Proficient synthesis of zinc oxide nanoparticles from Tabernaemontana heyneana Wall. via green combustion method: Antioxidant, anti-inflammatory, antidiabetic, anticancer and photocatalytic activities

Abstract

The zinc oxide nanoparticles (T-ZnO NPs) were synthesized successfully by the application of leaf, stem and callus extracts of Tabernaemontana heyneana Wall. via the green combustion method. The structural, bonding and morphological features of T. heyneana mediated ZnO NPs (T-ZnO NPs) were explored using XRD (X-ray powder diffraction), UV–Vis (Ultra-violet visible spectroscopy), FESEM-EDS (Field Emission-SEM and energy-dispersive X-ray spectra), DLS (Dynamic light scattering) and FTIR (Fourier transform infrared) techniques. UV–Vis spectra revealed the presence of a band in the region between 370 and 376 nm approving the presence of T-ZnO NPs. XRD, FESEM-EDS, TEM and DLS analysis confirmed the formation of nanosized, spherical shaped, highly stable and pure crystalline wurtzite T-ZnO NPs. FTIR spectra revealed the presence of most probable phytochemicals from plant extracts involved in the processes of reduction and stabilization of T-ZnO NPs. The T-ZnO NPs could effectively inhibit the activity of DPPH (1, 1-Diphenyl-2-picrylhydrazyl) radical (IC50 value between 467.7 and 752.3 µg/ml) exhibiting potent radical scavenging activity. The T-ZnO NPs exhibited strong anti-inflammatory (membrane stabilization) activity. The antidiabetic potential of T-ZnO NPs was assessed and found to exhibit excellent α-glucosidase (IC 50 at 16.3 µg/ml) and α-amylase (IC 50 at 42.3 µg/ml) activity. The cytotoxic effect of T-ZnO NPs was investigated against A549 cell line (human lung cancer) by MTT assay which showed dose dependent response. IC50 values were found to be in the range of 89.47–185.8 µg/ml demonstrating their higher cytotoxic efficacy. AO/EB staining indicated the presence of early apoptotic cells. The percentage degradation of carcinogenic methylene blue dye was studied and an outstanding catalytic activity of 87–100% was recorded by ZnO-NPs within 160 min. Hence, T-ZnO NPs proved to be better candidates for futuristic biomedical and industrial applications.