Large-scale preparative isolation of bergenin standard substance from Saxifraga atrata using polyamide coupled with MCI GEL® CHP20P as stationary phases in medium pressure chromatography

Separation Methods of Phenolic Compounds from Plant Extract as Antioxidant Agents Candidate

In recent years, discovering new drug candidates has become a top priority in research. Natural products have proven to be a promising source for such discoveries as many researchers have successfully isolated bioactive compounds with various activities that show potential as drug candidates. Among these compounds, phenolic compounds have been frequently isolated due to their many biological activities, including their role as antioxidants, making them candidates for treating diseases related to oxidative stress. The isolation method is essential, and researchers have sought to find effective procedures that maximize the purity and yield of bioactive compounds. This review aims to provide information on the isolation or separation methods for phenolic compounds with antioxidant activities using column chromatography, medium-pressure liquid chromatography, high-performance liquid chromatography, counter-current chromatography, hydrophilic interaction chromatography, supercritical fluid chromatography, molecularly imprinted technologies, and high-performance thin layer chromatography. For isolation or purification, the molecularly imprinted technologies represent a more accessible and more efficient procedure because they can be applied directly to the extract to reduce the complicated isolation process. However, it still requires further development and refinement.

Microwave extraction and molecular imprinted polymer isolation of bergenin applied to the dendrochronological chemical study of Peltophorum dubium

This study describes methodologies for extracting and isolating bergenin, a C-glucoside of 4-O-methylgallic acid found in some plants and it presents various in vitro and in vivo biological activities. Bergenin was previously obtained from the Pelthophorum dubim (Fabaceae) roots with a good yield. Conventional chromatographic procedures of the CHCl3 soluble fraction of the MeOH extract gave 3.62% of this glucoside. An HPLC/DAD method was also developed and validated for bergenin and its precursor, gallic acid quantifications. Microwave extractions with different solvents were tested to optimize the extraction of bergenin, varying the temperature and time. MAE (Microwave Assisted Extraction) was more efficient than conventional extraction procedures, giving a higher yield of bergenin per root mass (0.45% vs. 0.0839%). Molecularly imprinted polymer (MIP) and non-imprinted polymer (NIP) based on bergenin as the template molecule, methacrylic acid, and ethylene glycol dimethacrylate were synthesized and characterized by FTIR and SEM (Scanning Electron Microscopy). Bergenin adsorption experiments using MIP and NIP followed by molecular imprinted solid phase extraction (MISPE) showed that MIP had a higher selectivity for bergenin than NIP. A dendrochronological study using the proposed method for detection and quantification of gallic acid and bergenin in five P. dubium growth rings of a 31-year-old heartwood and in the phelloderm and barks indicated that bergenin was more abundant in the 11-14th growth rings of the heartwood and decreased from the heartwood to the barks.

Exploring the hypolipidemic effects of bergenin from Saxifraga melanocentra Franch: mechanistic insights and potential for hyperlipidemia treatment

OBJECTIVE

The goal of this study was to explore the hypolipidemic effects of bergenin extracted from Saxifraga melanocentra Franch (S. melanocentra), which is a frequently utilized Tibetan medicinal plant known for its diverse bioactivities. Establishing a quality control system for black stem saxifrage is crucial to ensure the rational utilization of its medicinal resources.

METHODS

A one-step polyamide medium-pressure liquid chromatography technique was applied to isolate and prepare bergenin from a methanol extract of S. melanocentra. A zebrafish model of hyperlipidemia was used to investigate the potential hypolipidemic effects of bergenin.

RESULTS

The results revealed that bergenin exhibited substantial hypo efficacy in vivo. Specifically, bergenin significantly reduced the levels of triglycerides (TG), total cholesterol (TC), and low-density lipoprotein cholesterol (LDL-c) while simultaneously increasing high-density lipoprotein cholesterol (HDL-c) levels. At the molecular level, bergenin exerted its effects by inhibiting the expression of FASN, SREBF1, HMGCRα, RORα, LDLRα, IL-1β, and TNF while promoting the expression of IL-4 at the transcriptional level. Molecular docking analysis further demonstrated the strong binding affinity of bergenin to proteins such as FASN, SREBF1, HMGCRα, RORα, LDLRα, IL-4, IL-1β, and TNF.

CONCLUSIONS

Findings indicate that bergenin modulates lipid metabolism by regulating lipid and cholesterol synthesis as well as inflammatory responses through signaling pathways associated with FASN, SREBF1, and RORα. These results position bergenin as a potential candidate for the treatment of hyperlipidemia.

Targeted isolation of cyclooxygenase-2 inhibitors from Saussurea obvallata using affinity ultrafiltration combined with preparative liquid chromatography

Saussurea obvallata (S. obvallata) is widely used in Qinghai-Tibet Plateau with high medicinal and edible values of reducing inflammation. But, the individual components and mechanisms of action still ill-defined. In this work, an integrated method using affinity ultrafiltration combined with preparative liquid chromatography was developed to identify and separate cyclooxygenase-2 (COX-2) inhibitors from S. obvallata. The sample was pretreated using on-line medium pressure liquid chromatography to yield the active fraction. Then, the potential COX-2 ligands were screened out using affinity ultrafiltration from the targeted fraction and the identified compounds were isolated via preparative liquid chromatography. As a result, four main compounds, coniferin (1), syringin (2), roseoside (3) and grasshopper ketone (4) were targeted isolated with IC₅₀ values of 12.34 ± 1.81, 4.04 ± 0.43, 13.91 ± 2.46 and 7.97 ± 1.21 µM, respectively. Results of this work demonstrated that the developed strategy was effective for the targeted separation of COX-2 inhibitors from natural product extracts.

Ethyl Acetate Extract of Dracocephalum heterophyllum Benth Ameliorates Nonalcoholic Steatohepatitis and Fibrosis via Regulating Bile Acid Metabolism, Oxidative Stress and Inhibiting Inflammation

Dracocephalum heterophyllum Benth is well-known for its ability to alleviate liver heat. In this study, Dracocephalum heterophyllum Benth ethyl acetate extracts were evaluated on mouse models of nonalcoholic steatohepatitis and liver fibrosis. After 6 and 8 weeks of treatment, serum parameters and gene expressions in tissue samples, as well as stained tissue sections, demonstrated that the ethyl acetate extracts were effective in treating these liver diseases. The principal bioactive constituent (rosmarinic acid) was identified and screened by high pressure liquid chromatography-1,1-diphenyl-2-picrylhydrazyl and affinity ultrafiltration-HPLC. The rosmarinic acid was separated from extracts with high purity by medium- and high-pressure liquid chromatography. Finally, the interactions between rosmarinic acid and the key targets of lipid metabolism, oxidative stress and inflammation were verified by molecular docking. Thereby, an indirect regulation of lipid and cholesterol metabolism and inhibition of liver inflammation and liver fibrosis by the studied extract has been observed. This study demonstrated that Dracocephalum heterophyllum Benth ethyl acetate extracts have the potential to treat nonalcoholic steatohepatitis and liver fibrosis, revealing their multi-target and multi-pathway therapeutic characteristics.

Combination of Medium- and High-Pressure Liquid Chromatography for Isolation of L-tryptophan (Q-marker) from Medicago sativa Extract

Medicago sativa (alfalfa) is a widely used animal feed. However, its quality has been difficult to control due to the lack of appropriate marker compounds. Therefore, it is very necessary to select an appropriate quality marker (Q-marker) to control its quality. In this study, medium-pressure liquid chromatography and high-pressure liquid chromatography were employed to effectively prepare the separation of the Q-marker (L-tryptophan) from Medicago sativa. Firstly, using MCI GEL® CHP20P as the stationary phase, 2.5 g of the target fraction Fr3 was enriched from crude Medicago sativa extract (2.9 kg) by medium-pressure liquid chromatography. Secondly, Sephadex LH-20 was used to further separate Fr3 fractions, and the Fr34 fraction (358.3 mg) was enriched after 14 repetitions. Lastly, using the ReproSil-Pur C18 AQ preparative column, 63.4 mg of L-tryptophan was obtained by high-pressure liquid chromatography, and the purity was above 95%. The results showed that medium-pressure liquid chromatography (MCI GEL® CHP20P and Sephadex LH-20) combined with high-pressure liquid chromatography (ReproSil-Pur C18 AQ) could be used to effectively prepare the Q-marker from natural products with satisfactory purity.

Anti-inflammatory properties of novel galloyl glucosides isolated from the Australian tropical plant Uromyrtus metrosideros

Two new galloyl glucosides, galloyl-lawsoniaside A (4) and uromyrtoside (6), were isolated from the polar fraction of Uromyrtus metrosideros leaf extract along with another four previously identified phytochemicals (1, 2, 3, and 5). The structures of these six compounds were characterised using low and high-resolution mass spectrometry (L/HRMS) and 1D and 2D Nuclear Magnetic Resonance (NMR) spectroscopy. These compounds were not toxic to human peripheral blood mononuclear cells (PBMCs) at 10 μg/mL over 24 h, yet showed significant in vitro suppression of proinflammatory cytokines involved in the pathogenesis of inflammatory bowel disease (IBD). Specifically, the release of interferon γ (IFN-γ), interleukin (IL)-17A, and IL-8 from phorbol myristate acetate/ionomycin (P/I) and anti-CD3/anti-CD28-activated cells were significantly suppressed by compounds 4 and 5. Interestingly, no effect on tumour necrosis factor (TNF) release was observed. These results show that the newly characterised compound 4 has promising cytokine suppressive properties, which could be further investigated as a candidate for IBD treatment.

Screening and Isolation of Potential Anti-Inflammatory Compounds from Saxifraga atrata via Affinity Ultrafiltration-HPLC and Multi-Target Molecular Docking Analyses

In this study, a 100 g sample of Saxifraga atrata was processed to separate 1.3 g of 11-O-(4′-O-methylgalloyl)-bergenin (Fr1) after 1 cycle of MCI GEL® CHP20P medium pressure liquid chromatography using methanol/water. Subsequently, COX-2 affinity ultrafiltration coupled with reversed-phase liquid chromatography was successfully used to screen for potential COX-2 ligands in this target fraction (Fr1). After 20 reversed-phase liquid chromatography runs, 74.1 mg of >99% pure 11-O-(4′-O-methylgalloyl)-bergenin (Fr11) was obtained. In addition, the anti-inflammatory activity of 11-O-(4′-O-methylgalloyl)-bergenin was further validated through molecular docking analyses which suggested it was capable of binding strongly to ALOX15, iNOS, ERBB2, SELE, and NF-κB. As such, the AA metabolism, MAPK, and NF-κB signaling pathways were hypothesized to be the main pathways through which 11-O-(4′-O-methylgalloyl)-bergenin regulates inflammatory responses, potentially functioning by reducing pro-inflammatory cytokine production, blocking pro-inflammatory factor binding to cognate receptors and inhibiting the expression of key proteins. In summary, affinity ultrafiltration-HPLC coupling technology can rapidly screen for multi-target bioactive components and when combined with molecular docking analyses, this approach can further elucidate the pharmacological mechanisms of action for these compounds, providing valuable information to guide the further development of new multi-target drugs derived from natural products.

Targeted isolation of 1,1-diphenyl-2-picrylhydrazyl inhibitors from Saxifraga atrata and their antioxidant activities

Saxifraga atrata is an important traditional Tibetan medicine used to treat cough and pneumonia, and has tremendous medicinal potential. In this study, we devised a technique to separate 1,1-diphenyl-2-picrylhydrazyl inhibitors from a methanol extract of Saxifraga atrata. The material was first processed using MCI GEL® CHP20P medium-pressure liquid chromatography, yielding 1.1 g of the target fraction Fr2. Subsequently, online hydrophilic interaction liquid chromatography-1,1-diphenyl-2-picrylhydrazyl assay was used to identify prospective 1,1-diphenyl-2-picrylhydrazyl inhibitors, and two 1,1-diphenyl-2-picrylhydrazyl inhibitor fractions (Fr24 and Fr25) were identified from Fr2. Then, medium-pressure preparation was continued using an XIon column to separate two 1,1-diphenyl-2-picrylhydrazyl inhibitor fractions (Fr24 and Fr25). The target compound was concentrated in fractions Fr24 and Fr25 using reverse-phase liquid chromatography during further separation procedures. Finally, the purity, structure, and 1,1-diphenyl-2-picrylhydrazyl inhibitory activity of the isolated 1,1-diphenyl-2-picrylhydrazyl inhibitors were determined. Two 1,1-diphenyl-2-picrylhydrazyl inhibitors (adenosine with the half maximal inhibitory concentration of 66.87 ± 14.33 μM and (-)-4-O-(E)-Caffeoyl-L-threonic acid with the half maximal inhibitory concentration of 59.06 ± 5.02 μM) were isolated with purities exceeding 95%. The results showed that this technology is effective in the targeted separation of antioxidants from natural products. This article is protected by copyright. All rights reserved.

Extraction, preparative monomer separation and antibacterial activity of total polyphenols from Perilla frutescens

Polyphenols exhibit potential functional activities, especially rosmarinic acid (RosA) and caffeic acid (CafA). In this study, two different methods, ultrasonic-assisted ethanol extraction (60%) and ultrasound-assisted cellulase (≥15 000 Ug-1, 2%) hydrolysis, were used for the extraction of the total phenolics from 44 species of Perilla frutescens. The Folin-Ciocalteu method of detection showed that the content of the total phenolics extracted by cellulase hydrolysis was the highest and attained up to 28.00 mgGAE per gextracts for ZB1. Continuously, the extracts were purified using XDA-8 macroporous resin and medium-pressure liquid chromatography (MPLC), and the content of the total phenolics improved to 66.62 mgGAE per gextract. A high-performance liquid chromatography (HPLC) assay showed that the total polyphenols were mainly composed of gallic acid, caffeic acid, rosmarinic acid, luteolin and apigenin. Besides, a sequential XDA-8 macroporous resin combined with high-speed counter-current chromatography (HSCCC)/MPLC system was established for the simultaneous isolation and preparation of RosA (purity 98.29%) and CafA (purity 97.01%) from the extracts. Furthermore, the antibacterial activities of the total polyphenols were evaluated by the disc diffusion method and scanning electron microscopy (SEM) observation. The results verified that the total polyphenols had effective antibacterial activity on three kinds of bacteria including E. coli, S. aureus, and B. subtilis in a concentration-dependent manner. All of these results demonstrated that the ultrasound-assisted cellulase hydrolysis extraction of the total polyphenols and the proposed three-step separation of RosA and CafA gave high yields and good purity, and they exhibited effective antibacterial ability.