Inula viscosa (L.) Aiton leaves and flower buds: Effect of extraction solvent/technique on their antioxidant ability, antimicrobial properties and phenolic profile

Abstract

This study was designed to establish the most effective solvent/technique for extracting antioxidant phytoconstituents from leaves and flower buds of Inula viscosa (L.) Aiton (Asteraceae) grown wild in Morocco. Maceration and hot extraction with methanol or water and Soxhlet ethanol extraction were utilized. The antioxidant potential was evaluated in vitro by DPPH, reducing power, and ferrous ions chelating activity assays. I. viscosa leaf and flower bud extracts displayed the strongest effect in the DPPH test, being the Soxhlet ethanol the most active ones (IC₅₀ = 54.24 ± 0.21 μg/mL and 39.77 ± 0.23 μg/mL); thus, they were selected for further investigations. The antimicrobial efficacy of the Soxhlet ethanol extracts against ATCC and food isolates strains was assayed; the leaf extract showed the best activity, and Candida albicans was the most sensitive strain (MIC = 125 µg/mL). The extracts resulted non-toxic against Artemia salina. Among the phenolics characterised by HPLC-PDA-ESI-MS, hispidulin hexoside, patuletin and spinacetin were identified for the first time.

Graphical Abstract

Keywords:

• Inula viscosa (L.) Aiton
• extraction solvent/technique
• antioxidant activity
• antimicrobial activity
• Artemia salina Leach
• phenolic compounds
• HPLC-PDA-ESI-MS

Acknowledgements

This work was carried out within the program Erasmus+/KA107 Higher Education Agreement between the University of Messina (Italy) and the Moulay Ismail University, Meknes (Morocco). This research was presented at the XXVII SILAE Congress of Ethnomedicine, Milazzo (Messina, Italy), September 9–13, 2018. The authors gratefully thank Prof. Jalal el Oualidi for plant identification.

Conflict of interest

The authors declare no potential conflict of interest, including any financial interest.