Sweet pepper (Capsicum annuum L.) is one of the most widely produced vegetable plants in the world. Fusarium wilt of pepper is one of the most dangerous soil-borne fungal diseases worldwide. Herein, we investigated the antifungal activities and the potential application of two chalcone derivatives against the phytopathogenic fungus, Fusarium equiseti, the causal agent of Fusarium wilt disease in vitro and in vivo. The tested compounds included 3-(4-dimethyl amino-phenyl)-1-{6-[3-(4 dimethyl amino-phenyl)-a cryloyl]-pyridin-2-yl}-propanone (DMAPAPP) and its metal complex with ruthenium III (Ru-DMAPAPP). Both compounds had potent fungistatic activity against F. equiseti and considerably decreased disease progression. The tested compounds enhanced the vegetative growth of pepper plants, indicating there was no phytotoxicity on pepper plants in greenhouse conditions. DMAPAPP and Ru-DMAPAPP also activated antioxidant defense mechanisms that are enzymatic, including peroxidase, polyphenole oxidase, and catalase, and non-enzymatic, such as total soluble phenolics and total soluble flavonoids. DMAPAPP and Ru-DMAPAPP also promoted the overexpression of CaCu-SOD and CaAPX genes. However, CaGR and CaMDHAR were downregulated. These results demonstrate how DMAPAPP and Ru-DMAPAPP could be employed as a long-term alternative control approach for Fusarium wilt disease as well as the physiological and biochemical mechanisms that protect plants.

A novel azo dye ligand, formed by the coupling of 5-aminosalycalic acid (mesalamine drug) with 2-amino pyrimidine (H 2 L) and its Co 2+ , Ni 2+ , and Cu 2 + complexes, was synthesized. The structures of ligand and its complexes have been described by elemental analysis, inductively coupled plasma (ICP), thermogravimetric analysis (TGA), magnetic moment measurements, molar conductance, ultraviolet-visible (UV-Vis), X-ray powder diffraction, infrared (IR), 1 H-nuclear magnetic resonance (NMR), 13 C NMR, and electron impact (EI) mass spectral studies. The obtained data detected that the H 2 L ligand acts as monobasic tridentate via C=N, azo nitrogen, and deprotonated OH groups. The data supported the formation of 1:2 (M:L) for Co 2+ complex, while Ni 2+ and Cu 2+ gave 1:1 (M:L) complexes mononuclear formulation. The Co 2+ and Ni 2+ complexes have octahedral structures, while Cu 2+ complex has tetrahedral geometry. The ligand and its Co 2+ , Ni 2+ , and Cu 2+ complexes were applied as an antifungal against a set of root rot-associated soil-born phytopathogenic fungi and compared with the effect of Hatric (recommended fungicide). Our findings revealed that the metal complexes exhibited greater antifungal activity than the parent ligand. The Cu 2+ complex was found to be the most effective compound.The effect of Hatric and Cu 2+ complex on structural alterations of Fusarium semitectum was studied by scanning electron microscopy (SEM).

Sweet pepper (Capsicum annuum L.), also known as bell pepper, is one of the most widely grown vegetable crops worldwide. It is attacked by numerous phytopathogenic fungi, such as Fusarium equiseti, the causal agent of Fusarium wilt disease. In the current study, we proposed two benzimidazole derivatives, including 2-(2-hydroxyphenyl)-1-H benzimidazole (HPBI) and its aluminum complex (Al−HPBI complex), as potential control alternatives to F. equiseti. Our findings showed that both compounds demonstrated dose-dependent antifungal activity against F. equiseti in vitro and significantly suppressed disease development in pepper plants under greenhouse conditions. According to in silico analysis, the F. equiseti genome possesses a predicted Sterol 24-C-methyltransferase (FeEGR6) protein that shares a high degree of homology with EGR6 from F. oxysporum (FoEGR6). It is worth mentioning that molecular docking analysis confirmed that both compounds can interact with FeEGR6 from F. equiseti as well as FoEGR6 from F. oxysporum. Moreover, root application of HPBI and its aluminum complex significantly enhanced the enzymatic activities of guaiacol-dependent peroxidases (POX), polyphenol oxidase (PPO), and upregulated four antioxidant-related enzymes, including superoxide dismutase [Cu-Zn] (CaSOD-Cu), L-ascorbate peroxidase 1, cytosolic (CaAPX), glutathione reductase, chloroplastic (CaGR), and monodehydroascorbate reductase (CaMDHAR). Additionally, both benzimidazole derivatives induced the accumulation of total soluble phenolics and total soluble flavonoids. Collectively, these findings suggest that the application of HPBI and Al−HPBI complex induce both enzymatic and nonenzymatic antioxidant defense machinery.