AIM:To investigate the relationship between plasma acylated ghrelin levels and the pathophysiology of functional dyspepsia.METHODS:Twenty-two female patients with functional dyspepsia and twelve healthy volunteers wer...AIM:To investigate the relationship between plasma acylated ghrelin levels and the pathophysiology of functional dyspepsia.METHODS:Twenty-two female patients with functional dyspepsia and twelve healthy volunteers were recruited for the study.The functional dyspepsia patients were each diagnosed based on the Rome Ⅲ criteria.Eligible patients completed a questionnaire concerning the severity of 10 symptoms.Plasma acylated ghrelin levels before and after a meal were determined in the study participants using a commercial human acylated enzyme immunoassay kit;electrogastrograms were performed for 50 min before and after a standardized 10-min meal containing 265 kcal.RESULTS:There were no significant differences in plasma acylated ghrelin levels between healthy volunteers and patients with functional dyspepsia.However,in patients with functional dyspepsia,there was a negative correlation between fasting plasma acylated ghrelin levels and the sum score of epigastric pain(r =-0.427,P = 0.047) and a positive correlation between the postprandial/fasting plasma acylated ghrelin ratio and the sum score of early satiety(r = 0.428,P =0.047).Additionally,there was a negative correlation between fasting acylated ghrelin plasma levels and fasting normogastria(%)(r =-0.522,P = 0.013).Interestingly,two functional dyspepsia patients showed paradoxically elevated plasma acylated ghrelin levels after the meal.CONCLUSION:Abnormal plasma acylated ghrelin levels before or after a meal may be related to several of the dyspeptic symptoms seen in patients with functional dyspepsia.展开更多
Previous phytochemical investigation of the leaves and seeds of Pittosporum angustifolium Lodd.led to the isolation and structural elucidation of polyphenols and triterpene saponins.Evaluation for cytotoxicity of isol...Previous phytochemical investigation of the leaves and seeds of Pittosporum angustifolium Lodd.led to the isolation and structural elucidation of polyphenols and triterpene saponins.Evaluation for cytotoxicity of isolated saponins revealed that the predominant structural feature for a cytotoxic activity are acyl substituents at the oleanane aglycon backbone.The present work reports the results of a screening of 10 selected acylated saponins for their potential to inhibit the human DNA-topoisomerase I,giving rise to IC50 values in a range of 2.8-46.5 lM.To clarify the mode of observed cytotoxic action and,moreover,to distinguish from a pure surfactant effect which is commonly accompanied with saponins,these results indicate an involvement of the topoisomerase I and its role as a possible target structure for a cytotoxic activity.In addition,computational predictions of the fitting of saponins to the topoisomerase I-DNA complex,indicate a similar binding mode to that of clinically used topoisomerase I inhibitors.Graphical Abstract Ten acylated triterpene saponins from Pittosporum angustifolium were investigated for their potential to inhibit the human DNA-topoisomerase I and computational predictions of the fitting of saponins to the topoisomerase I-DNA complex were carried out.展开更多
A new triterpenoid saponin, named silenoside, with sugar chains esterified by two different acyl groups was isolated from Silene szechuensis. Its structure was elucidated by chemical and spectral methods.
Fully acylated chitosan and N, N-diacyl chitosan were prepared. The products were characterized by elemental analysis, FTIR and 1H NMR. The experimental results indicate that the average degree of acylation depends ...Fully acylated chitosan and N, N-diacyl chitosan were prepared. The products were characterized by elemental analysis, FTIR and 1H NMR. The experimental results indicate that the average degree of acylation depends on the volume ratio of pyridine to chloroform in the reaction medium, the chain length of the acylation agent used, and the molecular weight of chitosan raw materials. The XRD measurements were carried out for pure chitosan, fully acylated chitosan and N, N-diacyl chitosan to verify the crystallinity change caused by the acylation.展开更多
Twelve anthocyanins （1-12） were isolated from the red flowers of Camellia hongkongensis Seem. by chromatography using open columns. Their structures were elucidated on the basis of spectroscopic analyses, that is, p...Twelve anthocyanins （1-12） were isolated from the red flowers of Camellia hongkongensis Seem. by chromatography using open columns. Their structures were elucidated on the basis of spectroscopic analyses, that is, proton-nuclear magnetic resonance, carbon 13-nuclear magnetic resonance, heteronuclear multiple quantum correlation, heteronuclear multiple bond correlation, high resolution electrospray ionization mass and ultraviolet visible spectroscopies. Out of these anthocyanins, a novel acylated anthocyanin, cyanidin 3-O-（6-O-（Z）-p-coumaroyl）-β-galactopyranoside （6）, two known acylated anthocyanins, cyanidin 3-O-（6-O-（E）-p-coumaroyl）-β-galactopyranoside （7） and cyanidin 3-O-（6-O-（E）-caffeoyl）-^- galactopyranoside （8）, and three known delphinidin glycosides （10-12） were for the first time isolated from the genus Camellia. Furthermore, pigment components in C. japonica L., C. chekiangoleosa Hu and C. semiserrata Chi were studied. The results indicated that the distribution of anthocyanins was differed among these species. Delphinidin glycoside was only detected in the flowers of C. hongkongensis, which is a special and important species in the section Camellia. Based on the characterization of anthocyanins in the section Camellia species, there is a close relationship among these species, and C. hongkongensis might be an important parent for creating new cultivars with bluish flower color.展开更多
Herein we describe the discovery and functional characterization of a steroidal glycosyltransferase(SGT) from Ornithogalum saundersiae and a steroidal glycoside acyltransferase(SGA) from Escherichia coli and their app...Herein we describe the discovery and functional characterization of a steroidal glycosyltransferase(SGT) from Ornithogalum saundersiae and a steroidal glycoside acyltransferase(SGA) from Escherichia coli and their application in the biosynthesis of acylated steroidal glycosides(ASGs). Initially,an SGT gene, designated as OsSGT1, was isolated from O. saundersiae. OsSGT1-containing cell free extract was then used as the biocatalyst to react with 49 structurally diverse drug-like compounds. The recombinant OsSGT1 was shown to be active against both 3β-and 17β-hydroxyl steroids. Unexpectedly,in an effort to identify OsSGT1, we found the bacteria lacA gene in lac operon actually encoded an SGA,specifically catalyzing the acetylations of sugar moieties of steroid 17β-glucosides. Finally, a novel enzymatic two-step synthesis of two ASGs, acetylated testosterone-17-O-β-glucosides(AT-17β-Gs) and acetylated estradiol-17-O-β-glucosides(AE-17β-Gs), from the abundantly available free steroids using OsSGT1 and EcSGA1 as the biocatalysts was developed. The two-step process is characterized by EcSGA1-catalyzed regioselective acylations of all hydroxyl groups on the sugar unit of unprotected steroidal glycosides(SGs) in the late stage, thereby significantly streamlining the synthetic route towards ASGs and thus forming four monoacylates. The improved cytotoxic activities of 30-acetylated testosterone17-O-β-glucoside towards seven human tumor cell lines were thus observable.展开更多
Indole[2,1-α]isoquinolines are an important class of bioactive molecules and show good antibacterial activity.In the present study,an efficient copper(I)-catalyzed acylation/cyclization has been developed for the con...Indole[2,1-α]isoquinolines are an important class of bioactive molecules and show good antibacterial activity.In the present study,an efficient copper(I)-catalyzed acylation/cyclization has been developed for the construction of indolo[2,1-α]isoquinoline derivatives by utilizing 2-aryl-N-acryloyl indole and benzohydrazide as reactants in the presence of CuI as catalyst and tert-butyl hydroperoxide as oxidant.The present protocol exhibits good functional group tolerance,and a series of acylated indole[2,1-α]isoquinolines were synthesized in moderate to good yields.Radical trapping experiments indicated that the reaction may involve a radical process.展开更多
Highly toxic phosgene,diethyl chlorophosphate(DCP)and volatile acyl chlorides endanger our life and public security.To achieve facile sensing and discrimination of multiple target analytes,herein,we presented a single...Highly toxic phosgene,diethyl chlorophosphate(DCP)and volatile acyl chlorides endanger our life and public security.To achieve facile sensing and discrimination of multiple target analytes,herein,we presented a single fluorescent probe(BDP-CHD)for high-throughput screening of phosgene,DCP and volatile acyl chlorides.The probe underwent a covalent cascade reaction with phosgene to form boron dipyrromethene(BODIPY)with bright green fluorescence.By contrast,DCP,diphosgene and acyl chlorides can covalently assembled with the probe,giving rise to strong blue fluorescence.The probe has demonstrated high-throughput detection capability,high sensitivity,fast response(within 3 s)and parts per trillion(ppt)level detection limit.Furthermore,a portable platform based on BDP-CHD was constructed,which has achieved high-throughput discrimination of 16 analytes through linear discriminant analysis(LDA).Moreover,a smartphone adaptable RGB recognition pattern was established for the quantitative detection of multi-analytes.Therefore,this portable fluorescence sensing platform can serve as a versatile tool for rapid and high-throughput detection of toxic phosgene,DCP and volatile acyl chlorides.The proposed“one for more”strategy simplifies multi-target discrimination procedures and holds great promise for various sensing applications.展开更多
Polyhydroxyalkanoate(PHA),a well-known biodegradable polymer,featuresβ-lactones as its monomers,which can be selectively synthesized through ring-expansion carbonylation of epoxides using well-defined[Lewis acid]^(+)...Polyhydroxyalkanoate(PHA),a well-known biodegradable polymer,featuresβ-lactones as its monomers,which can be selectively synthesized through ring-expansion carbonylation of epoxides using well-defined[Lewis acid]^(+)[Co(CO)_(4)]^(-)catalysts.However,the decomposition of[Co(CO)_(4)]^(-)species at temperatures exceeding 80℃presents a hurdle for the development of commercially viable processes under high-temperature reaction conditions to reduce reaction time.Drawing insights from stable{(acyl)Co(CO)n}intermediates involved in historical HCo(CO)_(4)-catalyzed hydroformylation processes,we sought to the high-temperature catalytic activity of epoxide ring-expansion carbonylation.The developed catalyst system,[(acetyl)Co(CO)_(2)dppp]and[(TPP)CrCl],exhibited exceptional catalytic performance with an unprecedented initial turnover frequency of 4700 h^(-1)at 100℃and a turnover numbers of 93000.Notably,the catalyst displayed outstanding stability,operating at 80℃for 168 h while selectively generatingβ-lactones.展开更多
Mechanistic studies of the cleavage and transformation of unactivated C_(sp3)-H bonds are a significant field of chemistry.Overcoming the inherent low acidity of C-H bonds to activate the inert substrates is challenge...Mechanistic studies of the cleavage and transformation of unactivated C_(sp3)-H bonds are a significant field of chemistry.Overcoming the inherent low acidity of C-H bonds to activate the inert substrates is challenge under mild conditions.And their complex multi-step transformations may also hinder mechanistic understanding.Herein,we perform theoretical calculations and experimental studies to explore the C_(sp3)-H bonds activation and acylation mechanisms of toluene/thioether using the relatively weak base LDA.A synergistic"main and auxiliary"model was revealed involving dual lithium metal by LDA dimers,and the aryl dilithium species as an intermediate base can facilitate C_(sp3)-H activation.This model not only aids in understanding the acidity of unactivated C_(sp3)-H bonds and the nucleophilicity of their conjugate bases for their kinetic control through cooperative interactions,but also predicts unusual kinetic isotope effects(KIE)for newly designed 2-(methylthio)naphthalene that are experimentally validated.This research is expected to provide a crucial scenario for the cleavage and transformation of unactivated C_(sp3)-H bonds and the development of new functionalities for alkali metal reagents.展开更多
Ghrelin is a 28 amino acid peptide mainly derived from the oxyntic gland of the stomach. Both acylated(AG) and unacylated(UAG) forms of ghrelin are found in the circulation. Initially, AG was considered as the only bi...Ghrelin is a 28 amino acid peptide mainly derived from the oxyntic gland of the stomach. Both acylated(AG) and unacylated(UAG) forms of ghrelin are found in the circulation. Initially, AG was considered as the only bioactive form of ghrelin. However, recent advances indicate that both AG and UAG exert distinct and common effects in organisms. Soon after its discovery, ghrelin was shown to promote appetite and adiposity in animal and human models. In response to these anabolic effects, an impressive number of elements have suggested the influence of ghrelin on the regulation of metabolic functions and the development of obesityrelated disorders. However, due to the complexity ofits biochemical nature and the physiological processes it governs, some of the effects of ghrelin are still debated in the literature. Evidence suggests that ghrelin influences glucose homeostasis through the modulation of insulin secretion and insulin receptor signaling. On the other hand, insulin was also shown to influence circulating levels of ghrelin. Here, we review the relationship between ghrelin and insulin and we describe the impact of this interaction on the modulation of glucose homeostasis.展开更多
The regioselective acylation of unprotected phenylethyl glucoside withcinnamoyl chloride leads to 6-OH cin-namoylated glucoside. In this manner, thirteen phenylpropanoidglycoside analogs were designed and prepared. Th...The regioselective acylation of unprotected phenylethyl glucoside withcinnamoyl chloride leads to 6-OH cin-namoylated glucoside. In this manner, thirteen phenylpropanoidglycoside analogs were designed and prepared. Their structure was confirmed by ~1H NMR and ^(13)CNMR spectra.展开更多
Several phenylselenyl esters were selected as precursors of acyl radicals and synthesised by our established method. Treatment of these phenylselenyl esters with tributyltinhydride and AIBN ge...Several phenylselenyl esters were selected as precursors of acyl radicals and synthesised by our established method. Treatment of these phenylselenyl esters with tributyltinhydride and AIBN generated the corresponding acyl radicals, which were found to proceed in 5 exo trig or 6 endo trig cyclisations to afford high yields of cyclopentanones and cyclohexanones, The substitution groups on the substrates have played an important role on the regioselectivity of cyclisations.展开更多
Development of modified plastics has been studied through the LDPE-acylated starch blend films to examine the effect of different acyl groups and degrees of substitution （DS） on properties of films. Corn starch was ...Development of modified plastics has been studied through the LDPE-acylated starch blend films to examine the effect of different acyl groups and degrees of substitution （DS） on properties of films. Corn starch was modified with acetyl and hutyryl groups and films were prepared by blending acylated starch with low density polyethylene （LDPE）. Systematic studies were done to observe the effect of acyl groups, DS and starch concentration on the properties and biodegradability of the blend films. It was observed that blend films containing 5% acetylated and butyrylated starches of high DS （2.5, 1.7） maintained 75% and 83% of tensile strength of LDPE films. Thermal analysis results indicated that acetylated and butyrylated starch blend films decomposed at 370℃ and 389℃ which were higher than the decomposition temperature of native starch film （349℃）. Scanning electron micrographs of blend films containing high DS acylated starch showed well dispersed starch particles due to improvement in dispersion between starch and LDPE. Water absorption capacity of high DS acetylated and butyrylated starch blend films （4.18% and 3.76%, respectively） was lower than that of native starch films （5%）. This study has an advantage because of blown films prepared can be integrated with the present manufacturing systems without any other requirement.展开更多
AIM：To investigate the levels of ghrelin（Gh）,acylated ghrelin（AGh） and AGh/Gh ratio in the humor aqueous（HA） of cases with pseudoexfoliation syndrome（PXS）,pseudoexfoliation glaucoma（PXG）,primary open angle ...AIM：To investigate the levels of ghrelin（Gh）,acylated ghrelin（AGh） and AGh/Gh ratio in the humor aqueous（HA） of cases with pseudoexfoliation syndrome（PXS）,pseudoexfoliation glaucoma（PXG）,primary open angle glaucoma（POAG） and to compare these with control subjects.METHODS：A prospective examination was made of the total Gh,and AGh levels in HA of 67 patients undergoing cataract surgery.Patients were divided into 4 groups.HA samples were aspirated at the beginning of the surgery,stored at -70℃.Gh and AGh quantification was performed with ELISA kits and the AGh/total-Gh ratios were calculated.ANOVA,Kruskal-Wallis,Chi-square and post-hoc tests were used for statistical analysis.RESULTS：Total Gh levels in HA were 189.2±45.6 pg/mL in the control group,199.2±32.9 pg/mL in PXS,180.6±20.9 pg/mL in PXG and 176.8±21.4 pg/mL in POAG groups（P〉0.05）.AGh levels in HA were 23.09±5.01 pg/mL in the control group,24.13±5.22 pg/mL in PXS,22.29±1.55 pg/m L in PXG and 19.69±2.93 pg/mL in POAG groups（P〉0.05）.The ratio of AGh/Gh was 10.3%±2.34% in the control group,13.03%±2.58% in PXS,12.3%±1.54% in PXG and 11.79%±1.41% in POAG groups（P=0.044）.The difference between the PXS and control groups was significant（P=0.03）.CONCLUSION：In spite of statistically insignificant results,the HA total Gh levels were lower than those of the control subjects but not parallel with the AGh levels in glaucoma patients.The relative increase in the AGh/Gh ratio in glaucoma cases supports the view that proportional increases of AGh might play a role in the pathogenesis of glaucoma.展开更多
Two new acylated C-glycosylflavones were isolated from the leaves of Iris lactea var. chinensis, and their structures were elucidated on the basis of extensive NMR experiments and mass spectrometry methods and were as...Two new acylated C-glycosylflavones were isolated from the leaves of Iris lactea var. chinensis, and their structures were elucidated on the basis of extensive NMR experiments and mass spectrometry methods and were assigned as 5-hydroxy-4＇- methoxyflavone-7-O-（β-D-2＇＇＇＇4＇＇＇＇-diacetylrhamnopyranosyl）-6-C-[ O-（α-L-6＇＇＇-acetyl-glucpyranosyl）-1→2-β-D-glucopyrano- side] （irislactin A） and 5-hydroxy-4＇,7-dimethoxyflavone-6-C-[O-（α-L-2＇＇＇,3＇＇＇-diacetylrhanmo-pyranosyl）-1→ 2-β-D-glucopyranoside] （irislactin B）.展开更多
A support made of mussel-inspired polydopamine-coated magnetic iron oxide nanoparticles （PD-MNPs） was prepared and characterized. The widely used Aspetyillus niger lipase （ANL） was immobilized on the PD-MNPs （ANL...A support made of mussel-inspired polydopamine-coated magnetic iron oxide nanoparticles （PD-MNPs） was prepared and characterized. The widely used Aspetyillus niger lipase （ANL） was immobilized on the PD-MNPs （ANL@PD-MNPs） with a protein loading of 138 mg/g and an activity recovery of 83.6% under optimized conditions. For the immobilization, the pH and immobilization time were investigated. The pH and thermal and storage stability of the ANL@PD-MNPs significant- ly surpassed those of free ANL. The ANL@PD-MNPs had better solvent tolerance than free ANL. The secondary structure of free ANL and ANL@PD-MNPs was analyzed by infrared spectroscopy, A kinetic study demonstrated that the ANL@PD-MNPs had enhanced enzyme-substrate affinity and high catalytic efficiency. The ANL@PD-MNPs was applied as a biocatalyst for the regioselective acylation of dihydromyricetin （DMY） in DMSO and gave a conversion of 79.3%, which was higher than that of previous reports. The ANL@PD-MNPs retained over 55% of its initial activity after 10 cycles of reuse. The ANL@PD-MNPs were readily separated from the reaction system by a magnet. The PD-MNPs is an excellent support for ANL and the resulting ANL@PD-MNPs displayed good potential for the efficient synthesis of dihydromyricetin-3-acetate by enzymatic regioselective acylation.展开更多
By analyzing the key steps that restricted the industrial synthesis of salidroside, selective protection of tyrosol with different acylation reagents was adopted. The strategy facilitated the crystallization of interm...By analyzing the key steps that restricted the industrial synthesis of salidroside, selective protection of tyrosol with different acylation reagents was adopted. The strategy facilitated the crystallization of intermediates, which allowed the scalable synthesis of salidroside. It included a reaction of penta-O-acetyl-β-D-glucose with acyl protected tyrosol in the presence of Lewis acid catalyst（ZnCl2）, followed by deacylation under basic condition（NaOMe/MeOH） to give the salidroside. The total yield of this three-step reaction was 47%. Final product and intermediates were purified by recrystallization, which significantly reduced the cost and made the large scale synthesis feasible.展开更多
文摘AIM:To investigate the relationship between plasma acylated ghrelin levels and the pathophysiology of functional dyspepsia.METHODS:Twenty-two female patients with functional dyspepsia and twelve healthy volunteers were recruited for the study.The functional dyspepsia patients were each diagnosed based on the Rome Ⅲ criteria.Eligible patients completed a questionnaire concerning the severity of 10 symptoms.Plasma acylated ghrelin levels before and after a meal were determined in the study participants using a commercial human acylated enzyme immunoassay kit;electrogastrograms were performed for 50 min before and after a standardized 10-min meal containing 265 kcal.RESULTS:There were no significant differences in plasma acylated ghrelin levels between healthy volunteers and patients with functional dyspepsia.However,in patients with functional dyspepsia,there was a negative correlation between fasting plasma acylated ghrelin levels and the sum score of epigastric pain(r =-0.427,P = 0.047) and a positive correlation between the postprandial/fasting plasma acylated ghrelin ratio and the sum score of early satiety(r = 0.428,P =0.047).Additionally,there was a negative correlation between fasting acylated ghrelin plasma levels and fasting normogastria(%)(r =-0.522,P = 0.013).Interestingly,two functional dyspepsia patients showed paradoxically elevated plasma acylated ghrelin levels after the meal.CONCLUSION:Abnormal plasma acylated ghrelin levels before or after a meal may be related to several of the dyspeptic symptoms seen in patients with functional dyspepsia.
文摘Previous phytochemical investigation of the leaves and seeds of Pittosporum angustifolium Lodd.led to the isolation and structural elucidation of polyphenols and triterpene saponins.Evaluation for cytotoxicity of isolated saponins revealed that the predominant structural feature for a cytotoxic activity are acyl substituents at the oleanane aglycon backbone.The present work reports the results of a screening of 10 selected acylated saponins for their potential to inhibit the human DNA-topoisomerase I,giving rise to IC50 values in a range of 2.8-46.5 lM.To clarify the mode of observed cytotoxic action and,moreover,to distinguish from a pure surfactant effect which is commonly accompanied with saponins,these results indicate an involvement of the topoisomerase I and its role as a possible target structure for a cytotoxic activity.In addition,computational predictions of the fitting of saponins to the topoisomerase I-DNA complex,indicate a similar binding mode to that of clinically used topoisomerase I inhibitors.Graphical Abstract Ten acylated triterpene saponins from Pittosporum angustifolium were investigated for their potential to inhibit the human DNA-topoisomerase I and computational predictions of the fitting of saponins to the topoisomerase I-DNA complex were carried out.
文摘A new triterpenoid saponin, named silenoside, with sugar chains esterified by two different acyl groups was isolated from Silene szechuensis. Its structure was elucidated by chemical and spectral methods.
文摘Fully acylated chitosan and N, N-diacyl chitosan were prepared. The products were characterized by elemental analysis, FTIR and 1H NMR. The experimental results indicate that the average degree of acylation depends on the volume ratio of pyridine to chloroform in the reaction medium, the chain length of the acylation agent used, and the molecular weight of chitosan raw materials. The XRD measurements were carried out for pure chitosan, fully acylated chitosan and N, N-diacyl chitosan to verify the crystallinity change caused by the acylation.
文摘Twelve anthocyanins （1-12） were isolated from the red flowers of Camellia hongkongensis Seem. by chromatography using open columns. Their structures were elucidated on the basis of spectroscopic analyses, that is, proton-nuclear magnetic resonance, carbon 13-nuclear magnetic resonance, heteronuclear multiple quantum correlation, heteronuclear multiple bond correlation, high resolution electrospray ionization mass and ultraviolet visible spectroscopies. Out of these anthocyanins, a novel acylated anthocyanin, cyanidin 3-O-（6-O-（Z）-p-coumaroyl）-β-galactopyranoside （6）, two known acylated anthocyanins, cyanidin 3-O-（6-O-（E）-p-coumaroyl）-β-galactopyranoside （7） and cyanidin 3-O-（6-O-（E）-caffeoyl）-^- galactopyranoside （8）, and three known delphinidin glycosides （10-12） were for the first time isolated from the genus Camellia. Furthermore, pigment components in C. japonica L., C. chekiangoleosa Hu and C. semiserrata Chi were studied. The results indicated that the distribution of anthocyanins was differed among these species. Delphinidin glycoside was only detected in the flowers of C. hongkongensis, which is a special and important species in the section Camellia. Based on the characterization of anthocyanins in the section Camellia species, there is a close relationship among these species, and C. hongkongensis might be an important parent for creating new cultivars with bluish flower color.
基金supported by the CAMS Innovation Fund for Medical Sciences (CIFMS, No. 2016-I2M-3–012)Beijing Natural Science Foundation (No. 7172143)
文摘Herein we describe the discovery and functional characterization of a steroidal glycosyltransferase(SGT) from Ornithogalum saundersiae and a steroidal glycoside acyltransferase(SGA) from Escherichia coli and their application in the biosynthesis of acylated steroidal glycosides(ASGs). Initially,an SGT gene, designated as OsSGT1, was isolated from O. saundersiae. OsSGT1-containing cell free extract was then used as the biocatalyst to react with 49 structurally diverse drug-like compounds. The recombinant OsSGT1 was shown to be active against both 3β-and 17β-hydroxyl steroids. Unexpectedly,in an effort to identify OsSGT1, we found the bacteria lacA gene in lac operon actually encoded an SGA,specifically catalyzing the acetylations of sugar moieties of steroid 17β-glucosides. Finally, a novel enzymatic two-step synthesis of two ASGs, acetylated testosterone-17-O-β-glucosides(AT-17β-Gs) and acetylated estradiol-17-O-β-glucosides(AE-17β-Gs), from the abundantly available free steroids using OsSGT1 and EcSGA1 as the biocatalysts was developed. The two-step process is characterized by EcSGA1-catalyzed regioselective acylations of all hydroxyl groups on the sugar unit of unprotected steroidal glycosides(SGs) in the late stage, thereby significantly streamlining the synthetic route towards ASGs and thus forming four monoacylates. The improved cytotoxic activities of 30-acetylated testosterone17-O-β-glucoside towards seven human tumor cell lines were thus observable.
文摘Indole[2,1-α]isoquinolines are an important class of bioactive molecules and show good antibacterial activity.In the present study,an efficient copper(I)-catalyzed acylation/cyclization has been developed for the construction of indolo[2,1-α]isoquinoline derivatives by utilizing 2-aryl-N-acryloyl indole and benzohydrazide as reactants in the presence of CuI as catalyst and tert-butyl hydroperoxide as oxidant.The present protocol exhibits good functional group tolerance,and a series of acylated indole[2,1-α]isoquinolines were synthesized in moderate to good yields.Radical trapping experiments indicated that the reaction may involve a radical process.
基金the financial support of the National Natural Science Foundation of China(No.22168009)。
文摘Highly toxic phosgene,diethyl chlorophosphate(DCP)and volatile acyl chlorides endanger our life and public security.To achieve facile sensing and discrimination of multiple target analytes,herein,we presented a single fluorescent probe(BDP-CHD)for high-throughput screening of phosgene,DCP and volatile acyl chlorides.The probe underwent a covalent cascade reaction with phosgene to form boron dipyrromethene(BODIPY)with bright green fluorescence.By contrast,DCP,diphosgene and acyl chlorides can covalently assembled with the probe,giving rise to strong blue fluorescence.The probe has demonstrated high-throughput detection capability,high sensitivity,fast response(within 3 s)and parts per trillion(ppt)level detection limit.Furthermore,a portable platform based on BDP-CHD was constructed,which has achieved high-throughput discrimination of 16 analytes through linear discriminant analysis(LDA).Moreover,a smartphone adaptable RGB recognition pattern was established for the quantitative detection of multi-analytes.Therefore,this portable fluorescence sensing platform can serve as a versatile tool for rapid and high-throughput detection of toxic phosgene,DCP and volatile acyl chlorides.The proposed“one for more”strategy simplifies multi-target discrimination procedures and holds great promise for various sensing applications.
文摘Polyhydroxyalkanoate(PHA),a well-known biodegradable polymer,featuresβ-lactones as its monomers,which can be selectively synthesized through ring-expansion carbonylation of epoxides using well-defined[Lewis acid]^(+)[Co(CO)_(4)]^(-)catalysts.However,the decomposition of[Co(CO)_(4)]^(-)species at temperatures exceeding 80℃presents a hurdle for the development of commercially viable processes under high-temperature reaction conditions to reduce reaction time.Drawing insights from stable{(acyl)Co(CO)n}intermediates involved in historical HCo(CO)_(4)-catalyzed hydroformylation processes,we sought to the high-temperature catalytic activity of epoxide ring-expansion carbonylation.The developed catalyst system,[(acetyl)Co(CO)_(2)dppp]and[(TPP)CrCl],exhibited exceptional catalytic performance with an unprecedented initial turnover frequency of 4700 h^(-1)at 100℃and a turnover numbers of 93000.Notably,the catalyst displayed outstanding stability,operating at 80℃for 168 h while selectively generatingβ-lactones.
基金the National Key Research and Development Program of China(No.2021YFA1500100)the National Natural Science Foundation of China(Nos.92156017 and 21890722)+1 种基金“Frontiers Science Center for New Organic Matter”,Nankai University(No.63181206)Haihe Laboratory of Sustainable Chemical Transformation of Tianjin(No.24HHWCSS00019)for generous financial support。
文摘Mechanistic studies of the cleavage and transformation of unactivated C_(sp3)-H bonds are a significant field of chemistry.Overcoming the inherent low acidity of C-H bonds to activate the inert substrates is challenge under mild conditions.And their complex multi-step transformations may also hinder mechanistic understanding.Herein,we perform theoretical calculations and experimental studies to explore the C_(sp3)-H bonds activation and acylation mechanisms of toluene/thioether using the relatively weak base LDA.A synergistic"main and auxiliary"model was revealed involving dual lithium metal by LDA dimers,and the aryl dilithium species as an intermediate base can facilitate C_(sp3)-H activation.This model not only aids in understanding the acidity of unactivated C_(sp3)-H bonds and the nucleophilicity of their conjugate bases for their kinetic control through cooperative interactions,but also predicts unusual kinetic isotope effects(KIE)for newly designed 2-(methylthio)naphthalene that are experimentally validated.This research is expected to provide a crucial scenario for the cleavage and transformation of unactivated C_(sp3)-H bonds and the development of new functionalities for alkali metal reagents.
基金Supported by Fonds de Recherche du Québec en Santé(toLaplante M and St-Pierre DH)Operating grants from NaturalSciences and Engineering Research Council of Canada and Diabète QuébecLaplante M also holds operating grants from the Canadian Institutes of Health Research,Canadian Liver Foundation and the Fondation de l’Institut Universitaire de Cardiologieet de Pneumologie de Québec
文摘Ghrelin is a 28 amino acid peptide mainly derived from the oxyntic gland of the stomach. Both acylated(AG) and unacylated(UAG) forms of ghrelin are found in the circulation. Initially, AG was considered as the only bioactive form of ghrelin. However, recent advances indicate that both AG and UAG exert distinct and common effects in organisms. Soon after its discovery, ghrelin was shown to promote appetite and adiposity in animal and human models. In response to these anabolic effects, an impressive number of elements have suggested the influence of ghrelin on the regulation of metabolic functions and the development of obesityrelated disorders. However, due to the complexity ofits biochemical nature and the physiological processes it governs, some of the effects of ghrelin are still debated in the literature. Evidence suggests that ghrelin influences glucose homeostasis through the modulation of insulin secretion and insulin receptor signaling. On the other hand, insulin was also shown to influence circulating levels of ghrelin. Here, we review the relationship between ghrelin and insulin and we describe the impact of this interaction on the modulation of glucose homeostasis.
文摘The regioselective acylation of unprotected phenylethyl glucoside withcinnamoyl chloride leads to 6-OH cin-namoylated glucoside. In this manner, thirteen phenylpropanoidglycoside analogs were designed and prepared. Their structure was confirmed by ~1H NMR and ^(13)CNMR spectra.
文摘Several phenylselenyl esters were selected as precursors of acyl radicals and synthesised by our established method. Treatment of these phenylselenyl esters with tributyltinhydride and AIBN generated the corresponding acyl radicals, which were found to proceed in 5 exo trig or 6 endo trig cyclisations to afford high yields of cyclopentanones and cyclohexanones, The substitution groups on the substrates have played an important role on the regioselectivity of cyclisations.
文摘Development of modified plastics has been studied through the LDPE-acylated starch blend films to examine the effect of different acyl groups and degrees of substitution （DS） on properties of films. Corn starch was modified with acetyl and hutyryl groups and films were prepared by blending acylated starch with low density polyethylene （LDPE）. Systematic studies were done to observe the effect of acyl groups, DS and starch concentration on the properties and biodegradability of the blend films. It was observed that blend films containing 5% acetylated and butyrylated starches of high DS （2.5, 1.7） maintained 75% and 83% of tensile strength of LDPE films. Thermal analysis results indicated that acetylated and butyrylated starch blend films decomposed at 370℃ and 389℃ which were higher than the decomposition temperature of native starch film （349℃）. Scanning electron micrographs of blend films containing high DS acylated starch showed well dispersed starch particles due to improvement in dispersion between starch and LDPE. Water absorption capacity of high DS acetylated and butyrylated starch blend films （4.18% and 3.76%, respectively） was lower than that of native starch films （5%）. This study has an advantage because of blown films prepared can be integrated with the present manufacturing systems without any other requirement.
基金Supported by the Ankara Ophthalmology Society,a branch of the Turkish Society of Ophthalmology
文摘AIM：To investigate the levels of ghrelin（Gh）,acylated ghrelin（AGh） and AGh/Gh ratio in the humor aqueous（HA） of cases with pseudoexfoliation syndrome（PXS）,pseudoexfoliation glaucoma（PXG）,primary open angle glaucoma（POAG） and to compare these with control subjects.METHODS：A prospective examination was made of the total Gh,and AGh levels in HA of 67 patients undergoing cataract surgery.Patients were divided into 4 groups.HA samples were aspirated at the beginning of the surgery,stored at -70℃.Gh and AGh quantification was performed with ELISA kits and the AGh/total-Gh ratios were calculated.ANOVA,Kruskal-Wallis,Chi-square and post-hoc tests were used for statistical analysis.RESULTS：Total Gh levels in HA were 189.2±45.6 pg/mL in the control group,199.2±32.9 pg/mL in PXS,180.6±20.9 pg/mL in PXG and 176.8±21.4 pg/mL in POAG groups（P〉0.05）.AGh levels in HA were 23.09±5.01 pg/mL in the control group,24.13±5.22 pg/mL in PXS,22.29±1.55 pg/m L in PXG and 19.69±2.93 pg/mL in POAG groups（P〉0.05）.The ratio of AGh/Gh was 10.3%±2.34% in the control group,13.03%±2.58% in PXS,12.3%±1.54% in PXG and 11.79%±1.41% in POAG groups（P=0.044）.The difference between the PXS and control groups was significant（P=0.03）.CONCLUSION：In spite of statistically insignificant results,the HA total Gh levels were lower than those of the control subjects but not parallel with the AGh levels in glaucoma patients.The relative increase in the AGh/Gh ratio in glaucoma cases supports the view that proportional increases of AGh might play a role in the pathogenesis of glaucoma.
基金the National Natural Science Foundation of China (No.30170103).
文摘Two new acylated C-glycosylflavones were isolated from the leaves of Iris lactea var. chinensis, and their structures were elucidated on the basis of extensive NMR experiments and mass spectrometry methods and were assigned as 5-hydroxy-4＇- methoxyflavone-7-O-（β-D-2＇＇＇＇4＇＇＇＇-diacetylrhamnopyranosyl）-6-C-[ O-（α-L-6＇＇＇-acetyl-glucpyranosyl）-1→2-β-D-glucopyrano- side] （irislactin A） and 5-hydroxy-4＇,7-dimethoxyflavone-6-C-[O-（α-L-2＇＇＇,3＇＇＇-diacetylrhanmo-pyranosyl）-1→ 2-β-D-glucopyranoside] （irislactin B）.
基金supported by the National Natural Science Foundation of China(21336002,21222606,21376096)the Key Program of Guangdong Natural Science Foundation(S2013020013049)+1 种基金the Fundamental Research Funds for the Chinese Universities(2015PT002,2015ZP009)the Program of State Key Laboratory of Pulp and Paper Engineering(2015C04)~~
文摘A support made of mussel-inspired polydopamine-coated magnetic iron oxide nanoparticles （PD-MNPs） was prepared and characterized. The widely used Aspetyillus niger lipase （ANL） was immobilized on the PD-MNPs （ANL@PD-MNPs） with a protein loading of 138 mg/g and an activity recovery of 83.6% under optimized conditions. For the immobilization, the pH and immobilization time were investigated. The pH and thermal and storage stability of the ANL@PD-MNPs significant- ly surpassed those of free ANL. The ANL@PD-MNPs had better solvent tolerance than free ANL. The secondary structure of free ANL and ANL@PD-MNPs was analyzed by infrared spectroscopy, A kinetic study demonstrated that the ANL@PD-MNPs had enhanced enzyme-substrate affinity and high catalytic efficiency. The ANL@PD-MNPs was applied as a biocatalyst for the regioselective acylation of dihydromyricetin （DMY） in DMSO and gave a conversion of 79.3%, which was higher than that of previous reports. The ANL@PD-MNPs retained over 55% of its initial activity after 10 cycles of reuse. The ANL@PD-MNPs were readily separated from the reaction system by a magnet. The PD-MNPs is an excellent support for ANL and the resulting ANL@PD-MNPs displayed good potential for the efficient synthesis of dihydromyricetin-3-acetate by enzymatic regioselective acylation.
基金the National Basic Research Program of China(973 Program,Grant No.2012CB822100)the National Key Technology R&D Program"New Drug Innovation"of China(Grant No.2012ZX09502001-001)the National Natural Science Foundation of China(Grant No.21232002,21072016 and 21072017)
文摘By analyzing the key steps that restricted the industrial synthesis of salidroside, selective protection of tyrosol with different acylation reagents was adopted. The strategy facilitated the crystallization of intermediates, which allowed the scalable synthesis of salidroside. It included a reaction of penta-O-acetyl-β-D-glucose with acyl protected tyrosol in the presence of Lewis acid catalyst（ZnCl2）, followed by deacylation under basic condition（NaOMe/MeOH） to give the salidroside. The total yield of this three-step reaction was 47%. Final product and intermediates were purified by recrystallization, which significantly reduced the cost and made the large scale synthesis feasible.
