Measurement and Correlation of Solubility of Loratadine in Different Pure Solvents and Binary Mixtures

The solubility of loratadine in pure solvents and binary mixed solvents is measured at the temperature range from 283.15 to 323.15 K using a laser technique. The results indicate that the solubility of loratadine increases with the increasing temperature in all these selected solvents. The solubility of loratadine reaches the maximum value when the mole fraction of methanol is 0.7 in the binary solvent mixtures of methanol + acetonitrile. Also, in the system of <i>n</i>-pentanol + acetonitrile mixed solvent the solubility reaches the maximum value when the mole fraction of <i>n</i>-pentanol is 0.6. The modified Apelblat equation and three parameters van’t Hoff equation are applied to correlate the experimental solubility in pure solvents. In binary mixed solvents, the modified Apelblat equation and Jouyban-Acree model are used to correlate the solubility data

Experimental and Theoretical Study for Vapor Phase Aldol Condensation of Methyl Acetate and Formaldehyde over Alkali Metal Oxides Supported on SBA-15

Alkali metal oxides supported on SBA-15, M/SBA-15 (M = Li, Na, K, Rb, and Cs), prepared by the impregnation method were characterized and tested for the aldol condensation of methyl acetate and formaldehyde to methyl acrylate (MA). M/SBA-15 catalysts are active for the formation of MA while the support is inert. The supported alkali metals react with hydroxyl groups on SBA-15 by replacing the H atoms and generate weak and medium basic sites. The latter plays an important role in promoting the reaction. Coke formation results in deactivation of Cs/SBA-15, and the deactivated catalyst can be regenerated by burning off the coke. Two possible reaction pathways for the formation of MA were explored using quantum calculations. The predicated activity for M/SBA-15 is consistent with the experimental observations. A pathway with adsorbed enol molecule as an intermediate was suggested to be predominant for the formation of MA

Measurement and Correlation of Solubility on Reactive Crystallization of Methyl D‑(−)-4-Hydroxy-phenylglycinate

In this paper, the solubility of methyl D-(−)-4-hydroxy-phenylglycinate was measured under the different pH levels, pure solvents, mixed solvents, ionic strength, and impurities in the temperature range from 283 to 323 about 5 K intervals by using laser method at atmospheric pressure. The results reveal that the solubility of methyl D-(−)-4-hydroxy-phenylglycinate increases with increasing temperature in all selected solvents, which decreases with increasing mole fraction composition of water in the mixed solvents. The solubility curve of methyl D-(−)-4-hydroxy-phenylglycinate in the aqueous solution at different pH is “U” shape and the solubility of methyl D-(−)-4-hydroxy-phenylglycinate increases with concentrations of ammonium chloride and has no obvious changes when its concentration increases up to 1.25 mol/kg. It is beneficial to maximize the reaction conversion rate of D-4-hydroxyphenylglycine methyl ester hydrochloride and reduce the residual D-4-hydroxyphenylglycine methyl ester hydrochloride on reactive crystallization of methyl D-(−)-4-hydroxy-phenylglycinate. Furthermore, the modified Apelblat equation and <i>C</i>_T = <i>C</i>₀(α_H⁺/<i>k</i>₁ + <i>k</i>₂/α_H⁺ + 1) type correlation regression model have made good correlation of the experimental solubility in pure solvents, mixed solvents, and the aqueous solution at different pH, respectively

Digital Circulating Tumor Cells Quantification

Circulating tumor cells (CTCs) are an emerging but vital biomarker for cancer management. An efficient methodology for accurately quantifying CTCs remains challenging due to their rareness. Here, we develop a digital CTC detection strategy using partitioning instead of enrichment to quantify CTCs. By utilizing the characteristics of droplet microfluidics that can rapidly generate a large number of parallel independent reactors, combined with Poisson distribution, we realize the quantification of CTCs in the blood directly. The limit of detection of our digital CTCs quantification assay is five cells per 5 mL of whole blood. By simultaneously detecting multiple genetic mutations, our approach achieves highly sensitive and specific detection of CTCs in peripheral blood from NSCLC patients (AUC = 1). Our digital platform offers a potential approach and strategy for the quantification of CTCs, which could contribute to the advancement of cancer medical management

Metabolic Engineering of Escherichia coli for Efficient Production of Pseudouridine

Pseudouridine-incorporated mRNA vaccines can enhance protein expression and reduce immunogenicity, leading to a high demand for pseudouridine to be used in mRNA drug production. To achieve the low-cost production of pseudouridine, Escherichia coli was systematically modified to utilize inexpensive raw materials to efficiently produce pseudouridine. First, in the pyrimidine biosynthesis pathway, genes related to the precursor competing pathway and the negative regulator were deleted, which increased pseudouridine production. Second, two critical genes, pseudouridine-5′-phosphate glycosidase (psuG) and phosphatase genes from different bacteria, were screened and employed in various genetic constructs, and the pseudouridine yield of the optical strain increased to 599 mg/L. The accumulation of pseudouridine was further increased by the deletion of pseudouridine catabolism-related genes. Ultimately, the pseudouridine titer in a 5 L bioreactor reached 7.9 g/L, and the yield of pseudouridine on glucose was 0.15 g/g. Overall, a cell factory producing pseudouridine was successfully constructed and showed potential for industrial production

A new species of <i>Cyathocarpus</i> with <i>in situ</i> spores from the lower Permian of Gansu, northwestern China

<p>Well-preserved Marattialean fertile fronds are analyzed in this paper that come from the Cisuralian Shanxi Formation of Yongchang, Gansu Province, northwestern China. In particular, synangium in fronds and <i>in situ</i> spores are analyzed in the lab. Data show that the synangium of this species contains between four and five radially arranged pedicellate sporangia. The spores of this plant are small, between 21 and 30 μm, monolete and microgranulate with no visible annule. The fossils presented in this study are included within the genus <i>Cyathocarpus</i>. Furthermore, these spore masses and spores <i>in situ</i> of this genus are described in detail at the first time as a component of the Cathaysian flora. Based on comparisons with previously reported fossil records of these plants, we determined a series of differences. Thus, the fossils presented here are referred to a new species. In addition, the reproductive organs of the new fossils described in this paper provide some valuable taxonomic information. Based on the paleogeographic distribution of <i>Cyathocarpus</i> and the position of paleoplates in Late Paleozoic, we speculated that one of the possible migrated routes of <i>Cyathocarpus</i> is from the Euramerica to the North China Block and Alashan Terrane, terminating in the South China Block.</p

New fossil leaves and fruits of Lauraceae from the Middle Miocene of Fujian, southeastern China differentiated using a cluster analysis

<p>The fossil record of Lauraceae can be traced back to the Early Cretaceous of eastern Asia based on fossil flowers. Here, we refer a number of new occurrences of leaf and fruit fossils of Lauraceae from the Middle Miocene of Zhangpu, Fujian, China, to seven species. These data provide evidence supporting the fact that a diverse subtropical, or tropical, Lauraceae-dominated evergreen forest surrounded this region 15 million years ago (Mya). The Lauraceae fossils presented in this paper provide evidence for the evolution of this group as well as new materials that enable the study of the Fujian Province Neogene flora. The fossils described in this paper fill in the gaps in studies about Lauraceae pollen in the Middle Miocene from Fotan, Fujian, China. In addition, these fossils also enrich the Middle Miocene fossil records of Lauraceae in eastern Asia, especially improving the study of the macrostructures and reproductive organs of fossil Lauraceae from southern China. The similarity between fossil and modern fruits shows that during the Middle Miocene the fruit morphological of Lauraceae have changed very little. We also identify families where the fossils we report belong to their closest relatives and can be used to reconstruct the paleoenvironment of Fujian in the Middle Miocene.</p

The diversity and paleoenvironmental significance of <i>Calophyllum</i> (Clusiaceae) from the Miocene of southeastern China

<p>Three species within the genus <i>Calophyllum</i> collected from middle Miocene Fotan Group sediments in Zhangpu County, Fujian, southeastern China are described in this paper. These fossils include <i>Calophyllum zhangpuensis</i> sp. nov., <i>Calophyllum striatum</i>, and <i>Calophyllum suraikholaensis</i>. The new fossil species <i>C. zhangpuensis</i> sp. nov. is oval, possesses entire leaves with closely spaced parallel secondary veins and has a round, or slightly retuse, apex. These specimens represent the first known fossil records of this relative wide leaf-type form of <i>Calophyllum</i> from China and have a length:width (L:W) ratio less than 3:1. In combination with the known modern geographic distribution and habitats of this wide leaf-type <i>Calophyllum</i> and other plants, data suggest that the middle Miocene Fotan flora is indicative of a warm climate. Thus, based on available fossil data, we speculate that this genus probably originated in India during the Paleocene before spreading from India to Bangladesh and into China, Sumatra, Malaysia, Indonesia, and Java during the Neogene, leading to its modern distribution. At least, the 3 fossil species in this region can explain floristic exchange between India, Fujian, and South China, which is consistent with previous studies; the occurrence of these 3 species indicates that <i>Calophyllum</i> began to diversity in China no later than the Miocene.</p

Table_3_Streptomyces nigra sp. nov. Is a Novel Actinobacterium Isolated From Mangrove Soil and Exerts a Potent Antitumor Activity in Vitro.pdf

<p>A new bacterial strain, designated 452^T, was isolated from the rhizosphere soil of the mangrove Avicennia marina in China. As determined, its cell wall peptidoglycan contained LL-diaminopimelic acid; MK-9(H8) and MK-9(H6) were the major isoprenoid quinones; and iso-C_16:0 (31.3%), anteiso-C_15:0 (16.9%), and iso-C_15:0 (12.5%) were the major cellular fatty acids (>10.0%). Phylogenetic analysis based on the 16S rRNA gene sequence revealed that strain 452^T formed a distinct lineage in the clade of the genus Streptomyces, and was closely related to S. coerulescens DSM 40146^T (99.6% sequence identity), S. bellus DSM 40185^T (99.5%), and S. coeruleorubidus DSM 41172^T (99.3%). The DNA-DNA relatedness between strain 452^T and these type strains ranged between 29.3 and 42.3%. Based on the phenotypic, chemotaxonomic, and phylogenetic features, the strain 452^T is considered to represent a novel species of the genus Streptomyces, for which the name Streptomyces nigra sp. nov. is proposed. The type strain is 452^T (=KCTC 39960^T = MCCC 1K03346^T). Further, strain 452^T extracts exhibited a pronounced antitumor activity against human cancer cell lines A549, HCT-116, and HepG2, but not against normal human colon cells CCD-18Co. Active substances in the fermentation broth of strain 452^T were isolated by bioassay-guided analysis, and then purified using a macroporous resin, silica gel, sephadex LX-20 column, and semi-preparative high-performance liquid chromatography (HPLC). Eight proline-containing diketopiperazines, namely, cyclo(Pro-Ala), cyclo(Pro-Gly), cyclo(Pro-Phe), cyclo(Pro-Met), cyclo(Pro-Val), cyclo(Pro-Leu), cyclo(Pro-Tyr), and cyclo(L-Leu-trans-4-hydroxy-L-Pro), were identified by electrospray ionization mass spectrometry (MS) and nuclear magnetic resonance (NMR). The compounds displayed different levels of cytotoxicity. The highest cytotoxicity was exhibited by cyclo(Pro-Ala) and cyclo(Pro-Met) against A549 cells, and cyclo(Phe-Pro) and cyclo(Pro-Ala) against HCT-116 cells, with average IC₅₀ values equal to 18.5, 27.3, 32.3, and 47.6 μg/mL, respectively. The diversity of diketopiperazines and other chemicals produced by 452^T was further investigated using gas chromatography (GC)-MS and liquid chromatography (LC)-MS. The analysis revealed 16 types of metabolites with antitumor activity and 16 other types of diketopiperazines. Hence, extracts of the newly identified strain may be used a starting material for the development of antitumor agents.</p

Image_2_Streptomyces nigra sp. nov. Is a Novel Actinobacterium Isolated From Mangrove Soil and Exerts a Potent Antitumor Activity in Vitro.pdf

<p>A new bacterial strain, designated 452^T, was isolated from the rhizosphere soil of the mangrove Avicennia marina in China. As determined, its cell wall peptidoglycan contained LL-diaminopimelic acid; MK-9(H8) and MK-9(H6) were the major isoprenoid quinones; and iso-C_16:0 (31.3%), anteiso-C_15:0 (16.9%), and iso-C_15:0 (12.5%) were the major cellular fatty acids (>10.0%). Phylogenetic analysis based on the 16S rRNA gene sequence revealed that strain 452^T formed a distinct lineage in the clade of the genus Streptomyces, and was closely related to S. coerulescens DSM 40146^T (99.6% sequence identity), S. bellus DSM 40185^T (99.5%), and S. coeruleorubidus DSM 41172^T (99.3%). The DNA-DNA relatedness between strain 452^T and these type strains ranged between 29.3 and 42.3%. Based on the phenotypic, chemotaxonomic, and phylogenetic features, the strain 452^T is considered to represent a novel species of the genus Streptomyces, for which the name Streptomyces nigra sp. nov. is proposed. The type strain is 452^T (=KCTC 39960^T = MCCC 1K03346^T). Further, strain 452^T extracts exhibited a pronounced antitumor activity against human cancer cell lines A549, HCT-116, and HepG2, but not against normal human colon cells CCD-18Co. Active substances in the fermentation broth of strain 452^T were isolated by bioassay-guided analysis, and then purified using a macroporous resin, silica gel, sephadex LX-20 column, and semi-preparative high-performance liquid chromatography (HPLC). Eight proline-containing diketopiperazines, namely, cyclo(Pro-Ala), cyclo(Pro-Gly), cyclo(Pro-Phe), cyclo(Pro-Met), cyclo(Pro-Val), cyclo(Pro-Leu), cyclo(Pro-Tyr), and cyclo(L-Leu-trans-4-hydroxy-L-Pro), were identified by electrospray ionization mass spectrometry (MS) and nuclear magnetic resonance (NMR). The compounds displayed different levels of cytotoxicity. The highest cytotoxicity was exhibited by cyclo(Pro-Ala) and cyclo(Pro-Met) against A549 cells, and cyclo(Phe-Pro) and cyclo(Pro-Ala) against HCT-116 cells, with average IC₅₀ values equal to 18.5, 27.3, 32.3, and 47.6 μg/mL, respectively. The diversity of diketopiperazines and other chemicals produced by 452^T was further investigated using gas chromatography (GC)-MS and liquid chromatography (LC)-MS. The analysis revealed 16 types of metabolites with antitumor activity and 16 other types of diketopiperazines. Hence, extracts of the newly identified strain may be used a starting material for the development of antitumor agents.</p