Optimization of Extraction Conditions to Improve Chlorogenic Acid Content and Antioxidant Activity of Extracts from Forced Witloof Chicory Roots

Abstract

Chlorogenic acids are major phenolic constituents in many herbal medicines and exhibit various bioactivities that explain the growing interest in extracting chlorogenic acids from biomass. In this context, the present study aims to maximize 3-O-Caffeoylquinic acid (3-CQA) and 3,5-O-di-caffeoylquinic acid (3,5-diCQA) contents from forced witloof chicory roots and to analyze the extraction kinetic modelling. First, the solid–liquid ratio, ethanol concentration, extraction time and temperature were studied. The extraction conditions were optimized to maximize the extraction of these compounds. The maximum yields reached 5 ± 0.11 and 5.97 ± 0.30 mg/g dry matter (DM) for 3-O-Caffeoylquinic acid and 3,5-O-di-caffeoylquinic acid, respectively, in less than 6 min at 70 °C. Extraction with water as a solvent was assessed with the aim of proposing a second greener and less-expensive solvent. This extraction is very fast from 90 °C, with a maximum of 6.22 ± 0.18 mg/gDM of 3-O-Caffeoylquinic acid, and instantaneous for 3,5-O-di-caffeoylquinic acid with a maximum of 6.44 ± 0.59 mg/gDM. In the second step, response surface methodology was employed to optimize the ultrasound-assisted extraction of antioxidants. The higher antioxidant activities were found at temperatures from 40 °C and at percentages of ethanol in the range of 35–70%.

Optimization of the Accelerated Solvent Extraction of Caffeoylquinic Acids from Forced Chicory Roots and Antioxidant Activity of the Resulting Extracts

“…For comparison, two studies found yields between 2 and 6 mg/g DM of chlorogenic acid using respectively methanol and 80% ethanol during 15 min [ 3 ]. Only [ 4 ] quantified the 3,5-diCQA in the forced chicory roots. The 3,5-diCQA extraction optimum (5.97 ± 0.30 mg/g DM ) is similar to those presented in our study afterwards (5.41 ± 0.79 mg/g DM ).…”

“…A second effect appears at relatively high temperature, namely the thermal transformation of phenolic compounds. For 3,5-diCQA, the extraction yield decreases at high temperature, mostly due to the isomerisation of 3,5-diCQA to 4,5-diCQA [ 4 ] and 3,4-diCQA (data not shown). For 5-CQA, the decrease in yield occurs at a higher temperature than for 3,5-diCQA.…”

“…The extract samples were first diluted from 7.5 to 25 with methanol and then 300 µL of solution was mixed with 900 µL of DPPH solution (46.7 mg/L) prepared with methanol. The determination method has been slightly modified from the method described by Brand-Williams et al (1995) and was similar to our previous work [ 4 ]. Briefly, the scavenging capacity was determined by monitoring the decrease in absorbance (UV-vis spectrophotometer Agilent Technologies Cary 60, Wilmington, DE, USA) at 515 nm after 80 min of reaction at room temperature to fully complete the oxidation reaction.…”

“…However, these forced roots are rich in bioactive compounds with interesting properties such as phenolic compounds and sesquiterpenes lactones [ 3 ]. The main phenolic compounds in forced roots are chlorogenic acid (5-CQA) and 3,5-dicaffeoylquinic acid (3,5-diCQA) ( Figure 1 ) [ 4 ].…”

“…Water is environmentally friendly and less expensive than organic solvents, although it results in a low extraction yield at room temperature [ 13 ]. Extraction temperature plays an important role in improving the extraction yield of CQAs [ 4 , 14 ]. Increasing the temperature reduces solvent viscosity and improves the solubility of extracted molecules [ 15 ].…”