activity, total phenolics, total flavonoids and LC–MS/MS characterisation of phenolic constituents in Stachys lavandulifolia

Abstract

The aim of this study was to evaluate phenolics profile and antioxidant activity of Stachys lavandulifolia. Total phenolics (TP), total flavonoids (TF), DPPH• assay (IC50), ferric ion reducing antioxidant power (FRAP) and total antioxidant capacity (TAC) of the methanolic extract were measured. The content of TP, TF, IC50, FRAP and TAC, were obtained as 16.59 gallic acid equiv./g dry matter (DM), 4.48 mg quercetin equiv./g DM, 2.07 (μg/mL), 0.014 (absorbance/mg phenolic) and 14.61 (mg BHT equiv./g DM), respectively. The results showed that S. lavandulifolia, compared to other species of Stachys, had moderate TP content with desirable antioxidant activity. Subsequently, 59 various phenolic compounds were identified and confirmed in the methanolic extract of S. lavandulifolia using high mass accuracy by MS2 experiments. The compounds consisted of 6 hydroxybenzoic acids and hydroxybenzoic aldehydes, 9 hydroxycinnamic acids, 1 coumarin, 32 flavonoids, 3 lignans, 2 stilbenes, 3 tannins and 3 other phenolics.

Keywords:

• Stachys lavandulifolia
• phenolic compounds
• antioxidant activity
• LC–ESI–MS/MS

Acknowledgements

The authors would like to thank Shahrood University of Technology and Isfahan University of Technology for the financial support of this work.