Kenaf is a rich source of bioactive compounds and has been ethnopharmacologically valued for its diverse biological activities. This study aimed to extract and enrich flavonoids from kenaf using macroporous polymeric resins to enhance their purity and potential health benefits. Three different macroporous resins were selected based on their adsorption and desorption properties to evaluate their efficiency in flavonoid enrichment from the kenaf extract. Optimal flavonoid adsorption on the selected resins occurred at pH 7, reaching equilibrium within 1440 min at an initial concentration of 20 mg/mL and a temperature of 338 K. The adsorption process was well described by the pseudo-second-order kinetics model, and the adsorption isotherm data exhibited a strong fit with the Freundlich model. Furthermore, thermodynamic analysis confirmed the endothermic nature of the adsorption process. The total flavonoid content of the desorbed solutions using HP-20, XAD-4, and LXA-817 resins was 3.6 mg QCE/g, 3.2 mg QCE/g, and 1.68 mg QCE/g, respectively, representing an 11-fold, 10-fold, and 5-fold increase compared to the initial total flavonoid content of 0.32 mg QCE/g in the original kenaf extract. LC-Q-TOF-MS/MS analysis identified key flavonoids, including kaempferol derivatives, apigenin, quercetin, and myricetin. Antioxidant assays confirmed strong free radical scavenging activity, with both crude and enriched kenaf extracts exhibiting a promising potency. This variation in antioxidant activity between the kenaf extracts is likely due to the synergistic or additive effects of other bioactive compounds primarily polyphenolic and flavonoid constituents present in the kenaf extracts. These findings suggest that macroporous resin is a practical and cost-effective method for purifying flavonoids from kenaf.
Aljawarneh et al. (Tue,) studied this question.