Optimization of high-speed counter-current chromatography for separation of polyphenols from the extract of hawthorn (Crataegus laevigata) with response surface methodology

Optimisation of isolation of polyphenols from Malus pumila Mill. Leaves by high-speed countercurrent chromatography using response surface methodology

Considering comprehensive utilization of natural products, isolation and activity determination processes of bioactive compounds are essential. In this study, a combined high-speed countercurrent chromatography (HSCCC) with preparative HPLC method was developed to isolate the five antioxidant polyphenols from 75% ethanol extract of Malus pumila Mill. leaves. The HSCCC conditions were optimized by response surface methodology (RSM) considering two response indexes including retention of stationary phase and analysis time. The optimal HSCCC conditions were flow rate of 2.11 mL/min, revolution speed of 717 rpm, and temperature of 25℃, with a solvent system of ethyl acetate/methanol/water (10:1:10, v/v/v). The unseparated fractions obtained from HSCCC were subjected to preparative HPLC for further isolation. As a result, phloridzin (15.3 mg), isoquercitrin (2.1 mg), quercetin 3-O-xyloside (1.9 mg), quercetin-3-O-arabinoside (4.0 mg), and quercitrin (2.0 mg) were isolated from 200.0 mg extracts. The purities of these compounds were all above 92%. Their chemical structures were identified by mass spectrometer and nuclear magnetic resonance. The five isolated compounds were further investigated for their rat hippocampal neuroprotective effects against hydrogen peroxide-induced oxidative stress. No cytotoxicity was observed in all tested concentrations. While all five compounds except phloridzin showed significantly neurogenic activities and neuroprotective effects, especially at the concentration of 0.5 mg/L. These results demonstrate that RSM is a suitable technique for optimisation of HSCCC and the isolated polyphenols can be used as antioxidants in pharmaceutical and food products.

Preparation of highly purified oleuropein by combinative technology off line of HSCCC-PHPLC based on dual wavelength

Oleuropein is the main active substance in foods or functional foods produced from olive (Olea europaea L.) leaves. In the present study, the combinative technology off line of HSCCC-PHPLC based on dual wavelength was used to separate highly purified oleuropein from oleuropein extract. Response surface methodology was used to optimize the conditions of HSCCC. Furthermore, a large amount of higher purified oleuropein was obtained through HSCCC at the wavelength of 254 nm, and oleuropein with the purity greater than 98.5% was obtained by PHPLC at the wavelength of 300 nm. Finally, the purity and structure identification of highly purified oleuropein were determined by various methods and its stability was investigated. As a result, oleuropein was stable in solution, and had good stability under the condition of dark storage at 4°C within a week or under the condition of dark storage at -20°C within one year. PRACTICAL APPLICATION: In this study, an efficient method for purification and refining of oleuropein by combinative technology off line of HSCCC-PHPLC based on dual wavelength was established. Oleuropein with the purity greater than 98.5% was macro-obtained via the technology. The highly purified oleuropein could be used to control the quality of olive products.

Agriculture waste valorisation as a source of antioxidant phenolic compounds within a circular and sustainable bioeconomy

Agro-food industrial waste is currently being accumulated, pushing scientists to find recovery strategies to obtain bioactive compounds within a circular bioeconomy. Target phenolic compounds have shown market potential by means of optimization extraction techniques.

Chemistry and Pharmacology of the Kazakh Crataegus Almaatensis Pojark: An Asian Herbal Medicine

Crataegus almaatensis, an endemic ornamental plant in Kazakhstan is used in popular medicine due to its cardiotonic properties. The most studied species of the same genus are commonly found in Europe, which shows the importance of having the Kazakh species validated via its chemical and pharmacological studies. High-speed countercurrent chromatography (HSCCC) operated under optimized conditions enabled an isolation of the three main compounds from the aqueous phase of the leaves ethanol extract, further identified by nuclear magnetic resonance (NMR), as quercetin 3-O-rhamnoside (quercitrin) (4.02% of the crude extract-CECa); quercetin 3-O-β-galactoside (hyperoside) (1.82% of CECa); kaempferol 3-O-α-L-rhamnoside (afzelin) (0.94% of CECa). The CECa, the aqueous phase of the crude extract (APCa) together with the isolates were evaluated for their vascular (vascular reactivity in human internal mammary artery-HIMA), anti-nociceptive (formalin-induced liking response and hot plate) and anti-inflammatory (subcutaneous air-pouch model-SAP) activities. CECa at the concentrations of 0.014 and 0.14 mg/mL significantly increased the maximum contractility response of HIMA to noradrenaline. The APCa CR curve (0.007–0.7 mg/mL) showed an intrinsic relaxation effect of the HIMA. APCa at the dose of 100 mg/kg i.p. significantly decreased the total leukocyte count and the IL-1β release in the SAP wash.

Optimization of polyphenol removal from kiwifruit juice using a macroporous resin

BACKGROUND

The separation of polyphenols from kiwifruit juice is essential for enhancing sensory properties and prevent the browning reaction in juice during processing and storage.

RESULTS

The present study investigated the dynamic adsorption and desorption of polyphenols in kiwifruit juice using AB-8 resin. The model obtained could be successfully applied to predict the experimental results of dynamic adsorption capacity (DAC) and dynamic desorption quantity (DDQ). The results showed that dynamic adsorption of polyphenols could be optimised in a juice concentration of 19 °Brix, with a feed flow-rate of 1.3 mL min^-1 and a feed volume of 7 bed volume (BV). The optimum conditions for dynamic desorption of polyphenols from the AB-8 resin were an ethanol concentration of 43% (v/v), an elute flow-rate of 2.2 mL min^-1 and an elute volume of 3 BV. The optimized DAC value was 3.16 g of polyphenols kg^-1 resin, whereas that for DDQ was 917.5 g kg^-1 , with both values being consistent with the predicted values generated by the regression models. The major polyphenols in the dynamic desorption solution consisted of seven compositions.

CONCLUSION

The present study could be scaled-up using a continuous column system for industrial application, thus contributing to the improved flavor and color of kiwifruit juice. © 2016 Society of Chemical Industry.

Countercurrent Separation of Natural Products: An Update

This work assesses the current instrumentation, method development, and applications in countercurrent chromatography (CCC) and centrifugal partition chromatography (CPC), collectively referred to as countercurrent separation (CCS). The article provides a critical review of the CCS literature from 2007 since our last review (J. Nat. Prod. 2008, 71, 1489-1508), with a special emphasis on the applications of CCS in natural products research. The current state of CCS is reviewed in regard to three continuing topics (instrumentation, solvent system development, theory) and three new topics (optimization of parameters, workflow, bioactivity applications). The goals of this review are to deliver the necessary background with references for an up-to-date perspective of CCS, to point out its potential for the natural product scientist, and thereby to induce new applications in natural product chemistry, metabolome, and drug discovery research involving organisms from terrestrial and marine sources.

Ultrasound-assisted extraction and preliminary purification of proanthocyanidins and chlorogenic acid from almond (Prunus dulcis) skin

An aqueous solution of polyethylene glycol (PEG) as a green solvent was employed for the first time to develop the ultrasound-assisted extraction of proanthocyanidins (PA) and chlorogenic acid (CA) from almond skin. The optimized extraction parameters were determined based on response surface methodology, and corresponded to an ultrasound power of 120 W, a liquid-to-solid ratio of 20:1 (mL/g), and a PEG concentration of 50% (v/v). Under these optimized conditions, the extraction yields of PAs and CA from almond skin were 32.68 ± 0.22 and 16.01 ± 0.19 mg/g, respectively. Compared with organic solvent extraction, PEG solution extraction produced higher yields. Different macroporous resins were compared for their performance in purifying PAs and CA from almond skin extract. Static adsorption/desorption experimental results demonstrated that AB-8 resin exhibits excellent purification performance at pH 4. Under the optimized dynamic adsorption/desorption conditions on the AB-8 column, the total recovery of purification for PAs and CA was 80.67%. The total content of PAs and CA in the preliminarily purified extract was 89.17% (with respective contents of 60.90 and 28.27%).