3-Indole carbaldehyde

Indole‐3‐carbaldehyde based novel ligand (E)‐2‐((1‐benzyl‐1H‐indol‐3‐yl)methylene)‐ N ‐methylhydrazine‐1‐carbothioamide ( MBIHC ) and its metal complexes [(MBIHC) 2 FeCl 2 ]Cl( C1 ), [(MBIHC − ) 2 Co] ( C2 ), [(MBIHC − ) 2 Ni] ( C3 ), and [(MBIHC − ) 2 Cu] ( C4 ) have been synthesized. All synthesized compounds have been characterized by various spectroanalytical techniques. The structure of MBIHC was confirmed by single‐crystal X‐ray data. The geometry of metal complexes was determined by spectroscopic and computational studies. In the case of iron complex, ligand MBIHC coordinated to the metal ion in bidentate mode ( via nitrogen, sulphur donor atoms) while in the case of cobalt, nickel, and copper complexes ligand act as a tridentate ligand ( via nitrogen, sulphur, carbene donor atoms). In vitro , antifungal and antibacterial studies of ligand and metal complexes were assayed against C. albicans , C. glabrata, E. coli , and K. pneumoniae pathogens. In antifungal activity, complex C1 exhibited a greater inhibition zone than the other compounds for the both examined fungi C. albicans (24±0.32 mm) and C. glabrata (20±0.16 mm). However, the antifungal activities of complex C2 has shown better activity against both E. coli (25±0.24 mm) and K. pneumoniae (16±0.80 mm) pathogens than the other examined compound. Complex C2 has found even better than the benchmark drug Ampiciline in case of E. coli . Further, the DFT calculations and molecular docking studies also validate the experimental bioactivity results of examined compounds.

Sexual mating of compatible sporida is essential for Sporisorium scitamineum to form dikaryotic mycelia and then cause infection on sugarcane. Our previous work identified a Pseudomonas sp. ST 4 from a soil sample, which showed a promising biocontrol potential by inhibiting the mating of S. scitamineum sporida and hyphal growth. In this study, we set to isolate the active compounds from Pseudomonas sp. ST 4 through solid fermentation. High‐performance liquid chromatography ( HPLC ) separation coupling with bioassay showed that Pseudomonas sp. ST 4 produced a range of antimicrobial compounds. Two of the major components were purified following acetate extraction, silica gel and HPLC separation. Nuclear magnetic resonance ( NMR ) and liquid chromatography–mass spectrometry ( LC ‐ MS ) analysis identified these active compounds are 4‐hydroxybenzaldehyde and indole‐3‐carbaldehyde respectively. Further analysis showed that the former compound only inhibited the hyphal growth of the fungus at a concentration of 3  mM , while the latter interfered the fungal sexual mating at a concentration of 0.6  mM and affected hyphal growth at a concentration of 2  mM . Treatment of corn plants with 3  mM indole‐3‐carbaldehyde significantly inhibited corn smut infection, with a control rate up to 94%. Further analysis of the structure and activity relationship revealed that indole has a much stronger inhibitory activity against the fungal sexual mating than indole‐3‐carbaldehyde. The results from this study provide new agents for control and prevention of the sugarcane smut disease, and the active compounds could also be used to probe the molecular mechanisms of fungal sexual mating.