Alkylated Salicylaldehydes and Prenylated Indole Alkaloids from the Endolichenic Fungus Aspergillus chevalieri and Their Bioactivities

• DOI: 10.1021/acs.jafc.1c01148
• Publication Date: 2021-06-07T13:19:42Z
• Authors: Li-Bin Lin; Yu-Qi Gao; Rui Han; Jian Xiao; Yi-Meng Wang; Qiang Zhang; Yi-Jie Zhai; Wen-Bo Han; Wen-Li Li; Jin-Ming Gao
• Keywords: Molecular Docking Simulation; 0301 basic medicine; Aldehydes; 03 medical and health sciences; Aspergillus; Molecular Structure; Fungi; 01 natural sciences; Indole Alkaloids; 0104 chemical sciences

Sixteen metabolites, including seven C7-alkylated salicylaldehyde derivatives (1-7) and nine prenylated indole alkaloids (8-16), three of which are new, namely, asperglaucins A and B (1 and 2) and neoechinulin F (8), were separated from the endolichenic fungus Aspergillus chevalieri SQ-8. Asperglaucin A (1) represents an unusual phthalide-like derivative with a benzo[c]thiophen-1(3H)-one scaffold. All compounds were assessed in vitro for antibacterial, antineuroinflammatory, and antioxidant activities. Notably, asperglaucins A and B exhibited potent antibacterial activities against two plant pathogens Pseudomonas syringae pv actinidae (Psa) and Bacillus cereus, with an MIC value of 6.25 μM; further SEM analyses illustrated that the possible bacteriostatic mechanisms for compounds 1 and 2 were to alter the external structure of B. cereus and Psa, and to cause the rupture or deformation of the cell membranes, respectively, and the results suggest that compounds 1 and 2 may serve as potential promising candidates for lead compounds of agrochemical bactericides. Furthermore, compounds 6 and 10 significantly inhibited nitric oxide production with an IC50 value of ca. 12 μM, and the possible anti-inflammatory mechanisms involved were also studied by molecular docking. Finally, the tested phenolics 3-5 showed significant antioxidative effects. Thus, strain SQ-8 represents a novel resource of these bioactive metabolites to be utilized.