An experimental study of buckwheat polysaccharide in adjuvant therapy for S180 sarcoma mice.

Introduction: To discuss the auxiliary therapeutic effect of buckwheat polysaccharide (BP) on S180 sarcoma. Material and methods: Buckwheat polysaccharide was extracted with water and precipitated with ethanol. Solid tumor and ascites tumor mice models were established. The mice in the high, medium and low dosing groups (n = 24, each group) had their stomachs filled with different doses of BP. The cyclophosphamide (CTX) group and the model group (n = 24, each group) were used as control groups. The influence on the life cycle, the rate of suppressing the tumor, the thymus index, and the spleen index were evaluated. Tumor cells were cultured in vitro and intervened with drugs; flow cytometry was used to detect the changes in the cell cycle. Results: Buckwheat polysaccharide significantly improved the lifespan and survival rate of the mice. The group of mice treated with the medium dose showed the best survival rate when compared to the ones that received high and low doses of BP (p < 0.01). The tumor cells cultured in vitro were arrested in the G0/G1 phase to some extent (p > 0.05). The cyclophosphamide arrested the cycle of the tumor cells in the G2/M period (p < 0.01). Buckwheat polysaccharide could increase the thymus index, spleen index and the rate of suppressing the tumor, but the differences were not statistically significant. Conclusions: Buckwheat polysaccharide had no obvious effect in inhibiting the growth of tumors, but it significantly extended the lifespan, increased the survival rate and reduced the toxic effect of CTX.

Collagen derived species-specific peptides for distinguishing donkey-hide gelatin (Asini Corii Colla).

Objective: As an important food therapy product with traditional Chinese medicine (TCM) applications, donkey-hide gelatin (Asini Corii Colla, ACC) has been used for thousands of years. However, till now few effective strategy had been proposed to distinguish ACC from other animal hide gelatins, especially closely related horse- and mule-hide gelatins, which was an embarrassment of ACC quality control. Methods: Combined mass spectrometry and bioinformatic methods have been applied to identify and verify two ACC-specific peptides (Pep-1 and Pep-2) capable of distinguishing ACC from other closely related animal gelatins with high selectivity. Results: It confirmed that these two peptides could be not only used for distinguishing ACC from highly homologous horse-hide and mule-hide gelatins as well as other animal hide gelatins. Conclusion: The present study provides a simple method for species-specific peptides discovery, which can be used for assessing the quality of animal gelatin products, and ensure they are authenticable and traceable.

Characterization and gas adsorption of a novel three-dimensional metal-organic framework (MOF) generated from a new polydentate fluorene-bridged ligand.

A polydentate ligand bridged by a fluorene group, namely 9,9-bis(2-hydroxyethyl)-2,7-bis(pyridin-4-yl)fluorene (L), has been prepared under solvothermal conditions in acetonitrile. Crystals of the three-dimensional metal-organic framework (MOF) poly[[[µ3-9,9-bis(2-hydroxyethyl)-2,7-bis(pyridin-4-yl)fluorene-κ3N:N':O]bis(methanol-κO)(µ-sulfato-κ2O:O')nickel(II)] methanol disolvate], {[Ni(SO4)(C27H24N2O2)(CH3OH)]·2CH3OH}n, (I), were obtained by the solvothermal reaction of L and NiSO4 in methanol. The ligand L forms a two-dimensional network in the crystallographic bc plane via two groups of O-H...N hydrogen bonds and neighbouring two-dimensional planes are completely parallel and stack to form a three-dimensional structure. In (I), the NiII ions are linked by sulfate ions through Ni-O bonds to form inorganic chains and these Ni-containing chains are linked into a three-dimensional framework via Ni-O and Ni-N bonds involving the polydentate ligand L. With one of the hydroxy groups of L coordinating to the NiII atom, the torsion angle of the hydroxyethyl group changes from that of the uncoordinated molecule. In addition, the adsorption properties of (I) with carbon dioxide were investigated.

Determination of the n-octanol/water partition coefficients of weakly ionizable basic compounds by reversed-phase high-performance liquid chromatography with neutral model compounds.

A strategy to utilize neutral model compounds for lipophilicity measurement of ionizable basic compounds by reversed-phase high-performance liquid chromatography is proposed in this paper. The applicability of the novel protocol was justified by theoretical derivation. Meanwhile, the linear relationships between logarithm of apparent n-octanol/water partition coefficients (logKow '') and logarithm of retention factors corresponding to the 100% aqueous fraction of mobile phase (logkw ) were established for a basic training set, a neutral training set and a mixed training set of these two. As proved in theory, the good linearity and external validation results indicated that the logKow ''-logkw relationships obtained from a neutral model training set were always reliable regardless of mobile phase pH. Afterwards, the above relationships were adopted to determine the logKow of harmaline, a weakly dissociable alkaloid. As far as we know, this is the first report on experimental logKow data for harmaline (logKow = 2.28 ± 0.08). Introducing neutral compounds into a basic model training set or using neutral model compounds alone is recommended to measure the lipophilicity of weakly ionizable basic compounds especially those with high hydrophobicity for the advantages of more suitable model compound choices and convenient mobile phase pH control.

Buckwheat Rutin Inhibits AngII-induced Cardiomyocyte Hypertrophy via Blockade of CaN-dependent Signal Pathway.

Buckwheat rutin has been found to be able to inhibit angiotensin II (AngII) - induced hypertrophy in cultured neonatal rat cardiomyocytes, but the mechanism remains uncertain. In this study, myocardial hypertrophy model was made by adding AngII to the medium of cardiac myocytes of neonatal rats; meanwhile, different concentrations of buckwheat rutin were applied to observe their effects. Intracellular Ca(2+) level was detected by Hitachi - 850 fluorospectrophotometer, calcineurin (CaN) activity was measured by colorimetric method, the expression of CaN protein was observed with immunocytochemistry, and the proto - oncogene c - fos mRNA expression was assessed with reverse transcription polymerase chain reaction (RT - PCR). Compared with control group, AngII could greatly stimulate the increase of intracellular Ca(2+) level, the activities and protein expression of cardiomyocytes CaN, and the expression of proto - oncogene c - fos mRNA in cultured neonatal rat cardiomyocytes, which could be effectively decreased by buckwheat rutin. Our results demonstrated that buckwheat rutin exhibited inhibitory effect on AngII - induced hypertrophy in cultured neonatal rat cardiomyocytes via Ca(2+) antagonism action thus block the CaN - dependent signal pathway.

Influence of variation in mobile phase pH and solute pK(a) with the change of organic modifier fraction on QSRRs of hydrophobicity and RP-HPLC retention of weakly acidic compounds.

The variation in mobile phase pH and ionizable solute dissociation constant (pK(a)) with the change of organic modifier fraction in hydroorganic mobile phase has seemingly been a troublesome problem in studies and applications of reversed phase high performance liquid chromatography (RP-HPLC). Most of the early studies regarding the RP-HPLC of acid-base compounds have to measure the actual pH of the mixed mobile phase rigorously, sometimes bringing difficulties in the practices of liquid chromatographic separation. In this paper, the effect of this variation on the apparent n-octanol/water partition coefficient (K(ow)″) and the related quantitative structure-retention relationship (QSRR) of logK(ow)″ vs. logk(w), the logarithm of retention factor of analytes in neat aqueous mobile phases, was investigated for weakly acidic compounds. This QSRR is commonly used as a classical method for K(ow) measurement by RP-HPLC. The theoretical and experimental derivation revealed that the variation in mobile phase pH and solute pK(a) will not affect the QSRRs of acidic compounds. This conclusion is proved to be suitable for various types of ion-suppressors, i.e., strong acid (perchloric acid), weak acid (acetic acid) and buffer salt (potassium dihydrogen phosphate/phosphoric acid, PBS). The QSRRs of logK(ow)″ vs. logk(w) were modeled by 11 substituted benzoic acids using different types of ion-suppressors in a binary methanol-water mobile phase to confirm our deduction. Although different types of ion-suppressor all can be used as mobile phase pH modifiers, the QSRR model obtained by using perchloric acid as the ion-suppressor was found to have the best result, and the slightly inferior QSRRs were obtained by using acetic acid or PBS as the ion-suppressor.

Determination of n-octanol/water partition coefficients of weak ionizable solutes by RP-HPLC with neutral model compounds.

The utilization of neutral compounds as model compounds is put forward for determination of the n-octanol/water partition coefficient (K(ow)) of highly hydrophobic, weak acidic compounds by reversed-phase high performance liquid chromatography (RP-HPLC). It is based on a linear relationship between the logarithm of apparent n-octanol/water partition coefficient (log K(ow)″), expressing hydrophobicity of acidic solutes more accurately, and the logarithm of RP-HPLC retention factor of the solutes corresponding to the neat aqueous fraction of mobile phase (log k(w)). The availability of neutral model compounds was theoretically tested for this novel protocol. Moreover, a high consistency of linear log K(ow)″-log k(w) correlations was demonstrated between a mixed training set of neutral and acidic model compounds, and a training set of neutral model compounds. It is proved in theory that for a certain set of compounds investigated, all derived linear relationships between log K(ow)″ and log k(w) have a unit slope and the same intercept, regardless of mobile phase pH. This model was applied to measure log K(ow) of lipophilic aristolochic acid I (AA I) and aristolochic acid II (AA II). Log K(ow) values for AA I and AA II are 4.45±0.07 and 3.99±0.06, respectively. To the best of our knowledge, this is the first report on experimental log K(ow) data for AAs. The proposed strategy solves the problem of lacking suitable acidic model compounds with reliable experimental K(ow) in determining K(ow) of lipophilic acidic solutes by RP-HPLC.

A novel evaluation method for extrapolated retention factor in determination of n-octanol/water partition coefficient of halogenated organic pollutants by reversed-phase high performance liquid chromatography.

The retention factor corresponding to pure water in reversed-phase high performance liquid chromatography (RP-HPLC), k(w), was commonly obtained by extrapolation of retention factor (k) in a mixture of organic modifier and water as mobile phase in tedious experiments. In this paper, a relationship between logk(w) and logk for directly determining k(w) has been proposed for the first time. With a satisfactory validation, the approach was confirmed to enable easy and accurate evaluation of k(w) for compounds in question with similar structure to model compounds. Eight PCB congeners with different degree of chlorination were selected as a training set for modeling the logk(w)-logk correlation on both silica-based C(8) and C(18) stationary phases to evaluate logk(w) of sample compounds including seven PCB, six PBB and eight PBDE congeners. These eight model PCBs were subsequently combined with seven structure-similar benzene derivatives possessing reliable experimental K(ow) values as a whole training set for logK(ow)-logk(w) regressions on the two stationary phases. Consequently, the evaluated logk(w) values of sample compounds were used to determine their logK(ow) by the derived logK(ow)-logk(w) models. The logK(ow) values obtained by these evaluated logk(w) were well comparable with those obtained by experimental-extrapolated logk(w), demonstrating that the proposed method for logk(w) evaluation in this present study could be an effective means in lipophilicity study of environmental contaminants with numerous congeners. As a result, logK(ow) data of many PCBs, PBBs and PBDEs could be offered. These contaminants are considered to widely exist in the environment, but there have been no reliable experimental K(ow) data available yet.

Determination of n-octanol/water partition coefficient for DDT-related compounds by RP-HPLC with a novel dual-point retention time correction.

n-Octanol/water partition coefficients (P) for DDTs and dicofol were determined by reversed-phase high performance liquid chromatography (RP-HPLC) on a C(18) column using methanol-water mixture as mobile phase. A dual-point retention time correction (DP-RTC) was proposed to rectify chromatographic retention time (t(R)) shift resulted from stationary phase aging. Based on this correction, the relationship between logP and logk(w), the logarithm of the retention factor extrapolated to pure water, was investigated for a set of 12 benzene homologues and DDT-related compounds with reliable experimental P as model compounds. A linear regression logP=(1.10±0.04) logk(w) - (0.60±0.17) was established with correlation coefficient R(2) of 0.988, cross-validated correlation coefficient R(cv)(2) of 0.983 and standard deviation (SD) of 0.156. This model was further validated using four verification compounds, naphthalene, biphenyl, 2,2-bis(4-chlorophenyl)-1,1-dichloroethane (p,p'-DDD) and 2,2-bis(4-chlorophenyl)-1,1-dichloroethene (p,p'-DDE) with similar structure to DDT. The RP-HPLC-determined P values showed good consistency with shake-flask (SFM) or slow-stirring (SSM) results, especially for highly hydrophobic compounds with logP in the range of 4-7. Then, the P values for five DDT-related compounds, 2-(2-chlorophenyl)-2-(4-chlorophenyl)-1,1,1-trichloroethane (o,p'-DDT), 2-(2-chlorophenyl)-2-(4-chlorophenyl)-1,1-dichloroethane (o,p'-DDD), 2-(2-chlorophenyl)-2-(4-chlorophenyl)-1,1-dichloroethene (o,p'-DDE), and 2,2,2-trichloro-1,1-bis(4-chlorophenyl)ethanol (dicofol) and its main degradation product 4,4'-dichlorobenzophenone (p,p'-DBP) were evaluated by the improved RP-HPLC method for the first time. The excellent precision with SD less than 0.03 proved that the novel DP-RTC protocol can significantly increases the determination accuracy and reliability of P by RP-HPLC.

The Effects of Total Flavonoids from Buckwheat Flowers and Leaves on Renal Damage and PTP1B Expression in Type 2 Diabetic Rats.

Clinical data showed consumption of buckwheat played a very positive role in the relief of diabetes and its complications. The purpose of this study was to explore the effects and mechanisms of the overall flavonoids from buckwheat flowers and leaves (TFBFL) on renal damage in type 2 diabetes mellitus (T2DM) rats. Seventy male Wistar rats were selected. Ten rats were randomly allocated into a normal group and the other sixty were intragastrically injected with a lipid emulsion and small doses of alloxan to induce the T2DM model. T2DM inducement was judged by the fasting blood glucose (FBG) and oral glucose tolerance test (OGTT). Those whose FBG was ≥ 16.7 mmol/L and less tolerant to glucose were considered as being T2DM rats. These rats were then randomly divided into a groups termed: model (purified water, 5 mL.kg(-1) . d(-1)), BNPL (positive control) (Benazepril, 4 mg.kg(-1) . d(-1)), L-TFBFL (TFBFL 100 mg.kg(-1) . d(-1)), M-TFBFL (TBFL 200 mg.kg(-1) . d(-1)) and H-TFBFL (TFBFL 400 mg.kg(-1) . d(-1)). Each group then received medication for a period of 4 weeks. The normal rats were treated with purified water in a synchronous manner. Subsequently, FBG, plasma insulin (INS), OGTT, 24 h urinary protein output, blood and urinary creatinine content were assayed. Then the insulin sensitive index (ISI), bilateral kidney index, and creatinine clearance rate (Ccr) were calculated. Renal morphological changes and expression of protein tyrosine phosphatase 1B (PTP1B) in the kidneys were observed. TFBFL lowered FBG, improved insulin resistance, caused Ccr, and renal morphological changes, down-regulated the expression of PTP1B in T2DM rats and showed dose-dependence. TFBFL had a significant protective effect on renal damage in T2DM rats. This effect may be due to lowering blood glucose and diminishing renal damage by inhibiting PTP1B expression.

Retention prediction and hydrophobicity estimation of weak acidic compounds by reversed-phase liquid chromatography using acetic and perchloric acids as ion suppressors.

Simple acids are usually applied to suppress the ionization of weakly ionizable acidic analytes in reversed-phase liquid chromatography. The purpose of this study is to investigate the retention behavior of various weak acidic compounds (monoprotic, diprotic, triprotic, and tetraprotic acids) using acetic or perchloric acid as ion suppressor in a binary hydroorganic mobile phase. The apparent n-octanol-water partition coefficient (K(ow)") was proposed to calibrate the n-octanol-water partition coefficient (K(ow)) of weak acidic compound. LogK(ow)" was found to have a better linear correlation with logk(w), the logarithm of the retention factor obtained by extrapolating to neat aqueous fraction of the mobile phase, for all weakly ionizable acidic compounds. This straightforward relationship offers a potential medium for direct measurement of K(ow) data of weak acidic analytes and can be used to predict retention behavior of these compounds in the ion suppression reversed-phase liquid chromatographic mode.

Chromatographic retention prediction and octanol-water partition coefficient determination of monobasic weak acidic compounds in ion-suppression reversed-phase liquid chromatography using acids as ion-suppressors.

Although simple acids, replacing buffers, have been widely applied to suppress the ionization of weakly ionizable acidic analytes in reversed-phase liquid chromatography (RPLC), none of the previously reported works focused on the systematic studies about the retention behavior of the acidic solutes in this ion-suppression RPLC mode. The subject of this paper was therefore to investigate the retention behavior of monobasic weak acidic compounds using acetic, perchloric and phosphoric acids as the ion-suppressors. The apparent octanol-water partition coefficient (K" ow) was proposed to calibrate the octanol-water partition coefficient (K(ow)) of these weak acidic compounds, which resulted in a better linear correlation with log k(w), the logarithm of the hypothetical retention factor corresponding to neat aqueous fraction of hydroorganic mobile phase. This log K" ow-log k w linear correlation was successfully validated by the results of monocarboxylic acids and monohydrating phenols, and moreover by the results under diverse experimental conditions for the same solutes. This straightforward relationship not only can be used to effectively predict the retention values of weak acidic solutes combined with Snyder-Soczewinski equation, but also can offer a promising medium for directly measuring K(ow) data of these compounds via Collander equation. In addition, the influence of the different ion-suppressors on the retention of weak acidic compounds was also compared in this RPLC mode.