Integrated GC-MS Profiling and Phytosynthesis of MnO₂ Nanoparticles Using Moringa oleifera: Assessment of Antioxidant, Cytotoxicity, and Potential In Vitro and In Silico Inhibitory Effects on α-Amylase and α-Glucosidase

Bioactive compounds from medicinal plants can enhance the therapeutic potential of trace metal-oxide nanoparticles. This study contributed to identifying the main volatile compounds and synthesizing manganese dioxide nanoparticles (MnO₂ NPs) using Moringa oleifera (MO) leaf extract and explored their biological applications. Gas chromatography-mass spectrometry (GC-MS) analysis identified 21 volatile compounds with known bioactivities from the leaves of MO. Transmission electron microscopy (TEM) and x-ray diffraction analysis showed that MnO₂ NPs were spherical and crystalline, averaging ∼8.3 nm in size. Antioxidant activity, assessed by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assays, revealed high potency (IC₅₀ = 9.08 ± 0.11 and 6.62 ± 0.12 µg/mL). Cell viability assays indicated relative non-toxicity, with IC₅₀ values greater than 20 µg/mL for human embryonic kidney (HEK 293) and liver (HEPG2) cells. The antidiabetic effects were evaluated against α-amylase and α-glucosidase enzymes, showing IC₅₀ values of 36.58 ± 0.74 and 55.03 ± 1.68 µg/mL, respectively, compared to FDA-approved acarbose. Docking studies yielded scores of -6.10 and -7.32 kcal/mol. Overall, these results highlight that the MO-synthesized MnO₂ NPs can be explored as potential antioxidant, cytoprotective, and antidiabetic agents for therapeutic uses.