Isothermal microcalorimetric investigation of the toxic action of the effective constituents of Podophyllum emodi Wall on Tetrahymena thermophila BF5

The effects of podophyllotoxin (PPT), etoposide (VP16), and teniposide (VM26) on the growth of Tetrahymena thermophila BF₅ (T.t.BF₅) was investigated by the TAM AIR isothermal microcalorimetric system. The extent and duration of toxic effects on T.t.BF₅ metabolism were evaluated by studying the growth rate constant (k), inhibitory ratio (I), maximum heat-output power (P _max), peak time of maximum heat-output power (t _p), and total heat production (Q _t). Experimental results showed that the value of t _p increased and the value of k and P _max decreased with the increasing compound concentrations. Furthermore, the growth rate constant k was linear with compound concentration. The corresponding I was obtained from different k values. According to the IC₁₀ (the concentration of inhibitor when the inhibitory ratio is 10 %), the relative toxicity of the three compounds was PPT (IC₁₀ = 49.6 μg mL^?1) > VP16 (IC₁₀ = 117.5 μg mL^?1) > VM26 (IC₁₀ = 359.1 μg mL^?1). The preliminary investigation of structure–activity relationships showed that the thienyl group was likely responsible for reducing the toxicity of the compounds.     

Influences of levofloxacin salts on the metabolism of Escherichia coli by microcalorimetry

A microcalorimetric technique was used to evaluate the influence of both Levofloxacin lactate in sodium chloride injection (drug A) and Levofloxacin hydrochloride in sodium chloride injection (drug B) on the metabolism of Escherichia coli. By means of an isothermal calorimeter and ampoule method at 37 °C, the power-time curves of E. coli growth were obtained under different conditions. The parameters such as the growth rate constant k, maximum power output P _m, time t _m corresponding to the maximum power output and inhibitory ratio I of these two drugs were obtained. The results reveal that the inhibitory abilities enhance with increasing concentrations of the two drugs. The critical growth concentration and the half-inhibitory concentration IC₅₀ were 0.15 and 0.079 μg mL^?1 (for drug A), 0.13 and 0.061 μg mL^?1 (for drug B), respectively. These results show the drug A has slightly better inhibitory effect on E. coli than that of drug B.     

Chemical composition and antibacterial activity of Tussilago farfara (L.) essential oil from Quebec,Canada

Abstract

The chemical composition of Tussilago farfara L. essential oil from the Saguenay-Lac-St-Jean region of Quebec, Canada was analyzed by gas chromatography–flame ionisation detector (GC-FID) and gas chromatography–mass spectrometry (GC-MS), and the antibacterial activity of the oil was tested against Escherichia coli and Staphylococcus aureus. Forty-five (45) compounds were identified from the GC profile. The main components were 1-nonene (40.1%), α-phellandrene (26.0%) and ρ-cymene (6.6%). The essential oil demonstrated antibacterial activity against E. coli (MIC₅₀ = 468 µg·mL^?1; MIC₉₀ = 6869 µg·mL^?1) and S. aureus (MIC₅₀ = 368 µg·mL^?1; MIC₉₀ = 773 µg·mL^?1). Dodecanoic acid was found to be active against both bacteria having a MIC₅₀ and MIC₉₀ of 16.4 µg·mL^?1 and 95 µg·mL^?1, respectively for E. coli and a MIC₅₀ and MIC₉₀ of 9.8 µg·mL^?1 and 27.3 µg·mL^?1, respectively for S. aureus. In addition, 1-decene and (E)-cyclodecene were also found to be active against E. coli.     

Microcalorimetric Study on Effect of Chromium(III) and Chromium(VI) Species on the Growth of Escherichia coli

The effects of Cr(III) and Cr(VI) species (Cr₂O₇^2?, CrO₄^2? and Cr³⁺) on the growth of Escherichia coli (E. coli) have been investigated in detail by microcalorimetry at 37 °C. Parameters including the growth rate constant (k), inhibitory ratio (I), half‐inhibitory concentration (IC₅₀), total heat output (Q_total), time of the maximum heat production (t_log) in the log phase have been obtained. The results showed that Cr(VI) and Cr(III) had the inhibition effect on the growth of E. coli in aquatic environment; however, the inhibitory ratio of Cr(III) to E. coli was smaller than that of Cr(VI). The k values of E. coli in the presence of Cr(VI) and at high concentrations of Cr(III) were decreased with increasing the concentrations of these chromium species. Among the three chromium species investigated, Cr₂O₇^2? was found to be the most poisonous species against E. coli with an IC₅₀ value of 35.52 µg·mL^?1. CrO₄^2? exhibited moderate toxicity on E. coli with an IC₅₀ of 50.24 µg·mL^?1, and Cr³⁺ had the lowest toxicity with an IC₅₀ of 84.30 µg·mL^?1. Microcalorimetry can provide a convenient, sensitive and reliable method to study the effect of various metal species on the growth of bacteria or other microorganisms.     

Microcalorimetry coupled with principal component analysis for comparing the effects of two Panax species on mice splenic lymphocytes

A powerful microcalorimetric method based on the cell heat production was applied to evaluate the effects of two Panax species on mice splenic lymphocytes growth. Some qualitative and quantitative information, such as the metabolic power-time curves, growth rate constant k, maximum heat-output power P _max, appearance time for the highest peak t _max, total heat production Q _t for all the metabolic progress of mice splenic lymphocytes were obtained to present the effects of Panax ginseng and American Ginseng on these cells. Coupled with principal component analysis (PCA) on these quantitative thermokinetic parameters, the effects of the two Panax species on mice splenic lymphocytes could be quickly evaluated by analyzing the change of the main parameter k. From the values of k, it could be concluded quickly and accurately that Panax ginseng and American Ginseng both showed strong inhibitory effects on mice splenic lymphocytes, and the inhibitory effects was strengthened with increasing concentration of the two Panax species in the concentration range of 0–3.2 mg mL^?1. Panax ginseng with IC ₅₀ of 1.38 mg mL^?1 showed stronger inhibitory effect on mice splenic lymphocytes growth than American Ginseng with IC ₅₀ of 2.08 mg mL^?1. This study indicates that microcalorimetry is a powerful tool for evaluating the drugs’ efficiency on living system, providing some useful references for the application of Panax ginseng and American Ginseng in practice.     

The effect of zinc(II) on the growth of <Emphasis Type="Italic">E . coli</Emphasis> studied by microcalorimetry

By using an LKB2277 Bioactivity Monitor, stop-flow mode, the power-time curves of E . coli at 37°C effected by zinc(II) were determined. Some parameters, such as growth rate constants k, inhibitory ratio I, the maximum heat production rate P _max heat output Q and the time in the maximum heat production t _max were obtained. According these parameters, we found that a low concentration of zinc(II) had a promoting action on the growth of E. coli, but a high concentration of zinc(II) had an inhibitory action. The toxicity of zinc(II) can also be expressed as half inhibitory concentration IC ₅₀ of zinc(II), i.e., 50% effective in this inhibition. The value of IC ₅₀ of zinc(II) on E. coliis 28.09 µg mL^-1. The assay is quantitative, inexpensive and versatile.     

Determination of Nateglinide in Human Plasma by LC-ESI-MS and Its Application to Bioequivalence Study

To evaluate the bioequivalence of nateglinide, a rapid and specific liquid chromatographic-electrospray ionization mass spectrometric method was developed and validated to determine nateglinide for human plasma samples. The analyte was detected using electrospray positive ionization mass spectrometry in the selected ion monitoring mode. Tinidazole was used as the internal standard. A good linear relationship obtained in the concentration ranged from 0.05 to 16 μg mL^?1 (r ² = 0.9993). Lower limit of quantification was 0.05 μg mL^?1 using 100 μL of plasma sample. Intra- and inter-day relative standard deviations were 2.1–7.5 and 4.7–8.9%, respectively. Among the pharmacokinetic data obtained, T _max was 2.09 ± 1.06 h for reference formulation and 2.40 ± 0.97 h for test formulation. C _max was 4.17 ± 1.31 μg mL^?1 for reference formulation and 4.37 ± 1.53 μg mL^?1 for test formulation. The half-life (t _½) was 1.93 ± 0.44 h for reference formulation and 1.92 ± 0.29 h for test formulation. AUC_0–10h was 13.67 ± 4.36 μg h mL^?1 for reference formulation and 13.21 ± 4.09 μg h mL^?1 for test formulation. This method was successfully applied to the pharmacokinetic study in human plasma samples.     

LC–MS Determination and Pharmacokinetic Study of Salidroside in Rat Plasma after Oral Administration of Traditional Chinese Medicinal Preparation Rhodiola crenulata Extract

A simple, rapid and sensitive liquid chromatography–mass spectrometry (LC–MS) method was developed for the quantification of salidroside in rat plasma and the study of its pharmacokinetics after oral administration of 15 g kg^?1 Rhodiola crenulata extract to Wistar rats. A 200 μL plasma sample was extracted by acetonitrile and performed on Kromasil C₁₈ column (150 mm × 4.6 mm, 5 μm) with the mobile phase of acetonitrile–water (11:89) within a run time of 8 min. The analyte was monitored with electrospray ionization (ESI) by selected ion monitoring (SIM) mode. The target ions were m/z 299.20 for salidroside and m/z 150.00 for internal standard (IS) paracetamol. A good linear relationship was obtained over the range of 100–20,000 ng mL^?1 and the lower limit of quantification was 100 ng mL^?1. The validated method was successfully applied for the pharmacokinetic study of salidroside in rat. After oral administration of Rhodiola crenulata extract, the main pharmacokinetic parameters T _max, T _1/2, C _max, AUC _0?t and AUC _0?∞ were 0.56 ± 0.21 h, 7.91 ± 4.42 h, 3,386 ± 2,138 ng mL^?1, 16,146 ± 6,558 ng h mL^?1 and 18,599 ± 6,529 ng h mL^?1, respectively.     

Synthesis,antifungal and insecticidal activity of novel [1,2,4]triazolo[4,3-<Emphasis Type="Italic">a</Emphasis>]pyridine derivatives containing a sulfide substructure

A series of [1,2,4]triazolo[4,3-a]pyridine derivatives bearing a sulfide substructure was designed, synthesized and characterized via ¹H·NMR, ¹³C·NMR, IR and elemental analyses. Bioassay Results indicated some of the derivatives displayed good fungicidal activity on Rhizoctonia cerealis, moderated insecticidal activity against Plutella xylostella and good insecticidal activity on Helicoverpa armigera. The inhibitory effects of compounds 4g and 4u against Rhizotonia cerealis were 70.9% at 50 μg mL^?1; the IC₅₀ values of compounds 4d and 4s against Plutella xylostella were 43.87 and 50.75 μg mL^?1, respectively. And the IC₅₀ values of compounds 4d, 4q, and 4s on Helicoverpa armigera were 58.3, 77.14 and 65.31 μg mL^?1, respectively, which were better than that of commercial chlorpyrifos (103.77 μg mL^?1).     

Anti-bacterial effect of four extracts from leaves of Dracontomelon dao on Escherichia coli growth using microcalorimetry coupled with principal component analysis

The anti-Escherichia coli activities of four extracts in leaves of Dracontomelon dao, a traditional folk herb in China were investigated and compared by microcalorimetry. The four extracts are PE fraction, CHCl₃ fraction, EtOAc fraction, and n-BuOH fraction. The heat flow power–time (HFP–time) curves of E. coli growth in the presence of the four extracts were measured using an ampoule method. Then the nine thermal kinetic parameters were obtained from the curves. From the result of principal component analysis, it can be seen that parameters k ₁, k ₂, P ₁, and Q _p2 might be the main parameters in evaluating the anti-E. coli effects. In the presence of CHCl₃ fraction, EtOAc fraction, and n-BuOH fraction, k ₂, Q _p2 of E. coli decreased with increasing concentrations of the extracts. The EtOAc fraction was observed to have the strongest anti-bacterial activity with half-inhibitory concentration IC50 of 98.5 μg mL^?1. So, it can be concluded that EtOAc fraction can be further developed as anti-bacterial bioactive fraction of leaves of Dracontomelon dao.     

Antimicrobial substances from the rare actinomycete Nonomuraea rhodomycinica NR4-ASC07T

Nonomuraea rhodomycinica NR4-ASC07^T is a rare actinomycete isolated from soil in Sirindhorn peat swamp forest. The crude extract of its culture broth exhibited antimicrobial and anticancer against diverse human pathogens and cancer cells. The chemical investigation of the crude extract led to the isolation of two new metabolites named nonomuric acid (1) and 3-hydroxy deoxydaunorubicinol aglycone (2), along with two known bioactive compounds [ε-rhodomycinone (3) and 7-deoxy-13-dihydrocarminomycinone (4)]. Compounds 1 and 3 showed antimalarial activity with the half maximal inhibitory concentration (IC₅₀) of 8.00 and 8.88 μg mL^?1, respectively. Compound 4 inhibited growth of Mycobacterium tuberculosis and Bacillus cereus at the minimum inhibitory concentrations of 50.0 and 12.50 μg mL^?1, respectively. Every compound exhibited cytotoxicity against cancer cells tested at IC₅₀ ≥ 6.34 μg mL^?1. These finding are the first report of bioactive metabolites produced by strain NR4-ASC07^T, suggesting that rare actinomycetes are yet promising sources for novel drug discovery.     

Voltammetric Determination of Rosiglitazone in Pharmaceutical Preparations and Human Plasma

Abstract

The voltammetric behavior of rosiglitazone was studied using direct current (DC_t), differential pulse (DPP), and alternating current (AC_t) polarography. The drug manifests cathodic waves over a pH range of 2–11.2. In Britton‐Robinson buffer (BRb; pH 4), the diffusion current–concentration relationship was found to be rectilinear over a range of 4–24 µg · mL^?1 and 0.1–16 µg · mL^?1 using DC_t and DPP modes, respectively, with minimum limits of detection (LOD) of 0.15 µg · mL^?1 and 0.07 µg · mL^?1 using the DC_t and DDP modes, respectively. The diffusion‐current constant (I _d) was 6.63±0.03 (n=5). The proposed method was successfully applied to the determination of the studied compound both in pure form and in formulations. The mean percentage recoveries in tablets were 100.09±1.18 and 100.85±0.88 (n=5) using DC_t and DPP modes, respectively. Furthermore, the proposed method, adopting the DPP mode, was applied to the determination of rosiglitazone in spiked human plasma and the obtained mean percentage recoveries were 99.14±3.29 (n=4).     

Antimicrobial and antiparasitic activities of three algae from the northwest coast of Algeria

The objective of this study was to investigate the biological activities of Algerian algae, Sargassum vulgare, Cladostephus hirsutus and Rissoella verruculosa. Antimicrobial activity of the crude extracts and their fractions was assessed using the disc diffusion assay, the minimum inhibitory concentration and the minimum bactericidal concentration. Antiparasitic activity was studied in vitro against the blood stream forms of Trypanosoma brucei brucei and the intraerythrocytic stages of Plasmodium falciparum. Ethyl acetate (EA) fractions of the three tested algae showed more potent antimicrobial activity against S. aureus (7–14.5 mm) and B. cereus (7–10.75 mm), MIC values ranged from 0.9375 to 7.5 mg mL^?1 and MBC values > 15 mg mL^?1. Concerning the antiparasitic activity, EA factions of S. vulgare (IC₅₀ = 9.3 μg mL^?1) and R. verruculosa (IC₅₀ = 11.0 μg mL^?1) were found to be more effective against T. brucei brucei, whereas the three EA fractions were little active against P. falciparum.     

LC Determination and Bioequivalence Study of Pantoprazole in Human Plasma

A selective and sensitive liquid chromatography (LC) method with rapid sample processing was developed for determination of pantoprazole in human plasma using omeprazole as internal standard (IS). The plasma sample (100 μL) was deproteined by precipitation with methanol. The supernatant was directly determined by LC using a Diamonsil C₁₈ ODS column and solution of 10 mM Na₂HPO₄ buffer (containing 0.01% H₃PO₄) and acetonitrile (68:32, v/v, pH = 6.8) as mobile phase with UV detector set at 288 nm. The retention time of IS and pantoprazole were 4.9 ± 0.2 and 5.6 ± 0.2 min, respectively. The method was validated with a linear range of 0.03–5.0 μg mL^?1 and the lowest limit of quantification was 0.03 μg mL^?1 for pantoprazole (r = 0.9999). The coefficient of variation for intra-day and inter-day accuracy and precision was less than 9.5%. The mean extraction recovery was 84.1%. Quality control samples were stable when kept at autosampler temperature for 24 h, at ?20 °C for 42 days and after three freeze-thaw cycles. The assay was successfully applied to a randomized, two-period cross-over bioequivalence study in 20 healthy Chinese volunteers following a single oral dose of 40 mg pantoprazole. Various pharmacokinetic parameters including AUC _0～t , AUC _0～∞, C _max, T _max and t _1/2 were determined from plasma concentration of both formulations. The results indicated that the analytical method was a specific, precise, sensitive and rapid procedure for determination of plasma pantoprazole concentration and therefore, a suitable and valuable tool in the investigation of the clinical pharmacokinetics and bioequivalence.     

Effect of bioclimatic area on the composition and bioactivity of Tunisian Rosmarinus officinalis essential oils

The chemical composition of eight Tunisian Rosmarinus officinalis L. populations (A–H) from different bioclimatic areas has been examined by gas chromatography (GC) and GC-mass spectrometry. The essential oils are characterised by high amounts of oxygenated monoterpenes (58.2–71.7%) followed by monoterpene hydrocabons (15.1–26.7%). 1,8-Cineole, camphor, α-pinene and borneol are the main representative components. The antioxidant activity was investigated by 2,2-diphenyl-1-picrylhydrazyl radical (DPPH), ferric reducing ability power assay and β-carotene bleaching test. Samples showed antiradical activity by inhibiting DPPH radical with IC₅₀ values ranging from 375.3 to 592.8 μg mL^? 1 for samples F and A, respectively. Sample A also showed the most promising activity in β-carotene bleaching test (IC₅₀ of 31.9 μg mL^? 1). The essential oils were also screened for acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activity. Sample G showed the highest activity against AChE (IC₅₀ of 64.7 μg mL^? 1) while sample D (IC₅₀ of 29.5 μg mL^? 1) exhibited the most potent activity against BChE.     

Crystal structures and in vitro anticancer studies on new unsymmetrical copper(II) Schiff base complexes derived from meso-1,2-diphenyl-1,2-ethylenediamine: a comparison with related symmetrical ones

Two new unsymmetrical copper(II) Schiff base complexes, [CuLⁿ(py)]ClO₄ (n = 1, 2) in which Lⁿ represents a tridentate N₂O type Schiff base ligand, were synthesized. Lⁿs were derived from monocondensation of meso-1,2-diphenyl-1,2-ethylenediamine with salicylaldehyde or 3-methoxysalicylaldehyde. The reaction between [CuLⁿ(py)]ClO₄ and other salicylaldehyde derivatives resulted in new N₂O₂ unsymmetrical tetradentate Cu^II complexes, CuL^3–6. Crystal structures of [CuL¹(py)]ClO₄, CuL⁴, and CuL⁵ were obtained. These new complexes as well as a series of related symmetrical ones (i.e. CuL^7–12) were tested for their in vitro anticancer activity against human liver cancer cell line (Hep-G2) by MTT and apoptosis assay. All of the complexes showed considerable cytotoxic activity against tumor cell lines (IC₅₀ = 5.13–16.24 μg mL^?1). The symmetrical CuL⁷ was the most potent anticancer derivative (IC₅₀ = 5.13 μg mL^?1) compared to the control drug 5-FU (IC₅₀ = 5.4 μg mL^-1, p < 0.05). Flow cytometry experiments showed that the copper derivatives especially [CuL²(py)]ClO₄ and CuL⁷ induced more apoptosis on Hep-G2 tumor cell lines compared to 5-FU.     

Antimalarial and cytotoxic constituents of Xylaria cf. cubensis PK108

Xylaria cf. cubensis PK108 was identified by its distinctive morphological characteristics and its internal transcribed spacers sequence analysis. The chromatographic separation and structural elucidation based on spectroscopic analysis of fungal crude extracts led to 10 compounds; tryptoquivaline L (1), fiscalin C (2), epi-fiscalin C (3), cytochalasin D (4), ergosterol (5), ergosterol peroxide (6), chevalone C (7), xylaranol B (8), helvolic acid (9) and cyclo-(l-Pro-l-Leu) (10). The bioassay screening showed that 4 displayed cytotoxicity against KB and NCI-H187 cancer cell lines with IC₅₀ values of 3.25 and 5.95 μg mL^? 1. 6 exhibited cytotoxicity against NCI-H187 with an IC₅₀ value of 5.81 μg mL^? 1. 7 and 9 showed antimalarial activity with IC₅₀ values of 25.00 and 6.25 μg mL^? 1, respectively. This result establishes Xylaria as broad spectrum bioactive compound producers.     

Ion-Pair LC Method for Simultaneous Determination of Aliskiren Hemifumarate,Amlodipine Besylate and Hydrochlorothiazide in Pharmaceuticals

A rapid and precise LC method was developed for the simultaneous determination of aliskiren hemifumarate (ALS), amlodipine besylate (AML) and hydrochlorothiazide (HCZ) using acetonitrile:25 mM octane sulfonic acid sodium salt monohydrate in water (60:40 v/v) as the mobile phase. The flow rate was maintained at 1.2 mL min^?1 on a stationary phase composed of Supelco, Discovery^® HS (C18) column (25 cm × 4.6 mm, 5 μm). Isocratic elution was applied throughout the analysis. Detection was carried out at λ _max (232 nm) at ambient temperature. The method was validated according to ICH guidelines. Linearity, accuracy and precision were satisfactory over the concentration ranges of 32–320, 2–44 and 4–64 μg mL^?1 for ALS, AML and HCZ, respectively. LOD and LOQ were estimated and found to be 0.855 and 2.951 μg mL^?1, respectively, for ALS, 0.061 and 0.202 μg mL^?1, respectively, for AML as well as 0.052 and 0.174 μg mL^?1, respectively, for HCZ. The method was successfully applied for the determination of the three drugs in their co-formulated tablets. The results were compared statistically with reference methods and no significant difference was found. The developed method is specific and accurate for the quality control and routine analysis of the cited drugs in pharmaceutical preparations.     

Chemical composition,N-nitrosamine inhibition and antioxidant and antimicrobial properties of essential oil from Coreopsis tinctoria flowering tops

Coreopsis tinctoria flowering (CTF) tops from the Kunlun Mountains in Xinjing (north-western China) have been used for tea production for about a century. This study was to assess antioxidant, nitrite-scavenging and N-nitrosamine inhibitory and antimicrobial activities of the essential oil extracted from CTF tops. The essential oil was extracted through hydrodistillation and its chemical compositions were analysed by GC–MS. Seventy compounds of the oil were identified, representing 81.87% of total oil. The antioxidant capacities of the oil with IC₅₀ values for scavenging DPPH and ABTS were 287.66 ± 12.60 and 1.251 ± 0.127 μg mL^? 1, respectively. The nitrite-scavenging and N-nitrosamine inhibitory activities (IC₅₀) were 0.3912 ± 0.0127 and 0.6564 ± 0.036 μg mL^? 1, respectively. The oil has a certain antimicrobial capacity, but its capacity was weaker than that of penicillinG (24 μg mL^? 1). The oil showed antioxidant and antimicrobial capacities and had a stronger nitrite-scavenging and N-nitrosamine inhibitory properties.     

Simultaneous Determination of Five Major Compounds in Polygonum cuspidatum by HPLC

An RP-HPLC method was developed for the first time to simultaneously determine five major compounds in Polygonum cuspidatum, namely resveratrol, polydatin, anthraglycoside B, emodin and physcion with UV detection at 306 nm. The column was an Agilent Zorbax SB-C₁₈ (250 × 4.6 mm i.d., 5 μm). The separation was carried out with a gradient program. The mobile phase was acetonitrile–water (containing 0.1% formic acid) at a flow rate of 1.0 mL min^?1. The standard curve was rectilinear in the range of 2.04–62.96 μg mL^?1 (r = 0.9998) for resveratrol, 20.13–239.7 μg mL^?1 (r = 0.9998) for polydatin, 7.19–71.92 μg mL^?1 (r = 1.0000) for anthraglycoside B, 2.68–83.68 μg mL^?1 (r = 0.9998) for emodin and 0.60–14.37 μg mL^?1 (r = 0.9997) for physcion. The recoveries of the markers were 96.0, 106.5, 97.8, 97.9 and 98.1%, respectively. The relative standard deviation of intra-day and inter-day were less than 5.0 and 2.3%. This method was simple, accurate and reproducible. The developed method was successfully applied to analyze five compounds in P. cuspidatum of 20 commercial brands.