Green Synthesis, Physicochemical Characterization, and In Vitro Biological Evaluation of Moringa concanensis-Mediated Zinc Oxide Nanoparticles with Keratinocyte Wound-Closure Activity.

Oxidative stress, hyperglycaemia and defective keratinocyte-mediated repair impair diabetic wound healing. Moringa concanensis is a lesser explored medicinal plant with wide phytochemical constituents and feasible for the nanoparticle mediated biomedical applications. The current research was focused on the green synthesis of zinc oxide nanoparticles (ZnO NPs) with M. concanensis hydromethanolic leaf extract, their physicochemical characterization, and initial in vitro assessment of antioxidant, antidiabetic enzyme inhibitory, cytocompatibility, and wound-closure activities. ZnO NPs were synthesized using the hydromethanolic leaf extract of M. concanensis and zinc nitrate under alkaline conditions and characterized using UV-visible spectroscopy, Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), dynamic light scattering (DLS), zeta potential analysis, scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy and gas chromatography-mass spectrometry (GC-MS). The antioxidant activity was determined by DPPH, ABTS and FRAP assay, and the α-amylase and α-glucosidase inhibition assay were used as preliminary biochemical indicators for antidiabetic activity. Cytocompatibility was evaluated in HaCaT human keratinocytes, with the MTT assay. The wound-closure activity was evaluated by an in vitro scratch assay. The synthesized ZnO NPs showed a characteristic UV-visible absorption maximum at 364 nm with an estimated optical band gap of 3.40 eV. The XRD confirmed the crystalline hexagonal wurtzite ZnO phase with an average crystallite size of about 35 nm and the Raman spectrum showed the characteristic E₂(high) mode at 438 cm-1. DLS showed an average hydrodynamic diameter of 245.2 nm, a polydispersity index of 0.540 and a zeta potential of -12.0 mV. From EDX analysis, the wt% of Zn and O was 69.54 and 30.46 respectively. HRTEM and SAED indicated that the nanoparticles were mostly hexagonal/polyhedral with clear lattice fringes. GC - MS analysis of M. concanensis extract showed tentative identification of 78 phytochemical constituents. The antioxidant activity of ZnO NPs was found to be concentration dependent with IC50 values of > 100 µg/mL, 74.6 µg/mL and 64.20 µg/mL for DPPH, ABTS and FRAP respectively. The IC 50 values for α-amylase and α-glucosidase inhibition were 86.53 and 72.95 µg/mL, respectively. The viability of HaCaT cells was > 50% in the concentration range tested (100-1000 µg/mL), which corresponds to an estimated IC₅₀ > 1000 µg/mL. ZnO NPs at 584 µg/mL (85.00 ± 1.05%) showed significantly increased scratch wound closure compared to control (61.71 ± 0.89%) after 48 h (p = 0.0017). All quantitative experiments were performed with appropriate replicates and are expressed as mean ± standard deviation. Statistical significance was determined by one-way ANOVA with Tukey's multiple-comparison test or an unpaired Student's t test where appropriate; p < 0.05 was considered to be statistically significant. ZnO NPs produced by Moringa concanensis demonstrated distinct physicochemical properties, concentration-dependent in vitro antioxidant and enzyme inhibitory activities, little cytotoxicity to HaCaT keratinocytes, and improved scratch wound closure. These results offer first proof that the biosynthesized ZnO NPs could be a valuable candidate material for more studies on wound healing. However, because suitable comparable nanoparticle controls were not included, the contribution of ZnO versus plant-derived surface phytochemicals cannot be independently proven, and the observed scratch closure indicates the combined effects of keratinocyte migration and proliferation. Therefore, before treatment efficacy can be determined, mechanistic studies, expanded biocompatibility evaluation, and in vivo investigations are necessary.