Gas chromatography–mass spectrometry (GC–MS) analysis of ethyl acetate root bark extract of Strychnos innocua (Delile)

Background Majority of phytochemicals have been known to bear valuable therapeutic activities such as insecticidal, antibacterial, antifungal, anticonstipative, spasmolytic, antiplasmodial and antioxidant activities. Strychnos innocua is straight-stemmed tree belonging to the family Loganiaceae and can grow up to 18 m tall. The plant is used for various pharmacological purposes. The aim of this study was to determine the chemical composition of the ethyl acetate extract of root bark of S. innocua using GC–MS analysis. The root bark was collected, air-dried and then crushed to powder. Standard extraction method (maceration) was used to obtain the ethyl acetate extract. The GC–MS was carried out on the extract using GC 7890B, MSD 5977A, Agilent Tech. Results Thirty-seven compounds were identified among which dibutyl benzene-1,2-dicarboxylate showed the highest peak area (31.03%) and monomethyl pimelate showed the lowest peak area (0.39%). The major compounds identified were cyclooctane (methoxymethoxy), 2,4-dimethylheptanedioic acid dimethyl ester, azelaic acid, 1,2-benzenedicarboxylic acid, bis(2-methylpropyl) ester, dibutyl benzene-1,2-dicarboxylate, butyl 8-methylnonyl benzene-1,2-dicarboxylate, 9,15-octadecadienoic acid, methyl ester, cis-vaccenic acid, linoleic acid ethyl ester and ethyl oleate. Conclusions In conclusion, these phytoconstituents might be responsible for the medicinal efficacy of the root bark of S. innocua and can be used as a source therapeutic drug.

Optimization of conditions for esterification of thiodiacetic acid in urine using mathematical planning for biological monitoring

Introduction. To assess the impact of the toxicants vinyl chloride (VC) and 1,2-dichloroethane (DCE) on humans, personalized biomonitoring of thiodiacetic acid (TDAA) is of most significant importance. Determination of TDAA in urine was carried out using the method of gas chromatography-mass spectrometry GC-MS. Materials and methods. Sample preparation consists of the analyte’s esterification in a biological matrix with methyl alcohol (with 10% boron trifluoride), extraction of the derivative by liquid extraction with ethyl acetate. We used an Agilent 7890A gas chromatograph with an HP-5MS capillary column and a mass-selective detector. TDAA was identified in the form of a dimethyl ester on a mass chromatogram according to the retention time and the ratio of the intensities of the registered ions. Results. To determine the rational parameters of the sample preparation process for the determination of TDAA in urine studies were carried out under the method of planning the experiment, which makes it possible to obtain the most accurate mathematical description of the processes. Optimization of the conditions for esterification of TDAA was carried out using mathematical planning, varying the temperature, process time, and the nature of the catalyst (BF3 or H2SO4). The scheduling matrix included eight experiments; the degree of conversion of TDAA served as an optimization parameter. Interpretation of the model showed that temperature makes more contribution to the formation of the degree of conversion than the processing time. The nature of the catalyst does not affect the degree of conversion. Conclusion. A mathematical model developed for optimizing the conditions for sample preparation of the biomarker of exposure to VC (TDAA) in urine, showed the contribution of three factors (reaction temperature, reaction time, catalyst nature) to the conversion rate, of which the reaction temperature makes the greatest contribution to the choice of optimal esterification conditions. The nature of the catalyst (BF3 or H2SO4) does not affect the conversion rate.

A Facile Synthesis of 2-Aminopropane-1,2,3-tricarboxylic Acid and Its Symmetrical Dimethyl Ester

A new convenient synthetic route to 2-aminopropane-1,2,3-tricarboxylic acid is described. The first two stages of the three-step synthesis are performed in a one-pot procedure and include the cyclization of hippuric acid with DCC followed by treatment with methyl bromoacetate to yield an alkylated oxazolone. Its hydrolysis with HCl provides 2-aminopropane-1,2,3-tricarboxylic acid as its HCl salt. Esterification of the resulting acid with methanol in the presence of thionyl chloride leads selectively to its symmetrical diester.

d-Cystine di(m)ethyl ester reverses the deleterious effects of morphine on ventilation and arterial blood gas chemistry while promoting antinociception

We have identified thiolesters that reverse the negative effects of opioids on breathing without compromising antinociception. Here we report the effects of d-cystine diethyl ester (d-cystine diEE) or d-cystine dimethyl ester (d-cystine diME) on morphine-induced changes in ventilation, arterial-blood gas chemistry, A-a gradient (index of gas-exchange in the lungs) and antinociception in freely moving rats. Injection of morphine (10 mg/kg, IV) elicited negative effects on breathing (e.g., depression of tidal volume, minute ventilation, peak inspiratory flow, and inspiratory drive). Subsequent injection of d-cystine diEE (500 μmol/kg, IV) elicited an immediate and sustained reversal of these effects of morphine. Injection of morphine (10 mg/kg, IV) also elicited pronounced decreases in arterial blood pH, pO2 and sO2 accompanied by pronounced increases in pCO2 (all indicative of a decrease in ventilatory drive) and A-a gradient (mismatch in ventilation-perfusion in the lungs). These effects of morphine were reversed in an immediate and sustained fashion by d-cystine diME (500 μmol/kg, IV). Finally, the duration of morphine (5 and 10 mg/kg, IV) antinociception was augmented by d-cystine diEE. d-cystine diEE and d-cystine diME may be clinically useful agents that can effectively reverse the negative effects of morphine on breathing and gas-exchange in the lungs while promoting antinociception. Our study suggests that the d-cystine thiolesters are able to differentially modulate the intracellular signaling cascades that mediate morphine-induced ventilatory depression as opposed to those that mediate morphine-induced antinociception and sedation.

Thermotropic Copolyesters Based on Polyethylene Terephthalate and 4-Hydroxybenzoic Acid for High Modulus Fibers

The copolyesters derived from dimethyl ester of terephthalic acid, ethylene glycol, and 4-hydroxybenzoic acid (HBA) have been synthesized via catalytically promoted polycondensation omitting the acetylation step. FTIR spectroscopy results have evidenced an insertion of HBA along a polymer backbone. Of note, thermal gravimetric analysis has shown that the HBA moieties substantially improved the thermal stability of polyesters. As found by differential scanning calorimetry and polarizing microscopy, the copolyesters are capable of forming an anisotropic phase in a temperature range of 150-170 °C. Additionally, the free surface energy of the samples was determined to evaluate the compatibility of thermotropic copolyesters with other high-molecular compounds.

D-Cystine di(m)ethyl Ester Reverses the Deleterious Effects of Morphine on Ventilation and Arterial Blood Gas Chemistry While Promoting Analgesia

We have identified thiolesters that reverse the negative effects of opioids on breathing without compromising analgesia. Here we report the effects of D-cystine diethyl ester (D-cystine diEE) or D-cystine dimethyl ester (D-cystine diME) on morphine-induced changes in ventilation, arterial-blood gas chemistry, A-a gradient (index of gas-exchange in the lungs) and analgesia in freely moving rats. Injection of morphine (10 mg/kg, IV) elicited negative effects on breathing (e.g., depression of tidal volume, minute ventilation, peak inspiratory flow, and inspiratory drive). Subsequent injection of D-cystine diEE (500 mmol/kg, IV) elicited an immediate and sustained reversal of these effects of morphine. Injection of morphine (10 mg/kg, IV) also elicited pronounced decreases in arterial blood pH, pO2 and sO2 accompanied by pronounced increases in pCO2 (all indicative of a decrease in ventilatory drive) and A-a gradient (mismatch in ventilation-perfusion in the lungs). These effects of morphine were reversed in an immediate and sustained fashion by D-cystine diME (500 mmol/kg, IV). Finally, the duration of morphine (5 and 10 mg/kg, IV) analgesia was augmented by D-cystine diEE. D-cystine diEE and D-cystine diME may be clinically useful agents that can effectively reverse the negative effects of morphine on breathing and gas-exchange in the lungs while promoting analgesia.

Synthesis, Characterization, and Encapsulation of Novel Plant Growth Regulators (PGRs) in Biopolymer Matrices

Novel plant growth regulators (PGRs) based on the derivatives of dehydroamino acids 2,3-dehydroaspartic acid dimethyl ester (PGR1), Z-isomer of the potassium salt of 2-amino-3-methoxycarbonylacrylic acid (PGR2) and 1-methyl-3-methylamino-maleimide (PGR3) have been synthesized and their growth-regulating properties investigated. Laboratory testing revealed their plant growth-regulating activity. PGR1 showing the most stimulating activity on all laboratory tested cultures were used in field experiments. Results showed that PGR1 is a highly effective environmentally friendly plant growth regulator with effects on different crops. Biopolymeric microcapsule formulations (chitosan/alginate microcapsule loaded with PGR) suitable for application in agriculture were prepared and characterized. Physicochemical properties and release profiles of PGRs from microcapsule formulations depend on the molecular interactions between microcapsule constituents including mainly electrostatic interactions and hydrogen bonds. The differences in the microcapsule formulations structure did not affect the mechanism of PGRs release which was identified as diffusion through microcapsules. The obtained results opened a perspective for the future use of microcapsule formulations as new promising agroformulations with a sustained and target release for plant growth regulation.