Highly Crystalline Covalent Organic Frameworks Act as a Dual-Functional Fluorescent-Sensing Platform for Myricetin and Water, and Adsorbents for Myricetin.

Selective detection of active ingredients in complex samples has always been a crucial challenge because there are many disturbing compounds, especially structural analogues that interfere with the detection. In this work, a fluorescent covalent organic framework (named COF-TD), which can be used for the selective fluorescence detection and enrichment of myricetin from complex samples, was reported for the first time. The highly crystalline COF-TD with bright blue fluorescence was formed through a solution polymerization method by the condensation reaction between 4,4',4″-(1,3,5-triazine-2,4,6-triyl)trianiline and 2,5-dihydroxy-1,4-benzenedicarboxaldehyde. Due to spatial size selectivity, multisites hydrogen bonding, and π-π interaction, myricetin can quench the fluorescence of COF-TD with an inner filter effect (IFE) and static quenching mechanisms as well as can be enriched on COF-TD. Myricetin can observably eliminate the interference of other compounds and selectively quench the fluorescence of COF-TD with a limit of detection (LOD) of 0.30 µg·mL-1. The high adsorption ability of COF-TD (Q = 124.6 mg·g-1) to myricetin was also obtained. Finally, a sensing platform based on COF-TD for myricetin was successfully developed and applied for the detection of myricetin from vine teas. In addition, COF-TD also showed good water sensing ability and could be used effectively to detect water content in organic solvent (1-18% water in acetone, 0.5-5% water in acetonitrile, 1-4.5% water in ethyl acetate, v/v). To the best of our knowledge, this is the first report where COF-TD was used to detect water in a relatively wide concentration range. In all, this work provided dual-functional fluorescent COFs with the properties of an adsorbent, opening up new methodologies for the simple, selective, and enrichment detection method for myricetin.

Extraction and determination of bioactive flavonoids from Abelmoschus manihot (Linn.) Medicus flowers using deep eutectic solvents coupled with high-performance liquid chromatography.

A highly efficient and ecofriendly extraction method using deep eutectic solvents was developed to extract bioactive flavonoids from Abelmoschus manihot (Linn.) Medicus flowers. First, a series of deep eutectic solvents using choline chloride as hydrogen bond acceptor with different hydrogen bond donors was successfully synthesized. Then, the types of deep eutectic solvents and the extraction conditions for bioactive flavonoids (hyperoside, isoquercitrin, and myricetin) were optimized based on the flavonoids extraction efficiencies. The optimized deep eutectic solvent for hyperoside and isoquercitrin extraction was composed of choline chloride and acetic acid with a molar ratio of 1:2. The optimized deep eutectic solvent for myricetin extraction was composed of one mole of choline chloride and two moles of methacrylic acid. The optimal extraction conditions were set as: solid to solvent ratio, 35:1 (mg/mL); extraction time, 30 min; extraction temperature, 30°C. Qualitative and quantitative analysis were performed using ultra high performance liquid chromatography with tandem mass spectrometry and high-performance liquid chromatography. And the extraction efficiencies of hyperoside, isoquercitrin, and myricetin under optimal extraction conditions were calculated as 11.57, 5.64, and 1.11 mg/g, much higher than those extracted by traditional extraction solvents. Therefore, the prepared deep eutectic solvents can be selected as alternative solvent to extract bioactive flavonoids.

Novel dual functional monomers based molecularly imprinted polymers for selective extraction of myricetin from herbal medicines.

Herein, novel dual functional monomers based molecularly imprinted polymers (MIPs) were successfully prepared and used to extract myricetin from Carthamus tinctorius L., also named safflower (family, Compositae) and the flower of Abelmoschus manihot (Linn.) Medicus (family, Malvaceae). The polymers were prepared using myricetin as template, 4-vinylpyridine (4-VP) and glycidyl methacrylate (GMA) as dual functional monomers, ethylene glycol dimethyl acrylate (EGDMA) as cross-linker and methanol-acetonitrile (1:2, v/v) as solvent, respectively. Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) were applied to characterize the polymers. Further, the adsorption and selectivity experiments of MIPs were evaluated. The results revealed that MIPs showed high adsorption ability and selectivity toward myricetin. Finally, MIPs were employed as adsorbents for solid phase extraction (SPE) of myricetin from safflower and the flowers of A. manihot (Linn.) Medicus. Further analysis was conducted by using high performance liquid chromatography-diode array detection (HPLC-DAD). The recovery of mrricetin in safflower and in the flowers of A. manihot ranged from 79.82% to 83.91%, 81.50% to 84.32%, respectively. These results indicated that MIPs can be applied to the extraction and separation of myricetin from various complex matrixes.

Preparation and evaluation of a reversed-phase/hydrophilic interaction/ion-exchange mixed-mode chromatographic stationary phase functionalized with dopamine-based dendrimers.

In this work, a novel dendritic stationary phase was synthesized by the repeated grafting of 1,4-butanediol diglycidyl ether (BDDE) and dopamine (DA) on the surface of silica for performing mixed-mode high-performance liquid chromatography (MHPLC). Elemental analysis (EA), thermogravimetric analysis (TGA) and Fourier transform infrared spectrometry (FT-IR) showed the successful preparation of the dendritic stationary phase. The prepared stationary phase showed the retention mechanisms of reversed-phase liquid chromatography (RPLC), hydrophilic interaction chromatography (HILIC) and ion-exchange chromatography (IEC) under different mobile phase conditions. In detail, alkylbenzenes, polycyclic aromatic hydrocarbons (PAHs) and hydrophobic positional isomers were separated successfully in the RPLC mode. The baseline separation of nucleobases, nucleosides and flavonoids was achieved under HILIC mode, respectively. Meanwhile, some acidic and basic analytes were used to evaluate the IEC mode. The effects of different chromatographic conditions, such as acetonitrile content, salt concentration and pH in the mobile phase, on the different chromatographic modes were also investigated. In addition, the application of the mixed-mode dendritic stationary phase was demonstrated by the analysis of traditional Chinese medicine (TCM), including Carthamus tinctorius L. and Abelmoschus manihot (Linn.) Medicus. Interestingly, the stationary phase also has the ability for the capture and separation of boric acids. These meaningful applications confirmed that the mixed-mode dendritic stationary phase can be potentially applied in the analysis of complex samples.

Characterization of active antiplatelet chemical compositions of edible Citrus limon through ultra-performance liquid chromatography single quadrupole mass spectrometry-based chemometrics.

Citrus limon L. (lemon, family: Rutaceae) is the third most popular edible fruit among the Citrus species. Our previous study has shown the significant antiplatelet activity of lemon extracts. The aim of the present study is to identify the features (retention time, m/z) associated with the antiplatelet activity of lemons by correlating a platelet aggregation assay with ultra-performance liquid chromatography single quadrupole mass spectrometry-based chemometrics analysis. The primary bioactivity-guided test results revealed that the butanol (BA) and ethyl acetate (EA) liquid-liquid extraction sections of the ethanol extract of lemons had significant inhibitory effects on platelet aggregation. Upon further separating the combined BA and EA sections with a silica column, four different active fractions were obtained, and their LC-MS data were collected. After modeling by two multivariate statistical techniques, namely, principal component analysis and orthogonal partial least squares discriminate analysis seven markers were predicted, identified, and tentatively classified as priority markers of bioactivity in lemons. Among them, the antiplatelet activity of four marker compounds, namely, oxypeucedanin hydrate, citric acid, diosmin, and limetin at concentrations lower than 300 µM was confirmed. Moreover, the specific mechanism of limetin interaction with the TP ß receptor of thromboxane A2 and the effect of limetin on the PI3 K/Rap-1b signaling pathway through the ßγ subunit of GPCR (i) in platelet aggregation were studied by differential proteomic analysis to illustrate the validity and persistence of these markers for application in lemon fruit platforms.

Comparing coagulation activity of Selaginella tamariscina before and after stir-frying process and determining the possible active constituents based on compositional variation.

CONTEXT: Selaginella tamariscina (P. Beauv.) Spring (Selaginellaceae) (ST) has been widely used in China as a medicine for improving blood circulation. However, its processed product, S. tamariscina carbonisatus (STC), possesses opposite haemostatic activity. OBJECTIVE: To comprehensively evaluate the activity of ST and STC on physiological coagulation system of rats, and seek potential active substances accounting for the activity transformation of ST during processing. MATERIALS AND METHODS: The 75% methanol extracts of the whole grass (fine powder) of ST and STC were prepared, respectively. Male Sprague-Dawley rats were randomly divided into five groups: control group, model group, model + ST group, model + STC group and positive control group (model + Yunnanbaiyao). The duration of intragastric administration was 72 h at 12 h intervals. Haemorheology parameters were measured using an LB-2 A cone-plate viscometer and the existed classic methods, respectively. SC40 semi-automatic coagulation analyzer was employed to determine coagulation indices. Meanwhile, HPLC and LC-MS were applied for chemical analyses of ST and STC extracts. RESULTS: STC shortened tail-bleeding time, increased whole blood viscosity (WBV) and plasma viscosity (PV), decreased erythrocyte sedimentation rate blood (ESR), reduced activated partial thromboplastin time (APTT) and increased the fibrinogen (FIB) content in the plasma of bleeding model rats. Although ST could shorten APTT and TT, the FIB content was significantly decreased by ST. Dihydrocaffeic acid with increased content in STC vs. ST showed haemostatic activity for promoting the platelet aggregation induced by collagen and trap-6, and reducing APTT and PT significantly with a concentration of 171.7 µM in vitro. Amentoflavone with reduced content in STC vs. ST inhibited ADP and AA-induced platelet aggregation significantly with a concentration of 40.7 µM. DISCUSSION AND CONCLUSIONS: As the processed product of ST, STC showed strong haemostatic activity on bleeding rat through regulating the parameters involved in haemorheology and plasma coagulation system. Two active compounds, dihydrocaffeic acid and amentoflavone, might be partially responsible for the haemostatic and anticoagulant activity of STC and ST, respectively.

Molecularly imprinted polymers for the selective extraction of tiliroside from the flowers of Edgeworthia gardneri (wall.) Meisn.

Nano-sized molecularly imprinted polymers for tiliroside were successfully prepared by a precipitation polymerization method. Acrylamide, ethylene glycol dimethacrylate, azobisisobutyronitrile, and acetonitrile/dimethyl sulfoxide were used as functional monomer, cross-linker, initiator, and porogen, respectively. The structural features and morphological characterization of tiliroside-imprinted polymers were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy, respectively. The adsorption experiments indicated that the tiliroside-imprinted polymers exhibited high selective recognition property to tiliroside. Scatchard analysis indicated that the homogeneous-binding sites were formed in the polymers. The selectivity test revealed that the adsorption capacity and selectivity of polymers to tiliroside was significantly higher than that of rutin, astragalin, and kaempferol. Finally, the tiliroside-imprinted polymers were employed as adsorbents in solid-phase extraction for the extraction of tiliroside from the ethyl acetate extract of the flowers of Edgeworthia gardneri (wall.) Meisn. The results demonstrated that the extraction recoveries of tiliroside ranged from 69.3 to 73.5% by using tiliroside-imprinted polymers coupled with solid-phase extraction method. These results indicated that the tiliroside-based molecularly imprinted solid-phase extraction method was proven to be an effective technique for the separation and enrichment of tiliroside from natural medicines.

The flower of Edgeworthia gardneri (wall.) Meisn. suppresses adipogenesis through modulation of the AMPK pathway in 3T3-L1 adipocytes.

ETHNOPHARMACOLOGICAL RELEVANCE: The flower of Edgeworthia gardneri (Wall.) Meisn., locally named "Lvluohua, ", has been widely used as Tibetan folk medicine for the treatment of metabolic diseases for a long time. AIM OF THIS STUDY: To evaluate the anti-adipogenesis effect of ethyl acetate extract of the flower of E. gardneri (EEG extract) in 3T3-L1 adipocytes. MATERIALS AND METHODS: Obesity-related parameters such as lipid accumulation and TG content were determined by Oil red O staining and enzymatic kit, respectively. Western blotting was used to determine the expressions of peroxisome proliferator-activated receptor γ (PPARγ), CCAAT/enhancer-binding protein-α (C/EBPα), phosphorylated adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC). Moreover, main constituents of EEG extract were analyzed by high performance liquid chromatography (HPLC). RESULTS: EEG extract decreased the lipid and triglyceride (TG) accumulations during the differentiation process and down-regulated the adipogenesis-related transcriptional factors PPARγ and C/EBPα. EEG extract treatment increased AMPK and ACC phosphorylation. In addition, pretreatment with AMPK inhibitor, weakened the inhibitory effects of EEG extract on the expressions of PPARγand C/EBPα. HPLC analysis indicated that tiliroside was the main constituent in EEG extract. CONCLUSIONS: These results suggest that EEG extract may exert anti-adipogenic effects through modulation of the AMPK signaling pathway.

In vitro Screening and Evaluation of 37 Traditional Chinese Medicines for Their Potential to Activate Peroxisome Proliferator-Activated Receptors-γ.

BACKGROUND: Peroxisome proliferator-activated receptors (PPAR)-γ is widely used as an attractive target for the treatment of type 2 diabetes mellitus. Thiazolidinediones, the agonists of PPARγ, has been popularly utilized as insulin sensitizers in the therapy of type 2 diabetes whereas numerous severe side-effects may also occur concomitantly. OBJECTIVE: The PPARγ activation activity of different polar extracts, including petroleum ether, ethyl acetate, n-butanol, residual of ethanol, the precipitate part of water and the supernatant of water extracts, from 37 traditional Chinese medicines were systematically evaluated. MATERIALS AND METHODS: HeLa cells were transiently co-transfected with the re-constructed plasmids of GAL4-PPARγ-ligand binding domain and pGL4.35. The activation of PPARγ by different polarity extracts were evaluated based on the PPARγ transactivation assay and rosiglitazone was used as positive control. RESULTS: Seven medicines (root bark of Lycium barbarum, Anoectochilus sroxburghii, the rhizome of Phragmites australis, Pterocephalus hookeri, Polygonatum sibiricum, fruit of Gleditsia sinensis, and Epimedium brevicornu) were able to significantly activate PPARγ. CONCLUSION: As seven medicines were able to activate PPARγ, the anti-diabetic activity of them is likely to be mediated by this nuclear receptor. SUMMARY: Lots of the tested medicinal products had activation effects on activating PPARγEthyl acetate extracts of root bark of L.barbarum, rhizome of P.saustralis and fruit of G.siasinensis showed good PPARγ activation effect similar or higher than that of positive control, 0.5 µg/mL rosiglitazonePetroleum ether extracts of A.roxburghii, P. hookeri, P. sibiricum, E.brevicornu also can significantly activate PPARγ, the effects of them were higher than t0.5 µg/mL rosiglitazoneSchisandra chinensis (Turcz.) Baill., the fruit Cornus officinalis Siebold and Zucc., Alisma plantago-aquatica L. and the root of Trichosanthes Kirilowii Maxim., traditional anti-diabetic mediciness in China, had no effects on the activation of PPARγ. Abbreviations used: PPARγ: Peroxisome Proliferator-activated Receptors-γ, TCMs: Traditional Chinese medicines, TZDs: Thiazolidinediones, LBD: Ligand binding domain, DMSO: Dimethyl sulfoxide, FBS: Fetal bovine serum, DMEM: Dulbecco's modified Eagle's medium.

In vitro evaluation of dual agonists for PPARγ/ß from the flower of Edgeworthia gardneri (wall.) Meisn.

ETHNOPHARMACOLOGICAL RELEVANCE: In Tibet, the flower of Edgeworthia gardneri (Wall.) Meisn., locally named "Lvluohua, [symbols: see text]", has been traditionally used to treat diabetes mellitus for many years. AIM OF THIS STUDY: To evaluate the activity of dual agonists for PPARγ/ß from the flower of E.gardneri in vitro. MATERIALS AND METHODS: HeLa cells were transiently co-transfected with the re-constructed plasmids of pBIND-PPARγ-LBD or pBIND-PPARß-LBD and rL4.35. The activities of crude extracts, secondary fractions and compounds from the flower of E.gardneri were evaluated with the transfected cells. Rosiglitazone (at 0.5 µg/mL) and L-165041 (at 0.5 µg/mL) were used as the positive controls for PPARγ and PPARß respectively. RESULTS: The results demonstrated that n-hexane, ethyl acetate and n-butanol extracts from the flower of E.gardneri were able to significantly activate PPARγ and PPARß respectively, and the activity of ethyl acetate extract was much better. We further observed that, among the 11 secondary fractions of ethyl acetate extract, the fr. 9 could activate PPARγ and PPARß significantly. Moreover, umbelliferone (from fr.9) and pentadecanoic acid could activate PPARγ and PPARß at the same time. CONCLUSIONS: The extracts from the flower of E.gardneri could significantly activate PPARγ and PPARß. Besides, umbelliferone and pentadecanoic acid isolated from the flower of E.gardneri were the new agonists for PPARγ and PPARß.