The δ-opioid receptor (DOR) continues to attract attention as a therapeutic target for the development of safer analgesics due to its ability to mediate pain relief with a lower risk of adverse effects compared to the μ-opioid receptor (MOR). Building upon our previous findings on KNT-127, a DOR-selective agonist with a morphinan scaffold, this study further explores the structure–signal relationships between quinoline ring modifications and the signaling bias toward Gi-protein activation while minimizing β-arrestin-2 recruitment. Our findings highlight the critical role of the 5′-position in modulating signaling bias. Bulky hydrophobic substituents, such as isopropoxy and cyclohexanoxy groups, effectively reduce β-arrestin-2 recruitment without compromising DOR binding affinity or Gi-protein activation. Molecular-docking and molecular dynamics simulations provided mechanistic insights, showing that these modifications change ligand interactions with the V281^6.55-W284^6.58-L300^7.35 sub-pocket, thus selectively favoring Gi-protein signaling. These insights clarify the key interactions for the signaling bias in DOR agonists, offering a new framework for the design of DOR-targeted therapies with an improved therapeutic profile.

The pandemic of coronavirus disease 2019, caused by the new coronavirus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), remains a serious concern worldwide. Although some effective vaccines have been developed, only a few anti-SARS-CoV-2 drugs have been approved for their clinical use. In this study, we designed and synthesized new anti-SARS-CoV-2 drugs based on the chemical structure of amodiaquine, which is known as an antimalarial drug. Consequently, we have identified amodiaquine analogs functionalized with dialkylamino-pendant aminophenol moieties that possess a high level of anti-SARS-CoV-2 activity with a low level of toxicity.

A concise approach is presented for preparing 4ʹ-modified thymidines from oxime imidates using readily generated 4ʹ-carbon radicals. This method produces 4ʹ-modified thymidines from natural thymidine using the Mitsunobu reaction, the protection of 3ʹ-hydroxy group (when necessary), and 1,5-hydrogen atom transfer (1,5-HAT)/intermolecular 1,4-addition with electron-deficient olefins. Moreover, using a one-pot synthesis involving 1,5-HAT/intermolecular 1,4-addition, followed by the hydrolysis of the imidate intermediate under basic conditions, 4′-modified thymidine was diastereoselectively isolated. This is because the 4′-isomer transferred to the water layer in the work-up process.

A squaramide organocatalyst was employed to efficiently promote asymmetric oxidative lactonization to construct spiro-fused 2-oxindoles in moderate-to-good yield and enantioselectivity (up to 81% enantiomeric excess (ee)). Herein, we report the first study accomplishing stereoselective oxidative cyclization from indole propionic acid using an organocatalyst, N-iodosuccinimide (NIS), and hydrogen peroxide under metal-free and mild reaction conditions.

Estrogen receptors (ERs) and their ligands regulate a variety of physiological processes in humans, and altered ER signaling is associated with serious disorders, including breast cancer. Estrogens also bind to other receptors such as G-protein-coupled receptor 30 (GPER), and so fluorescent estrogen ligands would be useful for various functional studies and for development of drug candidates. Here we describe fluorescent estrogen receptor ligands based on 3-aryl-7-hydroxycoumarin. Notably, these ligands also function as pH-dependent OFF-ON-OFF type fluorescent sensors, enabling the detection of specific ranges of pH.

Tableting is a critical process in the manufacture of pharmaceutical tablets that directly influences product quality. Ensuring consistent quality between the research and development phase and commercial-scale production is essential during scale-up. In this study, we investigated methods for evaluating time-dependent deformation behavior using four excipients that exhibit different compression deformation behaviors. Dicalcium phosphate dihydrate (DCPD) shows no viscoelasticity, whereas lactose monohydrate (LAC), cornstarch (CS), and microcrystalline cellulose (MCC) exhibit viscoelasticity and viscoplasticity, although the degree of viscosity varies between them. In addition to investigating the known strain rate sensitivity (SRS), we performed mechanical energy evaluation based on the area under the force–displacement curve and stress relaxation tests. A trapezoid waveform was applied during the test, with loading punch speeds of 0.5 and 100 mm/s, and a dwell time of 4.5 s. The SRS value for DCPD approached approximately one, indicating no speed dependence, and the SRS increased in the order of LAC < MCC < CS, consistent with previous studies that used a saw-tooth waveform. Among the mechanical energies, the ratio of plastic flow energy to plastic energy, which depends on dwell time, followed a similar trend to SRS for the three materials other than DCPD. We conclude that axial stress relaxation is affected by machine deformation, whereas radial stress relaxation provides insight into the viscous behavior of the material. Under the test conditions, the effects of the punch-displacement profile and compression pressure on the mechanical energy and stress relaxation were more pronounced than those of SRS.

Multivariate statistical process control (MSPC) has attracted considerable attention as a monitoring method for pharmaceutical continuous manufacturing. However, there are few examples of its application in pharmaceutical manufacturing, and previous studies have shown high false-positive rates. One of the reasons is the use of inappropriate scaling factors. In pharmaceutical processes, the number of experiments for MSPC modeling tends to be small because the active pharmaceutical ingredients are expensive. Subsequently, the standard deviation, a common scaling factor for some variables, becomes too small, and the model may become sensitive to small variations. In this study, we have proposed methods for determining the appropriate scaling factors. These methods were applied to granulation and drying processes in pharmaceutical continuous manufacturing. The MSPC model can detect changes in the process parameters and raw materials used during continuous wet granulation and fluidized bed drying using the proposed scaling method.

The δ-opioid receptor (DOR) is a promising target for developing novel analgesics due to its lower risk of causing side effects compared to the μ-opioid receptor (MOR), which is commonly associated with dependence, respiratory depression, and other adverse effects. KNT-127, a DOR-selective agonist with a morphinan skeleton, offers analgesic and antidepressant benefits without inducing convulsions at therapeutic doses, unlike the conventional DOR agonist SNC80. While previous studies have suggested that KNT-127 exhibits reduced β-arrestin recruitment, a signaling pathway implicated in adverse opioid effects, the ligand structural basis for this biased signaling remains unclear. In this study, we explored the structure–signal relationships of KNT-127, focusing on its quinoline moiety, which is known to serve as an address domain responsible for DOR selectivity. Modifying the quinoline moiety by removing the aromatic rings reduced DOR selectivity and potency in relation to G-protein activation while diminishing both the potency and efficacy of β-arrestin recruitment. These results suggest that the morphinan skeleton is critical for reduced β-arrestin recruitment, while the quinoline moiety differentially modulates G-protein activation and β-arrestin recruitment. Together, our study expands the message-address concept, previously limited to receptor selectivity, by providing structural insights into the G-protein-biased agonism of DOR agonists, thereby guiding the design of safer DOR-targeting therapeutics.

Building on our previously reported techniques, we developed a concise and highly stereoselective synthesis method for β,β-disubstituted α,β-unsaturated esters. This synthesis comprises 3 reactions: the aldol reaction of acetic ester derivatives with ketones, the acetylation of tert-alcohols, and an elimination reaction utilizing 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). During the acetylation process, acetic anhydride and 4-dimethylaminopyridine (DMAP) facilitated the smooth acetylation of bulky tert-alcohols; however, employing DBU as a base reduced the yields. Additionally, the removal of excess DMAP effectively suppressed the formation of unwanted byproducts during the elimination step.

Prealnumycin (1), a benzoisochromanequinone compound, produces biologically active exfoliamycin or alnumycin through hybridization with D-ribose or oxidation. We report herein a concise and stereoselective synthesis of 1. The anionic annulation of phthalide 5 with enone 6, prepared via a transition metal-catalyzed enantioselective route, afforded tricyclic lactone 4. This intermediate then underwent a highly diastereoselective introduction of an n-propyl group through nucleophilic addition followed by silane reduction. Subsequent regioselective arene oxidation of 18 using cerium(IV) ammonium nitrate (CAN) afforded naphthoquinone 2. Further manipulations, including acidic deprotection and elimination, yielded prealnumycin in 8 steps.

The pharmaceutical industry relies heavily on the safe and efficient packaging of drugs and injection glass vials play a pivotal role in this regard. Ensuring the quality and consistency of these vials is essential for safeguarding the potency of pharmaceutical formulations. In this study, the recent breakthroughs achieved in the manufacturing of injection glass vials by implementing advanced surface-processing technologies were examined. We developed potential injection glass vials using the novel vial-inner-surface treatment (VIST) technology to homogenize the inner surface of the vials. Compared with common vials, the elution of alkali contents and conductivity of these injection glass vials were reduced because of the VIST technology, resulting in the formation of smooth and homogeneous inner surfaces. In addition, drug adsorption onto the inner surface of the VIST vials was considerably lowered than that onto common vials. These results suggest that VIST vials are of excellent quality and could become the standard injection glass vials.

Here, a DNA cleavage reagent (1-(anthracen-9-ylmethyl)-1,5,9-triazacyclododecane = Ant-[12]aneN3) was designed and synthesized, and its DNA photocleavage activity under UV irradiation at λ = 365 nm was evaluated. Ant-[12]aneN3 is a molecule containing anthracene as the photosensitizer and [12]aneN3 ( = 1,5,9-triazacyclododecane) as the DNA-interacting component. The cyclic polyamine [12]aneN3 could coordinate with zinc ions (Zn^II) and affect DNA cleavage activity. Therefore, when Ant-[12]aneN3 reacted with Zn(NO₃)‧6H₂O, the product was not a Zn^II complex but an N-protonated form of Ant-[12]aneN3. In DNA cleavage experiments with the pUC19 plasmid, Ant-[12]aneN3 also showed DNA photocleavage activity in a Zn^II-independent manner. That is, [12]aneN3 enhances the DNA photocleavage activity of anthracene in a Zn^II-independent manner, unlike bpa (bis(2-picolyl)amine), which was previously reported to enhance DNA cleavage activity by chelating Zn^II. Under physiological conditions, the nitrogen atoms of [12]aneN3 appear protonated without the addition of Zn^II salts and showed an affinity for the negatively charged DNA. The results of this study may facilitate the design of effective DNA cleavage reagents.

Ion-pair extraction with tetracyanocyclopentadienides (TCCPs) is an effective method for isolating ammonium cations; however, predicting the extractability of ammonium-TCCP ion pairs is challenging. Herein, the measured extraction coefficients (LogK_ex) of ammonium-TCCP ion pairs allowed the values of A (an index for anion extractability) for the TCCP anions to be determined (–3.1 to –1.4); these values were higher than and similar to those of perchlorate and picrate anions, respectively. The correlation between LogK_ex and the sum of the values of A and the calculated Log P of ammonium cations revealed that LogK_ex can be estimated by the equation LogK_ex = A + CLOGP_NR4 + 1.6, where CLOGP_NR4 is the CLOGP value obtained using the “no-plus” ammonium structure. The LogK_ex value can be used to predict the extractability of quaternary ammonium ions.

This study investigates the influence of needleless versus needle-based electrospinning methods on the fiber diameter of polyamide 6 (PA6) nanofibers under comparable conditions, with an emphasis on potential pharmaceutical applications. Additionally, it examines how varying solvent systems impact fiber diameter specifically in needleless electrospinning. In this study, it was found that fibers produced by the needleless method were thicker compared to those produced by the needle-based method, a trend attributable to the specific solution characteristics and parameter settings unique to this study. Notably, a 2 : 1 acetic acid : formic acid solvent mixture yielded the largest fiber diameters among the solvent systems assessed for needleless electrospinning. These results underscore the potential of PA6 nanofibers in pharmaceutical applications, suggesting that further optimization of electrospinning conditions could enhance their suitability. The study also discusses the implications of scale-up production using needleless technology, highlighting its viability for industrial applications over single-needle electrospinning.

Osteoporosis is caused by an imbalance between bone resorption and formation, which decreases bone mass and strength and increases the risk of fracture. Therefore, osteoporosis is treated with oral resorption inhibitors, such as bisphosphonates, and parenteral osteogenic drugs, including parathyroid hormone and antisclerostin antibodies. However, orally active osteogenic drugs have not yet been developed. In the present study, to find novel candidates for oral osteogenic drugs, various benzofuran derivatives were synthesized and their effects on osteoblast differentiation were examined in mouse mesenchymal stem cells (ST2 cells). Among the compounds tested, 3-{4-[2-(2-isopropoxyethoxy)ethoxy]phenyl}benzofuran-5-carboxamide (23d) exhibited potent osteoblast differentiation-promoting activity, estimated as EC₂₀₀ for increasing alkaline phosphatase activity, and good oral absorption in female rats, resulting in high C_max/EC₂₀₀. Dual-energy X-ray absorptiometry scanning revealed that 23d at 10 mg/kg/d for 8 weeks increased femoral bone mineral density in ovariectomized rats with an elevation in plasma bone-type alkaline phosphatase activity, and micro-computed tomography showed that it increased bone volume, mineral contents, and strength in femoral diaphysis cortical, but not trabecular bone during the experiment period. 23d potently inhibited cyclin-dependent kinase 8 (CDK8) activity, suggesting that its osteoblastogenic activity is mediated by the suppression of CDK8, as previously reported for diphenylether derivatives. In conclusion, the structure–activity relationships of novel benzofuran derivatives were clarified and 3,5-disubstituted benzofuran was identified as a useful scaffold for orally active osteogenic compounds. Compound 23d exhibited potent osteoblastogenic activity through CDK8 inhibition and osteogenic effects in ovariectomized rats, indicating its potential as an orally active anti-osteoporotic drug.

In the present study, the stability of a supersaturated solution of indomethacin (IM) was evaluated in hydrophobically modified hydroxypropylmethylcellulose (HM-HPMC) solutions, with and without parent cyclodextrins (CDs). A highly supersaturated state of IM was maintained in the HM-HPMC solution and was further stabilized by the addition of α-CD and β-CD. Notably, the highest level of supersaturation was achieved in HM-HPMC/α-CD solution, which maintained a high concentration of IM for up to 120 h. IM concentrations in these solutions exceeded the amorphous solubility, indicating that phase separation had occurred. To explore this phase separation, Nile Red, a fluorescent probe sensitive to hydrophobic environments, was added to the supersaturated solutions. A higher fluorescence intensity was observed in the HM-HPMC/α-CD solution compared with the HM-HPMC solution, indicating a significant formation of colloidal amorphous aggregates in the supersaturated solution. Cryogenic transmission electron microscopy (Cryo TEM) analysis confirmed the presence of these aggregates, which appeared irregularly shaped. These findings suggest that the combination of HM-HPMC and α-CD effectively stabilized the colloidal amorphous aggregates in the IM supersaturated solution. The addition of α-CD facilitated the dissociation of HM-HPMC into smaller particles, increasing the number of hydrophobic stearyl moieties available for interactions with amorphous IM aggregates, thereby enhancing the stability of the supersaturated state. The combination of HM-HPMC and α-CD offers a promising approach to improving the oral bioavailability of drugs with poor water solubility.

A method for preparing the fused cyclohexane and pyrrolidine portion of the strychnos skeleton has been developed using domino intermolecular and intramolecular S_N2 cyclization. Using this method, the formation of pyrrolidine proceeded smoothly with good yield without the E2 elimination product. This reaction condition is effective for synthesizing the fused cyclohexane and pyrrolidine portion of the strychnos skeleton.

Optimization of the manufacturing process based on scientific evidence is essential for quality control of active pharmaceutical ingredients. Real-time monitoring can ensure the production of stable quality crystals in the crystallization process. Raman spectroscopy is an attractive tool for pharmaceutical quality evaluation and process analytical technology because of its ability to analyze samples non-destructively and rapidly. In this study, we attempted to monitor the crystal polymorphs of carbamazepine (CBZ I and CBZ III) during the dissolution and crystallization processes using low-frequency Raman spectroscopy, which can reflect differences in lattice vibrations originating from polymorphs in the scattering peaks. Furthermore, using multivariate analysis of the obtained spectra, we attempted to develop a model that enables the quantification of each polymorph. A partial least squares was performed to build the prediction model. The prediction model was built using a set of 33 calibration samples, and an external set of 12 validation samples was used to evaluate the model. The model presents a good prediction capacity. The quantitative results for the solid amount of carbamazepine in suspension calculated using the model during the dissolution and crystallization process showed results that correlated very well with the particle view results. It is suggested that low-frequency Raman spectroscopy can be used as a useful process analytical technology tool.

A total synthesis of javaberine A was achieved through a lithium amide-mediated intramolecular hydroamination of an N-allyl aminoalkene. The desired hydroamination was accomplished using an excess of i-Pr₂NH with a substoichiometric amount of n-BuLi. Using an excess of both n-BuLi and i-Pr₂NH led to tandem cyclization, however, resulting in the construction of a tricyclic structure through the formation of one C–N and two C–C bonds in a single operation. Additionally, epimerization of the H8-H14 cis-benzyl tetrahydroisoquinoline to the trans isomer was achieved via β-elimination followed by intramolecular hydroamination.

The main ingredients of Maobushisaishinto (MBST) are ephedrine (EP), methyl eugenol (ME), and aconitine (AC). The pharmacological effects are presumed to be due to the combined effects of these ingredients. In this study, we investigated the impact of the particles present in MBST suspensions on the absorption of the ingredients. Coarse, colloidal, and molecular dispersions were detected when MBST was dispersed in water at 25 and 70 °C. Regardless of temperature, the ratio of MBST in molecular dispersions was the highest, and the ratio of coarse dispersions was greater than that of colloidal dispersions. Particles ranging from 50 to 900 nm were observed in the colloidal dispersions prepared by treatment at 25 °C for 3 min. However, in 70 °C water, the mean particle size decreased, and the number of nanoparticles tended to increase. The levels of EP, ME, and AC in molecular dispersions were higher than those in coarse and colloidal dispersions, with no significant difference observed between the coarse and colloidal dispersions. On the other hand, in small intestinal penetration, the levels of EP, ME, and AC in colloidal dispersions were higher than those in the other two dispersions. Moreover, adding colloidal particles to the dissolved drug (molecular dispersions) increased the drug’s permeability through the small intestinal membrane. In conclusion, colloidal particles are produced when MBST is suspended. Furthermore, we showed that these colloidal particles enhance the absorption of the main ingredients of MBST.