Induced Resistance in Tomato Plants against Verticillium Wilt by the Binuclear Nickel Coordination Complex of the Ligand 2,5-Bis(pyridin-2-yl)-1,3,4-thiadiazole

Novel Flavonol Derivatives Containing 1,3,4-Thiadiazole as Potential Antifungal Agents: Design, Synthesis, and Biological Evaluation

In order to discover novel compounds with excellent agricultural activities, novel flavonol derivatives containing 1,3,4-thiadiazole were synthesized and evaluated for their antifungal activities. The bioassay results showed that some of the target compounds had good antifungal activities against Botrytis cinerea, Phomopsis sp. and Sclerotinia sclerotiorum in vitro. It is worth noting that the half-effective concentration (EC50) value of Y18 against B. cinerea was 2.4 μg/mL, which was obviously superior to that of azoxystrobin (21.7 μg/mL). The curative activity of Y18 at 200 μg/mL (79.9%) was better than that of azoxystrobin (59.1%), and its protective activity (90.9%) was better than that of azoxystrobin (83.9%). Morphological studies by using scanning electron microscopy and fluorescence microscopy revealed that Y18 could affect the normal growth of B. cinerea mycelium. In addition, the mechanism of action studies indicated that Y18 could affect the integrity of cell membranes by inducing the production of endogenous reactive oxygen species and the release of the malondialdehyde content, leading to membrane lipid peroxidation and the release of cell contents. The inhibitory activity of flavonol derivatives containing 1,3,4-thiadiazole on plant fungi is notable, offering significant potential for the development of new antifungal agents.

Self-assembly of new cobalt complexes based on [Co (SCN)4], synthesis, empirical, antioxidant activity, and quantum theory investigations

The cobalt (II) complexes have been synthesized from the reaction of the cationic entities (3,4-dimethylaniline (1) and histamine (2)) with metallic salt CoCl₂⋅6H₂O and thiocyanate ion (SCN⁻) as a ligand in H₂O/ethanolic solution and processing by the evaporation crystal growth method at room temperature to get crystals. The synthesized complex has been fully characterized by single-crystal X-ray diffraction. UV–Visible, FTIR spectroscopy, TGA analysis, and DFT circulations were also performed. The crystal structural analysis reveals that the solid (1) {[Co(SCN)₄] (C₈H₁₂N)₃}·Cl crystallizes in the monoclinic system with the space group P2₁/n and the solid (2) {[Co(SCN)₄](C₅H₁₁N₃)₂}·2Cl crystallizes in the monoclinic space group P2₁/m. Metal cations are joined into corrugated chains parallel to the b-axis direction in (1) and (2) by four thiocyanate anions. The crystal structures of (1) and (2) were calculated using XRPD data, indicating that they are closely connected to the DRX mono-crystal results. Different interactions pack the system into a ring formed by N–H⋯Cl and N–H⋯S hydrogen bonds. C–H⋯π and the π⋯π stacking of anilinuim ring for (1) and N–H⋯S intermolecular interactions for (1) and (2) increase the crystals' robustness. Hirshfeld surface analysis cum 2D fingerprint plots visualize the main intermolecular interactions with their contributions in the solid-state phase. The molecular geometries of both complexes obtained from the crystal structure were used for quantum chemical calculation. Here, frontier orbital analysis and electrostatic potential illustrate the chemical reactivities of metal–organic complexes. QTAIM and NCI analysis reveal the strength of interactions at the electronic level.

Novel Pyrimidine Derivatives Bearing a 1,3,4-Thiadiazole Skeleton: Design, Synthesis, and Antifungal Activity

In this study, twenty novel pyrimidine derivatives bearing a 1,3,4-thiadiazole skeleton were designed and synthesized. Then their antifungal activity against Botrytis cinereal (B. cinereal), Botryosphaeria dothidea (B. dothidea), and Phomopsis sp. were determined using the poison plate technique. Biological test results showed that compound 6h revealed lower EC₅₀ values (25.9 and 50.8 μg/ml) on Phompsis sp. than those of pyrimethanil (32.1 and 62.8 μg/ml).

Design, synthesis and antifungal mechanism of novel acetophenone derivatives containing 1, 3, 4-thiadiazole-2-thioethers

Plant pathogenic fungi could cause significant losses to agricultural productions. To discover new pesticides with novel structures and unique mechanisms of action, a series of novel acetophenone derivatives containing 1,3,4-thiadiazole-2-thioethers...

Design, Synthesis, Antibacterial Activity, and Mechanisms of Novel 1,3,4-Thiadiazole Derivatives Containing an Amide Moiety

To discover novel antibacterial agents, a series of novel 1,3,4-thiadiazole derivatives containing an amide moiety were designed and synthesized, and their antibacterial activities were tested. Compound 30 was designed and synthesized according to the CoMFA model. Compound 30 exhibited higher antibacterial activities against Xanthomonas oryzae pv. oryzicola and Xanthomonas oryzae pv. oryzae, with EC₅₀ values of 2.1 and 1.8 mg/L, respectively, which were superior to those of thiodiazole copper (99.6 and 92.5 mg/L). The protective and curative activities of compound 30 against rice bacterial leaf blight were 51.3 and 46.1%, respectively, which were better than those of thiodiazole copper (37.8 and 38.5%). The protective and curative activities of compound 30 against rice bacterial leaf streak were 45.9 and 40.5%, respectively, which were better than those of thiodiazole copper (36.2 and 31.1%). In addition, the protective activity of compound 30 against rice bacterial leaf streak was related to increased activities of related defense enzymes and upregulated the differentially expressed proteins of the glycolysis/gluconeogenesis pathway.

Design, Synthesis, and Antifungal Evaluation of 8-Hydroxyquinoline Metal Complexes against Phytopathogenic Fungi

Phytopathogenic fungal infections have become a major threat to agricultural production, food security, and human health globally, and novel antifungal agents with simple chemical scaffolds and high efficiency are needed. In this study, we designed and synthesized 38 8-hydroxyquinoline metal complexes and evaluated their antifungal activities. The results showed that most of the tested compounds possessed remarkable in vitro antifungal activity. Especially, compound 1e exhibited the highest antifungal potency among all target compounds, with EC₅₀ values of 0.0940, 0.125, 2.95, and 5.96 μg/mL, respectively, against Sclerotinia sclerotiorum, Botrytis cinerea, Fusarium graminearum, and Magnaporthe oryzae. Preliminary mechanistic studies had shown that compound 1e might cause mycelial abnormalities of S. sclerotiorum, cell membrane permeability changes, leakage of cell contents, and inhibition of sclerotia formation and germination. Moreover, the results of in vivo antifungal activity of compound 1e against S. sclerotiorum showed that 1e possessed higher curative effects than that of the positive control azoxystrobin. Therefore, compound 1e is expected to be a novel leading structure for the development of new antifungal agents.

2-[5-(Pyridin-2-yl)-1,3,4-thiadiazol-2-yl]pyridin-1-ium perchlorate

The cation of the title molecular salt, C12H9N4S+·ClO4 −, is approximately planar, with the pyridine and pyridinium rings being inclined to the central thiadiazole ring by 6.51 (9) and 9.13 (9)°, respectively. The dihedral angle between the pyridine and pyridinium rings is 12.91 (10)°. In the crystal, the cations are linked by N—H...O and C—H...O hydrogen bonds, involving the perchlorate anion, forming chains propagating along the [100] direction. The chains are linked by weak offset π–π interactions [inter-centroid distance = 3.586 (1) Å], forming layers parallel to the ab plane.

Triterpene derivatives from Euphorbia enhance resistance against Verticillium wilt of tomato

Oxidation of α-euphorbol and 31-norlanostenol, two triterpenic compounds isolated from the latex of Euphorbia resinifera and Euphorbia officinarum respectively, yielded four products named 3β-tosyloxy-4α,14α-dimethyl-5α-cholesta-7,9-diene; 4α,14α-dimethyl-5α-cholesta-7,9-dien-3β-ol; 24-methylen-elemo-lanosta-8,24-dien-3-one and elemo-lanost-8-en-3,11,24-trione. They were evaluated for protection of tomato plants against Verticillium dahliae in a greenhouse. The four semisynthesized products were phytotoxic at higher concentrations as they completely inhibited tomato germination at 100 and 500 μg/ml. However at lower concentrations (10 and 50 μg/ml) germination and root length were not affected. Disease resistance against Verticillium wilt was assessed in tomato plants derived from seeds that germinated in the presence of 10 and 50 μg/ml of the four products. All of them were able to reduce significantly disease severity, with 10 μg/ml being more effective than 50 μg/ml. Reduction of leaf alteration index and of stunting index ranged from 52 to 68% and from 43 to 67%, respectively, while vessel discoloration was reduced by at least 95%. The compounds were also able to elicit H₂O₂ accumulation before and after fungal inoculation and to significantly enhance peroxidase and polyphenol oxidase activities. These results suggest that the hemisynthetized triterpenes can be used as elicitors of disease resistance.

Crystal structure of bis-[2,5-bis-(pyridin-2-yl)-1,3,4-thia-diazole-κ(2) N (2),N (3)]bis-(thio-cyanato-κS)copper(II)

The mononuclear title complex, [Cu(SCN)2(C12H8N4S)2], was obtained by the reaction of 2,5-bis-(pyridin-2-yl)-1,3,4-thia-diazole and potassium thio-cyanate with copper(II) chloride dihydrate. The copper cation lies on an inversion centre and displays an elongated octa-hedral coordination geometry. The equatorial positions are occupied by the N atoms of two 2,5-bis-(pyridin-2-yl)-1,3,4-thia-diazole ligands, whereas the axial positions are occupied by the S atoms of two thio-cyanate anions. The thia-diazole and the pyridyl rings linked to the metal are approximately coplanar, with a maximum deviation from the mean plane of 0.190 (2) Å. The cohesion of the crystal structure is ensured by weak C-H⋯N hydrogen bonds and π-π inter-actions between parallel pyridyl rings of neighbouring mol-ecules [centroid-to-centroid distance = 3.663 (2) Å], leading to a three-dimensional network.