Endophytic bacterial strain, Brevibacillus brevis-mediated green synthesis of copper oxide nanoparticles, characterization, antifungal, in vitro cytotoxicity, and larvicidal activity

Abstract

The biomass filtrate containing various metabolites of endophytic bacterial strain, Brevibacillus brevis PI-5 was used as a biocatalyst for reducing and stabilizing copper oxide nanoparticles (CuO-NPs). UV-Vis spectroscopy, Fourier transform infrared, transmission electron microscopy, scanning electron microscopy with energy-dispersive X-ray (SEM-EDX), X-ray diffraction, and X-ray photoelectron spectroscopy were used for CuO-NPs characterization. A spherical, well-dispersed, and crystallographic structure with sizes of 2–28 nm was formed. The SEM-EDX confirmed the presence of Cu and O with weight percentages of 27.62% and 48.88%, respectively. The biological activities including antifungal, anticancer, and larvicidal of synthesized CuO-NPs were assessed using the fungal radial growth inhibition, MTT assay method, and mortality percentages, respectively. The obtained data showed that the CuO-NPs exhibit high activity in a dose-dependent manner. The growth of three phytopathogenic fungi, Fusarium oxysporum, Alternaria alternata, and Aspergillus niger was decreased by percentages of 64.5% ± 4.1%, 62.9% ± 0.3%, and 70.2% ± 2.3%, respectively at 300 µg·mL–1. Also, various clinical Candida spp. were successfully inhibited with varied zones of inhibition and minimum inhibitory concentration values in ranges of 6.25–50 µg·mL–1. The in vitro cytotoxicity exhibits target-orientation to breast cancer cells (T47D) at low concentration compared to normal cells (HFB4) with IC50 values of 122.3 ± 5.4 and 229.9 ± 5.7 μg·mL–1, respectively. The mortality percentages of I, II, III, and IV instar larvae of Culex antennatus were 60% ± 1.4%, 43.1% ± 1.1%, 36.2% ± 1%, and 32.1% ± 0.9%, at 10 mg·L–1 and increased to 86.9% ± 2.1%, 68.1% ± 1.7%, 64.4% ± 1.9%, and 53.1% ± 1.4% at 50 mg·L–1, respectively.

Keywords

• green synthesis
• cuo-nps
• phytopathogenic fungi
• breast cancer
• culex antennatus