Sweet spot matching: A thin-layer chromatography-based countercurrent solvent system selection strategy

Bioactivity-Guided High Performance Counter-Current Chromatography and Following Semi-Preparative Liquid Chromatography Method for Rapid Isolation of Anti-Inflammatory Lignins from Dai Medicinal Plant, Zanthoxylum acanthopodium var. timbor

The development of Dai medicine is relatively slow, and Zanthoxylum has great economic and medicinal value. It is still difficult to obtain medicinal components from the low-polarity parts of Zanthoxylum belonging to Dai medicine. In this study, we introduced one simple and quick strategy of separating target compounds from the barks of Z. acanthopodium var. timbor by high-performance countercurrent chromatography (HPCCC) with an off-line anti-inflammatory activity screening mode. The development of this strategy was based on the TLC-based generally useful estimation of solvent systems (GUESS) method and HPCCC in combination. This paper presented a rapid method for obtaining target anti-inflammatory compounds. Three lignins were enriched by HPCCC with an off-line inhibition mode of nitric oxide production in lipopolysaccharide-stimulated RAW264.7 macrophage cells, using petroleum ether-ethyl acetate-methanol-water (3:2:3:2) as the solvent system. The results showed that this method was simple and practical and could be applied to trace the anti-inflammatory components of the low-polarity part in Dai medicine.

The generally useful estimate of solvent systems method facilitates off-line two-dimensional countercurrent chromatography for isolating compositions from Siraitia grosvenorii roots

Solvent system selection is a crucial and the most time-consuming step for successful countercurrent chromatography separation. A thin-layer chromatography-based generally useful estimate of solvent systems method has been developed to simplify the solvent system selection. We herein utilized the method to select a solvent system for off-line two-dimensional countercurrent chromatography to separate chemical compositions from a complex fraction of the Siraitia grosvenorii root extract. The first-dimensional countercurrent separation using chloroform/methanol/water (10:5.5:4.5, v/v/v) yielded four compounds with high purity and three mixture fractions (Fr I, III, and VII). The second-dimensional countercurrent separation conducted on Fr I, III, and VII using the hexane/ethyl acetate/methanol/water (4:6:6:4, 3:7:3:7, v/v/v) and chloroform/methanol/water (10:9:6, v/v/v) solvent systems, respectively, produced another four compounds. Four triterpenoids and four lignans were finally isolated, including two novel compounds. Hence, the generally useful estimate of solvent systems method is a feasible and efficient approach for selecting an applicable solvent system for separating complex samples. In addition, the off-line two-dimensional countercurrent chromatography method can improve both the peak resolution and the capacity of countercurrent chromatography.

GUESS - A simple approach to accelerate optimization countercurrent separation

The generally useful estimate of solvent systems (GUESS) method, which is based on thin layer chromatography, is a simple and practical method for selecting solvent systems for countercurrent chromatography (CCC). However, it is rarely used for complex samples derived from natural products. In this study, GUESS was used for CCC solvent system selection and polarity-adjusted CCC separations of several fractions, which were obtained from a silica gel column containing complex compositions with a broad polarity from Salvia bowleyana Dunn. The GUESS method was performed on five fractions based on solvent systems in the n-hexane-ethyl acetate-methanol-water (HEMWat) family. Based on the GUESS results, the optimal solvent systems were selected for CCC separation. Twelve diterpenoids were obtained from the five silica gel column fractions of S. bowleyana Dunn using elution-extrusion countercurrent chromatography (EECCC). These demonstrate that GUESS guidance and the polarity adjustment of the solvent system accelerate the optimization of CCC separation conditions and simplify the process of accommodating a broad polarity of components in complicated mixture fractions. We therefore confirmed the feasibility and advantage of the GUESS method for complex natural chemical component separations.

Antioxidant, antibacterial, antifungal activities and gas chromatographic fingerprint of fractions from the root bark of Afzelia africana

BACKGROUND

Afzelia africana is a tropical plant with numerous ethno-medicinal benefits. The plant has been used for the treatment of pain, hernia, fever, malaria, inflammation and microbial infections.

OBJECTIVES

To perform bioassay-guided fractionation, antioxidant and antimicrobial activities of the bark of Afzelia africana.

METHODS

Column chromatography fractionation, antioxidant activity (% (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) and 1,1-diphenyl picrylhydrazyl (DPPH) scavenging activity))), antimicrobial activity (microbroth dilution: Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC), MBC/MIC ratio), and synergistic activities (Checkerboard assay: Fraction Inhibitory Concentration Index (FICI)).

RESULTS

Bioassay-guided fractionation of A. africana produced four fractions that displayed promising free radical scavenging activities in the ABTS (54-93)% and the DPPH (35-76)% assays in the ranking order of F1(93-54)>F4(81-58)>F2(74-58)>F3(72-55) and F3(77-42)>F1(64-46)>F4(55-44)>F2(47-35) respectively at a concentration range of 1.0-0.01 mg/mL. The fraction F1 (MBC: 2.5-5.0 mg/mL) and F4 (MBC: 1.25-10.0 mg/mL) exhibited broad spectrum of superior bactericidal effects than F2 (MBC≥100.0 mg/mL) and F3 (MBC: 12.5-100.0 mg/mL) against Staphylococcus mutans, Staphylococcus aureus, Escherichia coli, fluconazole-resistant Candida albicans, methicillin-resistant S. aureus, Bacillus subtilis, Klebsiella pneumonia, Pseudomonas aeruginosa, Salmonella typhi, and Candida albicans (standard strain). The two most active fractions (F1 and F4) reported synergistic effects (FICI≤0.5) against S. typhi whilst the F4 reported additional synergism against E. coli, K. pneumonia, and S. typhi when combined with ciprofloxacin. Furthermore, the two fractions reported synergistic effects against Escherichia coli, Klebsiella pneumonia, Salmonella typhi, and Pseudomonas aeruginosa when combined with tetracycline whilst F1 reported antifungal synergism against fluconazole resistant Candida albicans when combined with fluconazole and ketoconazole.

CONCLUSION

The study has confirmed the antioxidant, antimicrobial and synergistic uses of A. africana for the treatment of both infectious and non-infectious disease.

A simple and practical solvent system selection strategy for high-speed countercurrent chromatography based on the HPLC polarity parameter model

The selection of an appropriate solvent system is the most crucial step in high-speed countercurrent chromatography (HSCCC) separation. The compound polarity plays an important role in HPLC analysis and HSCCC separation, and it can be calculated by the HPLC polarity parameter model and the average polarity of the HSCCC solvent system, respectively. However, flow rates, columns and methanol concentrations of the HPLC experiment can influence the calculation of the compound polarity. Therefore, the applicability and accuracy of the HPLC polarity parameter model still needed to be extensively validated. We chose 14 compounds to conduct the shake-flask experiments and HPLC analysis on, such as apigenin, honokiol, phloridzin and dihydromyricetin. The HPLC analysis results showed that different flow rates and columns have negligible effects on the calculated compound polarities. However, there was a certain variation trend in the calculated polarities with different methanol concentrations. Although the polarity values of some compounds showed a difference between the HPLC analysis and shake-flask experiments, their partition coefficients (K) in the HSCCC solvent systems were still located in the range of 0.5 < K < 2.0. Guided by the HPLC polarity parameter model, the appropriate HSCCC solvent systems for mangosteen peel and Hypericum sampsonii Hance were selected, and the two main components (mangostin and quercetin) were isolated from their extracts, respectively. The separation results showed that the predicted compound polarities were sufficient to meet the HSCCC separation requirements. Meanwhile, this method required only 1 to 2 HPLC analyses with reference compounds, greatly improved the efficiency of the HSCCC solvent system selection, and shortened the experimental time. The polarity parameter model was a fast and efficient analysis method for the selection of an appropriate HSCCC solvent system.

Antibacterial Activities of Monsonia Angustifolia and Momordica Balsamina Linn Extracts against Carbapenem-Resistant Acinetobacter Baumannii

Carbapenemase-producing Acinetobacter baumannii (A. baumannii) is resistant to most of the available antibiotics and poses serious therapeutic challenges. The study investigated Monsonia angustifolia (M. angustifolia) and Momordica balsamina Linn (M. balsamina Linn) extracts for antibacterial activity against a clinical isolate of carbapenemase-producing A. baumannii using the Kirby Bauer disc diffusion and TLC coupled with bioautography. MIC determination experiments were conducted on a molecularly characterized A. baumannii isolate identified using VITEK2. Positive PCR detection of bla_OXA-51 and bla_OXA-23 confirmed isolate identity and the presence of a carbapenemase-encoding gene. Antibacterial activity was observed with the methanolic extract of M. balsamina Linn with a MIC of 0.5 mg/mL. Compounds with Rf values of 0.05; 0.17; 0.39 obtained from M. angustifolia hexane extract; compounds with Rf values of 0.58; 0.78; 0.36; 0.48; 0.5; 0.56; 0.67; 0.9 obtained from M. angustifolia dichloromethane extract; compounds with Rf values of 0.11; 0.56; 0.24; 0.37 obtained from M. angustifolia acetone extract and compounds with Rf values of 0.11; 0.27 obtained from M. angustifolia methanol extract demonstrated a level of antibacterial activity. M. angustifolia and M. balsamina Linn plant extracts have a clinically significant antibacterial activity against a carbapenemase-producing A. baumannii strain.

[Preparation of cucurbitacin compounds in Siraitia grosvenorii roots by high speed countercurrent chromatography]

Siraitia grosvenorii (Swingle) C. Jeffrey, belonging to the family Cucurbitaceae, is a natural sweetener. The roots of this plant are used in folk medicine for the treatment of rheumatoid arthritis. Cucurbitacins play an important role in the resistance of this plant to insects and adversity, and have anti-inflammatory, anti-tumor, and other biological activities. They usually exist as a variety of similar structures in Cucurbitaceae plants. Separation of a large amount of high-purity monomer compounds by the conventional separation method based on column chromatography is difficult, which limits the research and application of their activities. Therefore, we chose a new method for this separation. High-speed countercurrent chromatography (HSCCC) is a liquid-liquid chromatographic technique characterized by high recovery and reproducibility, and is considered a very effective method for the separation of natural compounds present in various plant extracts. An appropriate solvent system is the key for efficient separation, but its selection is tedious, which hampers the wider implementation of HSCCC in chemical research involving preparative separations. In this study, based on the general estimation strategy by using the TLC solvent system (GUESS), the corresponding relationship between the partition distribution coefficient (K value) and the TLC retention factor (Rf value) of the compounds was established by the partition experiment. The Rf value and separation coefficient α were calculated using the water-saturated organic phase as the expansion agent, which could minimize the number of countercurrent separation experiments required in solvent system selection. In this study, HSCCC was used to establish an efficient method for the extraction of cucurbitacins from the root extract of Siraitia grosvenorii. A fraction rich in cucurbitacins was obtained from the ethanol extract of Siraitia grosvenorii roots after separation by column chromatography on HPD-100, MCI, and C18 columns. Six types of solvent systems with different compositions were investigated using the GUESS method. The results showed that employing the solvent system of n-hexane-ethyl acetate-methanol-water (3∶7∶3∶7, v/v/v/v) to partition the cucurbitacin fraction could remove a large number of impurities. The components retained in the upper phase in the partition experiment were subsequently purified by HSCCC. The favorable solvent system for HSCCC was n-hexane-ethyl acetate-methanol-water (4∶6∶5∶5, v/v/v/v), while the upper and lower phases were selected as the stationary and mobile phases, respectively, with a flow rate of 2.0 mL/min, a rotation speed of 860 r/min, and an injected sample weight of 280 mg. Five cucurbitacin compounds were obtained by one-time separation. The weights of the five compounds were 14.73, 8.82, 30.74, 5.03, and 3.81 mg. The purities of these compounds were 97.0%, 95.4%, 96.3%, 91.6%, and 95.3%, respectively. Their structures were identified as cucurbitacin Q1, 23,24-dihydrocucurbitacin F-25-acetate, cucurbitacin B, 23,24-dihydrocucurbitacin B, and dihydroisocucurbitacin B-25-acetate by1H-NMR and 13C-NMR spectroscopies, along with comparison with the literature. This study demonstrated how GUESS guidance accelerates the selection of HSCCC solvent systems, simplifies the workflow, and it provides an efficient preparative method for the separation of chemical constituents from the Siraitia grosvenorii roots, which can also be used as a new method for the large-scale preparation of cucurbitacin compounds.

Investigation of red clover (Trifolium pratense) isoflavonoid residual complexity by off-line CCS-qHNMR

The importance of Trifolium pratense L. as a dietary supplement and its use in traditional medicine prompted the preparation of a thorough metabolite profile. This included the identification and quantitation of principal constituents as well as low abundant metabolites that constitute the residual complexity (RC) of T. pratense bioactives. The purity and RC of isoflavonoid fractions from standardized red clover extract (RCE) was determined using an off-line combination of countercurrent separation (CCS) and two orthogonal analytical methodologies: quantitative ¹H NMR spectroscopy with external calibration (EC-qHNMR) and LC-MS. A single-step hydrostatic CCS methodology (Centrifugal Partition Chromatography [CPC]) was developed that fractionated the isoflavonoids with a hexanes-ethyl acetate-methanol-water (HEMWat) 5.5/4.5/5/5, v/v solvent system (SS) into 75 fractions containing 3 flavonolignans, 2 isoflavonoid glycosides, as well as 17 isoflavonoids and related compounds. All metabolites were identified and quantified by qHNMR spectroscopy. The data led to the creation of a complete isoflavonoid profile to complement the biological evaluation. For example, fraction 69 afforded 90.5% w/w biochanin A (17), with 0.33% w/w of prunetin (16), and 0.76% w/w of maackiain (15) as residual components. Fraction 27 with 89.4% w/w formononetin (13) as the major component had, in addition, a residual complexity consisting of 3.37%, 0.73%, 0.68% w/w of pseudobaptigenin (11), kaempferol (10) and pratensein (8), respectively. Despite the relatively high resolving power of CPC, and not unexpectedly, the chromatographic fractions retained varying degrees of the original metabolomic diversity. Collectively, the extent of metabolomic diversity should be recognized and used to guide the development of isolation strategies, especially when generating samples for bioactivity evaluation. The simultaneous structural and quantitative characterization enabled by qNMR, supported by LC-MS measurements, enables the evaluation of a relatively large number of individual fractions and, thereby, advances both the chemical and biological evaluation of active principles in complex natural products.

Development of a strategy for a quick process for separation of volatile compounds in counter-current chromatography: purification of cinnamaldehyde from Cinnamomum cassia by high performance counter-current chromatography

It is a challenge for many researchers to separate volatile compounds. In this study, we introduce a rapid and efficient method of separating target compound from the twigs of Cinnamomum cassia by high performance counter-current chromatography. Under the bioassay guidance, the total extract exhibited a potential activity against NO production in RAW 264.7 macrophages and the total extract was further separated by high performance counter-current chromatography. Cinnamaldehyde (1) was enriched by counter-current chromatography (CCC) with reversed-phase mode using n-hexane-ethyl acetate-methanol-water (1:1:1:1,v/v/v/v) as the solvent system. Further identification was achieved by high performance liquid chromatography (HPLC).

The Untargeted Capability of NMR Helps Recognizing Nefarious Adulteration in Natural Products

Curcuma longa (turmeric) has an extensive history of ethnomedical use for common ailments, and "curcumin"-containing dietary supplements (CDS) are a highly visible portion of today's self-medication market. Owing to raw material cost pressure, CDS products are affected by economically motivated, nefarious adulteration with synthetic curcumin ("syncumin"), possibly leading to unexpected toxicological issues due to "residual" impurities. Using a combination of targeted and untargeted (phyto)chemical analysis, this study investigated the botanical integrity of two commercial "turmeric" CDS with vitamin and other additives that were associated with reported clinical cases of hepatotoxicity. Analyzing multisolvent extracts of the CDS by 100% quantitative ¹H NMR (qHNMR), alone and in combination with countercurrent separation (CCS), provided chemical fingerprints that allowed both the targeted identification and quantification of declared components and the untargeted recognition of adulteration. While confirming the presence of curcumin as a major constituent, the universal detection capability of NMR spectroscopy identification of significant residual impurities, including potentially toxic components. While the loss-free nature of CCS captured a wide polarity range of declared and unwanted chemical components, and also increased the dynamic range of the analysis, (q)HNMR determined their mass proportions and chemical constitutions. The results demonstrate that NMR spectroscopy can recognize undeclared constituents even if they represent only a fraction of the mass balance of a dietary supplement product. The chemical information associated with the missing 4.8% and 7.4% (m/m) in the two commercial samples, exhibiting an otherwise adequate curcumin content of 95.2% and 92.6%, respectively, pointed to a product integrity issue and adulteration with undeclared synthetic curcumin. Impurities from synthesis are most plausibly the cause of the observed adverse clinical effects. The study exemplifies how the simultaneously targeted and untargeted analytical principle of the 100% qHNMR method, performed with entry-level high-field instrumentation (400 MHz), can enhance the safety of dietary supplements by identifying adulterated, non-natural "natural" products.

Selective Chlorophyll Removal Method to "Degreen" Botanical Extracts

Chlorophylls are present in all extracts from the aerial parts of green plant materials. Chlorophylls may act as in vitro bioassay nuisance compounds, possibly preventing the reproducibility and accurate measurement of readouts due to their UV/vis absorbance, fluorescence properties, and tendency to precipitate in aqueous media. Despite the diversity of methods used traditionally to remove chlorophylls, details about their mode of operation, specificity, and reproducibility are scarce. Herein, we report a selective and efficient 45 min liquid-liquid/countercurrent chlorophyll cleanup method using Centrifugal Partition Chromatography (CPC) with a solvent system composed of hexanes-EtOAc-MeOH-water (5:5:5:5, v/v) in elution-extrusion mode. The broader utility of the method was assessed with four different extracts prepared from three well-characterized plant materials: Epimedium sagittatum (leaves), Senna alexandrina (leaves), and Trifolium pratense (aerial parts). The reproducibility of the method, the selectivity of the chlorophyll removal, as well as the preservation of the phytochemical integrity of the resulting chlorophyll-free ("degreened") extracts were evaluated using HPTLC, UHPLC-UV, 1H NMR spectroscopy, and LC-MS as orthogonal phytochemical methods. The cleanup process adequately preserves the metabolomic diversity as well as the integrity of the original extracts. This method was found to be sufficiently rapid for the "degreening" of botanical extracts in higher-throughput sample preparation for further biological screening.

Studying Mass Balance and the Stability of (Z)-Ligustilide from Angelica sinensis Helps to Bridge a Botanical Instability-Bioactivity Chasm

Numerous reports assigning (Z)-ligustilide (1) the role of a major bioactive principle in Apiaceae botanicals are called into question by the recurrent demonstrations of 1 being an unstable, rapidly degrading compound, ultimately leading to dynamic residual complexity. While Angelica sinensis is recognized for its therapeutic value in (peri-)menopausal symptom management, its purported active principle, 1, represents a typical example of the instability-bioactivity chasm of botanicals. To help bridge the gap, this study used both the essential oil and purified 1 obtained from A. sinensis to investigate the factors that influence the chemical transformation of 1, the products formed, and the rationale for monitoring 1 in natural product preparations. Countercurrent separation was used to purify 1 from a supercritical fluid extract of A. sinensis, achieving 93.4% purity in a single step. Subsequent purification by preparative HPLC afforded 1 with a 98.0% purity. Providing a mass balance setting, we monitored chemical changes occurring to highly purified 1 under various conditions and at different time points, in sealed NMR tubes by quantitative 1H NMR (qHNMR). The nondestructive nature of NMR enabled a comprehensive assessment of degradation products. Moreover, in being a mole-based determination, the total intensity (integral) of all NMR signals intrinsically represents the theoretical mass balance within the sample solution. The results demonstrated that 1 is most stable while within the original plant material. Exposure to light had a profound impact on the chemical transformation of 1, leading to the formation of ligustilide dimers and trimers, as verified by both NMR and LC-HRMS studies. Moreover, the results shown for 1, augmented by other recent outcomes, have serious implications for the meaningful biological evaluation of NPs that exhibit instability/reactivity, while having a plethora of "promising" bioactivities reported in the literature and being frequently associated with unsubstantiated health claims.

Strategies in anti-Mycobacterium tuberculosis drug discovery based on phenotypic screening

The rise of multi- and extensively drug-resistant Mycobacterium tuberculosis (M. tb) strains and co-infection with human immunodeficiency virus has escalated the need for new anti-M. tb drugs. Numerous challenges associated with the M. tb, in particular slow growth and pathogenicity level 3, discouraged use of this organism in past primary screening efforts. From current knowledge of the physiology and drug susceptibility of mycobacteria in general and M. tb specifically, it can be assumed that many potentially useful drug leads were missed by failing to screen directly against this pathogen. This review discusses recent high-throughput phenotypic screening strategies for anti-M. tb drug discovery. Emphasis is placed on prioritization of hits, including their extensive biological and chemical profiling, as well as the development status of promising drug candidates discovered with phenotypic screening.

Selective Depletion and Enrichment of Constituents in "Curcumin" and Other Curcuma longa Preparations

Much uncertainty exists in science and herbal products referencing turmeric (T), turmeric extract (TE), curcuminoid-enriched turmeric extract (CTE), further processed curcuminoid-enriched materials (CEM), or curcumin as a single-chemical entity. To facilitate the rational chemical and biological assessment of turmeric-derived NPs, we introduced the DESIGNER approach of Depleting and Enriching Select Ingredients to Generate Normalized Extract Resources to Curcuma longa preparations. Countercurrent separation of a commercial CTE yielded four key materials-lipophilic metabolites; purified curcumin ("purcumin"); a mixture of curcumin, demethoxycurcumin, and bisdemethoxycurcumin ("purcuminoids"); and hydrophilic metabolites-and enabled production of a curcuminoid-free TE ("nocumin"). Their characterization utilized TLC, ¹H (q)NMR spectroscopy, and HPLC.

Evidence for Chemopreventive and Resilience Activity of Licorice: Glycyrrhiza Glabra and G. Inflata Extracts Modulate Estrogen Metabolism in ACI Rats

Women are increasingly using botanical dietary supplements (BDS) to reduce menopausal hot flashes. Although licorice (Glycyrrhiza sp.) is one of the frequently used ingredients in BDS, the exact plant species is often not identified. We previously showed that in breast epithelial cells (MCF-10A), Glycyrrhiza glabra (GG) and G. inflata (GI), and their compounds differentially modulated P450 1A1 and P450 1B1 gene expression, which are responsible for estrogen detoxification and genotoxicity, respectively. GG and isoliquiritigenin (LigC) increased CYP1A1, whereas GI and its marker compound, licochalcone A (LicA), decreased CYP1A1 and CYP1B1 The objective of this study was to determine the distribution of the bioactive licorice compounds, the metabolism of LicA, and whether GG, GI, and/or pure LicA modulate NAD(P)H quinone oxidoreductase (NQO1) in an ACI rat model. In addition, the effect of licorice extracts and compounds on biomarkers of estrogen chemoprevention (CYP1A1) as well as carcinogenesis (CYP1B1) was studied. LicA was extensively glucuronidated and formed GSH adducts; however, free LicA as well as LigC were bioavailable in target tissues after oral intake of licorice extracts. GG, GI, and LicA caused induction of NQO1 activity in the liver. In mammary tissue, GI increased CYP1A1 and decreased CYP1B1, whereas GG only increased CYP1A1 LigC may have contributed to the upregulation of CYP1A1 after GG and GI administration. In contrast, LicA was responsible for GI-mediated downregulation of CYP1B1 These studies highlight the polypharmacologic nature of botanicals and the importance of standardization of licorice BDS to specific Glycyrrhiza species and to multiple constituents.

Countercurrent separation assisted identification of two mammalian steroid hormones in Vitex negundo

Countercurrent separation (CCS) has been widely used for the separation of high abundance compounds. However, the identification of low abundance compounds, such as mammalian steroid hormones, from natural sources is still a challenging task. A mixture of 14 human steroid hormone reference compounds was prepared for the development of a CCS enrichment strategy. The TLC-based GUESS (Generally Useful Estimate of Solvent Systems) method along with partitioning experiments were implemented to develop a process for the enrichment of these low abundance compounds with CCS. The application of CCS to the steroid hormone enrichment of Vitex negundo extracts was demonstrated by the identification of progesterone and estriol. This method provides a CCS-driven strategy to mine plant sources for low abundance compounds.

The influence of natural deep eutectic solvents on bioactive natural products: studying interactions between a hydrogel model and Schisandra chinensis metabolites

Natural Deep Eutectic Solvent (NADES) species can exhibit unexpected solubilizing power for lipophilic molecules despite their simple composition: hydrophilic organic molecules and water. In the present study, the unique properties of NADES species were applied in combination with a model polymer system: a hydrophilic chitosan/alginate hydrogel. Briefly, NADES species (e.g., mannose-dimethylurea-water, 2:5:5, mole/mole) formed matrices to 1) dissolve lipophilic molecules (e.g., curcumin), 2) load lipophilic molecule(s) into the hydrogel, and 3) spontaneously vacate from the system. NADES species ubiquitously occur in natural sources, and a crude extract is a mixture of the NADES species and bioactive metabolites. Based on these ideas, we hypothesized that the crude extract may also allow the loading of natural bioactive molecules from a natural NADES species into (bio)hydrogel systems. To evaluate this hypothesis in vitro, Schisandra chinensis fruit extract was chosen as a representative mixture of lipophilic botanical molecules and hydrophilic NADES species. The results showed that the NADES matrix of S. chinensis was capable of loading at least three bioactive lignans (i.e., gomisin A, gomisin J, and angeloylgomisin H) into the polymer system. The lipophilic metabolites can subsequently be released from the hydrogel. The outcomes suggest that a unique drug delivery mechanism may exist in nature, thereby potentially improving the bioavailability of lipophilic metabolites through physicochemical interactions with the NADES.

The 9th International Countercurrent Chromatography Conference held at Dominican University, Chicago, USA, August 1-3, 2016

The 9th International Countercurrent Chromatography Conference (CCC 2016) was held at Dominican University near Chicago, IL (USA), from August 1st-3rd, 2016. The biennial CCC 20XX conferences provide an opportunity for countercurrent chromatography and centrifugal partition chromatography (CCC/CPC) manufactures, marketers, theorists, and research scientists to gather together socially, learn from each other, and advance countercurrent separation technology. A synopsis of the conference proceedings as well as a series of short reviews of the special edition articles is included in this document. Many productive discussions and collegial conversation at CCC 2016 attested to the liveliness, connectivity, and productivity of the global countercurrent research community and bodes well for the success of the 10th conference at the University of Braunschweig, Germany on August 1-3, 2018.