Green-Synthesized Gold Nanoparticles Using Pfaffia glomerata Extract Improve Maternal Hypertension and Angiogenic Markers in Pregnant Hypertensive Rats

Background: Hypertensive disorders of pregnancy present a major global health challenge. Green nanotechnology offers a strategy to enhance the stability and efficacy of bioactive natural products. This study evaluated gold nanoparticles green-synthesized with Pfaffia glomerata extract (AuNPs-PG) against gestational hypertension and fetal complications in spontaneously hypertensive rats (SHRs). Methods: P. glomerata root extract was characterized by UHPLC-MS/MS. AuNPs-PG were green-synthesized with 2 mmol/L HAuCl4 (1:5 v/v) at 40 °C and characterized by UV-Vis and DLS. Pregnant Wistar-Kyoto and SHRs were divided into naive, negative control (NC), amlodipine (5 mg/kg), and AuNPs-PG groups (0.03, 0.1, and 0.3 mg/kg) treated daily on gestational days 1–18 to evaluate maternal cardiovascular, renal, biochemical, and reproductive outcomes. Results: UHPLC-MS/MS identified 38 compounds. AuNPs-PG showed a plasmon band at 520–550 nm and 88.1 nm hydrodynamic diameter. In SHRs, 0.3 mg/kg AuNPs-PG reduced systolic blood pressure by 18.5% and mean arterial pressure by 15.4%, while mitigating vascular dysfunction by lowering phenylephrine vasoconstriction by 52.7% and boosting acetylcholine vasodilation by 239.3%. Treatment shortened QTc interval by 26.4%, normalized T-wave inversion, and restored renal excretion, increasing urinary volume by 75.0% and sodium by 94.2%. Furthermore, AuNPs-PG elevated placental growth factor by 180.9%, lowered malondialdehyde by 63.5%, and preserved placental histology. Consequently, mean fetal weight increased by 21.6%, implantation index by 50.5%, and offspring-to-mother ratio by 129.6%. Conclusions: AuNPs-PG (0.3 mg/kg) effectively mitigate maternal and fetal complications in gestational hypertension. Gold nanoparticles serve as nanocarriers, whereas surface-adsorbed phytochemicals drive the biological effects.