Background The overuse of antibiotics leads to the emergence of antibiotic-resistant microbes which causes high mortality worldwide. Therefore, the synthesis of new active compounds has multifunctional activities are the main challenge. Nanotechnology provides a solution for this issue. Method The endophytic fungal strain Aspergillus terreus BR.1 was isolated from the healthy root of Allium sativum and identified using internal transcribed spacer (ITS) sequence analysis. The copper oxide nanoparticles (CuO-NPs) were synthesized by harnessing the metabolites of the endophytic fungal strain. The UV-Visble spectroscopy, Fourier-transform infrared spectroscopy (FT-IR), Transmission electron micrscopy (TEM), Energy dispersive X-ray (EDX), X-ray diffraction (XRD), Dynamic light scattering (DLS), and zeta potential (zeta) were used for the characterization of synthesized CuO-NPs. The activity against different pathogenic bacteria and Candida species were investigated by agar well-diffusion method. The biocombatibility and anticancer activity were assessed by MTT assay method. The scavenging of DPPH was used to investigate the antioxidant activity of synthesized CuO-NPs. Results Data showed the successful formation of crystalline nature and spherical shape CuO-NPs with sizes in the ranges of 15-55 nm. The EDX reveals that the as-formed sample contains ions of C, O, Cl, and Cu with weight percentages of 18.7, 23.82, 11.31, and 46.17%, respectively. The DLS and zeta-potential showed high homogeneity and high stability of synthesized CuO-NPs with a polydispersity index (PDI) of 0.362 and zeta-value of -26.6 mV. The synthesized CuO-NPs exhibited promising antibacterial and anti-Candida activity (concentration-dependent) with minimum inhibitory concentration (MIC) values in the ranges of 25-50 mu g mL(-1). Moreover, the fungal mediated-CuO-NPs targeted cancer cells of MCF7 and PC3 at low IC50 concentrations of 159.2 +/- 4.5 and 116.2 +/- 3.6 mu g mL-1, respectively as compared to normal cells (Vero and Wi38 with IC50 value of 220.6 +/- 3.7 and 229.5 +/- 2.1 mu g mL(-1), respectively). The biosynthesized CuO-NPs showed antioxidant activity as detected by the DPPH method with scavenging percentages of 80.5 +/- 1.2% at a concentration of 1000 mu g mL(-1) and decreased to 20.4 +/- 4.2% at 1.9 mu g mL(-1) as compared to ascorbic acid (control) with scavenging activity of 97.3 +/- 0.2 and 37.5 +/- 1.3% at the same concentrations, respectively. Conclusion The fungal mediated-CuO-NPs exhibited promising activity and can be integrated into various biomedical and theraputic applications.
