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Synthesis of benzo[a]fluorene, benzo[c]fluorene, and benzo[j]fluoranthene have been accomplished from readily accessible enol ether precursors via a Lewis acid‐catalyzed Prins‐type cycloaromatization. Mechanistically, it was proposed that Lewis acids catalyze the generation of oxonium species, which accelerate subsequent annulation and aromatization. This protocol offers the benefit of an operationally simple, transition‐metal‐free, and air‐tolerant reaction condition, enabling gram‐scale syntheses of the desired products. The total synthesis of viridistratin A further supported this synthetic strategy for establishing polycyclic aromatic hydrocarbon architectures. [ABSTRACT FROM AUTHOR]

This article highlights the contributions of researchers from the Asia-Pacific region to the field of biomedical engineering. The special issue showcases innovative research articles focusing on drug delivery, disease diagnosis, and biomedical devices. The advancements discussed in the article have the potential to impact clinical practice. Topics covered include drug delivery systems, in vivo stability of therapeutics, disease diagnosis techniques, and advancements in medical devices. The article aims to provide valuable insights and keep readers well-informed in the field of biomedical engineering. [Extracted from the article]

Alizarin (1,2‐dihydroxyanthraquinone) is an anthraquinone reddish dye widely used for painting and textile dyeing. As the biological activity of alizarin has recently attracted increasing attention from researchers, its therapeutic potential as complementary and alternative medicine is of interest. However, no systematic research has been conducted on the biopharmaceutical and pharmacokinetic aspects of alizarin. Therefore, this study aimed to comprehensively investigate the oral absorption and intestinal/hepatic metabolism of alizarin using a simple and sensitive tandem mass spectrometry method developed and validated in‐house. The present method for the bioanalysis of alizarin has merits, including a simple pretreatment procedure, small sample volume, and adequate sensitivity. Alizarin exhibited pH‐dependent moderate lipophilicity and low solubility with limited intestinal luminal stability. Based on the in vivo pharmacokinetic data, the hepatic extraction ratio of alizarin was estimated to be 0.165–0.264, classified as a low level of hepatic extraction. In an in situ loop study, considerable fractions (28.2%–56.4%) of the alizarin dose were significantly absorbed in gut segments from the duodenum to ileum, suggesting that alizarin may be classified as the Biopharmaceutical Classification System class II. An in vitro metabolism study using rat and human hepatic S9 fractions revealed that glucuronidation and sulfation, but not NADPH‐mediated phase I reactions and methylation, are significantly involved in the hepatic metabolism of alizarin. Taken together, it can be estimated that the fractions of oral alizarin dose unabsorbed from the gut lumen and eliminated by the gut and liver before reaching the systemic circulation are 43.6%–76.7%, 0.474%–36.3%, and 3.77%–5.31% of the dose, respectively, resulting in a low oral bioavailability of 16.8%. Therefore, the oral bioavailability of alizarin depends primarily on its chemical degradation in the gut lumen and secondarily on first‐pass metabolism. [ABSTRACT FROM AUTHOR]

The gut microbiome is closely linked to gastrointestinal health and disease status. Oral administration of known probiotic strains is now considered a promising therapeutic strategy, especially for refractory diseases such as inflammatory bowel disease. In this study, we developed a nanostructured hydroxyapatite/alginate (HAp/Alg) composite hydrogel that protects its encapsulated probiotic Lactobacillus rhamnosus GG (LGG) by neutralizing hydrogen ions that penetrate the hydrogel in a stomach without inhibiting LGG release in an intestine. Surface and transection analyses of the hydrogel revealed characteristic patterns of crystallization and composite‐layer formation. TEM revealed the dispersal of the nanosized HAp crystals and encapsulated LGG in the Alg hydrogel networks. The HAp/Alg composite hydrogel maintained its internal microenvironmental pH, thereby enabling the LGG to survive for substantially longer. At intestinal pH, the encapsulated LGG was completely released upon disintegration of the composite hydrogel. In a dextran sulfate sodium‐induced colitis mouse model, we then assessed the therapeutic effect of the LGG‐encapsulating hydrogel. This achieved intestinal delivery of LGG with minimal loss of enzymatic function and viability, ameliorating colitis by reducing epithelial damage, submucosal edema, inflammatory cell infiltration, and the number of goblet cells. These findings reveal the HAp/Alg composite hydrogel as a promising intestinal‐delivery platform for live microorganisms including probiotics and live biotherapeutic products. [ABSTRACT FROM AUTHOR]

N‐Acetylserotonin (NAS) is an intermediate in the melatonin biosynthetic pathway. We investigated the anti‐inflammatory activity of NAS by focusing on its chemical feature oxidizable to an electrophile. NAS was readily oxidized by reaction with HOCl, an oxidant produced in the inflammatory state. HOCl‐reacted NAS (Oxi‐NAS), but not NAS, activated the anti‐inflammatory nuclear factor erythroid 2‐related factor 2 (Nrf2)‐heme oxygenase (HO)‐1 pathway in cells. Chromatographic and mass analyses demonstrated that Oxi‐NAS was the iminoquinone form of NAS and could react with N‐acetylcysteine possessing a nucleophilic thiol to form a covalent adduct. Oxi‐NAS bound to Kelch‐like ECH‐associated protein 1, resulting in Nrf2 dissociation. Moreover, rectally administered NAS increased the levels of nuclear Nrf2 and HO‐1 proteins in the inflamed colon of rats. Simultaneously, NAS was converted to Oxi‐NAS in the inflamed colon. Rectal NAS mitigated colonic damage and inflammation. The anticolitic effects were significantly compromised by the coadministration of an HO‐1 inhibitor. [ABSTRACT FROM AUTHOR]

Understanding the intrinsic phase stability and inherent band gap of formamidinium lead triiodide (FAPbI3) perovskites is crucial to further improve the performance of perovskite solar cells (PSCs). Herein, we explored the α‐ to δ‐phase transition and band gap of FAPbI3 single crystals grown by an inverse temperature solubility method. We found that the residual γ‐butyrolactone solvents in the inner empty space of the FAPbI3 single crystal accelerate the phase transition at kinetics. By adopting 2‐methoxyethanol as the solvent, over 2000 h of stable α‐FAPbI3 crystals could be acquired. This proves that although FAPbI3 is regarded as unstable at thermodynamics, it could own excellent kinetic stability without any doping or additives because of the slow solid to solid phase transition instead of the fast phase transition assisted by the solvents. Furthermore, we revealed that the bulk FAPbI3 single crystal with a size above 100 μm can have an inherent band gap of 1.41 eV. Thus, our work provides key scientific guidance for high‐performance FAPbI3‐based PSCs. [ABSTRACT FROM AUTHOR]

The article in Advanced Synthesis & Catalysis discusses the synthesis of non-alternant polycyclic aromatic hydrocarbons through a Lewis acid-catalyzed Prins-type cycloaromatization reaction. The reaction is notable for its air tolerance, high productivity, short reaction times, and scalability. The authors propose a mechanism in which Prins-type benzannulation competes with oxonium-ene cyclization. The reaction was successfully applied to the total synthesis of a natural compound called viridistratin A. The details of the study can be found in the communication by Hwayoung Yun and co-workers. [Extracted from the article]

We generated a Burkholderia mutant, which is deficient of an N -acetylmuramyl- l -alanine amidase, AmiC, involved in peptidoglycan degradation. When non-motile Δ amiC mutant Burkholderia cells harboring chain form were orally administered to Riptortus insects, Δ amiC mutant cells were unable to establish symbiotic association. But, Δ amiC mutant complemented with amiC gene restored in vivo symbiotic association. Δ amiC mutant cultured in minimal medium restored their motility with single-celled morphology. When Δ amiC mutant cells harboring single-celled morphology were administered to the host insect, this mutant established normal symbiotic association, suggesting that bacterial motility is essential for the successful symbiosis between host insect and Burkholderia symbiont. [ABSTRACT FROM AUTHOR]

ABSTRACT A series of biocompatible and degradable hyperbranched polyether esters, poly(2-hydroxyethyl 2-methyloxirane-2-carboxylate) (pHEMOC) with controlled molecular weight (MW) and polydispersity (PD), have been synthesized via oxyanionic ring-opening polymerization of HEMOC that was prepared by the epoxidation of 2-hydroxyethyl methacrylate. pHEMOCs of their MWs ranging from about 500 to 20,000 with their PD values less than 1.5 are obtained simply by controlling 1,1,1- tris-hydroxymethylpropane initiator to HEMOC ratio. The pHEMOCs comprised of ether and ester backbones and multiple hydroxyl groups on the core and periphery results in materials that exhibit good degradability and low cytotoxicity, enabling them to be an ideal candidate material for biomedical applications. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 1643-1651 [ABSTRACT FROM AUTHOR]