فهرست مطالب saeid ghahari

Antibacterial, antifungal and antioxidant activity of methanolic extracts of Colocynth (Citrullus colocynthis) seeds, Camelthorn  (Alhagi maurorum) fruit and Chinaberry (Melia azedarach) leaves on eight bacteria and three fungi, which usually cause damage to agricultural products examined in this research.

Antimicrobial activity of selected plants in six concentrations on 11 microorganisms including, three gram-positive bacteria vs. Bacillus subtilis, Staphylococcus aureus, and Rathayibacter toxicus, and five gram-negative bacteria vs. Escherichia coli, Pseudomonas aeruginosa, Pseudomonas syringae subsp. syringae, Pseudomonas viridiflava, and Xanthomonas campestris pv. campestris, as well as three fungi vs. Pyricularia oryzae, Fusarium oxysporum and Botrytis cinerea was measured using the disk diffusion method. Also, the antioxidant activity of the extracts of these  plants was evaluated by measuring the enzymes of catalase and guaiacol peroxidase and evaluating the ability to trap DPPH radicals. In addition, the amount of total phenols and flavonoids in these plants extracts were measured.

Methanolic extract of Colocynth seeds had the highest antibacterial activity, the highest activity of catalase and guaiacol peroxidase enzymes and the highest percentage of DPPH radical inhibition. Methanolic extracts of these plants had no effect on fungal colony growth.

Methanolic extract of Colocynth seeds can be considered as potential sources of bactericides in agriculture.

As much as human beings become aware of the side effects of chemical pesticides, the demand for natural alternatives increases. In this study, antibacterial effects of different concentrations of methanolic extract of henna leaves (0.50, 0.25, 0.12, 0.06, 0.03 and 0.01 mg/mL DMSO) on three gram-positive bacteria (Bacillus subtilis, Staphylococcus aureus, and Rathayibacter toxicus), and five gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Pseudomonas syringae subsp. syringae, Pseudomonas viridiflava, and Xanthomonas campestris pv. Campestris) was measured with disk diffusion method. Also, silver nanoparticles were synthesized at different amounts of silver nitrate, extract, temperature, time, and pH. The size and shape of the synthesized particles were determined by DLS and SEM techniques. The results showed that the methanolic extract of henna leaves has an excellent antibacterial effect on all tested bacteria except Pseudomonas aeruginosa and Pseudomonas viridiflava. In addition, the antibacterial activity of the synthesized nanoparticles at a concentration of 0.01 M was measured on the tested bacteria and the results showed that the optimized nanoparticles were effective in terms of antibacterial properties. Also, the nanoparticle size in the presence of aqueous extract of henna leaves was 8.5 nm. The results of this study show that nanoparticles can be considered in the field of organic agriculture.