抗生育植物栀子花化学成分的研究：Ⅱ.栀子花甲酸的结构

我们已报道从栀子(Gardenia jasminoidesEllis)花的乙酸乙酯提取物中分得一种对大鼠有明显抗早孕作用的新三萜酸——栀子花乙酸(1),本文继续报道从该提取物中分得的另一种新三萜酸——栀子花甲酸(Gardenolicacid A,以下简称甲酸,2)的结构。 2为白色针状结晶,m.p.212～214℃,Liebermann-Burchard试验阳性,[α]_D~(17) 38.3,C_(30)H(46)O_(4),属三萜类。     

多巴胺在咖啡酸修饰电极上的电化学行为

研究了咖啡酸修饰玻碳电极的制备及其电化学性质,测定了电极反应的动力学常数。实验结果表明,在pH7.0的磷酸盐缓冲溶液中,多巴胺(DA)在该修饰电极上产生一灵敏的氧化峰,峰电流与DA浓度在5.0×10-6～1.0×10-4mol/L范围内良好线性关系,检出限为9.0×10-7mol/L。该修饰膜对DA有增敏作用,可望用于DA的测定。     

Contemporary Approaches to α,β-Dehydroamino Acid Chemical Modifications

As one of the most common unnatural amino acids(uAAs), α, β-dehydroamino acids(α,β-dhAAs) can be found in various ribosomally synthesized and post-translationally modified peptides(RiPPs) and other naturally occurring peptides. In recent years, novel reactions for α,β-dhAA modification continue to emerge. Due to their unique electrophilicity different from 20 natural amino acids, α,β-dhAAs, especially dehydroalanine(Dha), have become powerful tools for site-selective protein modification. In this review, we mainly focus on the latest research progress of C-C and C-heteroatom(C-X, X=S, N, Se, Si, P, B) bond formation methods based on α,β-dhAAs in the past five years. Particularly, we pay much attention to the α,β-dhAA derivatization methodologies used in the late-stage modification for natural peptides and proteins. In addition, we also focus on the downstream functionalization and therapeutic biologic applications of these modifications.     

Synthesis of strontium substituted hydroxyapatite by solution combustion route

Hydroxyapatite is a versatile compound resembling natural bone mineral. HAP insinuates feasibility with substitution ensuing in its application in various fields. The properties of calcium and strontium are cognate and pose as a bone-seeking trace-element that accumulates in new trabecular bone. Strontium substituted hydroxyapatite, Ca₉.₅Sr_0.5(OH)₂(PO₄)₆, was synthesized using citric acid as fuel and calcined 900 ​°C. The as-prepared product notably was characterized by powder X-ray diffraction, Fourier - Transform Infrared spectroscopy and Scanning Electron Microscope along with Energy Dispersive Spectroscopy. FT-IR analysis exhibited stretching and bending vibrations of (PO₄)^3- and OH⁻ groups along without any signal of carbonate group. Studies showed that product formed is strontium substituted hydroxyapatite, and calcination temperature plays an essential role in the formation of hydroxyapatite phase. The precursors when calcined resulted in 46–50 ​nm of Sr substituted hydroxyapatite.     

Effect of small amounts of Al on the surface silanol structure and their correlation to the improved catalytic performances of WOx/SiO2–Al2O3 in the propene self-metathesis

Surface silanol structures, acid properties, and tungsten dispersion of the sol-gel-derived 7W/SiO₂–xAl₂O₃ (x = 0.2–23 wt%) were investigated by means of ²⁹Si, ²⁷Al, and ¹H MAS NMR, NH₃-TPD, in-situ NH₃-IR spectroscopy, XRD, and Raman spectroscopy. The surface silanol structure changed upon Al and tungsten loadings; however, loading of 1 wt% Al₂O₃ appeared to be the threshold for preserving the Si(OH)Al with isolated bridge after impregnation of 7 wt% W. The 7W/SiO₂–1Al₂O₃ (1 wt% Al₂O₃) was also found to exhibit the lowest ratio of Bronsted to Lewis acid with the highest amount of Lewis acid sites and the best catalyst performances in propene self-metathesis at 550 °C in terms of both propene conversion and ethylene/butene selectivity. Despite its low tungsten dispersion, the metathesis activity was correlated well with the higher amount of tungsten carbene species, which were formed on the catalysts containing higher isolated bridge silanol and the presence of higher Lewis acid sites.     

The Concept of Folic Acid in Health and Disease

Folates have a pterine core structure and high metabolic activity due to their ability to accept electrons and react with O-, S-, N-, C-bounds. Folates play a role as cofactors in essential one-carbon pathways donating methyl-groups to choline phospholipids, creatine, epinephrine, DNA. Compounds similar to folates are ubiquitous and have been found in different animals, plants, and microorganisms. Folates enter the body from the diet and are also synthesized by intestinal bacteria with consequent adsorption from the colon. Three types of folate and antifolate cellular transporters have been found, differing in tissue localization, substrate affinity, type of transferring, and optimal pH for function. Laboratory criteria of folate deficiency are accepted by WHO. Severe folate deficiencies, manifesting in early life, are seen in hereditary folate malabsorption and cerebral folate deficiency. Acquired folate deficiency is quite common and is associated with poor diet and malabsorption, alcohol consumption, obesity, and kidney failure. Given the observational data that folates have a protective effect against neural tube defects, ischemic events, and cancer, food folic acid fortification was introduced in many countries. However, high physiological folate concentrations and folate overload may increase the risk of impaired brain development in embryogenesis and possess a growth advantage for precancerous altered cells.     

Synthesis and Biological Evaluation of New N-Acyl-α-amino Ketones and 1,3-Oxazoles Derivatives

In order to develop novel bioactive substances with potent activities, some new valine-derived compounds incorporating a 4-(phenylsulfonyl)phenyl fragment, namely, acyclic precursors from N-acyl-α-amino acids and N-acyl-α-amino ketones classes, and heterocycles from the large family of 1,3-oxazole-based compounds, were synthesized. The structures of the new compounds were established using elemental analysis and spectral (UV-Vis, FT-IR, MS, NMR) data, and their purity was checked by reversed-phase HPLC. The newly synthesized compounds were evaluated for their antimicrobial and antibiofilm activities, for toxicity on D. magna, and by in silico studies regarding their potential mechanism of action and toxicity. The 2-aza-3-isopropyl-1-[4-(phenylsulfonyl)phenyl]-1,4-butanedione 4b bearing a p-tolyl group in 4-position exhibited the best antibacterial activity against the planktonic growth of both Gram-positive and Gram-negative strains, while the N-acyl-α-amino acid 2 and 1,3-oxazol-5(4H)-one 3 inhibited the Enterococcus faecium biofilms. Despite not all newly synthesized compounds showing significant biological activity, the general scaffold allows several future optimizations for obtaining better novel antimicrobial agents by the introduction of various substituents on the phenyl moiety at position 5 of the 1,3-oxazole nucleus.     

Anticancer Effects of Ursi Fel Extract and Its Active Compound,Ursodeoxycholic Acid,in FRO Anaplastic Thyroid Cancer Cells

Anaplastic thyroid cancer (ATC) is one of the most fatal human malignancies. Ursi Fel (UF) is the bile of a brown bear that has been traditionally used for heat clearance and toxin relief in Korean and Chinese medicines. In this study, we determined the anticancer effects of a UF extract and its active compound, ursodeoxycholic acid (UDCA), in FRO human ATC cells. FRO cells were treated with UF extract and UDCA at different concentrations for various durations. Cell viability was measured using an MTT assay. Cell apoptosis was investigated by flow cytometric analysis following Annexin V and propidium iodide (PI) staining, and Hoechst staining was used to observe nuclear fragmentation. The expression of pro-apoptotic (Bax, caspase-3, cytochrome c, and PARP), anti-apoptotic (Bcl-2), and angiogenetic (TGF-β, VEGF, N-cadherin, and sirtuin-1) proteins and the phosphorylation of Akt and mechanistic target of rapamycin (mTOR) were determined by western blot analysis. Treatment with UF extract at 10, 25, and 50 μg/mL and UDCA at 25, 50, and 100 μM/mL significantly inhibited the growth of FRO cells in a dose-dependent manner. Flow cytometry and Hoechst staining revealed an increase in the apoptosis of FRO cells mediated by UF extract and UDCA in a dose-dependent manner. UF extract (25 and 50 μg) and UDCA (50 and 100 μM) significantly increased the expression of Bax, caspase-3, cytochrome c, and PARP and inhibited the expression of Bcl-2, TGF-β, VEGF, N-cadherin, and sirtuin-1 in FRO cells. Furthermore, UF extract and UDCA treatment stimulated Akt phosphorylation and inhibited mTOR phosphorylation in these cells. These results indicate that UF extract and UDCA exert anticancer properties in FRO cells by inducing apoptosis and inhibiting angiogenesis via regulating the Akt/mTOR signaling pathway.     

由两种单体借助酯交换反应制备三元共聚物

本文讨论了甲基丙烯酸羟乙酯和甲基丙烯酸在乙醇中进行溶液聚合时,借助酯交换反应,在该亲水体系中引入第三疏水组分,从而制备三元共聚物的可行性.