Polyphenolic profile, antibacterial activity and brine shrimp toxicity of leaf extracts from six Tunisian spontaneous species

Abstract

The aim of this study was to investigate the polyphenolic profile and biological properties of leaves acetonic extracts from six Tunisian spontaneous plants of Marrubium vulgare L., Rhus tripartita (Ucria) D.C., Hernaria fontanesii J. Gay subsp. fontanesii, Ziziphus lotus L., Plantago ovata Forsk., Thymelaea hirsuta (L.) Endl. Bioassay-guided and HPLC-PDA-ESI-MS procedures demonstrated that R. tripartita contained the highest amount of phenolic compounds (1475.1 µg/g), followed by Z. lotus (1087.8 µg/g) and P. ovata (1027.6 µg/g). Interestingly, in R. tripartita myricetin‐3-O-galactoside turned out to be the most abundant one. The plant extracts showed antimicrobial efficacy against Listeria monocytogenes, Staphylococcus aureus and S. epidermidis including methicillin resistant strains; no activity was detected against Gram-negative bacteria. R. tripartita revealed the best MIC and MBC values and caused significant decrease of S. aureus biofilm. Both R. tripartita and Z. lotus did not display any toxicity against Artemia salina Leach (LC₅₀ > 1000 μg/mL).

Graphical Abstract

Keywords:

• Tunisian plant extracts
• HPLC
• phenolic compounds
• antibacterial activity
• biofilm
• Artemia salina lethality bioassay

Acknowledgements

This work was conducted within the program Erasmus+/KA1 Higher Education Agreement between the University of Messina, Italy and the University of Gabes, Tunisia. The authors thank Prof. Mohamed Neffati, from Laboratory of Pastoral Ecosystems and Valorization of Spontaneous Plants and Associated Microorganisms, Medenine, Tunisia, as an expert in the field of the ethnobotanical value of the spontaneous plants of the Tunisian arid zones, for botanical identification. The authors are thankful to Shimadzu and Merck Life Science Corporations for the continuous support.

Disclosure statement

No potential conflict of interest was reported by the authors.