Development of chitosan nanoparticle loaded with <i>Tricholoma fracticum</i> extract and evaluation of <i>in vitro</i> antioxidant activity

Abstract The objective of this study was to develop Tricholoma fracticum extract-loaded chitosan nanoparticles (TFNPs) by ionic gelation method and to evaluate their in vitro antioxidant activity. Phenolic and flavonoid contents in the T. fracticum extract were measured spectrophotometrically and chromatographically. Characterisation of NPs was evaluated by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), ZETA analysis, Fourier-transform infrared spectroscopy (FT-IR), UV–visible spectroscopy (UV–Vis) and thermogravimetric analysis (TGA). In vitro antioxidant capacity was determined using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assays. The phenolic and flavonoid contents in the T. fracticum extract were measured as 7.1 ± 0.3 mg Gallic Acid Equivalent/g extract and 5.5 ± 0.6 mg Quercetin Equivalent/g extract, respectively. The particle size, polydispersity index (PDI) and zeta potential of Blank NP1 and TFNP were 265.5 ± 15.8 nm, 0.4, 38.7 ± 4.0 mV and 333.2 ± 16.3 nm, 0.4, 37.0 ± 4.1 mV, respectively. The highest antioxidant activity was observed in TFNP, followed by T. fracticum extract, chitosan and blank NP, respectively. The preserved or enhanced antioxidant activity observed in the encapsulated T. fracticum extract indicates the potential for loading similar mushroom extracts onto chitosan and thus preserving their bioactive properties.