Since diabetes mellitus and osteoarthritis are highly prevalent diseases, combinations of antidiabetic agents like repaglinide (REP) and non-steroidal anti-inflammatory drugs (NSAID) like celecoxib (CEL) could be commonly used in clinical practice. In this study, a simple and sensitive bioanalytical HPLC method combined with fluorescence detector (HPLC-FL) was developed and fully validated for simultaneous quantification of REP and CEL. A simple protein precipitation procedure and reversed C18 column with an isocratic mobile phase (mixture of ACN and pH 6.0 phosphate buffer) were employed for sample preparation and chromatographic separation. The fluorescence detector was set at a single excitation/emission wavelength pair of 240 nm/380 nm. The linearity (10–2000 ng/mL), accuracy, precision, extraction recovery, matrix effect, and stability for this method were validated as per the current FDA guidance. The bioanalytical method was applied to study pharmacokinetic interactions between REP and CEL in vivo, successfully showing that concurrent administration with oral REP significantly altered the pharmacokinetics of oral CEL. Furthermore, an in vitro metabolism and protein binding study using human materials highlighted the possibility of metabolism-based interactions between CEL and REP in clinical settings.

Echinochrome A, a natural naphthoquinone pigment found in sea urchins, is increasingly being investigated for its nutritional and therapeutic value associated with antioxidant, anticancer, antiviral, antidiabetic, and cardioprotective activities. Although several studies have demonstrated the biological effects and therapeutic potential of echinochrome A, little is known regarding its biopharmaceutical behaviors. Here, we aimed to investigate the physicochemical properties and metabolic profiles of echinochrome A and establish a physiologically-based pharmacokinetic (PBPK) model as a useful tool to support its clinical applications. We found that the lipophilicity, color variability, ultraviolet/visible spectrometry, and stability of echinochrome A were markedly affected by pH conditions. Moreover, metabolic and pharmacokinetic profiling studies demonstrated that echinochrome A is eliminated primarily by hepatic metabolism and that four possible metabolites, i.e., two glucuronidated and two methylated conjugates, are formed in rat and human liver preparations. A whole-body PBPK model incorporating the newly identified hepatic phase II metabolic process was constructed and optimized with respect to chemical-specific parameters. Furthermore, model simulations suggested that echinochrome A could exhibit linear disposition profiles without systemic and local tissue accumulation in clinical settings. Our proposed PBPK model of echinochrome A could be a valuable tool for predicting drug interactions in previously unexplored scenarios and for optimizing dosage regimens and drug formulations.

We investigated the therapeutic potential and mechanisms of HR-19011, a novel eukaryotic translation initiation factor 2 subunit α (eIF2α) phosphorylation inducer, with a focus on its effects on the integrated stress response (ISR) pathway and cell-cycle regulation in K562 cells. Our findings revealed that HR-19011 exerts its anticancer effects primarily through the activation of heme-regulated inhibitor (HRI), leading to the phosphorylation of eIF2α, the induction of ISR signaling, and subsequent G1/S cell-cycle arrest. RNA sequencing analysis further highlighted significant changes in gene expression associated with the ISR pathway, particularly those involving the key components, activating transcription factor 4 and CHOP, underscoring the specific targeting of HRI by HR-19011. Additionally, HR-19011 suppressed the mTORC1 pathway, a critical regulator of cell growth and metabolism, through the downregulation of components such as phosphorylated S6K and phosphorylated 4EBP1, mediated by activating transcription factor 4 and CHOP. In vivo studies demonstrated that HR-19011 effectively inhibited tumor growth in a K562 xenograft model, without significant toxicity, and its broad efficacy across various hematologic malignancies further suggests its potential as a versatile anticancer agent. Our findings position HR-19011 as a promising candidate for targeting the HRI–eIF2α axis in cancer treatment, warranting further investigation and optimization for clinical application.

Sequences of siRNAs used for gene silencing

Apoptotic analysis of K562 cells following HR-19011 treatment

Western blotting analysis of eIF2α phosphorylation induced by 37 compounds in K562 cells