Four New Gallate Derivatives from Wine-Processed Corni Fructus and Their Anti-Inflammatory Activities

Four new gallate derivatives—ornusgallate A, ent-cornusgallate A, cornusgallate B and C (1a, 1b, 2, 3)—were isolated from the wine-processed fruit of Cornus officinalis. Among them, 1a and 1b are new natural compounds with novel skeletons. Their chemical structures were elucidated by comprehensive spectroscopy methods including NMR, IR, HRESIMS, UV, ECD spectra and single-crystal X-ray diffraction analysis. The in vitro anti-inflammatory activities of all compounds were assayed in RAW 264.7 cells by assessing LPS-induced NO production. As the result, all compounds exhibited anti-inflammatory activities at attested concentrations. Among the tested compounds, compound 2 exhibited the strongest anti- inflammatory activity.     

Methoxy-Substituted Tyramine Derivatives Synthesis,Computational Studies and Tyrosinase Inhibitory Kinetics

Targeting tyrosinase for melanogenesis disorders is an established strategy. Hydroxyl-substituted benzoic and cinnamic acid scaffolds were incorporated into new chemotypes that displayed in vitro inhibitory effects against mushroom and human tyrosinase for the purpose of identifying anti-melanogenic ingredients. The most active compound 2-((4-methoxyphenethyl)amino)-2-oxoethyl (E)-3-(2,4-dihydroxyphenyl) acrylate (Ph9), inhibited mushroom tyrosinase with an IC₅₀ of 0.059 nM, while 2-((4-methoxyphenethyl)amino)-2-oxoethyl cinnamate (Ph6) had an IC₅₀ of 2.1 nM compared to the positive control, kojic acid IC₅₀ 16700 nM. Results of human tyrosinase inhibitory activity in A375 human melanoma cells showed that compound (Ph9) and Ph6 exhibited 94.6% and 92.2% inhibitory activity respectively while the positive control kojic acid showed 72.9% inhibition. Enzyme kinetics reflected a mixed type of inhibition for inhibitor Ph9 (K_i 0.093 nM) and non-competitive inhibition for Ph6 (K_i 2.3 nM) revealed from Lineweaver–Burk plots. In silico docking studies with mushroom tyrosinase (PDB ID:2Y9X) predicted possible binding modes in the catalytic site for these active compounds. Ph9 displayed no PAINS (pan-assay interference compounds) alerts. Our results showed that compound Ph9 is a potential candidate for further development of tyrosinase inhibitors.     

A Novel N-Tert-Butyl Derivatives of Pseudothiohydantoin as Potential Target in Anti-Cancer Therapy

Tumors are currently more and more common all over the world; hence, attempts are being made to explain the biochemical processes underlying their development. The search for new therapeutic pathways, with particular emphasis on enzymatic activity and its modulation regulating the level of glucocorticosteroids, may contribute to the development and implementation of new therapeutic options in the treatment process. Our research focuses on understanding the role of 11β-HSD1 and 11β-HSD2 as factors involved in the differentiation and proliferation of neoplastic cells. In this work, we obtained the 9 novel N-tert-butyl substituted 2-aminothiazol-4(5H)-one (pseudothiohydantoin) derivatives, differing in the substituents at C-5 of the thiazole ring. The inhibitory activity and selectivity of the obtained derivatives in relation to two isoforms of 11β-HSD were evaluated. The highest inhibitory activity for 11β-HSD1 showed compound 3h, containing the cyclohexane substituent at the 5-position of the thiazole ring in the spiro system (82.5% at a conc. 10 µM). On the other hand, the derivative 3f with the phenyl substituent at C-5 showed the highest inhibition of 11β-HSD2 (53.57% at a conc. of 10 µM). A low selectivity in the inhibition of 11β-HSD2 was observed but, unlike 18β-glycyrrhetinic acid, these compounds were found to inhibit the activity of 11β-HSD2 to a greater extent than 11β-HSD1, which makes them attractive for further research on their anti-cancer activity.     

Preparation and Antimicrobial Activity of Chitosan and Its Derivatives: A Concise Review

Despite the advantages presented by synthetic polymers such as strength and durability, the lack of biodegradability associated with the persistence in the environment for a long time turned the attention of researchers to natural polymers. Being biodegradable, biopolymers proved to be extremely beneficial to the environment. At present, they represent an important class of materials with applications in all economic sectors, but also in medicine. They find applications as absorbers, cosmetics, controlled drug delivery, tissue engineering, etc. Chitosan is one of the natural polymers which raised a strong interest for researchers due to some exceptional properties such as biodegradability, biocompatibility, nontoxicity, non-antigenicity, low-cost and numerous pharmacological properties as antimicrobial, antitumor, antioxidant, antidiabetic, immunoenhancing. In addition to this, the free amino and hydroxyl groups make it susceptible to a series of structural modulations, obtaining some derivatives with different biomedical applications. This review approaches the physico-chemical and pharmacological properties of chitosan and its derivatives, focusing on the antimicrobial potential including mechanism of action, factors that influence the antimicrobial activity and the activity against resistant strains, topics of great interest in the context of the concern raised by the available therapeutic options for infections, especially with resistant strains.     

微纳米纤维素功能膜在能源与环境领域的应用

探寻绿色清洁的资源与材料以维持高效的社会经济增长是未来数十年人们面临的最大挑战之一. 可持续资源与绿色材料的开发是降低传统化石能源与材料比重的最有前途的方案. 纤维素作为一种可持续发展、 可生物再生、 储量丰富且低成本的天然高分子聚合物, 在众多领域中具有广泛的应用, 并且纤维素可以加工成各种构型, 包括气凝胶、 泡沫、 海绵和薄膜等. 本文介绍了不同形态的纤维素及其衍生物组装而成的功能膜在能源与环境中的应用, 综述了微纳米纤维素及其衍生物在先进功能化储能器件方面的最新进展和制备方案, 以及在用于水处理的膜分离技术中的应用, 其中重点讨论了微纳米纤维素及其衍生物功能膜在电池、 电容器及水处理等领域中的作用, 如隔膜、 柔性电极膜和分离膜等. 此外, 还对纤维素及其衍生物功能膜的未来发展进行了总结和展望.     

肿瘤乏氧靶向响应的罗丹明荧光探针及其成像介导手术治疗

基于罗丹明的良好荧光性能, 经化学偶联反应制备并表征了一个偶氮乏氧特异响应的“Off-On”型荧光成像探针(FY-4). 从分子层面证实了其荧光“Off-On”性能和响应机制; 在L02正常细胞及4T1, HeLa和A549肿瘤细胞层面考察了其对受试细胞株的毒性和不同乏氧时间的荧光成像性能; 再利用4T1肿瘤模型, 分别以肿瘤原位注射和尾静脉注射的方式考察了其荧光成像性能, 并探究了其荧光成像介导切除肿瘤性能, 最后还考察了FY-4的生物安全性. 结果表明, FY-4有高的肿瘤乏氧靶向特异“关-开”响应的荧光成像差异显影及荧光成像介导切除肿瘤的潜能, 结合其良好的光物理性能、 生物安全性和明晰的给药时间等特性, 有望为生物医学荧光成像介导肿瘤切除提供新的研究工具.     

吲哚多样化环化合成咔唑衍生物研究进展

咔唑是一类特殊的含氮芳杂环分子,咔唑衍生物理化性质独特、结构多样,在天然产物、药物和功能材料领域有着广阔的应用,其合成方法一直备受关注.从吲哚直接环化到咔唑的合成方法简洁高效,原料廉价易得、产物种类多样.总结了近5年来以2,3-未取代吲哚为原料合成咔唑衍生物的方法,典型环化策略包含以下三种:[2+2′+2′]环化反应、[2+2′+2″]环化反应和[4+2]苯环化反应,探讨了每种方法的特点,并对未来的发展前景进行展望.     

N-[2,6-二氯-4-(1,2,4-噁二唑-3-基)苯基]-2-甲氧基烟酰胺的合成、晶体结构及抗肿瘤活性研究

报道一种新型1,2,4-噁二唑衍生物,N-[2,6-二氯-4-(1,2,4-噁二唑-3-基)苯基]-2-甲氧基烟酰胺（C15H10Cl2N4O3）的合成,其结构通过1H NMR、13C NMR、HRMS以及X-射线单晶衍射进行表征。该晶体结构属于三斜晶系, P 1(—) 空间群,晶胞参数 a = 7.1291 (9), b = 8.4352 (10), c = 14.0021 (18) ?, α = 73.834 (3), β = 77.407 (3), γ = 70.019 (3)°, Mr = 366.18, V = 752.97 (16) ?3, Z = 2, Dc = 1.611 g/cm3, μ(MoKα) = 0.454 mm-1, F(000) = 372.0 , 晶体尺寸为 0.36 × 0.2 × 0.1 mm,Rint = 0.023。初步活性研究发现,该化合物对LoVo, A549, SK-BR-3, HeLa这四种肿瘤细胞株具有明显的抑制作用,尤其是对HeLa细胞的抑制活性与阳性药物5-氟尿嘧啶 (5-FU)相当。     

修饰吡啶衍生物的染料敏化光阳极水氧化性能的研究

染料敏化光电化学电池(DSPECs)是构建人工光合作用体系的潜在方式,其优势在于可通过优化染料结构来拓展可见光吸收范围,从根本上提高太阳能利用效率.染料敏化光阳极在受激发产生电荷分离之后,激发电子注入TiO₂半导体导带,由于其导带位置比传统的可见光半导体,如BiVO4和Fe3O4等相比较负,因此理论上可以在较小的偏压下取得较大的光电转换效率,也更有利于和光阴极相耦合实现无偏压分解水.电荷传输动力学研究表明,注入到TiO₂导带的电子向氧化态光敏剂和催化剂的回传是造成体系能量损失的主要原因,集中体现在光电流密度和效率的降低.目前,已经报道了多种手段来减少DSPECs光阳极表面的电子回传,包括使用带有长烷基链的锚定基团对水氧化催化剂进行修饰,在半导体表面引入电子中介体以及使用核-壳结构的基底等.其中,SnO2/TiO₂基底被广泛应用在染料敏化光阳极中,这种基底可以提高光生电子的注入效率,同时两种金属氧化物之间的异质结有效抑制了电子回传,从而提高了DSPECs的光电活性.然而,核-壳结构基底需要使用原子层沉积技术来制备,所以操作相对复杂.本文基于Ru-bda(bda=2,2'-联吡啶-6,6'-二羧酸)结构的分子水氧化催化剂和带有磷酸修饰基团的三联吡啶钌通过共吸附的方式制备染料敏化光阳极,在不使用核-壳结构基底的情况下,利用吡啶衍生物对TiO₂电极表面的修饰来减少电子回传.本文利用一系列吡啶衍生物作修饰负载在TiO₂光阳极上(TiO₂|RuP,1;RuP=Ru(4,4'-(PO3H2)2-2,2'-联吡啶)(2,2'-联吡啶)2;1=Ru(bda)(L)2,bda=2,2'-联吡啶-6,6'-二羧酸,L=(10-吡啶-4-基氧基)癸基)膦酸.在100 mW/cm2的白光照射下(λ>400 nm),TiO₂|RuP,1,P1(P1=4-羟基吡啶)光阳极在0.4 V(vs.NHE)的外加偏压下获得了1 mA/cm2的光电流密度,其光电流比未修饰吡啶的光阳极增加了42%.同时,其入射光子-电流转化效率在470 nm波长的单色光光照下达到最大,为13.6%.经过吡啶衍生物所修饰的光阳极光电性能和文献中利用核-壳结构基底所制备的类似光阳极性能相当,且光电流密度随吡啶对位取代基供电性能的增强而增大.瞬态吸收光谱和电化学阻抗谱测试表明,吡啶吸附在光阳极上能有效地抑制界面上的电子回传,延长电荷分离寿命,是光电流增加的根本原因,这也表明有机小分子修饰是提高染料敏化光阳极性能的简单、有效的策略.     

限域NiCo合金纳米颗粒高效催化生物质衍生物水相加氢脱氧

将储量丰富的生物质及其衍生物转化为具有高附加值的燃料和化学品被认为是一种有前景的绿色途径,可以极大地减少人们对传统化石资源的依赖.作为木质纤维素热解的直接产物和生物油升级的模型化合物,香草醛可以通过加氢脱氧(HDO)过程选择性地转化为2-甲氧基-4-甲基苯酚(MMP).MMP是一种有价值的化学品,常用于香料和药物等重要中间体的合成.在过去十年里,大量的金属催化剂被用来催化香草醛HDO转化为MMP.其中,贵金属(Pt,Pd,Ru和Au)虽然活性高,但是其储量低、价格昂贵,不利于工业化应用;而非贵金属(Fe,Co,Ni和Cu)的催化活性普遍较低,需要苛刻的反应条件来提高转化效率和选择性.此外,这类HDO反应大都在有机溶剂中进行,容易造成环境污染.因此,开发高效、稳定的非贵金属催化剂用于水相HDO反应是一个巨大的挑战.一般来说,合金纳米颗粒(NPs)具有强烈的协同效应,能产生良好的配位结构和电子环境,从而显著提升催化活性和选择性.基于此,本文首次采用了一种简单可控的合成方法来制备三聚氰胺海绵负载的氮掺杂碳纳米管(N-CNTs)限域的Ni-Co合金NPs(NiCo@N-CNTs/CMF)催化剂.该催化剂具有优异的HDO性能,在2 MPa H2,120oC反应6 h条件下,能在水相中将生物质衍生的香草醛高效转化为MMP,转化率和选择性均达到100％.相比于单金属的Ni@N-CNTs/CMF和Co@N-CNTs/CMF催化剂,香草醛转化率和MMP选择性都有大幅度的提高.而且,在温和的反应条件下,该催化剂对香草醛衍生物和其他芳香醛类化合物同样表现出优异的HDO性能,拥有100％的转化率以及较高的MMP选择性(91.5％～100％).XPS结果表明,Ni-Co形成合金后发生了电子结构的偏移,即Co原子可以从邻近的Ni原子处得到电子,提高Co电子云密度,从而促进对香草醛中C=O键的吸附.DFT计算结果表明,相比于单金属的Ni和Co,Ni-Co合金化后能显著提高对C=O键的选择性吸附和活化.同时,H2解离后形成的活性H*物种在Ni-Co合金NPs表面更容易脱附并参与催化反应.因此,Ni-Co@N-CNTs/CMF催化剂优异的HDO性能主要是由于Ni-Co合金NPs的协同作用大大促进了其对C=O键的选择性吸附和活化,以及活化氢物种的脱附.本文为设计和制备高效的非贵金属催化剂应用于水相的HDO反应提供了一个新策略.