Enantiomeric Dibenzo-α-Pyrone Derivatives from Alternaria alternata ZHJG5 and Their Potential as Agrochemicals

Abstract

Three pairs of enantiomeric dibenzo-α-pyrone derivatives (1−3) including two pairs of new racemates (±)-alternaone A ( 1) and (±)-alternaone B (2) and one new enantiomer (−)-alternatiol (3), together with five known compounds (4−8) were isolated from the fungus Alternaria alternata ZHJG5. Their structures were confirmed by spectroscopic data and single-crystal X-ray diffraction analysis. All enantiomers were separated via chiral high-performance liquid chromatography, with their configurations determined by electronic circular dichroism calculation. Biogenetically, a key epoxy-rearrangement step was proposed for the formation of skeletons in 1−3; (+) 1, (−)-1, and 5 presented moderate antibacterial inhibition on phytopathogenic bacteria Xanthomonas oryzae pv. oryzae and Xanthomonas oryzae pv. oryzicola. In the antifungal test, compounds 7 and 8 showed a moderate protective effect against Botrytis cinerea in vivo.

Genome Mining and Heterologous Expression Guided the Discovery of Antimicrobial Naphthocyclinones from Streptomyces eurocidicus CGMCC 4.1086

“…sojae. The results were observed following cultivation at 25 °C for 36 h. , Azoxystrobin was assayed as the positive control. The area of lesions in the infected leaves was imaged using ImageJ.…”

Spiro Derivatives in the Discovery of New Pesticides: A Research Review

“…Compound 74 (EC 50 = 7.83 μg/g) basically had the same fungicidal activity against Sphaeotheca fuliginea as azoxystrobin (EC 50 = 7.16 μg/g) . Compound 82 also displayed good fungicidal activity against Magnaporthe oryzae ; the tricyclic spiro compound 50 described above also exhibited significant fungicidal activity against Cercospora arachidicola (EC 50 = 16 mg/L) and racemic compounds (±)- 86 had moderate bactericidal activity against Xanthomonas oryzae pv oryzae and Xanthomonas oryzae pv oryzicola …”

“…88 Compound 82 also displayed good fungicidal activity against Magnaporthe oryzae; 107 the tricyclic spiro compound 50 described above also exhibited significant fungicidal activity against Cercospora arachidicola (EC 50 = 16 mg/L) and racemic compounds (±)-86 had moderate bactericidal activity against Xanthomonas oryzae pv oryzae and Xanthomonas oryzae pv oryzicola. 108 A review of the literature has shown that many spiro compounds displaying high fungicidal activity are based on an indole structure, and the introduction of electron-withdrawing groups into their structure can often increase this activity. 89,93,109−112 For example, compounds 99 and 100 discovered by Jia et al showed broad-spectrum fungicidal activity with a minimum inhibitory concentration of 1.1−36.9 μM against Colletotrichum gloeosporioides, Valsa mali, Alternaria alternata, and Alternaria brassicae.…”

Design, Synthesis, and Bioactivity of Spiro Derivatives Containing a Pyridine Moiety

“…Unlike ordinary organic compounds, spiro compounds have special characteristics, such as a rigid structure, spiro conjugation, and spiro hyperconjugation, , offering them great potential for binding with biomolecules . This binding potential can somewhat change the water solubility and lipophilicity of drug molecules, facilitating the development of optimized lead molecules into drugs and reducing resistance. , Several molecules derived from spiro compounds exhibit various types of biological activities, such as insecticidal, antibacterial, antifungal, herbicidal, and antiviral activities and plant growth regulator properties in pesticides as well as antioxidant, antitumor, anticancer, and anti-inflammatory activities in medicine. Currently, the most common commercial pesticides containing a spiro skeleton include three types of tetronic-acid insecticidesspirodiclofen, spirotetramat, and spiromesifenwhich were developed by Bayer and could inhibit the lipid synthesis in pests through acetyl-CoA carboxylase to achieve efficient and rapid insecticidal effects. − …”