Scalable extraction of pongamol from Pongamia pinnata for synthesis and application of colloidally stable iron nanoparticles

Abstract

Pongamol, a flavonoid that constitutes a major bioactive fraction of Pongamia pinnata oil, is attracting interest as a renewable antioxidant, antimicrobial and anti-inflammatory agent. Its wider use is hindered by labor-intensive schemes that rely on preparative chromatography. Here we introduce a scalable two-solvent recrystallization (ethanol : water) that yields pongamol at high purity (>97%), eliminating the need for more sophisticated instrumentation. Extraction at pH 5.8 followed by the recrystallization achieved high recovery while suppressing co-extractables. UV-Vis, ¹H/¹³C-NMR, LC-MS and HPLC verified the identity and isomeric integrity of the product. We further show that purified pongamol serves simultaneously as a reducing agent and capping ligand for a one-pot, room-temperature “green” synthesis of iron nanoparticles (FeNPs). The resulting FeNPs exhibited a mostly spherical morphology, a mean hydrodynamic diameter of ∼12 nm, and a negative zeta potential that conferred colloidal stability comparable to, or better than, FeNPs synthesized with green tea extract, as confirmed by DLS and TEM. This dual-purpose protocol integrates bio-based extraction with benign nanoparticle synthesis, offering an efficient route to value-added utilization of P. pinnata oil in sustainable nanomaterials. Moreover, we also demonstrated synthesized pongamol-FeNPs can degrade methylene blue effectively as a photocatalyst and promote Pseudomonas defensor growth at low concentrations.