In Vitro Antioxidant, Antibacterial and Mechanisms of Action of Ethanolic Extracts of Five Tunisian Plants against Bacteria

Khaoula Nefzi; Mariem Ben Jemaa; Mokhtar Baraket; Sarra Dakhlaoui; Kamel Msaada; Zouheir Nasr

doi:10.3390/app12105038

Applied Sciences (May 2022)

In Vitro Antioxidant, Antibacterial and Mechanisms of Action of Ethanolic Extracts of Five Tunisian Plants against Bacteria

Khaoula Nefzi,
Mariem Ben Jemaa,
Mokhtar Baraket,
Sarra Dakhlaoui,
Kamel Msaada,
Zouheir Nasr

Affiliations

Khaoula Nefzi: LR11INRGREF0 Laboratory of Management and Valorization of Forest Resources, National Research Institute of Rural Engineering, Water and Forests (INRGREF), Carthage University, Ariana 2080, Tunisia
Mariem Ben Jemaa: Laboratory of Aromatic and Medicinal Plants, Biotechnology Center in Borj-CedriaTechnopark, P.O. Box 901, Hammam-Lif 2050, Tunisia
Mokhtar Baraket: LR11INRGREF0 Laboratory of Management and Valorization of Forest Resources, National Research Institute of Rural Engineering, Water and Forests (INRGREF), Carthage University, Ariana 2080, Tunisia
Sarra Dakhlaoui: Laboratory of Aromatic and Medicinal Plants, Biotechnology Center in Borj-CedriaTechnopark, P.O. Box 901, Hammam-Lif 2050, Tunisia
Kamel Msaada: Laboratory of Aromatic and Medicinal Plants, Biotechnology Center in Borj-CedriaTechnopark, P.O. Box 901, Hammam-Lif 2050, Tunisia
Zouheir Nasr: LR11INRGREF0 Laboratory of Management and Valorization of Forest Resources, National Research Institute of Rural Engineering, Water and Forests (INRGREF), Carthage University, Ariana 2080, Tunisia

DOI: https://doi.org/10.3390/app12105038
Journal volume & issue: Vol. 12, no. 10
p. 5038

Abstract

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Pistacia lentiscus, Rosmarinus officinalis, Erica multiflora, Calicotome villosa, and Phillyrea latifolia were considered important medicinal herbs and were used to treat various ailments. The present study was designed to evaluate the antioxidant and antimicrobial activities of ethanolic extracts (EEs). P. lentiscus and R. officinalis were the richest species in phenolic compounds. Similarly, both species showed the highest values of flavonoids. While the EEs of P. lentiscus, E. multiflora, and C. villosa had higher amounts of tannins. These phenolic compounds were evaluated by two different tests, namely diphenyl picrylhydrazyl (DPPH) and ferric iron-reducing power (FRAP). The IC50 values were found to be significant (p 0.05) for P. lentiscus and E. multiflora. Similarly, both plants showed the highest ferric-reducing antioxidant power (FRAP). This study has been conducted to evaluate the antibacterial potential of EEs against selected bacteria—Gram-positive bacteria (Staphylococcus aureus ATCC 29213, Listeria monocytogenes ATCC 7644) and Gram-negative bacteria (Escherichia coli ATCC 8739, Salmonella typhimurium NCTC 6017)—and determine their modes of action. The ethanolic extracts inhibited bacterial growth by producing concentration-dependent zones of inhibition. Treatment with these extracts at their minimum inhibitory concentrations (MICs) showed a significant reduction (p 0.05) in the viability of bacteria. The extracts did not induce total lysis. Bacteria organisms treated with EEs at MICs showed a significant (p 0.05) loss of tolerance to NaCl (5%). Our results highlighted the use of plant extracts as natural antibacterials that can be safely used in health care and led to the understanding of the antibacterial mechanism of plant extracts.

Published in Applied Sciences

ISSN: 2076-3417 (Online)
Publisher: MDPI AG
Country of publisher: Switzerland
LCC subjects: Technology: Engineering (General). Civil engineering (General); Science: Biology (General); Science: Physics; Science: Chemistry
Website: http://www.mdpi.com/journal/applsci

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