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Nanotechnology has become an extensive area of study due to the peculiar properties of nanoparticles. Chitosan is considered the most promising material for future applications. The purpose of this study was to highlight the antimicrobial and hepatoprotective properties of Chitosan nanoparticles (CTS), as well as their efficacy against multidrug-resistant pathogens and various applications as a natural antioxidant in the biomedical field. CTS were prepared with or without surfactant (L—lecithin, Tween 80) based on inotropic gelation of chitosan with sodium alginate. The nanoparticle obtained displayed a spherical shape with a particle size ranging from 54.3±20.8 to 1256±16.8 nm, zeta potential ranging from 24±1.2 to 30.8±1.1 mV, and polydispersity index ranging from 0.274±0.09 to 0.553±0.06. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) calculations were used to evaluate the antibacterial activity of CTS against four human pathogens: Bacillus subtilis ATCC6633, Staphylococcus aureus NRRLB-767, Escherichia coli ATCC25955, and Pseudomonas aeruginosa ATCC101455. The MIC values were 156.3, 39.4, 78.1, and 78.1 ug/mL, while the MBC values were 500,156.3, 312.5, and 312.5 ug/mL, respectively. S.aureus was the most susceptible, while B. subtilis was the most resistant. The hepatoprotective effect was determined by measuring antioxidant, antiapoptotic, and inflammatory biomarkers, histopathological and immunohistochemical studies. Hepatoprotective results showed a remarkable ameliorative effect against hepatotoxicity induced by CCl4.

Phytostimulation microorganisms (PSM) viz. Trichoderma harzianum (TH), Bacillus subtilis (BS) and arbuscular mycorrhizal (AM) fungi were tested individually or in mixed culture for their ability to induce pathogenesis-related (PR)proteins (chitinase, β-1,3-glucanase, peroxidase, phenylalanine ammonia-lyase PAL) and phenolics in tomato plants grown in sterilized soilless medium artificially infested with or without the Fusarium oxysporum f. sp. radicis-lycopersici (FORT). PSM-treated plants were more developed than non-treated control or inoculation with FORT. PSM-treated plants were effective in reducing diseases produced by FORT infection. Plants application with PSM significantly increased the activity of peroxidase, chitinase, β-1, 3-glucanase and PAL and accumulated phenolics in tomato plants compared to untreated control. Among the treatments, AM fungi recorded the maximum increase in the activities of all defense-related enzymes and accumulated phenolics followed by T. harzianum and B subttilis. The maximum increase in the activities of peroxidase, β-1, 3-glucanase, PAL and accumulated phenolics were observed 6 days after application of PSM. However, the maximum increase in the activities of chitinase was observed 9 days after application of PSM. Several fold increase in the accumulation of phenolics and activities of defense enzymes was observed when the induced plants were inoculated with Fusarium oxysporum f. sp. radicis-lycopersici (FORT). These results suggest that enhanced activities of defense enzymes and elevated content of phenolics by inoculation with PSM may contribute to protection of tomato plants against F. oxysporum.

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