Ionic-liquid-based ultrasound-assisted extraction of isoflavones from Belamcanda chinensis and subsequent screening and isolation of potential α-glucosidase inhibitors by ultrafiltration and semipreparative high-performance liquid chromatography

Metabolic profiling, antioxidant, and enzyme inhibition potential of Iris pseudacorus L. from Egypt and Japan: A comparative study

Genus Iris comprises numerous and diverse phytoconstituents displaying marked biological activities. The rhizomes, and aerial parts of Iris pseudacorus L. cultivars from Egypt and Japan were subjected to comparative metabolic profiling using UPLC-ESI-MS/MS. The antioxidant capacity was determined using DPPH assay. In vitro enzyme inhibition potential against α-glucosidase, tyrosinase and lipase was evaluated. In silico molecular docking was conducted on the active sites of human α-glucosidase and human pancreatic lipase. Forty-three compounds were tentatively identified including flavonoids, isoflavonoids, phenolics and xanthones. I. pseudacorus rhizomes extracts (IPR-J and IPR-E) exhibited the highest radical scavenging activity with IC₅₀ values of 40.89 µg/mL and 97.97 µg/mL, respectively (Trolox IC₅₀ value was 14.59 µg/mL). Moreover, IPR-J and IPR-E exhibited promising α-glucosidase inhibitory activity displaying IC₅₀ values of 18.52 µg/mL, 57.89 µg/mL, respectively being more potent as compared to acarbose with IC₅₀ value of 362.088 µg/mL. All extracts exerted significant lipase inhibitory activity exhibiting IC₅₀ values of 2.35, 4.81, 2.22 and 0.42 µg/mL, respectively compared to cetilistat with IC₅₀ value of 7.47 µg/mL. However, no tyrosinase inhibitory activity was observed for all I. pseudacorus extracts up to 500 µg/mL. In silico molecular modelling revealed that quercetin, galloyl glucose, and irilin D exhibited the highest fitting scores within the active sites of human α-glucosidase and pancreatic lipase. ADMET prediction (absorption, distribution, metabolism, excretion, and toxicity) showed that most of the phytoconstituents exhibited promising pharmacokinetic, pharmacodynamics and tolerable toxicity properties. According to our findings, I. pseudacorus might be considered as a valuable source for designing novel phytopharmaceuticals.

Cellulose filter paper immobilized α-glucosidase and its application to screening inhibitors from traditional Chinese medicine

In this study, α-glucosidase was successfully immobilized on cellulose filter paper and further applied to screening inhibitors from traditional Chinese medicines combined with CE analysis. For α-glucosidase immobilization, cellulose filter paper was used as the carrier and grafted with amino groups by coating chitosan, then α-glucosidase was covalently bonded on the amino-modified carrier via epoxy ring-opening reaction using polyethylene glycol diglycidyl ether as the crosslinker. Several parameters influencing the enzyme immobilization were optimized and the optimal values were enzyme concentration of 4 U mL^-1 , polyethylene glycol diglycidyl ether concentration of 1.25%, chitosan concentration of 7.5 mg mL^-1 , immobilization pH 7.0, crosslinking time of 4 h and immobilization time of 2 h. The immobilized α-glucosidase exhibited good batch-to-batch reproducibility (RSD = 2.1%, n = 5), excellent storage stability (73.5% of its initial activity after being stored at 4°C for 15 days) and reusability (75% of its initial activity after 10 repeated cycles). The Michaelis constant of immobilized α-glucosidase and half-maximal inhibitory concentration of acarbose were calculated to be 1.12 mM and 0.38 μM, respectively. Finally, the immobilized α-glucosidase was used for screening inhibitors from 14 kinds of Traditional Chinese Medicine extracts, and Sanguisorbae Radix showed the strongest inhibitory effect on α-glucosidase. This article is protected by copyright. All rights reserved.

The application of amino acid ionic liquids as additives in the ultrasound-assisted extraction of plant material

The aim of the present study was to determine the antioxidant activity of the aqueous extracts from Lycopodium clavatum, Cetraria islandica and Dipsacus fullonum obtained using aqueous solutions of ionic liquids by the ultrasound-assisted extraction (IL-UAE) method. Triethanolammonium salts [TEAH]⁺[AA]⁻ of four amino acids of different hydrophobicity – isoleucine – Ile, methionine – Met, threonine – Thr and arginine – Arg, were chosen as ionic liquids, because they are based on natural, bio-renewable raw materials, such as amino acids and contain a pharmaceutically and cosmetically acceptable counterion of triethanolamine. Triethanolammonium salts were synthesized, identified by spectroscopic methods (NMR and FT-IR) and characterized by thermal methods (DSC and TGA). The 2.5% w/v aqueous solutions of triethanolammonium amino acid salts were used as the solvents in combination with ultrasound assisted extraction (UAE). The estimation of antioxidant properties was carried out using the DPPH, FRAP and CUPRAC assays. Total polyphenol content was measured using the reagent Folin–Ciocalteu. The results showed that the use of [TEAH]⁺[Thr]⁻ or [TEAH]⁺[Met]⁻ aqueous solutions increased the antioxidant activity of extracts in comparison to that achieved for extracts with pure water. The use of [TEAH]⁺[Thr]⁻ as an additive for ultrasound-assisted extraction was characterized by obtaining plant extracts with the highest antioxidant potential, even 2.4-fold. The use of the AAIL-UAE method allowed obtaining higher amounts of polyphenols compared to pure water extracts, even 5.5-fold. The used method allowed the extraction of thermosensitive natural compounds, shortened the extraction time and lowered energy consumption.

The antioxidant activity of the aqueous extracts from Lycopodium clavatum, Cetraria islandica and Dipsacus fullonum obtained by ionic liquids and ultrasound-assisted extraction (IL-UAE) method was determined.

A novel online preparative high-performance liquid chromatography system with the multiple trap columns-valve switch technique for the rapid and efficient isolation of main flavonoids from Epimedium koreanum Nakai

In this work, a new online preparative high-performance liquid chromatography was developed for the fast and efficient separation of complex chemical mixtures from natural products. This system integrates two chromatographic systems into an online automatic separation system using the technique of multiple trap columns with valve switching. The sample was first separated into 18 subfractions in the online preparative high-performance liquid chromatography, and the sample eluents were then diluted and captured online on 18 trap columns by the multiple trap columns technique, respectively. Each subfraction retained on the trap column was transferred online to the separation column for the second separation. Finally, the target compounds were purified by appropriate separation conditions and multiple heart-cutting strategies. Importantly, the system was successfully used to separate 18 high-purity flavonoids from the crude extract of Epimedium koreanum Nakai online in one step. The entire separation time was approximately 20 h, and the structures were characterized by the high-performance liquid chromatography quadrupole time-of-flight tandem mass spectrometry and nuclear magnetic resonance. This online preparative high-performance liquid chromatography system represents an efficient and rapid separation system that has the potential for a wide array of applications in the separation of complex chemical components from natural products.

Determination of Ferulic Acid in Angelica sinensis by Temperature-Controlled Hydrophobic Ionic Liquids-Based Ultrasound/Heating-Assisted Extraction Coupled with High Performance Liquid Chromatography

Hydrophilic ionic liquids are often used to extract the active ingredients of medicinal plants, while hydrophobic ionic liquids are rarely used to directly extract solid samples. In this paper, a simple, novel and efficient temperature-controlled hydrophobic ionic liquids-based ultrasound/heating-assisted extraction (TC-ILs-UHAE) procedure coupled with high-performance liquid chromatography (HPLC) was developed and applied to the determination of ferulic acid (FA) in Chinese herbal medicine Angelica sinensis. During the extraction procedure, hydrophobic ionic liquids (ILs) were dispersed into water to form cloudy solution (fine droplets) with the aid of ultrasound and heating simultaneous. After extraction, phase separation was easily achieved by centrifuging at 0 °C. Among all ILs used, 1-butyl-3-methylimidazolium bis(trifluoromethanesulphonyl)imide ([C₄mim]NTf₂) exhibited the highest extraction ability and the possible extraction mechanism was discussed. Additionally, the synergistic effect of heating and ultrasound on the extraction efficiency was investigated. Under the optimized conditions, a good linearity was observed with correlation coefficient (r) of 0.9995. The limit of detection of FA (LOD, S/N = 3) was 9.6 µg/L and the spiked recoveries of FA for real samples were in the range of 91.67 to 102.00% with relative standard deviation (RSD) lower than 3.87%. Compared with the traditional extraction methods, the proposed method gave the highest yield of FA and had the shortest extraction time. Therefore, this method is a potential simple, green and highly efficient technique and expected to be applied to the extraction of other bioactive ingredients in medicinal plants.

UPLC-Q-Exactive Orbitrap MS Analysis for Identification of Lipophilic Components in Citri Sarcodactylis Fructus from Different Origins in China Using Supercritical CO2 Fluid Extraction Method

To thoroughly evaluate the quality of Citri Sarcodactylis Fructus (CSF) and acquire knowledge of the lipophilic components of CSF from different origins, a simple and efficient approach based on supercritical fluid extraction (SFE) combined with ultraperformance liquid chromatography plus Q-Exactive Orbitrap tandem mass spectrometry (UPLC-Q-Exactive Orbitrap/MS) detection for the discrimination of components from CSF was set up for the first time in this work. Eight batches of CSF samples from five main producing areas were extracted by SFE under optimized conditions, and then SFE extracts were dissected via UPLC-Q-Exactive Orbitrap/MS. The results indicated that 39 lipophilic compounds were successfully separated and unambiguously or tentatively identified, where 4 coumarins, 6 polymethoxyflavones, 3 phthalides, 6 terpenes, and 4 phenolics were not reported formerly. It was illustrated that CSF may be abundant in polymethoxyflavones, as in coumarins. Moreover, there were significant differences in the components of CSF from different origins. Especially, coumarin, dehydrocostus lactone, atractylenolide II, and atractylenolide I were exclusively found in CSF from the Guangdong province; isopsoralen was almost exclusively found in CSF from the Guangxi province; and ferulic acid was exclusively found in CSF from the Zhejiang province. These observations indicated that SFE joint with UPLC-Q-Exactive Orbitrap/MS owing to the potential of characterizing the lipophilic components could be used to promote quality assessment and chemotaxonomic investigation in phytology sciences of CSF.

Stepwise rapid tracking strategy to identify active molecules from Ixeris sonchifolia Hance based on "'affinity mass spectrometry-atomic force microscopy imaging'" technology

In this study, a novel stepwise rapid tracking strategy was reported to identify the active molecules from Ixeris sonchifolia Hance (IsH) in the treatment of coronary heart disease (CHD) based on "affinity mass spectrometry (MS)-atomic force microscopy (AFM) imaging" technology. First, vascular endothelial growth factor receptor 2 (VEGFR2) of the vascular endothelial growth factor (VEGF) signal transduction pathway located on the cell membrane was revealed to be the core target protein in CHD treatment through network pharmacology and bioinformatics. In addition, affinity MS screening based on VEGFR2 identified isochlorogenic acid A and luteolin-7-O-glucuronide as having stronger affinity with VEGFR2. Then, the active molecule was elucidated based on the observation that its actions accompanied the molecular morphological changes by AFM imaging and it could act on the binding pocket of VEGFR2 through molecular docking which further demonstrated the analysis and inference of AFM imaging. The methyl thiazolyl tetrazolium (MTT) assay finally confirmed that the active molecules specifically combined with the potential core target protein to protect the viability of cardiomyocytes, which identified the main potential active molecules in IsH for the treatment of CHD and provided a possible mechanism for the protective role of the drug. The technology established in this study could facilitate the rapid tracing of potential active molecules in traditional Chinese medicine (TCM), which would provide further a reference for research on quality, molecular mechanisms and new drugs.

Isolation of naturally occurring novel isoflavonoids: an update

This review covers the literature concerning the isolation and identification of new naturally occurring isoflavonoids from Leguminosae and non-Leguminous species between 2012–2017.

Ionic Liquid Solutions as a Green Tool for the Extraction and Isolation of Natural Products

In the past few years, the application of ionic liquids (ILs) had attracted more attention of the researchers. Many studies focused on extracting active components from traditional herbals using ILs as alternative solvents so as to address the issue caused by the traditional methods for extraction of natural products (NPs) with organic chemical reagents. Through the summary of reported research work, an overview was presented for the application of ILs or IL-based materials in the extraction of NPs, including flavonoids, alkaloids, terpenoids, phenylpropanoids and so on. Here, we mainly describe the application of ILs to rich the extraction of critical bioactive constituents that were reported possessing multiple therapeutic effects or pharmacological activities, from medicinal plants. This review could shed some light on the wide use of ILs in the field of natural products chemistry to further reduce the environmental damage caused by large quantity of organic chemical reagents.

Ionic liquids-ultrasound based efficient extraction of flavonoid glycosides and triterpenoid saponins from licorice

Flavonoid glycosides and triterpenoid saponins are the main chemical constituents of licorice. In this study, an ionic liquids-ultrasound based extraction (IL-UAE) method was established to simultaneously extract liquiritin (LQ), liquiritin apioside (LA), isoliquiritin (ILQ), isoliquiritin apioside (ILA) and glycyrrhizic acid (GA) from licorice. A series of 1-alkyl-3-methylimidazolium ILs with different anions and alkyl chain lengths of cations were investigated and compared, and 1-butyl-3-methylimidazolium acetate ([C₄MIM]Ac) was finally selected as the extractant. The extraction parameters of the IL-UAE procedure were optimized, and the established method was validated in linearity, stability, precision, repeatability and recovery. The IL-UAE approach exhibited much higher extraction efficiency comparing with conventional UAE, and needed shorter extraction time and smaller solvent to solid ratio comparing with the pharmacopoeia method. In addition, the microstructures of licorice powders were observed before and after extraction with help of a scanning electron microscope (SEM) in order to explore the extraction mechanism. The results suggested that ILs as green solvents were effective for extraction of flavonoid glycosides and triterpenoid saponins from licorice.

An ionic liquids-ultrasound based method for efficient extraction of flavonoid glycosides and triterpenoid saponins from licorice was established.

Bioactive compounds of Shuang-Huang-Lian prescription and an insight into its binding mechanism by β2 -adrenoceptor chromatography coupled with site-directed molecular docking

Owing to the promising clinical efficacy and relatively simple composition, Shuang-Huang-Lian prescription is widely prescribed for the treatment of acute upper respiratory tract infection and acute bronchitis in practice. This necessitates the understanding of the bioactive compounds of the prescription and their binding mechanism to β₂ -adrenoceptor, which mediates the aforementioned ailments. In this work, a column containing immobilized β₂ -adrenoceptor was prepared using a diazonium salt reaction. The bioactive compound collected from the β₂ -adrenoceptor column was identified as chlorogenic acid by using high-performance liquid chromatography coupled with ion trap mass spectrometry. Using an injection amount dependent method, chlorogenic acid proved the binding to β₂ -adrenoceptor through two kinds of sites. The numbers of the sites were (1.42 ± 0.03) × 10^-8 and (9.06 ± 0.49) × 10^-8  M. The association constants were (2.72 ± 0.01) × 10⁵ and (2.80 ± 0.01) × 10⁴  M^-1 , respectively. Molecular docking analysis of the interaction between chlorogenic acid and β₂ -adrenoceptor indicated that the binding mainly occurred on Ser¹⁶⁹ , Ser¹⁷³ , and Phe²⁸⁷ of β₂ -adrenoceptor. These results paved the way to screen bioactive compounds of other traditional medicines by receptor chromatography.