Standard Reference Compounds Research Articles

Synthesis, characterization, and monoamine transporter activity of the new psychoactive substance 3',4'-methylenedioxy-4-methylaminorex (MDMAR).

The recent occurrence of deaths associated with the psychostimulant cis-4,4'-dimethylaminorex (4,4'-DMAR) in Europe indicated the presence of a newly emerged psychoactive substance on the market. Subsequently, the existence of 3,4-methylenedioxy-4-methylaminorex (MDMAR) has come to the authors' attention and this study describes the synthesis of cis- and trans-MDMAR followed by extensive characterization by chromatographic, spectroscopic, mass spectrometric platforms and crystal structure analysis. MDMAR obtained from an online vendor was subsequently identified as predominantly the cis-isomer (90%). Exposure of the cis-isomer to the mobile phase conditions (acetonitrile/water 1:1 with 0.1% formic acid) employed for high performance liquid chromatography analysis showed an artificially induced conversion to the trans-isomer, which was not observed when characterized by gas chromatography. Monoamine release activities of both MDMAR isomers were compared with the non-selective monoamine releasing agent (+)-3,4-methylenedioxymethamphetamine (MDMA) as a standard reference compound. For additional comparison, both cis- and trans-4,4'-DMAR, were assessed under identical conditions. cis-MDMAR, trans-MDMAR, cis-4,4'-DMAR and trans-4,4'-DMAR were more potent than MDMA in their ability to function as efficacious substrate-type releasers at the dopamine (DAT) and norepinephrine (NET) transporters in rat brain tissue. While cis-4,4'-DMAR, cis-MDMAR and trans-MDMAR were fully efficacious releasing agents at the serotonin transporter (SERT), trans-4,4'-DMAR acted as a fully efficacious uptake blocker. Currently, little information is available about the presence of MDMAR on the market but the high potency of ring-substituted methylaminorex analogues at all three monoamine transporters investigated here might be relevant when assessing the potential for serious side-effects after high dose exposure.

Chemical taxonomy of tree peony species from China based on root cortex metabolic fingerprinting

The section Moutan of the genus Paeonia consists of eight species that are confined to a small area in China. A wide range of metabolites, including monoterpenoid glucosides, flavonoids, tannins, stilbenes, triterpenoids, steroids, paeonols, and phenols, have been found in the species belonging to section Moutan. However, although previous studies have analyzed the metabolites found in these species, the metabolic similarities that can be used for the chemotaxonomic distinction of section Moutan species are not yet clear. In this study, HPLC–DAD-based metabolic fingerprinting was applied to the classification of eight species: Paeoniasuffruticosa, Paeoniaqiui, Paeoniaostii, Paeoniarockii, Paeoniajishanensis, Paeoniadecomposita, Paeoniadelavayi, and Paeonialudlowii. In total, of the 47 peaks that exhibited an occurrence frequency of 75% in all 23 tree peony samples, 43 of these metabolites were identified according to their retention times and UV absorption spectra, together with combined HPLC–QTOF-MS. These data were compared with reference standard compounds. The 43 isolated compounds included 17 monoterpenoid glucosides, 11 galloyl glucoses, 5 flavonoids, 6 paeonols and 4 phenols. Principal component analysis (PCA), and hierarchical cluster analysis (HCA), showed a clear separation between the species based on metabolomics similarities and four groups were identified. The results exhibited good agreement with the classical classification based on the morphological characteristics and geographical distributions of the subsections Vaginatae F.C. Stern and Delavayanae F.C. Stern with the exception of P. decomposita, which was found to be a transition species between these two subsections. According to their metabolic fingerprinting characteristics, P. ostii and P. suffruticosa can be considered one species, and this result is consistent with the viewpoint of medicinal plant scientists but different from that of classical morphological processing. Significantly large variations were obtained in the metabolic profiles of P. delavayi, whereas no significant difference was found between P. delavayi and P. ludlowii. This indicates that these two species have a close genetic relationship. In conclusion, the combination of HPLC–DAD and multivariate analyses has great potential for guiding future chemotaxonomic studies to examine the potential pharmaceutical value of the effective constituents of tree peony species and appears to be able to clarify the confusion and skepticism associated with the reported morphology- and molecular phylogenetics-based taxonomy of tree peonies.

Determination of log P values of new cyclen based antimalarial drug leads using RP-HPLC.

Lipophilicity, expressed by log P, is an important physicochemical property of drugs that affects many biological processes, including drug absorption and distribution. The main purpose of this study to determine the log P values of newly discovered drug leads using reversed-phase high-performance liquid chromatography (RP-HPLC). The reference standards, with varying polarity ranges, were dissolved in methanol and analyzed by RP-HPLC using a C18 column. The mobile phase consisted of a mixture of acetonitrile, methanol and water in a gradient elution mode. A calibration curve was plotted between the experimental log P values and obtained log k values of the reference standard compounds and a best fit line was obtained. The log k values of the new drug leads were determined in the same solvent system and were used to calculate the respective log P values by using the best fit equation. The log P vs. log k data gave a best fit linear curve that had an R2 of 0.9786 with Pvalues of the intercept and slope of 1.19 x 10(-6) and 1.56 x 10(-10), respectively, at 0.05 level of significance. Log P values of 15 new drug leads and related compounds, all of which are derivatives of macrocyclic polyamines and their metal complexes, were determined. The values obtained are closely related to the calculated log P (Clog P) values using ChemDraw Ultra 12.0. This experiment provided efficient, fast and reasonable estimates of log P values of the new drug leads by using RP-HPLC.

Eco-sustainable synthesis and biological evaluation of 2-phenyl 1,3-benzodioxole derivatives as anticancer, DNA binding and antibacterial agents

The current research and development scenario in medicinal chemistry demands small molecules synthesized in a simple, fast and effective way with enhanced activity and fewer side effects than the existing ones. Therefore, one-pot, microwave assisted green and efficient synthesis of a series of derivatives belonging to 2-phenyl 1,3-benzodioxole (1a–14a) and 2-phenyl 1,3-benzodioxole-4-ol (1b–14b) class were carried out and subsequently investigated for their anticancer, antibacterial and DNA binding potential. Compound 3c proved to be the most active one among the screened derivatives possessing anticancer and antibacterial potency greater than the standard reference compound (cisplatin and cinoxacin for anticancer and antibacterial activity, respectively). The most active compound in terms of DNA binding capacity was found to be 5b. A rewarding feature of the work is a facile, convenient, eco friendly one step synthesis of compounds demonstrating attenuated activity against cancer and bacterial cell with an inherent potential of binding to DNA. Subsequently, a hit molecule for further anticancer, antibacterial (compound 3c) and DNA binding studies (compound 5b) was also identified.

Evaluating State Dependence and Subtype Selectivity of Calcium Channel Modulators in Automated Electrophysiology Assays

Voltage-gated Ca2+ channels play essential roles in control of neurosecretion and muscle contraction. The pharmacological significance of Cav channels stem from their identification as the molecular targets of calcium blockers used in the treatment of cardiovascular diseases, such as hypertension, angina, and arrhythmia, and neurologic diseases, such as pain and seizure. It has been proposed that state-dependent Cav inhibitors, that is, those that preferentially bind to channels in open or inactivated states, may improve the therapeutic window over relatively state-independent Cav inhibitors. High-throughput fluorescent-based functional assays have been useful in screening chemical libraries to identify Cav inhibitors. However, hit confirmation, mechanism of action, and subtype selectivity are better suited to automated patch clamp assays that have sufficient capacity to handle the volume of compounds identified during screening, even of modest sized libraries (≤500,000 compounds), and the flexible voltage control that allows evaluation of state-dependent drug blocks. IonWorks™ Barracuda (IWB), the newest generation of IonWorks instruments, provides the opportunity to accelerate the Cav drug discovery studies in an automated patch clamp platform in 384-well format capable of medium throughput screening and profiling studies. We have validated hCav1.2, hCav2.1, hCav2.2, and hCav3.2 channels assays on the IWB platform (population patch clamp mode) and demonstrated that the biophysical characteristics of the channels (activation, inactivation, and steady-state inactivation) obtained with the IWB system are consistent with known subtype-specific characteristics. Using standard reference compounds (nifedipine, BAY K8644, verapamil, mibefradil, and pimozide), we demonstrated subtype-selective and state- and use-dependent characteristics of drug–channel interactions. Here we describe the design and validation of novel robust high-throughput Cav channel assays on the IWB platform. The assays can be used to screen focused compound libraries for state-dependent Cav channel antagonists, to prioritize compounds for potency or to counterscreen for Cav subtype selectivity.

Assessment of Organic Pesticides in Ground and Surface Water in Bhopal India

Analytical assessment of surface and ground water samples for presence of organic pesticides is being reported in this paper. Analytical measurement was carried out for 15 samples each of surface and ground water collected from selected points near agricultural fields from river Betwa in Bhopal area. The sample size was stretched across 20sq.k.m .Pesticides were analysed by GLC and identified by comparing with standard reference compounds .Traces of Various pesticides including HCH ( α β Y isomer),Aldrin , Endosulphan were found in all samples. Pesticide content was more in surface than ground water suggesting primary entry of pesticides into river water due to run off from nearby fields. βHCH content was more than other isomers.

Synthesis and biological evaluation of 18F-labeled fluoropropyl tryptophan analogs as potential PET probes for tumor imaging

In the search for an efficient, fluorine-18 labeled amino acid based radiotracer for tumor imaging with positron emission tomography (PET), two new tryptophan analogs were synthesized and characterized in vitro and in vivo. Both are tryptophan alkyl-derivatives, namely 2-(3-[18F]fluoropropyl)-dl-tryptophan ([18F]2-FPTRP) and 5-(3-[18F]fluoro-propyl)-dl-tryptophan ([18F]5-FPTRP). Standard reference compounds and precursors were prepared by multi step approaches. Radiosynthesis was achieved by no-carrier-added nucleophilic [18F]fluorination in 29–34% decay corrected yields with radiochemical purity over 99%. In vitro cell uptake assays showed that both compounds are substrates for amino acid transport and enter small cell lung cancer cells (NCI-H69) most probably almost exclusively via large neutral amino acids transporter(s) (LAT). Small animal PET imaging with xenograft bearing mice revealed high tumor/background ratios for [18F]2-FPTRP comparable to the well established tyrosine analog O-(2-[18F]fluroethyl)-l-tyrosine ([18F]FET). Radiometabolite studies showed no evidence of involvement of a biotransformation step in tumor accumulation.

ISOLATION, IDENTIFICATION AND CHARACTERIZATION OF ROTENOIDS FROM CAJANUS CAJAN (L.) MILLSP. (LEGUMINOSEAE)

Natural insecticides now-a-days have a bright future because synthetic insectides are harmful to human beings. Among botanical pesticides, the rotenoids standout for their potency and effectiveness against many crop pests and are fifteen times more toxic than the nicotinic acid. Cajanus cajan primarily grown as a grain crop for human consumption (pulse, vegetable) and has not been analysed for it’s rotenoidal content. Chromatographic analysis showed the presence of four rotenoids namely elliptone, deguelin, rotenone and tephrosin, which were identified by co-tlc, melting point, GLC and IR spectral studies with that of the standard reference compounds. In the present investigation, rotenone (0.37 mg/gdw) was found in maximum quantity which was followed by deguelin (0.27 mg/gdw), tephrosin (0.21 mg/gdw) and elliptone (0.15 mg/gdw).

Association between the Emission Rate and Temperature for Chemical Pollutants in Building Materials: General Correlation and Understanding

The emission rate is considered to be a good indicator of the emission characteristics of formaldehyde and volatile organic compounds (VOCs) from building materials. In contrast to the traditional approach that focused on an experimental study, this paper uses a theoretical approach to derive a new correlation to characterize the relationship between the emission rate and temperature for formaldehyde emission. This correlation shows that the logarithm of the emission rate by a power of 0.25 of the temperature is linearly related to the reciprocal of the temperature. Experimental data from the literature were used to validate the derived correlation. The good agreement between the correlation and experimental results demonstrates its reliability and effectiveness. Using the derived correlation, the emission rate at temperatures other than the test condition can be obtained, greatly facilitating engineering applications. Further analysis indicates that the temperature-related emission rate of other scenarios, i.e., the standard emission reference and semi-volatile organic compounds (SVOCs), also conforms to the same correlation as that of formaldehyde. The molecular dynamics theory is introduced to preliminarily understand this phenomenon. Our new correlation should prove useful for estimating the emission characteristics of chemicals from materials that are subject to changes in temperature.

Compound‐specific stable carbon isotope analysis of galaxolide enantiomers in sediment using gas chromatography/isotope ratio monitoring mass spectrometry

Both chiral analysis and compound-specific stable carbon isotope analysis have limitations when applied to environmental research. However, the combination of these two techniques might overcome their respective limitation and give more insight into the enantioselective fate and source apportionment of chiral organic contaminants. After Soxhlet extraction and clean-up, sediment extracts were further pre-concentrated using normal-phase preparative high-performance liquid chromatography to isolate sufficient quantities of highly purified galaxolide (1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta(g)-2-benzopyran; HHCB). The enantiomeric fractions and stable carbon isotopes of the HHCB were determined using gas chromatography/mass spectrometry (GC/MS) and GC/isotope ratio mass spectrometry (IRMS). The method was validated by analysis of the enantiomeric fractions and the stable carbon isotope ratios of the HHCB standard at each step of the pre-concentration procedure, and no significant enantiomeric and isotopic fractionation was found. The sediment sample was further used to test the developed method, and it was shown that the HHCB enantiomers in the sediment sample exhibited significantly different δ(13) C values (-33.03 to -24.57‰) and a slight enantiomeric fractionation (0.507 and 0.490) from a HHCB standard reference compound (-26.50 to -26.21‰ for δ(13) C values, and 0.519 and 0.497 for enantiomeric fractions). This work offers a novel approach to elucidating the sources and the abiotic or biological transformation processes of HHCB in the environment and will offer a perspective for assessing the environment fate of any chiral organic compound.

Identification of Metabolites of Ganoderic Acid D by Ultra-Performance Liquid Chromatography/Quadrupole Time-of-Flight Mass Spectrometry

Ganoderic acid D (GD) is the major active triterpenoid in Ganoderma lucidum, a medicinal fungus used daily. However, the metabolic fate of GD remains unknown. To know whether GD is extensively metabolized, we first investigated the metabolism of GD in vitro and in vivo. The metabolic profiles of the bile samples obtained from rats in vivo were almost the same as those obtained in vitro. Using ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry, a total of 25 metabolites were identified from the bile sample. Few metabolites were found in the urine samples. These results indicated that biliary rather than renal clearance was the major route of excretion. The major metabolites were identified by comparison with the standard reference compounds. Metabolites at low concentrations were identified by interpreting the mass spectra. Both phase I and phase II metabolites were observed. The metabolic transformation included reduction, monohydroxylation, dihydroxylation, trihydroxylation, oxidation, desaturation, sulfation, and glucuronidation. The main metabolic soft spots in the chemical structure of GD were the 3-carbonyl group, angular methyl groups, the 7-hydroxy group, and the 26-carboxylic acid moiety. Overall, this study gives us an insight into the metabolism of GD, an active oxygenated tetracyclic triterpenoid.

In vitro free radical scavenging and anti-hyperglycemic activities of Achyranthes aspera extract in alloxan-induced diabetic mice

Medicinal plants have played an important role in the treatment and prevention of diseases since ancient times. They are also potential sources of nutrients and drugs. This study evaluated Achyranthes aspera ethanolic extracts for their in vitro antioxidant activity and anti-hyperglycemic effects on alloxan-induced diabetic mice. Diabetes was induced in Swiss albino mice through intra-peritoneal administration of alloxan and their blood glucose levels and weight were measured weekly. At the end of the experiment, all animals were sacrificed and tissue samples were collected. A. aspera extracts had potent antioxidant activity compared to reference standard compounds. Treatment with an A. aspera extract at doses of 200 mg/kg and 400 mg/kg significantly reduced blood glucose levels in alloxan-induced diabetic mice. A. aspera extract also prevented lipid peroxidation as gauged by thiobarbituric acid reactive substances (TBARS) and hydroperoxides. Moreover, A. aspera extract increased the activity of catalase and reduced NO levels in alloxan-induced diabetic mice. Results revealed significant anti-hyperglycemic activity of A. aspera extracts in alloxan-treated mice that may be mediated by diminished oxidative stress.

Identification of Fruity Aroma-Producing Compounds from Chryseobacterium sp. Isolated from the Western Ghats, India

A fruity aroma-producing strain WG4 was isolated from a water sample collected from the Western Ghats, India. The 16S rRNA gene sequence analysis of strain WG4 indicated that Chryseobacterium indologenes, a member of the family 'Flavobacteriaceae' is the closest related species with a pair-wise sequence similarity of 98.6%. Strain WG4 produces a fruity aroma when grown on nutrient or trypticase soy agar plates. The fruity aroma is more when the strain WG4 is grown on agar plates compared to their growth in broth. The aromatic compounds produced by the strain WG4 were identified as ester compounds and were confirmed as ethyl-2-methylbutyrate and ethyl-3-methylbutyrate based on Gas Chromatography-Mass Spectrometry (GC-MS) analysis and using standard reference compounds. Even after repeated subcultures strain WG4 produced the same aroma in high intensity. Thus, strain WG4 could serve as a source for the production of these flavour compounds.

Cucumis sativus fruit-potential antioxidant, anti-hyaluronidase, and anti-elastase agent

The aim of this study was to screen the antioxidant, anti-hyaluronidase, and anti-elastase activity of the lyophilized juice of Cucumis sativus fruit (CSLJ). The CSLJ was subjected to DPPH and superoxide radical scavenging assay in reference to butylated hydroxytoluene. The hyaluronidase and elastase inhibitory assay was performed in reference to oleanolic acid. Furthermore, the activities have been rationalized with HPLC analysis of the CSLJ with standard reference compound of ascorbic acid. The CSLJ exhibited DPPH-free radical and superoxide radical scavenging activity, IC(50) at a concentration of 14.73 ± 1.42 and 35.29 ± 1.30 μg/mL, respectively. The CSLJ also showed strong anti-hyaluronidase ((c) P < 0.001) and anti-elastase ((c) P < 0.001) activity, IC(50) at a concentration of 20.98 ± 1.78 and 6.14 ± 1.74 μg/mL, respectively. The HPLC 'chromatogram' of standard and CSLJ showed specific peak at retention time 2.905 and 3.066 min, respectively. Content of ascorbic acid was calculated with respect to the standard compound and it was found to be 3.5 ± 0.23% w/w. CSLJ is the rich source of ascorbic acid and this study thereby rationalizes the use of C. sativus as potential anti-wrinkle agent in cosmetic products.

Temperature-Dependent Vapor Pressure of Selected Cyclic and Linear Polydimethylsiloxane Oligomers

The isothermal retention times of seven cyclic (D4 to D10) and nine linear (L5 to L13) dimethylsiloxane oligomers on a nonpolar gas chromatographic column were determined at temperatures between (308.15 and 438.15) K. Using normal alkanes as standard reference and calibration compounds, these retention times were used to derive liquid state vapor pressures at 298.15 K as well as enthalpies of vaporization that allow for the estimation of vapor pressures over a wide range of temperatures. The data agree within 0.25 log units with vapor pressure values previously reported by Flaningam (1986) but extend those values to lower temperatures and larger oligomers. Cyclic dimethylsiloxanes are more volatile than linear dimethylsiloxanes of a similar size. Oligomers with 10 and more dimethylsiloxane units are expected to sorb appreciably to aerosol at environmentally relevant temperatures.

An amperometric biosensor based on peroxidases from Brassica napus for the determination of the total polyphenolic content in wine and tea samples

An amperometric biosensor based on peroxidases from Brassica napus hairy roots (PBHR) used to determine the total polyphenolic content in wine and tea samples is proposed by the first time. The method employs carbon paste (CP) electrodes filled up with PBHR, ferrocene (Fc), and multi-walled carbon nanotubes embedded in a mineral oil (MWCNT + MO) at a given composition (PBHR–Fc–MWCNT + MO). The biosensor was covered externally with a dialysis membrane, which was fixed at the electrode body side part with a Teflon laboratory film and an O-ring. Calibration curves obtained from steady-state currents as a function of the concentration of a polyphenolic standard reference compound such as t-resveratrol (t-Res) or caffeic acid (CA) were then used to estimate the total polyphenolic content in real samples. The reproducibility and the repeatability were of 7.0% and 4.1% for t-Res (8.4% and 5.2% for CA), respectively, showing a good biosensor performance. The calibration curves were linear in a concentration range from 0.05 to 52 mg L −1 and 0.06 to 69 mg L −1 for t-Res and CA, respectively. The lowest polyphenolic compound concentration values measured experimentally for a signal to noise ratio of 3:1 were 0.023 mg L −1 and 0.020 mg L −1 for t-Res and CA, respectively.

Chemical constituents and antimicrobial activity of Goniothalamus macrophyllus (Annonaceae) from Pasoh Forest Reserve, Malaysia.

The essential oils from the twig and root of Goniothalamus macrophyllus were obtained by hydrodistillation and subjected to Gas Chromatography (GC-FID) and Gas Chromatography/Mass Spectrometry (GC-MS) using CBP-5 capillary column in order to determine their chemical composition. Both twig and root oils and four reference standard compounds (α-pinene, linalool, geraniol and geranyl acetate) were evaluated for their antimicrobial properties against gram positive and gram negative bacteria, yeast and dermatophyte fungi using broth microdilution methods. The GCMS analysis revealed twenty-one and fourteen compounds from twig and root oils which represented 90.0 and 42.5% of the total oils, respectively. The oils were found to possess the following major components: twig: geranyl acetate (45.5%), geraniol (17.0%), linalool (12.7%) and camphene (7.5%); root: cyperene (9.8%), geranyl acetate (9.4%), geraniol (3.4%) and linalool (2.6%). Other components present in appreciable amounts in both essential oils were α-pinene (0.8%) and benzaldehyde (0.5%). The root oil exhibited the most notable inhibitory activity (0.3 mg/ml) against Vancomycin intermediate-resistance Staphylococcus aureus (VISA 24), Staphylococcus epidermidis and Candida albicans. α-pinene meanwhile inhibited the bacteria and fungal growth at 0.3 and 2.5 mg/ml. With regards to antimicrobial potential, α-pinene superceeds linalool, geraniol and geranyl acetate, respectively.

Correction of mass calibration gaps in liquid chromatography–mass spectrometry metabolomics data

High mass accuracy is an important goal in liquid chromatography-mass spectrometry experiments. Some manufacturers employ a mass calibration system that regularly switches between the analyte and a standard reference compound, and leads to gaps in the analyte data. We present a method for correction of such gaps in global molecular profiling applications such as metabolomics. We demonstrate that it improves peak detection and quantification, successfully recovering the expected number of peaks and intensity distribution in an example metabolomics dataset. Available in XCMS versions 1.23.3 and higher. Distributed via Bioconductor under GNU General Public License. (http://www.bioconductor.org/packages//2.7/bioc/html/xcms.html).

A sample preparation protocol for 1H nuclear magnetic resonance studies of water-soluble metabolites in blood and urine

We describe a general protocol for preparing protein-containing biofluids for 1H nuclear magnetic resonance (NMR) metabolomic studies. In this protocol, untreated samples are diluted in deuterated solvents to precipitate proteins and recover metabolites quantitated relative to standard reference compounds such as 3-trimethylsilylpropionic acid (TSP) and 2,2-dimethyl-2-silapentane-5-sulfonic acid (DSS). The efficacy of this protocol was tested using a bovine serum albumin/metabolite mix and human serum samples. This sample preparation method can be readily applied to any protein-containing biofluid for 1H NMR studies.

Cancer chemopreventive activity of the prenylated coumarin, umbelliprenin, in vivo

Umbelliprenin is a prenylated compound, which belongs to the class of sesquiterpene coumarins. In continuation of our earlier in-vitro finding, we determined to assess the cancer chemopreventive activity of umbelliprenin in vivo by using a two-stage carcinogenesis assay of mouse skin tumors induced by peroxynitrite as an initiator and TPA (12-O-tetradecanoylphorbol-13-acetate) as a promoter. In this assay, treatment with umbelliprenin along with peroxynitrite/TPA delayed the formation of papillomas up to week 9, and approximately 33.3 and 86.6% of the mice bore papillomas after 11 and 20 weeks of promotion, respectively. Umbelliprenin reduced the number of tumors per mouse by 45% after 20 weeks of promotion compared with the control group. Interestingly, this is equal to the corresponding value (45%) for curcumin, used as a reference standard compound in our study. In addition, the pattern of tumor promotion was slower in mice treated with umbelliprenin compared with the curcumin. Therefore, umbelliprenin might be valuable as a cancer chemopreventive agent.