Pillar[6]arene acts as a biosensor for quantitative detection of a vitamin metabolite in crude biological samples

Cyclic and acyclic acetals as safe, nonaqueous formaldehyde equivalents for the synthesis of pillararenes

Pillar[5]arene was synthesized using acyclic acetals diethoxymethane and dimethoxymethane, and cyclic acetals 1,3-dioxolane and 1,3,5-trioxane as an alternative to paraformaldehyde. Both Lewis and Brønsted acids were effective in catalyzing the hydrolysis of acetal and initiating the Friedel-Crafts reaction in pillararene synthesis.

A Supramolecular Biosensor for Rapid and High-Throughput Quantification of a Disease-Associated Niacin Metabolite

Metabolic abnormalities play a pivotal role in various pathological conditions, necessitating the quantification of specific metabolites for diagnosis. While mass spectrometry remains the primary method for metabolite measurement, its limited throughput underscores the need for biosensors capable of rapid detection. Previously, we reported that pillar[6]arene with 12 carboxylate groups (P6AC) forms host-guest complexes with 1-methylnicotinamide (1-MNA), which is produced in vivo by nicotinamide N-methyltransferase (NNMT). P6AC acts as a biosensor by measuring the fluorescence quenching caused by photoinduced electron transfer upon 1-MNA binding. However, the low sensitivity of P6AC makes it impractical for detecting 1-MNA in unpurified biological samples. In this study, we found that P6A with 12 sulfonate groups (P6AS) is a specific and potent supramolecular host for 1-MNA interactions even in biological samples. The 1-MNA binding affinity of P6AS in water was found to be (5.68 ± 1.02) × 106 M-1, which is approximately 700-fold higher than that of P6AC. Moreover, the 1-MNA detection limit of P6AS was determined to be 2.84 × 10-7 M, which is substantially lower than that of P6AC. Direct addition of P6AS to culture medium was sufficient to quantify 1-MNA produced by cancer cells. Furthermore, this sensor was able to specifically detect 1-MNA even in unpurified human urine. P6AS therefore enables rapid and high-throughput quantification of 1-MNA, and further improvement of our strategy will contribute to the establishment of high-throughput screening of NNMT inhibitors, diagnosis of liver diseases, and imaging of human cancer cells in vivo.

Shape-Persistent Triptycene-Derived Pillar[6]arenes: Synthesis, Host-Guest Complexation, and Enantioselective Recognitions of Chiral Ammonium Salts

Construction of macrocyclic hosts with a novel structure and excellent property has emerged as an intriguing undertaking for the past few years. Here, we reported the synthesis of shape-persistent triptycene-derived pillar[6]arene (TP[6]). The single crystal structure analysis revealed that the macrocyclic molecule adopts a hexagonal structure, featuring a helical and electron-rich cavity capable of encapsulating electron-deficient guests. In order to obtain chiral TP[6] from an enantiomerically pure triptycene building block, an efficient resolution of chiral triptycene was successfully developed through introducing chiral auxiliaries into triptycene skeletons. The ¹H NMR and isothermal titration calorimetry investigations demonstrated that chiral TP[6] exhibited enantioselectivity toward four pairs of chiral guests containing a trimethylamino group, implying a significant promising application in area of enantioselective recognition.

Nicotinamide N-methyltransferase is related to MELF pattern invasion in endometrioid carcinoma

Grade 1 (G1) endometrioid carcinoma (EC) is relatively a good prognosis. However, in a minority of cases, G1 shows an aggressive histological pattern known as the microcystic, elongated, and fragmented (MELF) pattern. We previously reported that EC with high expression levels of S100A4 and serum deprivation-response protein (SDPR) was related to MELF pattern invasion. However, the molecular features of the invasive front area of the MELF pattern have not been investigated. In this study, we searched for genes preferentially expressed in the invasive front area of EC with the MELF pattern using laser microdissection and RNA sequencing, and showed that nicotinamide N-methyltransferase (NNMT) is related to MELF pattern invasiveness. Immunohistochemical analyses confirmed high NNMT expression in the invasive front area of the MELF pattern. Moreover, NNMT promoted migration, invasion, colony formation, epithelial-mesenchymal transition (EMT), and chemoresistance using EC cell lines. We speculate that depletion of NNMT promotes histone methylation and leads to tumor suppression because NNMT consumes S-adenosyl methionine (SAM), which is an essential methylation cofactor. NNMT knockout cells showed enhanced expression of H3K9me2. RNA sequencing using NNMT knockout cell lines suggested that methylation of H3K9 leads to repression of the transcription of various oncogenic genes. Our findings demonstrate the possibility that NNMT inhibitors, which are expected to be used for the treatment of metabolic disorders, would be effective for the treatment of aggressive EC. This is the first report of gene analyses focusing on the morphological changes associated with MELF pattern invasion of EC.

Recent Applications of Pillar[n]arene-Based Host-Guest Recognition in Chemosensing and Imaging

Pillar[n]arene is a novel kind of synthetic supramolecular macrocyclic host characterized by its particular pillar-shaped structure consisting of an electron-rich cavity and two finely adjustable rims. Benefiting from its rigid structure, facile synthesis, ease of functionalization, and outstanding host-guest chemistry, pillar[n]arene shows great potential for diverse applications. Significantly, the host-guest recognition of pillar[n]arene provides a novel approach for chemosensing and imaging. Herein, this Review critically and comprehensively reviews the applications of pillar[n]arene-based host-guest recognition in chemosensing and imaging. The sensing and imaging mechanisms as well as the unique roles and advantages of pillar[n]arene-based host-guest recognition are summarized. In addition, preparations of hybrid materials based on pillar[n]arene and inorganic materials are also introduced comprehensively in the light of chemosensing and imaging. Finally, current challenges and perspectives on pillar[n]arene-based host-guest recognition in chemosensing and imaging are outlined.

On the Stability and Formation of Pillar[n]arenes: a DFT Study

The increased use of both pillar[5]arenes and pillar[6]arenes, stimulated by increasingly efficient syntheses of both, has brought forward the question as to what drives the intermediates in this Friedel-Crafts ring formation to form a pillar[5]arene, a pillar[6]arene, or any other sized macrocycle. This study sets out to answer this question by studying both the thermodynamics and kinetics involved in the absence and presence of templating solvents using high-end wB97XD/6-311G(2p,2d) DFT calculations.

Synergistic enhancement of the emergency treatment effect of organophosphate poisoning by a supramolecular strategy

Poisoning by organophosphorus agents (OPs) is a serious public health issue across the world. These compounds irreversibly inhibit acetylcholinesterase (AChE), resulting in the accumulation of acetylcholine (ACh) and overstimulation of ACh receptors. A supramolecular detoxification system (SDS) has been designed with a view to deliver pyridine-2-aldoxime methochloride (PAM) with a synergistic inhibition effect on the ACh-induced hyperstimulation through host-guest encapsulation. NMR and fluorescence titration served to confirm the complexation between carboxylatopillar[6]arene (CP6A) and PAM as well as ACh with robust affinities. Patch-clamp studies proved that CP6A could exert an inhibition effect on the ACh-induced hyperstimulation of ACh receptors. Support for the feasibility of this strategy came from fluorescence imaging results. In vivo studies revealed that complexation by CP6A serves to increase the AChE reactivation efficiency of PAM. The formation of the PAM/CP6A complex contributed to enhance in a statistically significant way the ability of PAM not only to relieve symptoms of seizures but also to improve the survival ratio in paraoxon-poisoned model rats. These favorable findings are attributed to synergistic effects that PAM reactivates AChE to hydrolyze ACh and excess ACh is encapsulated in the cavity of CP6A to relieve cholinergic crisis symptoms.