查找使用阿拉丁产品的科研文献

An undescribed biflavone from coastal halophyte Suaeda maritima subsp. salsa (L.) Soó

Di Zhang,Yujiang Dai,Xin Wang,Qi Mai,Lu Jiang,Tuanjie Wang,Huifang Li,Xing Ren,Rongbin Wei

The halophyte Suaeda maritima subsp. salsa (L.) Soó has been utilised as a traditional medicinal herb in China. Its phytochemical profile remains inadequately elucidated to date. In this study, twelve compounds, including one previously undescribed biflavonoid, 3′-methoxy-4′,4′″,5,5″-tetrahydroxy-[C7-O-C7″]-biflavone (1), and eleven known compounds (2∼12), were isolated from the whole plant of S. salsa. Their structures were fully determined via NMR, MS data analysis and literature comparison. The anti-microbial assay revealed that compounds 1, 9, and 12 exhibited an inhibitory effect against P. aeruginosa with an MIC of 25 μg/mL. Additionally, compounds 3, 5, 7, 9 and 12 displayed potent inhibitory activity against the growth of E. coli, with their MIC values ranging from 12.5 to 25 μg/mL. Furthermore, compound 1 showed the cytotoxic activity against human SGC-7901 cells with an IC50 of 89.04 ± 0.26 μm. Biflavonoid 1 represents the first reported occurrence of this class of compounds within the genus Suaeda.

Er-doped silicate fiber amplifiers in the L-band with flat gain

Yan Sun,Xin Wang,Qiubai Yang,Yafei Wang,Fan Wang,Lili Hu,Lili Hu,Lili Hu,Chunlei Yu,Chunlei Yu,Meisong Liao,Shubin Chen

Synthesis and Characterization of Terpolymers of poly(L-lactide-glycolide-ε-caprolactone)

Yun Yang,Wenjuan Liu,Jianjun Fang,Yunhui Zhao,Yanmin Zhao,Tianlong Huang,Jiale Cui,Wei Wu,Xiaofei Li,Zhihua Zhou

Random terpolymers of poly(L-lactide-glycolide-ε-caprolactone) (PLLGC) was prepared by ring-opening polymerization of L-lactide, glycolide and ε-caprolactone monomers initiated with stannous octanoate. Fourier transform infrared spectra, nuclear magnetic resonance and gel permeation chromatography were employed to characterize the obtained PLLGC terpolymers. The effects of polymerization temperature, reaction time, the amount of initiator and the polymerization pressure on the weight average molecular mass and polydispersity index of the PLLGC were investigated. In addition, the water contact angle of the PLLGC was also tested. The characterization of chemical structure showed that the PLLGC was successfully synthesized. For instance, a PLLGC terpolymer with a weight average molecular mass of about 12.435 × 104 Da and a polydispersity index of 1.28 was obtained when the polymerization was conducted with a molar ratio of monomer to initiator ([M]/[I]) of 2000, polymerization temperature of 140 °C, polymerization pressure of 5.0 Pa and reaction time of 24 h. The random incorporation of ε-CL monomer units decreased the wettability of the PLGA copolymers.

Engineering Tryptophan Synthase for Efficient Bioconversion of l-Tryptophan in Escherichia coli

Cheng Chen,Yamin Huang,Juan Li,Meijuan Xu,Hui Li,Guoqiang Xu,Jinsong Shi,Zhenghong Xu,Xiaomei Zhang

l-Tryptophan, an essential amino acid, serves as a critical precursor for the biosynthesis of numerous bioactive compounds. In this study, we engineered tryptophan synthase (TrpS) to develop an efficient cell factory for l-tryptophan production. Initially, EcTrpS from Escherichia coli K-12 was expressed in E. coli BL21 (DE3) to construct strain BS, which produced 836.43 mg/L of l-tryptophan. To alleviate substrate inhibition, we constructed a mutant library of 104–105 variants through two rounds of error-prone PCR and utilized a biosensor employing a green fluorescent protein to report l-serine consumption for screening TrpS mutants. Mutant C10 showed a 375% increase in enzyme activity compared with strain BS. Computational analysis was used to explore an improved catalytic mechanism. Finally, through systematic process optimization and catalytic strategy, strain C10 produced 94.2 g/L of l-tryptophan, the highest titer via whole-cell transformation. This study provides new perspectives and strategies for TrpS engineering and the industrial production of l-tryptophan.

Chiral Nanozyme for Highly Enantioselective Detection of 3,4-Dihydroxy-D/L-phenylalanine

Xintong Huan,Mingxin Jiang,Can Gao,Meixuan Liu,Xiaohuan Sun,Jie Han

Enantioselective sensing of 3,4-dihydroxyphenylalanine (DOPA) enantiomers is highly significant in biology and pharmaceutics, yet developing sensors with high enantioselectivity and analyte-specific output signals remains challenging. In this study, we constructed an L-cysteine (Cys)-Fe 2+ nanozyme through self-assembly of L-Cys and Fe 2+ . This nanozyme exhibited efficient peroxidase-like activity, with a K cat value of 2.1 × 10 −9 M·s −1 ·µg −1 toward 3,3“,5,5”-tetramethylbenzidine (TMB). When using D/L-DOPA as a substrate, we observed higher catalytic efficiency for L-DOPA than for D-DOPA, with a selectivity factor of 1.6. Mechanistic studies revealed that this enantioselectivity originates from the preferential adsorption of D-DOPA over L-DOPA on the nanozyme surface, which impedes the oxidation kinetics by blocking substrate access to the active sites. These chirality-specific changes induced in UV–vis absorption during catalysis enabled the establishment of analyte-specific calibration curves for D-DOPA, L-DOPA, and enantiomeric compositions in D/L-DOPA mixtures, achieving highly enantioselective sensing of DOPA enantiomers. This sensing platform demonstrated high sensitivity (limit of detection: 3.6 µM), excellent selectivity, and significant potential for practical applications. These findings provide novel insights for developing superior enantioselective sensors with high accuracy. Graphical Through the self-assembly of L-cysteine (Cys) and Fe 2+ , we constructed a novel chiral L-Cys-Fe 2+ nanozyme. This nanozyme achieved high enantioselectivity in discriminating 3,4-dihydroxy-D/L-phenylalanine (D/L-DOPA) due to enantioselective adsorption. This approach constitutes a promising new platform for reliable enantiomer detection.

Biomimetic mineralization of poly(L-lactic acid) nanofibrous microspheres for bone regeneration

Bo Li,Moyuan Qu,Haocheng Yang,Yue Shu,Wenqian Xiao,Songsong Zhu,Xiaoling Liao

Simulating the hierarchical structure of natural bone, mineralized synthetic polymer fibrils such as poly(L-lactic acid) (PLLA) in the form of microspheres show considerable potential as injectable scaffolds for bone defect repair. However, the hydrophobicity of PLLA restricts the deposition of bone-like apatite on the surface of PLLA directly, limiting its application in osteogenesis. In this paper, after sodium trimetaphosphate (STMP) modification, nanofibrous PLLA microspheres were immersed into 2.5 times simulated body fluid (2.5 ×SBF) for 3 days to produce abundant bone-like apatite on the surface of microspheres. The bioactivity in vitro and bone repair ability in vivo of surface mineralized PLLA microspheres were evaluated. The results indicated that surface mineralized nanofibrous PLLA microspheres improved MSCs proliferation and bone-related gene expression, including OPN, RUNX-2 and OCN. After the surface mineralized nanofibrous PLLA microspheres were implanted into rat skulls to repair bone defects (5 mm) for 6 weeks, the micro-CT and histology results showed that the surface mineralized nanofibrous PLLA microspheres improved bone regeneration compared to pure nanofibrous PLLA microspheres. Our study provides a feasible strategy for the rapid preparation of biomimetic mineralized PLLA scaffolds, the novel mineralized microspheres showed considerable bone repair potential.

The chemosensory protein 1 contributes to indoxacarb resistance in Plutella xylostella (L.)

Yifan Li,Shujun Ni,Yunping Wang,Ruichi Li,Hong Sun,Xuan Ye,Zhen Tian,Yalin Zhang,Jiyuan Liu

BACKGROUND Insecticide resistance continuously poses a threat to agricultural production. Chemosensory protein-mediated resistance is a new mechanism of insecticide resistance discovered in recent years. In-depth research on resistance mediated by chemosensory proteins (CSPs) provides new insight into aid insecticide resistance management. RESULTS Chemosensory protein 1 in Plutella xylostella ( PxCSP1 ) was overexpressed in the two indoxacarb-resistant field populations and PxCSP1 has a high affinity with indoxacarb. PxCSP1 was upregulated when exposed to indoxacarb and the knockdown of this gene elevated sensitivity to indoxacarb, which demonstrate that PxCSP1 is involved in the indoxacarb resistance. Considering that CSPs may confer resistance in insects via binding or sequestering, we explored the binding mechanism of indoxacarb in PxCSP1 -mediated resistance. Using molecular dynamics simulations and site-directed mutation, we found that indoxacarb forms a solid complex with PxCSP1 mainly through van der Waals interactions and electrostatic interactions. Between these, the electrostatic interaction provided by the Lys100 side chain in PxCSP1 , and especially the hydrogen bonding between the NZ atom and the O of the carbamoyl carbonyl group of indoxacarb, are the key factors for the high affinity of PxCSP1 to indoxacarb. CONCLUSIONS The overexpression of PxCPS1 and its high affinity to indoxacarb is partially responsible for indoxacarb resistance in P. xylostella . Modification of indoxacarb's carbamoyl group has the potential to alleviate indoxacarb resistance in P. xylostella . These findings will contribute to solving chemosensory protein-mediated indoxacarb resistance and provide a better understanding of the insecticide resistance mechanism. © 2023 Society of Chemical Industry.

Removal of atrazine from submerged soil using vetiver grass (Chrysopogon zizanioides L.)

Faming Zhang,Jiansong Peng,Yuhong Rong,Shixian Sun,Yi Zheng

The long-term widespread application of atrazine poses significant threats to the eco-environment and human health. To investigate the potential of vetiver (Chrysopogon zizanioides L.) for phytoremediation of the environmental media contaminated by atrazine, an indoor incubation experiment was conducted in submerged soil over 30 days. Results showed that the chlorophyll level of the vetiver was not significantly affected by exposure to atrazine. Vetiver could take up and accumulate atrazine from submerged soil and peaked around the 20th day with a concentration of 1.0 mg kg−1 in leaf. The metabolites Hydroxyatrazine (HA), deethylatrazine (DEA), Deisopropylatrazine (DIA), and didealkylatrazine (DDA) were detected in the leaf on the 30th day, indicating vetiver could degrade atrazine inside the leaf tissue. The atrazine removal rate in the vetiver planted and unplanted jars were 69.72 and 60.29%, respectively, indicating that 9.43% higher atrazine removal was achieved in the presence of vetiver (p < 0.05). The atrazine dissipation in the submerged soil followed first-order kinetics, the degradation constant was 0.066, and the half-life of atrazine dissipation was shortened by 6.86 days in the presence of vetiver. The present study suggests that vetiver can take up atrazine from submerged soil and accumulate in the leaf, which could then degrade in the leaf.Novelty statement: Although the fate of atrazine in agricultural soils has been extensively investigated through various experiments, little is known about the effect of vetiver grass on atrazine dissipation from submerged soil. With the identification of soil-leaf transportation and four metabolites in vetiver leaf and soils, significantly accelerated atrazine dissipation from the submerged soil was achieved in the presence of vetiver. Particularly, the formation of less toxic dealkylated products in the leaf indicated vetiver is a promising grass for atrazine removal from submerged soil.

Purification, Characterization and Bioactivities of Polysaccharides Extracted from Safflower (Carthamus tinctorius L.)

Qiongqiong Wang,Shiqi Liu,Long Xu,Bin Du,Lijun Song

Polysaccharides are the main bioactive components in safflower. In this study, safflower polysaccharides (SPs) were extracted by ultrasonic assisted extraction, and four purified safflower polysaccharide fractions (named SSP1, SSP2, SSP3, and SSP4, respectively) were obtained. The physicochemical properties and in vitro physiological activities of the four fractions were investigated. The molecular weights (MW) of the SSPs were 38.03 kDa, 43.17 kDa, 54.49 kDa, and 76.92 kDa, respectively. Glucuronic acid, galactose acid, glucose, galactose, and arabinose were the main monosaccharides. The Fourier transform infrared spectroscopy (FT-IR) indicated that the polysaccharides hadα- andβ-glycosidic bonds. Nuclear magnetic resonance (NMR) analysis showed that SSP1 had 6 different types of glycosidic bonds, while SSP3 had 8 different types. SSP3 exhibited relatively higher ABTS+scavenging activity, Fe+3-reduction activity, and antiproliferative activity. The results will offer a theoretical framework for the use of SPs in the industry of functional foods and medications.Keywords:safflower;polysaccharides;structures characterization;physiological activities

Production of Salvianic Acid A from l-DOPA via Biocatalytic Cascade Reactions

Ke Shun Hu,Chong Le Chen,Huan Ru Ding,Tian Yu Wang,Qin Zhu,Yi Chen Zhou,Jia Min Chen,Jia Qi Mei,Sheng Hu,Jun Huang,Wei Rui Zhao,Le He Mei

Salvianic acid A (SAA), as the main bioactive component of the traditional Chinese herbSalvia miltiorrhiza, has important application value in the treatment of cardiovascular diseases. In this study, a two-step bioprocess for the preparation of SAA froml-DOPA was developed. In the first step,l-DOPA was transformed to 3,4-dihydroxyphenylalanine (DHPPA) using engineeredEscherichia colicells expressing membrane-bound L-amino acid deaminase fromProteus vulgaris.After that, the unpurified DHPPA was directly converted into SAA by permeabilized recombinantE. colicells co-expressingd-lactate dehydrogenase fromPediococcus acidilacticiand formate dehydrogenase fromMycobacterium vaccaeN10. Under optimized conditions, 48.3 mM of SAA could be prepared from 50 mM ofl-DOPA, with a yield of 96.6%. Therefore, the bioprocess developed here was not only environmentally friendly, but also exhibited excellent production efficiency and, thus, is promising for industrial SAA production.Keywords:salvianic acid A;l-DOPA;membrane-boundl-amino acid deaminases;biocatalysis;molecular biology;biological engineering

Preparation, characterization and bioactivities of selenized polysaccharides from Lonicera caerulea L. fruits

Chuntian Shao,Jingwei Zhong,Junwen Liu,Yiyan Yang,Meilin Li,Yang Yu,Yaqin Xu,Libo Wang

Native polysaccharide was obtained from Lonicera caerulea L. fruits (PLP). Two selenized polysaccharides (PSLP-1 and PSLP-2) were synthesized by the microwave-assisted HNO 3 -Na 2 SeO 3 method, where the selenium (Se) contents were 228 ± 24 and 353 ± 36 μg/g, respectively. The molecular weights of PLP, PSLP-1, and PSLP-2 were 5.9 × 10 4 , 5.6 × 10 4 , and 5.1 × 10 4  kDa, respectively. PSLP-1 and PSLP-2 contained the same type of monosaccharides as PLP but with different molar ratios. The main chain structure of the native polysaccharide was not changed after selenization. PLP, PSLP-1, and PSLP-2 contained the same six types of glycosidic bonds. Bioactivity assays revealed that the two selenized polysaccharides possessed better antioxidant activities than PLP, but their bile acid-binding abilities and inhibitory activities on acetylcholinesterase (AChE) had weakened. In summary, PLP, PSLP-1, and PSLP-2 may be promising Se supplements in functional foods and inhibitors for the treatment of AChE.

The Response of Thiols to Cadmium Stress in Spinach (Spinacia Oleracea L.)

Ya Gao,Haipu Li,Yang Song,Fenglin Zhang,Zhaoguang Yang

The aim of this study is to examine the thiol species for the high cadmium (Cd) tolerance of spinach and provide information for the improvement of soil utilization. The spinach was cultured in aqueous solution with concentrations of Cd ranging from 1 to 9 mg/L. The time responses of glutathione (GSH) and phytochelatins (PCs, PC2-PC4) in the tissues of spinach were monitored via HPLC–MS/MS, and the concentrations of Cd in the roots, shoots and leaves were detected by ICP–OES. Data were analyzed via one-way ANOVA and Spearman correlation to assess the relationships among the types of thiols and the changes between types of thiols and Cd. As Cd stress increased, Cd concentrations in tissues also increased. The total thiol contents responded to Cd stresses with correlations r ranging from 0.394 (root), 0.520 (shoot) to 0.771 (leaf) (p< 0.01). GSH and PC3were dominant on most of the days under Cd stress. The correlationrbetween improvements in GSH and increments of Cd concentration in roots was −0.808 (p< 0.01), andrbetween changes in PC3and changes in Cd concentrations in leaves was −0.503 (p< 0.01). No correlation can be found between GSH and the subtypes of PCs in shoots, but strong positive correlations within the subtypes of PCs. Thiols can be produced in different tissues of spinach, while the shoots are only a transport tissue for GSH.Keywords:glutathione;subtypes of phytochelatin;cadmium;spinach;response