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Background: Phytopathogenic fungi remain the main infectious agents in plants, causing severe damage to the environment and human health. Thus, to reduce the usage of synthetically derived fungicides and perform agricultural crop production, the search for new control strategies including plant extracts constitutes an eco-friendly and safe alternative. Objectives: This study aimed to quantify the phytochemical constituents of the three plant (Mentha pulegium L., Mentha spicata L., and Mentha longifolia L.) extracts and to screen their phytochemical composition including total phenolic (TPC), flavonoids (TFC) and condensed tannins contents (TCTC), and to evaluate their antioxidant activities. The efficacy of all mint extracts will be investigated against phytopathogenic fungal species. Materials and Methods: The three plant extracts were screened to assess their total phenolic, flavonoids, and condensed tannin contents using spectrophotometric assays. The antioxidant activities include 1,1-diphenyl-2-picrylhydrazyl (DPPH), ferric ion reducing antioxidant power (FRAP), and β-carotene assays. The antifungal activities were investigated on phytopathogenic species including Botrytis cinerea, Fusarium culmorum, Fusarium oxysporum, Aspergillus niger, Aspergillus flavus, and Trichoderma sp. Results: Quantitative analyses of phytochemical constituents of Mentha genus extracts revealed that both ethyl acetate (EtAc) and chloroformic (Chl) extracts are a rich source of phenols, flavonoids, and condensed tannins. Ethyl acetate extract of M. longifolia (EtAc L) displayed the highest content of phenols (69.9 ± 1.35 mg GAE/g DW) and flavonoids (53.26 ± 2.11 mg CE/g DW), while M. pulegium ethyl acetate extract (EtAc P) has the highest condensed tannins content (2.13 ± 0.4 mg CE/g DW). Moreover, the tested extracts exhibited potent antioxidant activities at low concentrations for EtAc L, followed by M. spicata (EtAc S), and EtAc P (IC50 = 35.76 ± 1.32 µg/mL for scavenging DPPH free radicals; EC50 527.96 ± 5.45 µg/mL for FRAP, and IC50 = 106.3 ± 3.75 µg/mL for β-carotene bleaching test). Finally, all tested extracts were able to inhibit the growth of several phytopathogenic micro-organisms on both agar and broth media. Conclusion: The Mentha extracts derived from the three mint species (i.e., L, P, and S) could be used for their antifungal activities to provide sustainable crop pest management. [ABSTRACT FROM AUTHOR]

This study was conceived to evaluate the difference in the chemical composition of the essential oil of Mentha longifolia ssp. longifolia from two ecotypes (Sidi Bouzid and Gabes) as well as the difference of the composition of the oils extracted from the leaves and stems. The antimicrobial activity was also tested against 16 human pathogenic microorganisms. The chemical composition of the hydrodistilled essential oils of Mentha longifolia ssp. longifolia were analysed by GC and GC/MS system. Remarkable differences were recorded between the percentages of the few constituents from leaves and stems and between plants from the two geographical provinces. The chemical analysis of the essential oil obtained from leaves and stems showed the presence of 34 compounds. The most important ones were consecutively: 1,8-cineole (5.6–10.8%), menthone (20.7–28.8%), terpineol-4 (3.1–4.9%), menthol (19.4–32.5%), pulegone (7.8–17.8%) and piperitone (2.2–3.3%). These major components occur in different amounts depending on the organs (leaves or stems) and the geographical origin of the plant. The antimicrobial activity of the essential oil was tested using the disc-diffusion assay and minimal inhibition concentration (MIC) values were estimated according to the microdilution method. The results showed that the essential oil of Mentha longifolia ssp. longifolia had great potential of antimicrobial activity against all 8 bacteria and 8 yeast species tested. The (MIC) for bacteria was ranging from 0.195 to 3.12 × 103 μg/ml. [ABSTRACT FROM AUTHOR]

This study characterises 43 Vibrio alginolyticus strains associated with diseased juveniles and older fish of Sparus aurata reared in a marine hatchery installed along the seacoasts of Monastir (Centre of Tunisia). Vibrio alginolyticus strains were isolated using the TCBS modified agar plates and the biochemical activities were tested using the API 20 E strips. The exoenzymes production and antibiotics susceptibility were also investigated. The ERIC-PCR was used to evaluate the genetic diversity of these strains. Vibrio alginolyticus was isolated from seawater (n=16), juveniles with white nodular skin lesions (n=9) and from all the internal organs of the older fish presenting a large and deep lesions in the muscle and with a necrotic eyes (n=18). Most of the studied V. alginolyticus strains were β-haemolytic, hydrolyze the DNA and produce many exoenzymes such as lecithinase, caseinase, amylase and lipase. All tested strains were resistant to at least three antimicrobial agents. The ERIC-PCR profiles among the isolated bacteria were generally heterogeneous, showing a high polymorphism and suggesting independent circulation with some evidence of cross-transmission. [ABSTRACT FROM AUTHOR]