Biomimetic Total Synthesis of Hyperjapones A–E and Hyperjaponols A and C

Hyperjapones A–E and hyperjaponols A–C are complex natural products of mixed aromatic polyketide and terpene biosynthetic origin that have recently been isolated from Hypericum japonicum. We have synthesized hyperjapones A–E using a biomimetic, oxidative hetero‐Diels–Alder reaction to couple together dearomatized acylphloroglucinol and cyclic terpene natural products. Hyperjapone A is proposed to be the biosynthetic precursor of hyperjaponol C through a sequence of: 1) epoxidation; 2) acid‐catalyzed epoxide ring‐opening; and 3) a concerted, asynchronous alkene cyclization and 1,2‐alkyl shift of a tertiary carbocation. Chemical mimicry of this proposed biosynthetic sequence allowed a concise total synthesis of hyperjaponol C to be completed in which six carbon–carbon bonds, six stereocenters, and three rings were constructed in just four steps.     

Biomimetic Peptide Catalytic Bond-Forming Utilizing a Mild Brønsted Acid

Since the global peptide drug market demand has been predicted to increase, highly efficient and inexpensive mass scale peptides are required. However, the production process raises questions about the cost of energy input, scale-up production, raw materials, and solvents treatment. This paper introduces 2 methods for the 2–4 mer oligopeptides bond formation for batch reaction utilizing 50–100 mol% of a mild Brønsted acid under the mild condition. One of the methods has been capably adapted to flow synthesis at room temperature using organic solvents with boiling points below 100 °C. The method applies the tert-butoxycarbonyl amino methoxy group, forming the desired dipeptide without solvent at mild temperatures. Furthermore, the conversion of the carboxylic acid leaving the group to phenyl ester promotes peptide bond formation, and the reaction were applied to di, tri, and tetrapeptide bond formation in excellent yield without notable racemization at ambient temperature (up to >99 % yield and 99 : 1 dr). Finally, this study proposes this new production method to overcome the limited scale-up production by reaction device scale: liquid phase biomimetic catalytic peptide flow synthesis utilizing a mild Brønsted acid.     

2-Ketophenyl Assisted Biomimetic Synthesis of 3-Thio Substituted Glycals at Room Temperature

Herein we designed a strategy for the synthesis of regioselective and stereoselective displacement of C-3 acetate group in the presence of other C-4 and C-6 acetate of 2-ketophenyl-glycal by different aromatic and cyclic aliphatic thiol nucleophiles taking inspiration from cytosolic esterase mediated thiolation of glucosamine sugars into cellular glycan. Under a mild base condition at room temperature, the protocol generated a library of 3-arylthiosugars with excellent yields and high axial selectivity. This stereoselective approach tolerated well with different ester-protected glycals and thiophenols, aliphatic cyclic thiols, and mercaptans. A variety of control experiments were conducted to establish the mechanism and reason behind the stereoselectivity.     

Intrinsic Apyrase-Like Activity of Cerium-Based Metal–Organic Frameworks (MOFs): Dephosphorylation of Adenosine Tri- and Diphosphate

Apyrase is an important family of extracellular enzymes that catalyse the hydrolysis of high-energy phosphate bonds (HEPBs) in ATP and ADP, thereby modulating many physiological processes and driving life activities. Herein, we report an unexpected discovery that cerium-based metal–organic frameworks (Ce-MOFs) of UiO-66(Ce) have intrinsic apyrase-like activity for ATP/ADP-related physiological processes. The abundant Ce^III/Ce^IV couple sites of Ce-MOFs endow them with the ability to selectively catalyse the hydrolysis of HEPBs of ATP and ADP under physiological conditions. Compared to natural enzymes, they could resist extreme pH and temperature, and present a broad range of working conditions. Based on this finding, a significant inhibitory effect on ADP-induced platelet aggregation was observed upon exposing the platelet-rich plasma (PRP) to the biomimetic UiO-66(Ce) films, prefiguring their wide application potentials in medicine and biotechnology.     

Total Syntheses of (−)‐Minovincine and (−)‐Aspidofractinine through a Sequence of Cascade Reactions

We report 8‐step syntheses of (?)‐minovincine and (?)‐aspidofractinine using easily available and inexpensive reagents and catalyst. A key element of the strategy was the utilization of a sequence of cascade reactions to rapidly construct the penta‐ and hexacyclic frameworks. These cascade transformations included organocatalytic Michael‐aldol condensation, a multistep anionic Michael‐S_N2 cascade reaction, and Mannich reaction interrupted Fischer indolization. To streamline the synthetic routes, we also investigated the deliberate use of steric effect to secure various chemo‐ and regioselective transformations.     

基于微纳结构液体灌注的超滑表面的制备与应用

超滑表面利用其基底上的微纳结构通过毛细作用将润滑油等液体锁定在孔隙中,孔隙中浸润的润滑油在基底形成一层动态油膜,油膜与不溶液体的液-液界面代替了固体与液体的固-液界面,从而大幅减少了滑动阻力。与传统具有类似低滚动角特性的超疏水和超疏油表面相比,孔隙中填充润滑油比空气具有更好的压力稳定性,而且润滑油的毛细流动性使得超滑表面具有良好的自修复能力。由于其明显的优势,近些年超滑表面已成为国际学术界研究热点,应用也拓展到防结冰、强化传热、减阻、抗生物黏附、微流控等领域。目前超滑表面研究仍存在重要挑战,例如如何避免润滑油的挥发带来的性能退化、如何针对各种材质和结构设计合适的加工工艺制备微纳结构等,这些问题限制了超滑表面的广泛应用。本文综述了超滑表面的制备工艺以及应用,分析了现存的问题,并且对超滑表面未来的发展趋势进行了展望。     

Cancer Cell Membrane-Coated Nanosuspensions for Enhanced Chemotherapeutic Treatment of Glioma

Effective intracerebral delivery is key for glioma treatment. However, the drug delivery system within the brain is largely limited by its own adverse physical and chemical properties, low targeting efficiency, the blood–brain barrier and the blood–brain tumor barrier. Herein, we developed a simple, safe and efficient biomimetic nanosuspension. The C6 cell membrane (CCM) was utilized to camouflaged the 10-hydroxycamptothecin nanosuspension (HCPT-NS) in order to obtain HCPT-NS/CCM. Through the use of immune escape and homotypic binding of the cancer cell membrane, HCPT-NS/CCM was able to penetrate the blood–brain barrier and target tumors. The HCPT-NS is only comprised of drugs, as well as a small amount of stabilizers that are characterized by a simple preparation method and high drug loading. Similarly, the HCPT-NS/CCM is able to achieve targeted treatment of glioma without any ligand modification, which leads it to be stable and efficient. Cellular uptake and in vivo imaging experiments demonstrated that HCPT-NS/CCM is able to effectively cross the blood–brain barrier and was concentrated at the glioma site due to the natural homing pathway. Our results reveal that the glioma cancer cell membrane is able to promote drug transport into the brain and enter the tumor via a homologous targeting mechanism.     

Advances in Biomimetic Nanoparticles for Targeted Cancer Therapy and Diagnosis

Biomimetic nanoparticles have recently emerged as a novel drug delivery platform to improve drug biocompatibility and specificity at the desired disease site, especially the tumour microenvironment. Conventional nanoparticles often encounter rapid clearance by the immune system and have poor drug-targeting effects. The rapid development of nanotechnology provides an opportunity to integrate different types of biomaterials onto the surface of nanoparticles, which enables them to mimic the natural biological features and functions of the cells. This mimicry strategy favours the escape of biomimetic nanoparticles from clearance by the immune system and reduces potential toxic side effects. Despite the rapid development in this field, not much has progressed to the clinical stage. Thus, there is an urgent need to develop biomimetic-based nanomedicine to produce a highly specific and effective drug delivery system, especially for malignant tumours, which can be used for clinical purposes. Here, the recent developments for various types of biomimetic nanoparticles are discussed, along with their applications for cancer imaging and treatments.     

Shape‐Selective Interception by Hydrocarbons of the O2‐Derived Oxidant of a Biomimetic Nonheme Iron Complex

Picky ferryl : The complex [Fe(Tp)(BF)] (Tp=hydrotris(3,5‐diphenylpyrazolyl)borate; BF=benzoylformate) reacts with O₂ to generate an oxidant (see picture; O red, pink; Fe yellow; N blue; C gray; H white) that oxidizes added hydrocarbons shape‐selectively. Discrimination derives from a cleft formed by two phenyl groups of the Tp ligand, favoring oblate spheroidal substrates.