Development of adsorptive (non-ionic) macroporous resins and their uses in the purification of pharmacologically-active natural products from plant sources

Preparation of flavonoids from Amomum tsaoko and evaluation of their antioxidant and α-glucosidase inhibitory activities

Amomum tsaoko is an important homologous medicinal and food plant, and its fruit is rich in flavonoids. However, few studies have reported the preparation and bioactivity of flavonoids in A. tsaoko (ATF). In this study, the optimal conditions for ultrasound-assisted extraction of ATF were identified through response surface optimization. HPD300 was identified as the best resin for the purification of ATF, as it exhibited a Freundlich model-conformative adsorption isotherm. Among the different concentrations of ethanol, 20 % and 30 % resulted in higher flavonoid purity (>90 %) and stronger antioxidant and α-glucosidase inhibition activities. A widely targeted metabolomics assay revealed that the relative abundance of flavonoids in a mixture of 20 % and 30 % ethanol eluates was greater than 73 %, which mainly contained (+)-epicatechin, isoquercitrin, astragalin kaempferol-3-O-rutinoside, and procyanidin B2. These findings provide a theoretical basis for the in-depth development and potential use of ATF in the functional food, cosmetic and pharmaceutical industries.

Extraction and Purification of Flavonoids and Antiviral and Antioxidant Activities of Polygonum perfoliatum L

The aim of the present study was to optimize the process parameters for the extraction and purification of total flavonoids from Polygonum perfoliatum L., in addition to analyzing their chemical composition and evaluating their activity against varicella-zoster virus (VZV) and antioxidant activity. The optimum extraction process was determined using one-way and response surface methods with the following conditions: ethanol concentration of 82.00%, temperature of 90.29 °C, solid-to-liquid ratio of 1:32.78 g/mL, extraction time of 1.5 h, and two extractions with a yield of 14.98 ± 0.11 mg/g. Purification was then carried out using D101 macroporous resin to obtain a flavonoid purity of 43.00 ± 2.55%, which was 3.38 times higher than that of the crude extract (12.74 ± 1.04%). Further purification was carried out using a 1:9 hybrid column of macroporous resin and polyamide, and the purity of flavonoids was enhanced to 59.02 ± 2.23%, which is 1.37 times higher than that of the macroporous resin purifier (43.00 ± 2.55%) and 4.63 times higher than that of the crude extract (12.74 ± 1.04%). Seventy-nine flavonoids were identified using ultra-performance liquid chromatography-tandem high-resolution mass spectrometry (UPLC-HRMS). In addition, the purified flavonoids showed good anti-VZV and antioxidant activities. Therefore, this study can provide technical support and theoretical basis for the further development and utilization of Polygonum perfoliatum L. resources.

Effect of the Total Saponins of Bupleurum chinense DC. Water Extracts Following Ultrafiltration Pretreatment on Macroporous Resin Adsorption

Macroporous resin is an efficient separation technology that plays a crucial role in the separation and purification of traditional Chinese medicine (TCM). However, the application of macroporous resins in TCM pharmaceuticals is hindered by serious fouling caused by the complex materials used in TCM. This study examines the impact of ultrafiltration (UF) membrane technology on the macroporous resin adsorption behavior of TCM extracts. In this paper, Bupleurum chinense DC. (B. chinense) water extracts were included as an example to study the effect of UF pretreatment on the macroporous resin adsorption of total saponins. The study results indicated that the adsorption of total saponins constituents from the water extracts of B. chinense on the macroporous resin followed the pseudo-second-order kinetic model and the Langmuir model. The thermodynamic parameters of adsorption, including enthalpy changes and Gibbs free energies, were negative, while entropy changes were positive. These results demonstrated that the total saponin components form a monolayer adsorption layer by spontaneous thermal adsorption on the macroporous resin, and that the adsorption rate is not determined by the rate of intraparticle diffusion. Following treatment with a UF membrane with an average molecular weight cut-off of 50 kDa, the protein, starch, pectin, tannin, and other impurities in the water extracts of B. chinense were reduced, while the total saponin content was retained at 82.32%. The adsorption kinetic model of the saponin constituents on the macroporous resin remained unchanged and was consistent with both the second-order kinetic model and the Langmuir model; the adsorption rate of the second-order kinetic model increased by 1.3 times and in the Langmuir model at 25 °C, the adsorption performance improved by 1.16 times compared to the original extracts. This study revealed that UF technology as a pretreatment method can reduce the fouling of macroporous resin by TCM extracts and improve the adsorption performance of macroporous resin.

Properties, extraction and purification technologies of Stevia rebaudiana steviol glycosides: A review

For health and safety reasons, the search for green, healthy, and low-calorie sweeteners with good taste has become the demand of many consumers. Furthermore, the need for sugar substitutes of natural origin has increased dramatically. In this review, we briefly discussed the safety and health benefits of stevia sweeteners and enumerated some examples of physiological functions of steviol glycosides (SGs), such as anti-inflammatory, anti-obesity, antihypertensive, anti-diabetes, and anticaries, citing various evidence related to their application in the food industry. The latest advances in emerging technologies for extracting and purifying SGs and the process variables and operational strategies were discussed. The impact of the extraction methods and their comparison against the conventional techniques have also been demonstrated. These technologies use minimal energy solvents and simplify subsequent purification stages, making viable alternatives suitable for a possible industrial application. Furthermore, we also elucidated the potential for advancing and applying the natural sweeteners SGs.

A review of the polyphenols purification from apple products

Apple polyphenols are one of the major bioactive compounds in apple products and have strong anti-inflammatory effects and the ability to prevent chronic diseases with health benefits. The development of apple polyphenol products is dependent on the extraction, purification and identification of apple polyphenols. The extracted polyphenols need to be further purified to improve the concentration of the extracted polyphenols. This review, therefore, presents the studies on the conventional and novel methods for polyphenols purification from apple products. The different chromatography methods, as one of the most widely used conventional purification methods, for polyphenol purification from various apple products are introduced. In addition, the perspective of the adsorption-desorption process and membrane filtration technique in enhancing the purification of polyphenols from apple products are presented in this review. The advantages and disadvantages of these purification techniques are also discussed and compared in depth. However, each of the reviewed technologies has some disadvantages that need to be overcome, and some mechanisms need to be further identified. Therefore, more competitive polyphenols purification techniques need to emerge in the future. It is hoped that this review can provide a research basis for the efficient purification of apple polyphenols, which can facilitate their application in various fields.

Separation of bufadienolides from Helleborus thibetanus Franch. by a combination approach involving macroporous resin column chromatography and gradient countercurrent chromatography

In this study, a combination approach involving macroporous resin (MR) column chromatography and gradient countercurrent chromatography (CCC) was employed to enrich and purify bufadienolides from the roots and rhizomes of Helleborus thibetanus Franch. Initially, a D101 MR-packed column chromatography was utilized for fractionation and enrichment of the bufadienolides, which were effectively eluted from the column using a 60% ethanol solution. CCC was subsequently introduced to separate the enriched product using the ethyl acetate/n-butanol/water (EBuWat, 4:1:5, v/v) and EBuWat (5:0:5, v/v) solvent systems in a gradient elution mode. As results, five bufadienolides, including 6.1 mg of hellebrigenin-3-O-β-D-glucoside (1), 2.2 mg of tigencaoside A (2), 8.3 mg of deglucohellebrin (3), 3.5 mg of 14 β-hydroxy-3β-[β-D-glucopyranosyl-(1→6)-(β-D-glucopyranosyl)oxy]-5α-bufa-20,22-dienolide (4), and 3.0 mg of 14β-hydroxy-3β-[(β-D-glucopyranosyl)oxy]-5α-bufa-20,22-dienolide (5), were effectively separated from 300 mg of the enriched product. The respective high-performance liquid chromatography purities were as follows: 95.2%, 75.8%, 85.7%, 82.3%, and 92.8%. This study provides valuable insights for the efficient enrichment and separation of bufadienolides from Helleborus thibetanus Franch.

One-step enrichment of phenolics from Chaenomeles speciosa (Sweet) Nakai fruit using macroporous resin: Adsorption/desorption characteristics, process optimization and UPLC-QqQ-MS/MS-based quantification

Chaenomeles speciosa (Sweet) Nakai fruit is a good source of phenolics with many health benefits. In this work, the enrichment of C. speciosa fruit total phenolics (CSFTP) using macroporous resins was studied. NKA-Ⅱ resin was selected for enriching CSFTP due to its highest adsorption/desorption quantity. Adsorption characteristics of CSFTP on NKA-Ⅱ resin exhibited a good fit with the Langmuir isotherm model and pseudo-second order kinetics model. This adsorption was spontaneous, exothermic, and entropy-decreasing through a physisorption mechanism. The breakthrough-elution curves were studied to optimize CSFTP enrichment conditions. One-step enrichment increased CSFTP content in the extracts from 26.51 % to 78.63 %, with a recovery of 81.03 %. A UPLC-QqQ-MS/MS method in multiple reaction monitoring (MRM) mode was established and validated for the simultaneous quantification of seven phenolic compounds. This study demonstrates the feasibility of industrial enrichment of CSFTP using NKA-Ⅱ resin and proposes a reliable method for quality control of CSFTP-rich products.

Profiling the chemical properties of Foeniculum vulgare Mill. and its flavonoids through comprehensive LC-MS/MS to evaluate their anti-motion sickness effect

Foeniculum vulgare Mill. is a medicinal and food homologous plant, and it has various biological activities. Yet, no research has explored its anti-motion sickness effects. Chemical properties of fennel extracts (FvE) and flavonoids (Fvf) were analyzed based on UPLC-QTRAP-MS to elucidate its potential anti-motion sickness components in the present study. The mice models of motion sickness were stimulated by biaxial rotational acceleration. Behavioral experiments such as motion sickness index and open field test and the measurement of neurotransmitters were used to evaluate the efficacy of compounds on motion sickness. Results showed that FvE contains terpenes, alkaloids, flavonoids, etc. Eight flavonoids including quercetin-3β-D-glucoside, rutin, hyperoside, quercetin, miquelianin, trifolin, isorhamnetin and kaempferol were identified in the purified Fvf. FvE and Fvf significantly reduced the motion sickness index of mice by 53.2% and 48.9%, respectively. Fvf also significantly alleviated the anxious behavior of mice after rotational stimulation. Among the eight flavonoids, isorhamnetin had the highest oral bioavailability and moderate drug-likeness index and thus speculated to be the bioactive compound in fennel for its anti-motion sickness effect. It reduced the release of 5-HT and Ach to alleviate the motion sickness response and improve the work completing ability of mice and nervous system dysfunction after rotational stimulation. This study provided in-depth understanding of the anti-motion sickness bioactive chemical properties of fennel and its flavonoids, which will contribute to the new development and utilization of fennel.

Adsorption and desorption characteristics of flavonoids from white tea using macroporous adsorption resin

White tea contains the highest flavonoids compared to other teas. While there have been numerous studies on the components of different tea varieties, research explicitly focusing on the flavonoid content of white tea remains scarce, making the need for a good flavonoid purification process for white tea even more important. This study compared the adsorption and desorption performance of five types of macroporous resins: D101, HP20, HPD500, DM301, and AB-8. Among the tested resins, AB-8 was selected based on its best adsorption and desorption performance to investigate the static adsorption kinetics and dynamic adsorption-desorption purification of white tea flavonoids. The optimal purification process was determined: adsorption temperature 25 °C, crude tea flavonoid extract pH 3, ethanol concentration 80 %, sample loading flow rate and eluent flow rate 1.5 BV/min, and eluent dosage 40 BV. The results indicated that the adsorption process followed pseudo-second-order kinetics. Under the above purification conditions, the purity of the total flavonoids in the purified white tea flavonoid increased from approximately 17.69 to 46.23 %, achieving a 2.61-fold improvement, indicating good purification results. The purified white tea flavonoid can be further used for nutraceutical and pharmaceutical applications.

Mycochemical composition and antioxidant activity of root endophytic aquatic hyphomycetes isolated from the riparian area of Kumaun Himalaya, India

Endophytic fungi are essential sources of various bioactive natural compounds. The present study is aimed to investigate the chemical composition and antioxidant compounds of the root endophytic aquatic hyphomycetous fungi Tetracladium setigerum isolated from the roots of Barberries aristata growing in the riparian area of Nainital, Kumaun Himalaya. The chemical profiling was done by GC-MS analysis. The presence of 32 compounds characterised the fungal extract. 1, 2-Benzenedicarboxylic acid, diethyl ester; Bis(2-ethylhexyl) phthalate; and Bicyclo [3.2.1]octan-4-on-1-carbonsaeure,6-(6,10dimethyl-1,5,9-undecatrien-2-yl)-8-methyl-, ethyl ester were reported as major compounds in the ethyl acetate extract of T. setigerum. The antioxidant capacity of the extract was assessed by DPPH, MCA, and FRAP assay. In antioxidant analysis, the ethyl acetate extract of T. setigerum presents IC50, 42.34 µg/ml, and 46.90 µg/ml using DPPH and MCA, respectively. The tested extract also showed effective antioxidant activity 436.71 ± 9.3 mg AAE/g of the dry extract using FRAP assay.

Optimized Separation of Carthamin from Safflower by Macroporous Adsorption Resins and Its Protective Effects on PC12 Cells Injured by OGD/R via Nrf2 Signaling Pathway

The growing demand for safe natural products has reignited people's interest in natural food pigments. Here, we proposed the use of macroporous adsorption resins (MARs) to separate and purify carthamin from safflower. The optimal parameters for carthamin purification with HPD400 MAR were determined as follows: a mass ratio of crude carthamin in sample solution to wet resin of 0.3, a crude carthamin solution concentration of 0.125 g·mL-1, a pH of 6.00, a sample volume flow rate of 0.5 mL·min-1, an ethanol volume fraction of 58%, an elution volume of 4 BV, and an elution volume flow rate of 1.0 mL·min-1. Under the above purification conditions, the recovery rate of carthamin was above 96%. Carthamin dramatically improved the survival rate of PC12 cells damaged by oxygen-glucose deprivation/reoxygenation and protected them from oxidative stress by inhibiting the generation of reactive oxygen species and increasing the total antioxidant capacity and glutathione (GSH) levels. Carthamin promoted extracellularly regulated protein kinase phosphorylation into the nucleus, permitting Nrf2 nuclear translocation and upregulating the gene expression of the rate-limiting enzymes glutamate-cysteine ligase catalytic subunit and glutamate-cysteine ligase regulatory subunit of GSH synthesis to obliterate free radicals and exert antioxidant effects. This study revealed the purification method of carthamin and its antioxidant protective effects, providing important insights into the application of carthamin in functional foods.

Advances in extraction and purification of citrus flavonoids

Flavonoids are the representative active substances of citrus with various biological activities and high nutritional value. In order to evaluate and utilize citrus flavonoids, isolation and purification are necessary steps. This manuscript reviewed the research advances in the extraction and purification of citrus flavonoids. The structure classification, the plant and nutritional functions, and the biosynthesis of citrus flavonoids were summarized. The characteristics of citrus flavonoids and the selection of separation strategies were explained. The technical system of extraction and purification of citrus flavonoids was systematically described. Finally, outlook and research directions were proposed.

Enrichment of soy isoflavone extracts through macroporous resin for characterization of toxicity and estrogenic activities

Soy isoflavone extracts are widely researched for their distinctive potential in contributing to various functional foods. The research work focuses on testing the toxicity of purified soy isoflavone extracts in mice models. With an agreement of the animal ethics, acute toxicity is firstly used to screen the effects of test compounds in mice for therapeutic purposes. Moreover, tests were conducted on BALB/c for estrogen in vivo and MCF7 for in vitro, screening active protection of liver cells, lipid peroxidation and scavenging free radicals 2,2-diphenyl-1-picrylhydrazyl (DPPH). Genistin and daidzin were found to be the two major compounds accounting for 47% and 35% of total purified soy isoflavones. The acute toxicity test results exhibited no effect against physiological accretion of BALB/c after 7-day administration with the given dose of 10 g/kgBW. Moreover, modified E-screen assay on MCF7 cells proved that the estrogen of isoflavone extracts induces cell proliferation by 15% compared with other non-steroid culture techniques. Therefore, this research contributes to helping researchers apply soy isoflavones in functional food, to alleviate the difficulties in menopausal symptoms for women in the future.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-022-05491-4.

A macroporous resin purification process to obtain food-grade phlorotannin-rich extracts with α-glucosidase inhibitory activity from Chilean brown seaweeds: An UHPLC-MSn profiling

An efficient macroporous resin purification process was designed to obtain food-grade phlorotannin-rich extracts from the seaweeds Durvillaea incurvata and Lessonia spicata. Phlorotannins were profiled to relate structures with the α-glucosidase inhibitory activity of the extracts. Liquid chromatography-mass spectrometry was applied for tentative identification. The best phlorotannin purification performance was achieved with HP-20 resin and elution with 80% v/v ethanol. This is the first study that demonstrates the effectivity of HP-20 resin for removing potentially toxic elements (As, Cd) from seaweed extracts. Fucols/phlorethols/fucophlorethols isomers up to 4 phloroglucinol units (PGU) were the most representative phlorotannins. High molecular weight species (11-21 PGU), although in low abundances, were detected in D. incurvata for the first time. Eckols, carmalols, fuhalols, phenolic acids, and flavonoids were also detected. Some extracts' potent α-glucosidase inhibitory activities were related to their high phlorotannin abundances, the presence of phlorotannins of a high degree of polymerization, and the phlorotannins class.

A combination of surface-initiated atom transfer radical polymerization and photo-initiated "thiol-ene" click chemistry: Fabrication of functionalized macroporous adsorption resins for enrichment of glycopeptides

A hydrophilic adsorbent (Cys@poly(AMA)@MAR) was successfully prepared for the enrichment of N-glycopeptides via surface-initiated atom transfer radical polymerization (SI-ATRP) and photo-initiated "thiol-ene" reaction using monodisperse macroporous adsorbent resin (MAR) as adsorption matrix. Due to the presence of electron-deficient acrylic groups and electron-rich vinyl groups in allyl methacrylate (AMA), both of them can participate in free radical reaction. Therefore, the polymerization time of SI-ATRP was optimized. The resulting poly(AMA)@MAR was modified with l-cysteine (L-Cys) via photo-initiated "thiol-ene" reaction, and the amount of vinyl retained was determined by measuring the adsorption of Cu²⁺. The Cys@poly(AMA)@MAR pendant brushes with high density of amine and carboxyl groups could capture N-glycopeptides from IgG digest and human serum digest by hydrophilic interaction. The 22 N-glycopeptides were identified from IgG digest and the limit of detection reached 10 fmol. The 319 N-glycosylation sites and 583 N-glycopeptides were identified from 2 μL human serum digest and mapped to 147 glycoproteins. It demonstrates great potential and commercialization prospects for the enrichment of N-glycopeptides.

Bioactive polyphenols separated from hemp seed shells ameliorate H2 O2 -induced oxidative stress injury in human umbilical vein endothelial cells

In the present study, we investigated the protection of hemp seed polyphenols on human umbilical vein endothelial cells (HUVEC) from H₂ O₂ -mediated oxidative stress injury. Fractions with different polarities were obtained by separating the hemp seed extract using HPD300 macroporous resin-packed column. The fraction, desorbed by 50% ethanol, is rich in polyphenol (789.51 ± 21.92 mg GAE/g) and has the highest antioxidant activity in vitro. HPLC-QTOF-MS/MS identified the main polyphenol components in hemp seed shells: 4 hydroxycinnamic acid amides and 15 lignanamides. The protective effects of hemp seed polyphenol against oxidative-stress injury in HUVEC cells were evaluated by cell viability, intracellular antioxidant parameters, and cell apoptosis assay. After HUVEC cells were precultured with 50 µg/ml hemp seed polyphenols, the cell viability increased significantly from 53.07 ± 2.46% (model group) to 80.65 ± 1.32% (p < 0.01). In addition, the pretreatment of HUVEC cells with polyphenol could substantially increase their intracellular superoxide dismutase activity and reduce their intracellular reactive oxygen species level, malondialdehyde content, and lactate dehydrogenase leakage index. These findings demonstrate the defensive potential of hemp seed polyphenol in reducing the incidence of cardiovascular disease. PRACTICAL APPLICATION: Hemp seed shell waste is produced while producing hemp seed kernel and has abundant phenolic compounds. This research showed that hemp seed polyphenol has potent antioxidant activity in vitro and protects HUVEC cells against H₂ O₂ -induced oxidative stress injury, suggesting that hemp seed polyphenol has the defensive potential to reduce the incidence of cardiovascular disease. These results indicated that polyphenol separated from hemp seed shells is valuable for further research and development, which will improve the utilization rate of hemp seed.

Macroporous adsorptive resin-assisted enrichment of polyphenol from Psidium guajava leaves improved its in vitro antioxidant and anti-hemolytic properties

Phytochemical analyses of guava leaf extracts, commonly applied in traditional medicine, revealed the presence of several bioactive polyphenols. In this study, we optimized the enrichment of total polyphenol from Guava leaf ethanolic extract (GEE) using six macroporous adsorptive resins (MAR) including AB8, D101, X5, ADS17, S400, and AD7. Also investigated are the contributions of adsorption time, extract concentration, pH, elution time, and eluent ethanol concentrations on the polyphenol enrichment potential of MAR. The antioxidant and anti-hemolytic properties of the crude and polyphenol-rich extracts were determined. Our results indicate that treatment of GEE extract with AB8 MAR at a concentration of 15 mg GEE/g resin, adsorption time of 45 min, elution time of 40 min, and eluent ethanol concentration of 50% (v/v) improved the flavonoids and phenol concentration of GEE by 2 and 2.5 folds respectively. The DPPH radical scavenging, ferric reducing ability of the plasma (FRAP), anti-hemolytic and anti-peroxidation activity of the resultant polyphenol-rich extracts improved by 1.5, 1.6, 1.4, and 1.88 folds respectively, when compared to the crude extract. Our work shows that the MAR-assisted enrichment operation is a rapid, feasible, and economical strategy for enriching bioactive polyphenols from guava leaf extracts.

Monodisperse Ti4+-immobilized macroporous adsorbent resins with polymer brush for improved multi-phosphopeptides enrichment in milk

Enrichment of phosphopeptides before mass spectrometry (MS) analysis is essential due to the limitations of low abundance and poor ionization efficiency in complex biological samples. Immobilized metal affinity chromatography (IMAC), especially titanium ion (Ti⁴⁺)-IMAC, has become a popular strategy for enrichment of phosphopeptides due to high selectivity and sensitivity. Conventional Ti⁴⁺-immobilized macroporous adsorption resin (MAR) fabricated by monolayer modification can preferentially capture mono-phosphopeptide over multi-phosphopeptides, which takes on more functions in the regulation of cell behaviors of organism. In this paper, a kind of monodisperse MAR microsphere with functional polymer brush (Ti⁴⁺-Brush@MAR) was prepared and modified via surface-initiated atom transfer radical polymerization (SI-ATRP). Compared with common Ti⁴⁺-MAR without polymer brush, Ti⁴⁺-Brush@MAR exhibited high enrichment specificity not only for mono-phosphopeptides but also for multi-phosphopeptides in β-casein or milk digest samples. As a result, a total of 93 unique phosphopeptides mapped to 18 phosphoproteins were identified from 5 μL milk, and the limit of detection is 10 fmol. It is expected that Ti⁴⁺-Brush@MAR would be utilized to enrich both multi-phosphopeptides and mono-phosphopeptides in additional biological or food samples.

Preparation and Recognition Properties of Molecularly Imprinted Nanofiber Membrane of Chrysin

The separation and extraction of chrysin from active ingredients of natural products are of great significance, but the existing separation and extraction methods have certain drawbacks. Here, chrysin molecularly imprinted nanofiber membranes (MINMs) were prepared by means of electrospinning using chrysin as a template and polyvinyl alcohol and natural renewable resource rosin ester as membrane materials, which were used for the separation of active components in the natural product. The MINM was examined using Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The adsorption performance, adsorption kinetics, adsorption selectivity, and reusability of the MINM were investigated in static adsorption experiments. The analysis results show that the MINM was successfully prepared with good morphology and thermal stability. The MINM has a good adsorption capacity for chrysin, showing fast adsorption kinetics, and the maximum adsorption capacity was 127.5 mg·g⁻¹, conforming to the Langmuir isotherm model and pseudo-second-order kinetic model. In addition, the MINM exhibited good selectivity and excellent reusability. Therefore, the MINM proposed in this paper is a promising material for the adsorption and separation of chrysin.

Preparation of Rosin-Based Composite Membranes and Study of Their Dencichine Adsorption Properties

In this work, rosin-based composite membranes (RCMs) were developed as selective sorbents for the preparation of dencichine for the first time. The rosin-based polymer microspheres (RPMs) were synthesized using 4-ethylpyridine as a functional monomer and ethylene glycol maleic rosinate acrylate as a crosslinking. RCMs were prepared by spinning the RPMs onto the membranes by electrostatic spinning technology. The optimization of various parameters that affect RCMs was carried out, such as the ratio concentration and voltage intensity of electrospinning membrane. The RCMs were characterized by SEM, TGA and FT-IR. The performances of RCMs were assessed, which included adsorption isotherms, selective recognition and adsorption kinetics. The adsorption of dencichine on RCMs followed pseudo-second-order and adapted Langmuir–Freundlich isotherm model. As for the RCMs, the fast adsorption stage appeared within the first 45 min, and the experimental maximum adsorption capacity was 1.056 mg/g, which is much higher than the previous dencichine adsorbents reported in the literature. The initial decomposition temperature of RCMs is 297 °C, the tensile strength is 2.15 MPa and the elongation at break is 215.1%. The RCMs have good thermal stability and mechanical properties. These results indicated that RCMs are a tremendously promising adsorbent for enriching and purifying dencichine from the notoginseng extracts.

The applicability of pH-zone-refining counter-current chromatography for preparative separation of biosynthesis products: Glycosylation products as example

Biosynthesis is a research hot-spot in recent years, however, the purification of its final products is a tough work. Liquid stationary phase and large-scale separation ability of PZRCCC could easily avoid the commonly disadvantages occurred in traditional column chromatography. These characteristics makes PZRCCC particularly applicable for final products separation in biosynthesis. In this study, the glycosylation products of ellagic acid by one-pot glycosylation were successfully purified by PZRCCC to show the applicability of PZRCCC for preparative separation of biosynthesis products. An optimized ethyl acetate/n-buthanol/water (3:3:5, v/v/v) system was applied in this study, where 5 mM trifluoroacetic acid (TFA) as the retainer and 30 mM triethylamine (TEA) as the eluter were added. As a result, four ellagic acid glycosylation products, including 51 mg of ellagic acid-4, 3'-O-β-D-diglucoside (EG-1), 24 mg of ellagic acid-4, 4'-O-β-D-diglucoside (EG-2), 11 mg of ellagic acid-4-O-β-D-glucosyl (1→2)-β-D-glucoside (EG-3) and 64 mg of ellagic acid-4-O-β-D-glucoside (EG-4) were simultaneously separated from 500 mg of glycosylation crude products, with the purity of 93.3%, 91.2%, 89.4% and 95.5%, respectively. Their structures were identified by spectroscopic analysis.

Biotechnological interventions of in vitro propagation and production of valuable secondary metabolites in Stevia rebaudiana

Plant cell and tissue culture makes provision of a sustainable and nature-friendly strategy for the production of secondary metabolites, and modern progress in gene editing and genome engineering provides novel possibilities to improve both the qualitative and quantitative aspects of such phytochemicals. The ever-expanding quest for plant-based medicine to treat diabetes facilitates large-scale cultivation of Stevia rebaudiana to enhance the yield of its much-coveted low-calorie sweetener glycosides. The potential to process stevia as a "natural" product should enhance the acceptance of steviosides as a natural calorie-free sweetener especially suitable for use in diabetic and weight control drinks and foods. Besides sweetener agents, S. rebaudiana is a potent source of many antioxidant compounds and is used to cure immunodeficiencies, neurologic disorders, inflammation, diabetes mellitus, Parkinson's disease, and Alzheimer's disease. This comprehensive review presents the research outcomes of the many biotechnological interventions implicated to upscale the yield of steviol glycosides and its derivatives in in vitro cell, callus, tissue, and organ cultures with notes on the use of bioreactor and genetic engineering in relation to the production of these valuable compounds in S. rebaudiana. KEY POINTS: • Critical and updated assessment on sustainable production of steviol glycosides from Stevia rebaudiana. • In vitro propagation of S. rebaudiana and elicitation of steviol glycosides production. • Genetic fidelity and diversity assessment of S. rebaudiana using molecular markers.

The applicability of high-speed counter-current chromatography for preparative separation of biosynthesis products: Glycosylation products as example

Biosynthesis is a promising way to manufacture desired products, however, the purification of its final products is a tough work due to the huge amount of reaction matrix. Liquid stationary phase of high-speed counter-current chromatography could easily avoid the commonly disadvantages that occurred in traditional column chromatography in the field of biosynthesized products purification. This characteristic makes high-speed counter-current chromatography particularly applicable for final products separation in biosynthesis. In this study, the glycosylation products of Silybin B by one-pot glycosylation were successfully purified by high-speed counter-current chromatography to show the applicability of high-speed counter-current chromatography for preparative separation of biosynthesis products. An optimized n-hexane/ethyl acetate/methanol/water (2:5:2:3, v/v/v/v) system was applied in this study. As a result, four Silybin B glycosylation products, including 7 mg of Silybin B-5-O-β-D-glucoside (SG-1), 12 mg of Silybin B-3-O-β-D-glucoside (SG-2), 10 mg of Silybin B-7-O-β-D-glucoside (SG-3), and 24 mg of Silybin B-20-O-β-D-glucoside (SG-4), were simultaneously separated from 200 mg of glycosylation crude products, with the purity of 89.3, 95.2, 96.4, and 97.5%, respectively. Their structures were identified by spectroscopic analysis.

The isolation of water-soluble natural products - challenges, strategies and perspectives

Covering period: up to 2019Water-soluble natural products constitute a relevant group of secondary metabolites notably known for presenting potent biological activities. Examples are aminoglycosides, β-lactam antibiotics, saponins of both terrestrial and marine origin, and marine toxins. Although extensively investigated in the past, particularly during the golden age of antibiotics, hydrophilic fractions have been less scrutinized during the last few decades. This review addresses the possible reasons on why water-soluble metabolites are now under investigated and describes approaches and strategies for the isolation of these natural compounds. It presents examples of several classes of hydrosoluble natural products and how they have been isolated. Novel stationary phases and chromatography techniques are also reviewed, providing a perspective towards a renaissance in the investigation of water-soluble natural products.

Optimization of the Purifying Process for Columbianetin-β-D-Glucopyranoside from Angelicae Pubescentis Radix and Evaluation of Its Analgesic Activity Using Hot Plate Test

The objective of this work was to provide an economic and practical method for the purification of columbianetin-β-D-glucopyranoside from Angelicae Pubescentis Radix extract. In the static adsorption and desorption, the effects of resin type (D101, HP-20, AB-8, GDX-201, and DA201), contact time (10–360 min), and temperature (298–318 K) were assessed on columbianetin-β-D-glucopyranoside adsorption efficiency in laboratory. GDX-201 resin showed the best adsorption and desorption properties for columbianetin-β-D-glucopyranoside. The kinetic data revealed that the equilibrium time for columbianetin-β-D-glucopyranoside adsorption was achieved within 150 min. Moreover, the adsorption kinetic curve was well in accordance with the pseudo-second-order equation (R² > 0.99). The rate controlling step of the adsorption process was the intraparticle diffusion. The Langmuir isotherm models (R² > 0.99) could describe the whole adsorption process, which was exothermic and spontaneous according to the result of thermodynamics tests. In the dynamic adsorption and desorption process, the optimum loading flow (4, 5, and 6 BV/h), ethanol concentration (0–60%), and elution volume (10–230 mL) were optimized. Under optimal conditions of 4 BV/h loading flow, 6.7 BV loading volume, 25% ethanol, and 14 BV elution volume, the content of columbianetin-β-D-glucopyranoside in the product was increased 29.61-fold from 0.45% to 13.32 ± 0.64% with yield of 88.03 ± 2.76% by an experiment of lab-scale enlargement. Then, columbianetin-β-D-glucopyranoside was further purified by PHPLC and its purity was more than 98%. Additionally, the analgesic activity of the columbianetin-β-D-glucopyranoside was assessed by hot plate test. The experimental results showed that columbianetin-β-D-glucopyranoside significantly increased the latency of pain response in mice. This study demonstrated columbianetin-β-D-glucopyranoside could be as a potentially natural analgesic component. It could be summed up that the established method was successfully applied to purifying columbianetin-β-D-glucopyranoside from Angelicae Pubescentis Radix extract.

A facile macroporous resin-based method for separation of yellow and orange Monascus pigments

The yellow Monascus pigments (YMPs) named monascin and ankaflavin and the orange Monascus pigments (OMPs) named rubropunctatin and monascorubrin are two groups of bioactive components in a mixture state in the Monascus fermented products. In order to separate these two groups of bioactive pigments, a facile macroporous resin-based method was developed. The weak-polar resin CAD-40 was selected from the seven tested macroporous resins as it revealed better properties for the adsorption and desorption of the YMPs and OMPs. Then, CAD-40 resin was used for column-chromatographic separation. After eluted by 4 bed volumes of ethanol, the yellow group (monascin and ankaflavin) and the orange group (rubropunctatin and monascorubrin) were successfully separated and purified, with an increased content from 49.3% and 44.2% in the crude pigment extract to 85.2% and 83.0% in the final products, respectively. This method would be helpful for the large-scale separation and purification of Monascus pigment products with specific bioactivity.

Adsorption/Desorption Characteristics and Simultaneous Enrichment of Orientin, Isoorientin, Vitexin and Isovitexin from Hydrolyzed Oil Palm Leaf Extract Using Macroporous Resins

Oil palm leaves (OPL) containing flavonoid C-glycosides are abundantly generated as oil palm byproducts. The performances of three macroporous resins with different physical and chemical properties for the enrichment of isoorientin, orientin, vitexin, and isovitexin from acid-hydrolyzed OPL (OPLAH) extract were screened. The XAD7HP resin exhibited the best sorption capacities for the targeted flavonoid C-glycosides and was thus selected for further evaluation. Static adsorption using the XAD7HP resin under optimal conditions (extract adjusted to pH 5, shaken at 298 K for 24 h) gave adsorption kinetics that fit well with a pseudo-second-order kinetic model. The adsorption of isoorientin and orientin was well described by Langmuir isotherms, while vitexin and isovitexin fit well with the Freundlich isotherms. Dynamic sorption trials using the column-packed XAD7HP resin produced 55–60-fold enrichment of isovitexin and between 11 and 25-fold enrichment of isoorientin, vitexin, and orientin using aqueous ethanol. The total flavonoid C-glycoside-enriched fractions (enriched OPLAH) with isoorientin (247.28–284.18 µg/mg), orientin (104.88–136.19 µg/mg), vitexin (1197.61–1726.11 µg/mg), and isovitexin (13.03–14.61 µg/mg) showed excellent antioxidant free radical scavenging activities compared with their crude extracts, with IC50 values of 6.90–70.63 µg/mL and 44.58–200.00 µg/mL, respectively. Hence, this rapid and efficient procedure for the preliminary enrichment of flavonoid C-glycosides by using macroporous resin may have practical value in OPL biomass waste utilization programs to produce high value-added products, particularly in the nutraceuticals, cosmeceuticals, pharmaceuticals, and fine chemicals industries.

Optimization of Enzyme-Assisted Extraction and Purification of Flavonoids from Pinus koraiensis Nut-Coated Film and Antioxidant Activity Evaluation

Pinus koraiensis nut-coated film is a kind of by-product of nut processing, which has been shown to contain flavonoids, polyphenols, and other substances that can be used to produce natural antioxidant extracts. In this study, response surface methodology (RSM) was used to optimize the extraction process of flavonoids of P. koraiensis nut-coated film (PNF), and macroporous resin HPD600 was used to purify PNF (P-PNF). Its antioxidant activity was examined by DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging capacity, oxygen free radical absorption capacity (ORAC), total oxygen radical capture (TRAP), and iron ion reduction capacity. Under the ideal extraction conditions comprising a cellulase dosage of 90 U/g, a material/liquid ratio of 1:20 (g/mL), and an extraction time of 2 h, the PNF yield was 3.37%. Purification conditions were sample concentration of 2.0 mg/mL, pH of 5, water washing volume of 3 bed volume (BV), eluent ethanol concentration of 50%, and volume of 2 BV. The P-PNF recovery was 84.32%, and purity increased from 33.80% to 61.70%. Additionally, P-PNF showed increased antioxidant activity compared to PNF. Cumulatively, this study obtained the optimal values for the process parameters in order to achieve the maximum rates of extraction of PNF for economically optimal production at an industrial scale.

Facile preparation of bifunctional adsorbents for efficiently enriching N-glycopeptides and phosphopeptides

In bottom-up strategy, specific enrichment of glycopeptides and phosphopeptides from complicated biological samples is a prerequisite for efficient identifying glycosylation and phosphorylation by mass spectrometry. Although there were a plethora of materials used as either hydrophilic interaction liquid chromatography (HILIC) or immobilized metal affinity chromatography (IMAC) adsorbents, even several bifunctional materials for simultaneous enrichment of glycopeptides and phosphopeptides, most of them are not easily commercialized as many other well-performing adsorbents due to the complicated preparation process. In our case, a one-step modification strategy was developed to prepare bifunctional adsorbents for HILIC and IMAC, employing O-phospho-l-serine as the modifier and poly(GMA-co-EDMA) microspheres, a kind of macroporous adsorption resin (MAR) with epoxy groups, as the matrix. The MARs were directly modified with O-phospho-l-serine under facile condition for HILIC strategy and further chelated with Ti⁴⁺ for IMAC strategy. A total of 522 unique N-glycopeptides and 442 unique N-glycosylation sites mapped to 275 N-glycoproteins was identified from HeLa cell proteins, showing excellent enrichment efficiency in HILIC. Additionally, 3141 unique phosphopeptides were unambiguously identified from 200 μg of digest of HeLa cell proteins, demonstrating great enrichment efficiency in IMAC. Moreover, these materials have been successfully applied in the analysis of multiple biological samples including human serum and milk, demonstrating their feasibility for real sample applications and potential business value.

Bioactivity-Oriented Purification of Polyphenols from Cinnamomum cassia Presl. with Anti-Proliferation Effects on Colorectal Cancer Cells

Cinnamomum cassia Presl. (CCP) is a popular natural spice possessing various pharmacological properties. We obtained polyphenol-rich fraction (CCP-P) from CCP by bioactivity-oriented purification method and evaluated its Wnt signaling inhibition activity. Firstly, the phenolic components were identified as the main bioactive compounds with anti-colorectal cancer activity. Then, we compared the anti-colorectal cancer activity of CCP extract obtained from different solvent by cell morphology alteration and EdU assay. Ethanol extract showed higher antiproliferative activity compared to water extract on HCT116 cells, with proliferating cells reducing to 41.12 and 21.83% at 156.00 μg GAE/mL, respectively. Next, separation and enrichment of polyphenols from ethanol extract was performed on AB-8 macroporous resins under optimal conditions. Further evaluation of the CCP-P bioactivity revealed that it exerted more potent antiproliferative activity on RKO and HCT116 cells, showing higher selectivity for Wnt-dependent colorectal cancer cells (CRCs). Ten major polyphenols were identified in the CCP-P by UPLC-ESI-MS/MS. In summary, this study presents evidence that CCP-derived polyphenols are promising potential candidates as functional food ingredients against CRC.

Efficient preparation of c-di-AMP at gram-scale using an immobilized Vibrio cholerae dinucleotide cyclase DncV

Cyclic di-AMP is a bacterial nucleotide second messenger and evaluated as a potential vaccine adjuvant candidate. Here, we report a practical and economical enzymatic method for gram-scale preparation of c-di-AMP using an immobilized Vibrio cholerae dinucleotide cyclase DncV. The method mainly includes four steps: preparation of DncV-immobilized resin, enzymatic synthesis of c-di-AMP, purification using macroporous absorption resin SP207, and desiccation using rotary evaporation and lyophilization. Enzymatic synthesis is the most critical step, and almost all substrate ATP was converted to c-di-AMP under an optimum condition in which 300 mL of 300 mM NH₄Ac/NH₃ pH 9.5 buffer supplemented with 20 mM MnCl₂, 10 mM ATP and 4 mL of DncV-immobilized resin containing ∼19 mg DncV were incubated at 30 °C overnight. After purification, up to 1 g of the diammonium salt of c-di-AMP with weight purity of ≥98% was obtained as white powder, which corresponds to an overall yield of ∼80% based on the ATP input into the reaction. The method is easily performed in laboratory to prepare c-di-AMP on a gram scale and could be used in industry on a large scale.

Application of micro/nanomaterials in adsorption and sensing of active ingredients in traditional Chinese medicine

Traditional Chinese medicine (TCM) has been widely applied for the prevention and cure of various diseases for centuries. Ingredient with pharmacological activity is the key to the application of TCM. Hence, it is of significance to separate and detect active ingredients in TCM effectively. Micro/nanomaterial is the promising candidate for adsorption and sensing due to its unique physical and chemical properties. For years, many efforts have been made to develop functional micro/nanomaterials to realize the effective adsorption or sensing of bioactive compounds in TCM. In this review, we discussed recent progresses in the application of various functional micro/nanomaterials for adsorption or detection (electrochemical detection, fluorescent detection, and colorimetric detection) of active ingredients. Based on the kind of matrix materials, micro/nano-adsorbents or sensors can be classified into following categories: metal-based micro/nanomaterials, porous materials, carbon-based materials, graphene/graphite-liked micro/nanomaterials and hybrid micro/nanomaterials.

Synthesis of Acryl Group-Modified Adsorption Resins and Their Adsorption Properties for Matrine and Oxymatrine in Aqueous Solutions

Three series of resins with different functional groups (PS-EA, PS-MP, and PS-BA) based on D101 copolymer were prepared via the atom transfer radical polymerization method. The adsorption capacities of functionalized resins toward matrine (MT) and oxymatrine (OM) depended on the specific surface area, the surface chemistry, and the good polarity match between the target compound and porous material. It is noted that the accumulation of functional groups uploaded on the surface of resins increased the adsorption affinity difference between the MT-functionalized resin system and OM-modified copolymer system. The selectivity of modified resins to MT and OM would attribute to polarity matching. The results could provide a possible strategy for the design of efficient adsorbents applied for the isolation the bioactive compound from complex natural products.

Isolation and Purification of Kudinosides from Kuding Tea by Semi-Preparative HPLC Combined with MCI-GEL Resin

Background:

Kuding tea, a Traditional Chinese drink, has a history of thousands of years in China. Triterpenoid saponins in Kuding tea are regarded as one of the major functional ingredients.

Objective:

The aim of this paper was to establish separation progress for the isolation and purification of five triterpenoid saponins (kudinoside A, C, D, F, G) from Kuding tea.

Methods:

Nine types of resins, including seven macroporous resins and two MCI-GEL resins, were firstly used for purifying triterpenoid saponins by the adsorption and desorption tests. Further dynamic adsorption/desorption experiments were carried out to obtain the optimal parameters for the five targeted saponins. Then the purification of five triterpenoid saponins (kudinoside A, C, D, F, G) was completed by semi-preparative high-performance liquid chromatography (semi-pHPLC).

Results:

As of optimized results, the HP20SS MCI-GEL was selected as the optimal one. The data also showed that 65.24 mg of refined extract including 7.04 mg kudinoside A, 3.52 mg kudinoside C, 4.04 mg kudinoside D, 4.13 mg kudinoside F, and 34.45 mg kudinoside G, could be isolated and purified from 645.90 mg of crude extract in which the content of five saponins was 81.51% and the average recovery reached 69.76%. The final contents of five saponins increased 6.91-fold as compared to the crude extract.

Conclusion:

The established separation progress was highly efficient, making it a potential approach for the large-scale production in the laboratory and providing several markers of triterpenoid saponins for quality control of Kuding tea or its processing products.

Kaempferol separated from Camellia oleifera meal by high-speed countercurrent chromatography for antibacterial application

Natural biologically active substances have received continuous attention for the potentially beneficial health properties against chronic diseases. In this study, bacteriostatic active substance from Camellia oleifera meal, which is a major by-product of the Camellia oil processing industry, were extracted with continuous phase change extraction (CPCE) method and separated by HSCCC. Compared with traditional extraction methods, CPCE possessed higher extraction efficiency. Two main substances were separated and purified (above 90.0%). The structure of them were further identified by UV, LC-ESI-MS-MS, 1H-NMR, and 13C-NMR as flavonoids F2 kaempferol 3-O-[β-d-glucopyranosyl-(1 → 2)-α-l-rhamnopyranosyl-(1 → 6)]-β-d-glucopyranoside and J2 kaempferol 3-O-[β-d-xylopyranosyl-(1 → 2)-α-l-rhamnopyranosyl-(1 → 6)]-β-d-glucopyranoside for the first time in C. Oleifera meal. The results of antibacterial activity measurement showed that both compounds have excellent antibacterial activity. And the antibacterial stability of F2 were finally confirmed: F2 showed broad spectrum antibacterial activity against Escherichia coli, Staphylococcus aureus, Salmonella enteriditis, Bacillus thuringiensis, Aspergillus niger and Rhizopus nigricans. Besides, F2 exhibited relatively high stable property even at high temperature, acid and metal ion solutions. The findings of this work suggest the possibility of employing C. oleifera meal as an attractive source of health-promoting compounds, and at the same time facilitate its high-value reuse and reduction of environmental burden.

Preparation of Poly(glycidyl methacrylate) (PGMA) and Amine Modified PGMA Adsorbents for Purification of Glucosinolates from Cruciferous Plants

Glucosinolates (GLs) are of great interest for their potential as antioxidant and anticancer compounds. In this study, macroporous crosslinked copolymer adsorbents of poly (glycidyl methacrylate) (PGMA) and its amine (ethylenediamine, diethylamine, triethylamine)-modified derivatives were prepared and used to purify the GLS glucoerucin in a crude extract obtained from a cruciferous plant. These four adsorbents were evaluated by comparing their adsorption/desorption and decolorization performance for the purification of glucoerucin from crude plant extracts. According to the results, the strongly basic triethylamine modified PGMA (PGMA-III) adsorbent showed the best adsorption and desorption capacity of glucoerucin, and its adsorption data was a good fit to the Freundlich isotherm model and pseudo-second-order kinetics; the PGMA adsorbent gave the optimum decolorization performance. Furthermore, dynamic adsorption/desorption experiments were carried out to optimize the purification process. Two glass columns were serially connected and respectively wet-packed with PGMA and PGMA-III adsorbents so that glucoerucin could be decolorized and isolated from crude extracts in one process. Compared with KCl solution, aqueous ammonia was a preferable desorption solvent for the purification of glucoerucin and overcame the challenges of desalination efficiency, residual methanol and high operation costs. The results showed that after desorption with 10% aqueous ammonia, the purity of isolated glucoerucin was 74.39% with a recovery of 80.63%; after decolorization with PGMA adsorbent, the appearance of glucoerucin was improved and the purity increased by 11.30%. The process of using serially connected glass columns, wet-packed with PGMA and PGMA-III, may provide a simple, low-cost, and efficient method for the purification of GLs from cruciferous plants.

Effective isolation of antioxidant Phelligridin LA from the fermentation broth of Inonotus baumii by macroporous resin

Phelligridin LA (PLA) is a natural product with vigorous free radical scavenging activities accumulated in the liquid fermentation of herbal medicinal fungus Inonotus baumii. Aiming to establish an efficient isolation method of PLA from the fermentation broth, we evaluated the adsorption of PLA by macroporous resins. The best resin ADS-17 was screened for six candidates with various physical properties and adsorption behaviors. Studies on the thermodynamics and kinetics of the process revealed that the adsorption reaction could take place spontaneously, which implied that the heat generated in adsorption might compensate for the decrease in entropy. The Freundlich theory could be utilized to fit the experimental data. The pseudo-second-order equation could describe the process, and the adsorption rate was primarily controlled by liquid film diffusion and pore diffusion. The influencing operation factors (temperature, pH, and the ratio of fermentation broth to resin) of the adsorption process were optimized with response surface methodology. The optimized condition (temperature 22.81 °C, pH 5.19, and the ratio of fermentation broth to resin or RLS 5.11) supported an adsorption rate of 97.03%. These findings would be indispensable for further optimization of the efficient separation of PLA from the fermentation broth, and the fermentation production of PLA in which separation would be included.

The high-efficient production of phelligridin LA by Inonotus baumii with an integrated fermentation-separation process

The phelligridin LA was one of the valuable metabolites synthesized by the medicinal fungus Sanghuang in liquid fermentation. In the improvement of PLA productivity by fermentation, we investigated the optimal conditions for the efficient separation of PLA from the fermentation broth with a chromatographic column packed with the macroporous resin ADS-17. Based on the findings, we further developed an integrated bioreactor system that coupled the fermentation and separation of PLA. Fermentation experiments with the bioreactor system testified the performance of our design in fortification of the PLA production: an improvement of PLA production by 2.14 folds was successfully achieved due to the prompt removal of the PLA, while the formation of hyphae biomass was not affected. Also, the integrated system could afford a simultaneous purification of PLA to a purity of 92.95% with a recovery of 84.3%, which was comparable to that of the PLA purified with an additional process (97.53%), at a reasonable recovery. This study provided a feasible approach for the improved production of PLA by fermentation. Besides, the design of the integrated bioreactor system offered a useful reference for the fermentation process development of fungi for the production of diverse valuable metabolites.

Water-Soluble Glutamic Acid Derivatives Produced in Culture by Penicillium solitum IS1-A from King George Island, Maritime Antarctica

A new method of screening was developed to generate 770 organic and water-soluble fractions from extracts of nine species of marine sponges, from the growth media of 18 species of marine-derived fungi, and from the growth media of 13 species of endophytic fungi. The screening results indicated that water-soluble fractions displayed significant bioactivity in cytotoxic, antibiotic, anti-Leishmania, anti-Trypanosoma cruzi, and inhibition of proteasome assays. Purification of water-soluble fractions from the growth medium of Penicillium solitum IS1-A provided the new glutamic acid derivatives solitumine A (1), solitumine B (2), and solitumidines A-D (3-6). The structures of compounds 1-6 have been established by analysis of spectroscopic data, chemical derivatizations, and vibrational circular dichroism calculations. Although no biological activity could be observed for compounds 1-6, the new structures reported for 1-6 indicate that the investigation of water-soluble natural products represents a relevant strategy in finding new secondary metabolites.

Efficient enrichment of total flavonoids from Pteris ensiformis Burm. extracts by macroporous adsorption resins and in vitro evaluation of antioxidant and antiproliferative activities

The aim of this work is to develop an efficient and economical method for the enrichment of total flavonoids from Pteris ensiformis Burm. extracts. Resin screening, adsorption kinetics, adsorption isotherms and thermodynamics were successively researched prior to the dynamic adsorption and desorption tests. NKA-II resin was chosen as the best adsorbent, and the adsorption data were best described by the pseudo-second-order kinetics model and Langmuir isotherm model. The optimum enrichment conditions were as follows: for adsorption the total flavonoids concentration, flow rate and volume of sample were 1.84 mg/mL, 2 BV/h and 5 BV, respectively, and for desorption the flavonoids-loaded NKA-II resin column was desorbed by 7 BV of 50% ethanol at a rate of 2 BV/h. The product had a 6.63-fold higher total flavonoids content than crude extracts, and the recovery yield of total flavonoids was 80.65%. Furthermore, flavonoids-enriched extracts exhibited higher in vitro scavenging activity against superoxide anion radical and hydroxyl radical than crude extracts. In addition, higher antiproliferative activity of flavonoids-enriched extracts against MCF-7 and HepG-2 cell lines was also found as compared to the crude extracts. The developed method is appropriate for large-scale enrichment of total flavonoids from Pteris ensiformis Burm. extracts in the food and pharmaceutical industries.

Combined chromatographic strategy based on macroporous resin, high-speed counter-current chromatography and preparative HPLC for systematic separation of seven antioxidants from the fruit of Terminalia billerica

In the present study, combined chromatographic strategy based on macroporous resin, high-speed counter-current chromatography and preparative high-performance liquid chromatography for systematic separation of antioxidants from crude samples guided by high-performance liquid chromatography with 1,1-diphenyl-2-picrylhydrazyl has been successfully established. Based on this strategy, seven antioxidants including isorugosin A, _β -1,2,3,6-tetragalloyl-D-glucose, chebulinic acid, 1,2,3,4,6-penta-O-galloyl-_β -D-glucose, chebulagic acid, ethyl gallate, and gallic acid were obtained from the fruit of Terminalia billerica. First, high-performance liquid chromatography with 1,1-diphenyl-2-picrylhydrazyl experiment showed the presence of seven main antioxidants in the crude extract of the fruit of Terminalia billerica. Then, a macroporous resin column chromatography method was developed for the enrichment of these seven antioxidants. Finally, an efficient method based on high-speed counter-current chromatography and preparative high-performance liquid chromatography was developed for the separation of these antioxidants. In the selection of solvent systems, it was found that acetic acid could be a good regulator for modifying the partition coefficient values of tannins. The present study provides a reference for systematic separation of antioxidants from crude samples. Considering the general existence of antioxidants in crude samples, this combined chromatographic strategy might lead to broader application prospects.