Synthesis of Some Amidoalkyl naphthol and Benzoxanthene Derivatives by Zinc Oxide Nanoparticles as a Catalyst under Solvent-Free Condition and Evaluation of their Antimicrobial and Antioxidant Activities

Abstract

Synthesis of amidoalkyl naphthol and benzoxanthene is significant, because they have important pharmaceutical applications. They exhibit wide range of biological activities such as antimalarial, anticancer, antibacterial, antifungal, antiviral, anti-inflammatory, analgesic, antirheumatic and antianginal. In this research, some of amidoalkyl naphthol and benzoxanthene derivatives were synthesized by one-pot condensation reaction of aromatic aldehydes,betanaphthol and amide using zinc oxide nanoparticles (ZnO NPs). The structures of the synthesized compounds were characterized by spectroscopic techniques (FT-IR spectra and NMR spectra). The synthesized compounds have been screened for their biological activities such as antibacterial activities against gram positive bacterial strains (S.aureus ATCC 25923, B. subtilis ATCC 6623), gram negative bacterial strains (E. coli ATCC 25922, P.aeroginosa ATCC 7553 ) using tetracycline as positive control, antifungal activities against C. albicunas using fluconazole as positive control. Antioxidant activities of synthesized compounds were determined by using 2, 2-diphenyl-1-picryl-hydrazyl (DPPH) assay method and ascorbic acid as a standard. The corresponding synthesized amidoalkyl naphthols 27, 28 (89.8-90.4%) and benzoxanthenes 29, 30 and 31 (89.4-93.5%) were found higher yield than other reported methods. Antibacterial activity results of synthesized benzoxanthenes 30 and 31 showed activities with zone of inhibition (mm) against all gram negative strains (9-15mm) and gram positive bacterial strains (9-13mm) tested where as benzoxanthene 29 was active against B. subtilis (8,9,10mm), (10,11,12mm) for both B. subtilis and E.coli. Amidoalkyl naphthol 27 showed activity against B. subtilis (10, 11, 12mm) only and amidoalkyl naphthol 28 was active against both B. subtilis (9, 10,12mm) and E.coli (10, 11,15mm). Amongst all, the benzoxanthene 29 has only shown antifungal activity against C. albicuna (12, 14,16 mm zone of inhibition) even stronger than the standard fluconazole and amidoalkyl naphthol 28, 27 and benzoxanthenes 30, 31 were inactive against C. albicuna. Except benzoxanthene 31, All the remaining synthesized compounds have shown promising antioxidant activities with an IC50 values of 24.45, 17.65, 22.6 and 47.56 μg/ml for amidoalkyl naphthol 27, 28 and benxoxanthene 29, compared to standard ascorbic acid (9.28µg/ml)respectively.