A capillary electrophoresis method for the determination of the linagliptin enantiomeric impurity.

Linagliptin is a highly specific, long-acting inhibitor that is used as an orally administrable agent for type-2 diabetes treatment. Because only the R-enantiomer is of clinical use, we developed a capillary electrophoresis method for the determination of the enantiomeric impurity of this compound. Carboxymethyl-ß-cyclodextrin was selected as the chiral selector for the separation of linagliptin enantiomers. Design of experiments and desirability functions were used for the analytical optimization, which was focused on understanding and improving the electrophoretic process. The effects of significant parameters (background electrolyte concentration and pH, cyclodextrin concentration, temperature, and voltage) were thoroughly investigated. The complete separation of linagliptin and its enantiomeric impurity with baseline resolution was achieved within 10 min on an uncoated fused-silica capillary (50 µm inner diameter, 365 µm outer diameter, 64.5/56 cm in total/ effective length) maintained at 25°C, under an applied voltage of 28.0 kV. The background electrolyte contained 70 mM sodium acetate and 4.7 mM carboxymethyl-ß-cyclodextrin, and the pH was adjusted to 6.10. The method was validated, and a limit of quantitation of 0.05% for the impurity was estimated.

Ultrasonic-Assisted and Microwave-Assisted Extraction of Phenolics and Terpenoids from Abelmoschus sagittifolius (Kurz) Merr Roots Using Natural Deep Eutectic Solvents.

This research extracted phenolics and terpenoids from Abelmoschus sagittifolius (Kurz) Merr roots using natural deep eutectic solvent-based novel extraction techniques. Twelve natural deep eutectic solvents (NADESs) were produced for recovering phenolics and terpenoids. Citric acid/glucose and lactic acid/glucose, with a molar ratio of 2:1, were determined as the most appropriate NADESs for extracting phenolics and terpenoids, respectively. Afterward, the proper conditions for NADES-based ultrasonic-assisted and microwave-assisted extraction were investigated. Then, the time and liquid-to-solid ratios of ultrasonic- and microwave-combined extraction methods and the sequence of ultrasound and microwave treatments were examined. The conditions of ultrasonic-assisted extraction were 40 mL/g liquid-to-solid ratio, 40% water content, 30°C, 5 min, and 600 W ultrasonic power for the highest terpenoid recovery at 69 ± 2 mg UA/g dw, while 150 W ultrasonic power was suitable for phenolic recovery at 9.56 ± 0.17 mg GAE/g dw. The conditions of microwave-assisted extraction were 50 mL/g liquid-to-solid ratio, 20% water content, 400 W microwave power, and 2 min to acquire the highest phenolics and terpenoids at 22.13 ± 0.75 mg GAE/g dw and 90 ± 1 mg UA/g dw, respectively. Under appropriate conditions, the biological activities, phenolic content, and terpenoid content of obtained extracts from four extraction methods, including ultrasonic-assisted, microwave-assisted, ultrasonic-microwave-assisted, and microwave-ultrasonic-assisted extraction, were compared to select the most proper method. The conditions of ultrasonic-microwave-assisted extraction were 40 mL/g liquid-to-solid ratio, 5 min sonication, and 1 min microwave irradiation to obtain the highest phenolic and terpenoid contents (27.07 ± 0.27 mg GAE/g dw and 111 ± 3 mg UA/g dw, respectively). Ultrasonic-microwave-assisted extraction showed the highest phenolic content, terpenoid content, and biological activities among the four extraction techniques. The changes in the surface morphology were determined using scanning electron microscopy. This study demonstrated that ultrasonic-microwave-assisted extraction was an effective and sustainable method in food and pharmaceutical industries for recovering phenolics and terpenoids from Abelmoschus sagittifolius (Kurz) Merr.

Green extraction of phenolics and flavonoids from black mulberry fruit using natural deep eutectic solvents: optimization and surface morphology.

This study deployed ultrasonic-assisted extraction (UAE), combined with natural deep eutectic solvents (NADES), to extract phenolics and flavonoids from the black mulberry fruit, and the antioxidant activity was examined. The extraction yields of NADES-based UAE were assessed based on the yields of phenolics and flavonoids extracted from the black mulberry fruit. This study selected the molar ratios of hydrogen bond acceptors (HBA) and hydrogen bond donors HBD at 1:2 from previous studies. Choline chloride-lactic acid showed the highest solubility with phenolics and flavonoids among NADES systems. One-factor experiments evaluated the effect of UAE conditions (liquid-to-solid ratio (LSR), water content in NADES, temperature, and time) on TPC, TFC, and antioxidant activity. The suitable NADES-based UAE conditions for extracting phenolics and flavonoids from the black mulberry fruit were 60 ml/g of LSR, 40% water content, 70 °C, and 15 min. Response surface methodology with the Box-Behnken design model optimized the NADES-based UAE process based on response (TPC, TFC, ABTS, OH, and DPPH). The optimal conditions for the NADES-based UAE process were 70 ml/g of LSR, 38.9% water content in NADES, 67.9 °C, and 24.2 min of extraction time. The predicted values of the Box-Behnken design were compatible with the experimental results. Moreover, scanning electron microscopy (SEM) was used to survey the surface of black mulberry fruit with and without sonication. SEM can assist in demonstrating the destructive effect of NADES and ultrasonic waves on material surfaces. SEM findings indicated the high surface destruction capacity of NADES, which partially contributed to a superior extraction yield of NADES than conventional organic solvents. The study proposes an efficient and green method for extracting bioactive compounds from black mulberry fruits. The black mulberry fruit extracts can be applied to meat preservation and beverages with high antioxidants.

Green extraction of total phenolic and flavonoid contents from mangosteen (Garcinia mangostana L) rind using natural deep eutectic solvents.

This research combined ultrasonic-assisted extraction (UAE) and natural deep eutectic solvent (NADES) to recover phenolic and flavonoid components from mangosteen rind. The antioxidant activities were determined using DPPH, ABTS+, and hydroxyl assays. NADES prepared from lactic and 1,2-propanediol had the highest extraction efficiency based on the total flavonoid content (TFC) and phenolic contents (TPC). Single-factor experiments were employed to assess the influence of UAE conditions (liquid-to-solid ratio, temperature, water content in NADES, and time) on TFC, TPC, and antioxidant activities. NADES-based UAE conditions were optimized using response surface methodology with the Box-Behnken design model on five dependent responses (TPC, TFC, DPPH, ABTS, and OH). The optimal conditions for the lactic-1,2-Propanediol-based UAE process were 76.7 ml liquid/g solid with 30.3% of water content at 57.5 °C for 9.1 min. Scanning electron microscopy (SEM) was applied to examine the surface morphology of mangosteen rind before and after sonication. This study proposes an efficient, green, and practical approach for recovering phenolics and flavonoids from mangosteen rinds.

FGF21 negatively affects long-term female fertility in mice.

Objective: Obesity and associated liver disease are a growing public health concern. Pharmacological agents to treat non-alcoholic fatty liver disease are limited. FGF21, a hormone secreted by the liver and potent metabolic modulator, is a promising therapeutic target for this indication with several analogs currently in clinical development. However, concerns about a negative effect of FGF21 on female fertility have not been fully addressed. Methods: After induction of obesity, female C57BL/6N mice received a 7-day course of subcutaneously administered FGF21. Control groups received either high-fat diet (HFD) or a normal diet (ND). The mothers were then mated with lean males for 12 weeks. The estrous cycle was recorded for two weeks after breeding. The metabolic phenotype, liver steatosis and reproductive organs were assessed at sacrifice 14 weeks after treatment. Results: A short-course treatment of FGF21 leads to weight reduction during treatment but has no long-term impact on liver steatosis. A treatment with FGF21 leads to a reduction in the number of pregnancies (0 vs 1, p = 0.019) and no viable pup was born to a mother previously treated with FGF21. The FGF21 treatment affected the number of cycles (1 vs 3, p = 0.048) and amount in diestrus (54 vs 75%, p = 0.008) 12 weeks after the treatment. Additionally, the number of corpora lutea (0.8 vs 3.0, p = 0.016), and mature follicles (0 vs 1, p = 0.037) was reduced compared to the ND group while uterine histology remained unaffected. Conclusion: A short-term treatment with FGF21 has a long-term effect on female fertility in mice. This represents a potential safety concern for FGF21 analogs currently in clinical development. Reproductive health outcomes should be included in upcoming clinical trials.

High pressure response of 1H NMR chemical shifts of purine nucleotides.

The study of the pressure response by NMR spectroscopy provides information on the thermodynamics of conformational equilibria in proteins and nucleic acids. For obtaining a database for expected pressure effects on free nucleotides and nucleotides bound in macromolecular complexes, the pressure response of 1H chemical shifts and J-coupling constants of the purine 5'-ribonucleotides AMP, ADP, ATP, GMP, GDP, and GTP were studied in the absence and presence of Mg2+-ions. Experiments are supported by quantum-chemical calculations of populations and chemical shift differences in order to corroborate structural interpretations and to estimate missing data for AMP. The preference of the ribose S puckering obtained from the analysis of the experimental J-couplings is also confirmed by the calculations. In addition, the pressure response of the non-hydrolysable GTP analogues GppNHp, GppCH2p, and GTPγS was examined within a pressure range up to 200 MPa. As observed earlier for 31P NMR chemical shifts of these nucleotides the pressure dependence of chemical shifts is clearly non-linear in most cases. In di- and tri-phospho nucleosides, the resonances of the two protons bound to the ribose 5' carbon are non-equivalent and can be observed separately. The gg-rotamer at C4'- C5' bond is strongly preferred and the downfield shifted resonance can be assigned to the H5″ proton in the nucleotides. In contrast, in adenosine itself the frequencies of the two resonances are interchanged.

Pressure response of 31P chemical shifts of adenine nucleotides.

High pressure NMR spectroscopy is a powerful method for identifying rare conformational states of proteins from the pressure response of their chemical shifts. Many proteins have bound adenine nucleotides at their active centers, in most cases in a complex with Mg2+-ions. The 31P NMR signals of phosphate groups of the nucleotides can be used as probes for conformational transitions in the proteins themselves. For distinguishing protein specific pressure effects from trivial pressure responses not due to the protein interaction, data of the pressure response of the free nucleotides must be available. Therefore, the pressure response of 31P chemical shifts of the adenine nucleotides AMP, ADP, and ATP and their Mg2+-complexes has been determined at pH values several units distant from the respective pK-values. It is clearly non-linear for most of the resonances. A negative first order pressure coefficient B1 was determined for all 31P resonances except Mg2+·AMP indicating an upfield shift of the resonances with pressure. The smallest and largest negative values are obtained for the α-phosphate group of ADP and ß-phosphate group of Mg2+·ATP with -0.32 and -4.59ppm/GPa, respectively. With exception of the α-phosphate group of Mg2+·AMP the second order pressure coefficients are positive leading to a saturation like behaviour. The pressure response of the adenine nucleotides is similar but not identical to that observed earlier for guanine nucleotides. The obtained data show that the chemical shift pressure response of the different phosphate groups is rather different dependent on the position of phosphate group in the nucleotide and the nucleotide used.