Plant viruses and fungi are a serious threat to food security and natural ecosystems. The efficient and environmentfriendly control methods are urgently needed to help safeguard such resources. Here, we achieved the efficient synthesis of toad alkaloid dehydrobufotenine in eight steps with an overall yield of 8% from 5-methoxyindole. A series of dehydrobufotenine derivatives were designed, synthesized, and evaluated for their antiviral and fungicidal activities systematically. It was found for the first time that these compounds have good anti-plant virus activities and anti-plant pathogen activities. The antiviral activities of 21 compounds were similar to or better than those of ribavirin. Compounds 12 and 17 displayed better antiviral activities than ningnanmycin which is perhaps the most effective anti-plant virus agent. The antiviral mechanism research study of 12 revealed that it could make 20S CP disk fusion and aggregation. Further molecular docking results showed that there are hydrogen bonds between compounds 12, 17, and tobacco mosaic virus CP. The docking results are consistent with the antiviral activity. These compounds also displayed broad-spectrum fungicidal activities against 14 kinds of fungi, especially for Sclerotinia sclerotiorum. In this work, the synthesis, structure optimization, structure−activity relationship studies, and mode of action research of dehydrobufotenine alkaloids were carried out. It provides a reference for the development of the anti-plant virus agent and anti-plant pathogen agent from toad alkaloids.

Plant diseases seriously affect the growth of crops and the quality and yield of agricultural products. The search for plant-derived pesticide candidates based on natural products is a hot topic of current research. Marine natural products almazoles C−D were efficiently prepared and selected as the lead compounds in this work. Two series of almazole derivatives were designed and synthesized, and their antiviral and fungicidal activities were systematically evaluated. The results of anti-tobacco mosaic virus (anti-TMV) activity showed that almazoles C−D and their derivatives had good anti-TMV activities. Compounds 6,15, 16a, 16b, 16g, 16l, 16n, 20a, 20d, 20i, and 20n exhibited better anti-TMV activities than the commercial antiviral agent ribavirin. Anti-TMV mechanism studies showed that compound 16b could induce the polymerization of 20S CP (coat protein, CP), thereby affecting the assembly of TMV virus particles. Molecular docking results showed that compounds 15, 16b, and 20n could combine with amino acid residues through hydrogen bonds to achieve an excellent anti-TMV effect. In addition, most of the almazole derivatives were found to have broad-spectrum fungicidal activities against eight kinds of plant pathogens (Fusarium oxysporum f. sp. cucumeris, Cercospora arachidicola Hori, Physalospora piricola, Rhizoctonia cerealis, Alternaria solani, Pyricularia grisea, Phytophthora capsici, and Sclerotinia sclerotiorum). This study provides an important evidence for the research and development of almazole alkaloids containing indole and oxazole structural groups as novel agrochemicals.

N, N, N′, N′-tetrakis-(2-benzimidazolylmethyl)-1, 2-ethanediamine(TBIMEDA), was prepared by reaction of ethylenediamine tetra-acetic acid disodium salt(EDTA) with 1, 2-diaminobenzene in a refluxed glycol solution, and furthermore, three allomeric complexes[(M^IITBIMEDA) SO₄·5H₂O, M = Cd, Co, Ni] were selfassembled by solvothermal method based on reaction of this ligand with the relative sulfates respectively. These allomeric complexes were characterized by elemental analysis and IR spectroscopy and their crystal structures were determined by single crystal X-ray structural analysis. In the crystal architecture of these complexes, every metal(II) ion is chelated by one neutral TBIMEDA ligand to form an octahedral core with configuration of five heterocyclic rings (five- member ring). These cores then were linked to- gether by multi hydrogen bond interactions with sul- fate ions and water molecules to construct their 3D crystal architectures