Neuroprotective effect of Dictyopteris divaricata extract-capped gold nanoparticles against oxygen and glucose deprivation/reoxygenation.

Combination therapy remains a promising approach to ameliorate cerebral ischemia injury. Nevertheless, the primary mechanism of the neuroprotective properties of Dictyopteris divaricata extract-capped gold nanoparticles (DD-GNPs) is not completely understood. DD-GNPs displayed maximum absorption at 525 nm and a diameter of 62.6 ± 1.2 nm, with a zeta potential value of -26.1 ± 0.6 mV. High resolution-transmission electron microscopy confirmed the spherical shape and average diameter (28.01 ± 2.03 nm). Crystalline structure and gold nanoparticle synthesis of DD-GNPs were determined by X-ray powder diffraction, and the presence of elemental gold was confirmed by energy-dispersive X-ray spectroscopy and Fourier transform-infrared spectroscopy. We examined the neuroprotective properties of DD-GNPs and explored their potential mechanisms in human SH-SY5Y neuroblastoma cells treated with oxygen and glucose deprivation/reoxygenation (OGD/R). We found that DD-GNPs inhibited OGD/R-induced release of lactate dehydrogenase (LDH), loss of cell viability, and production of reactive oxygen species. This neuroprotection was accompanied by regulation of apoptosis-related proteins, as indicated by decreased levels of cleaved-caspase-3, cleaved-PARP, cleaved-caspase-9, p53, p21, and Bax, as well as an increased level of Bcl-2. Notably, the neuroprotective effects of DD-GNPs were partially abolished by HO-1, NQO1, Nrf2, and AMPK knockdown. Our results established that DD-GNPs effectively attenuated OGD/R-stimulated neuronal injury, as evidenced by reduced neuronal injury. Even though the accumulating evidence has indicated the low toxicity and minimal side effects of GNPs, experimental clinical trials of DD-GNPs are still limited because of the lack of knowledge regarding the effects of DD-GNPs as neuroprotective agents against neurodegenerative diseases.