Green chemical one-pot multicomponent condensation reaction of substituted 1H-indole-2,3-diones (1), various amino acids (2), and thiosemicarbazide (3) is found to be catalyzed by lemon juice as natural acid using water as a green solvent to give the corresponding Schiff bases (4) in good to excellent yields. This method is experimentally simple, clean, high yielding, and green, with reduced reaction times. The product is purified by simple filtration followed by washing with water and drying process. The synthesized compounds are characterized by FT-IR, 13 CNMR, and 1 HNMR spectroscopy and are screened for their antifungal activity against Aspergillus niger, Penicillium notatum, Fusarium oxysporum, Alternaria brassicicola, Chaetomium orium, and Lycopodium sp. and antibacterial activity against Gram-positive bacteria, Bacillus licheniformis, Staphylococcus aureus, and Micrococcus luteus, and Gram-negative bacteria, Pseudomonas aeruginosa and Escherichia coli. Compounds have also been evaluated for cytotoxic effects against human colon cancer cell line Colo205
