Optimization of a CUPRAC-Based HPLC Postcolumn Assay and Its Applications forGinkgo bilobaL. Extracts

Abstract

The aim of the present work was to improve and validate the HPLC-CUPRAC postcolumn method for the evaluation of active antioxidant markers from the acetonic extracts of Ginkgo biloba leaves. Improvement of the HPLC online assay was performed by evaluating the suitable loop temperature, the reaction loop length, and the impact of flow rate. Separation of the analytes was performed by the HPLC method on an ACE C18 analytical column using a gradient elution program. The separated antioxidant markers in the extracts reacted with copper(II)-neocuproine (Cu(II)-Nc) reagent in the postcolumn reaction coil. The reagent was reduced by antioxidants to the copper(I)-neocuproine (Cu(I)-Nc) chelate with a maximum absorption at 450 nm. Validation experiments confirmed sufficient precision, sensitivity, and effectiveness of the corresponding method, which could be used for further evaluations of active antioxidant compounds in similar plant materials.

Thermal fixation technologies affect phenolic profile, ginkgolides, bilobalide, product quality, and ginkgolic acids in Ginkgo biloba leaf tea

“…Rimkiene et al. (2015) identified quercetin as the antioxidants expressed as TEAC values from Ginkgo biloba extract. Copper was reduced primarily by quercetin.…”

“…The antioxidant mechanism works using the mechanism that involves the reduction of Cu 2+ to Cu 1+ (Latos-Brozio et al, 2021). Rimkiene et al (2015) identified quercetin as the antioxidants expressed as TEAC values from Ginkgo biloba extract. Copper was reduced primarily by quercetin.…”

Variation in Flavonoid Composition and Radical-Scavenging Activity inGinkgo bilobaL. due to the Growth Location and Time of Harvest

“…The raw material was air-dried at room temperature (20)(21)(22)(23)(24)(25) ∘ C) until reaching air-dried condition in well ventilated room, protected from direct sun rays. Loss on drying before the analysis was determined by applying the method indicated in the European Pharmacopoeia.…”

“…Quercetin, kaempferol, and isorhamnetin are assigned as markers that can be used to evaluate the quality and authenticity of G. biloba extracts and dosage forms [20,21]. Therefore, as described above, aglycones, which are used as markers, were chosen for our further investigations.…”