Current Drug Metabolism - Volume 25, Issue 5, 2024

Yunaconitine (YAC) is a hidden toxin that greatly threatens the life safety of patients who are prescribed herbal medicines containing Aconitum species; however, its underlying mechanism remains unclear.

The objective of this study is to elucidate the functions of P-glycoprotein (P-gp) in regulating the efficacy, toxicity, and pharmacokinetics of YAC.

The efflux function of P-gp on YAC was explored by using Caco-2 monolayers in combination with the P-gp inhibitor verapamil. The impact of P-gp on regulating the analgesic and anti-inflammatory effects, acute toxicity, tissue distribution, and pharmacokinetics of YAC was determined via male Mdr1a gene knocked-out mice and wild-type FVB mice.

The presence of verapamil significantly decreased the efflux ratio of YAC from 20.41 to 1.07 in Caco-2 monolayers (P < 0.05). Moreover, oral administration of 0.07 and 0.14 mg/kg YAC resulted in a notable decrease in writhing times in Mdr1a^-/- mice by 23.53% and 49.27%, respectively, compared to wild-type FVB mice (P < 0.05). Additionally, the deficiency of P-gp remarkably decreased the half-lethal dose (LD50) of YAC from 2.13 to 0.24 mg/kg (P < 0.05). Moreover, the concentrations of YAC in the tissues of Mdr1a^-/- mice were statistically higher than those in wild-type FVB mice (P < 0.05). Particularly, the brain accumulation of YAC in Mdr1a^-/- mice significantly increased by 12- and 19-fold, respectively, after oral administration for 30 and 120 min, when compared to wild-type FVB mice (P < 0.05). There were no significant differences in the pharmacokinetic characteristics of YAC between Mdr1a^-/- and wild-type FVB mice.

YAC is a sensitive substrate of P-gp. The absence of P-gp enhances the analgesic effect and toxicity of YAC by upregulating its brain accumulation. Co-administration with a P-gp inhibitor may lead to severe YAC poisoning.

Paclitaxel (PTX) is a key drug used for chemotherapy for various cancers. The hydroxylation metabolites of paclitaxel are different between humans and rats. Currently, there is little information available on the metabolic profiles of CYP450 enzymes in rats.

This study evaluated the dynamic metabolic profiles of PTX and its metabolites in rats and in vitro.

Ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS) and LC-MS/MS were applied to qualitative and quantitative analysis of PTX and its metabolites in rats, liver microsomes and recombinant enzyme CYP3A1/3A2. Ten specific inhibitors [NF (CYP1A1), FFL (CYP1A2), MOP (CYP2A6), OND (CYP2B6), QCT (CYP2C8), SFP (CYP2C9), NKT (CYP2C19), QND (CYP2D6), MPZ (CYP2E1) and KTZ (CYP3A4)] were used to identify the metabolic pathway in vitro.

Four main hydroxylated metabolites of PTX were identified. Among them, 3'-p-OH PTX and 2-OH PTX were monohydroxylated metabolites identified in rats and liver microsome samples, and 6α-2-di-OH PTX and 6α-5”-di-OH PTX were dihydroxylated metabolites identified in rats. CYP3A recombinant enzyme studies showed that the CYP3A1/3A2 in rat liver microsomes was mainly responsible for metabolizing PTX into 3'-p-OH-PTX and 2-OH-PTX. However, 6α-OH PTX was not detected in rat plasma and liver microsome samples.

The results indicated that the CYP3A1/3A2 enzyme, metabolizing PTX into 3'-p-OH-PTX and 2-OH-PTX, is responsible for the metabolic of PTX in rats. The CYP2C8 metabolite 6α-OH PTX in humans was not detected in rat plasma in this study, which might account for the interspecies metabolic differences between rats and humans. This study will provide evidence for drug-drug interaction research in rats.

Sakurasosaponin, a primary bioactive saponin from Aegiceras corniculatum, shows potential as an anti-cancer agent. However, there is a lack of information on its in vivo metabolism. This study aims to profile the in vivo metabolites of sakurasosaponin in rat feces, urine, and plasma after oral administration. An efficient strategy using ultra-high-performance liquid chromatography/quadrupole time-of-flight mass spectrometry was developed, which combined metabolic prediction, multiple mass defects filtering, and high-resolution extracted ion chromatograms for rapid and systematic analysis.

Firstly, a theoretical list of metabolites for sakurasosaponin was developed. This was done by considering the metabolic pathways of saponins. Next, the multiple mass defects filtering method was employed to identify potential metabolites in feces and urine, using the unique metabolites of sakurasosaponin as multiple mass defects filtering templates. Subsequently, a high-resolution extracted ion chromatogram was used to quickly determine the metabolites in rat plasma post-identification in feces and urine. Lastly, the analysis of accurate mass, typical neutral loss, and diagnostic ion of the candidate metabolites was carried out to confirm their structural elucidation, and metabolic pathways of sakurasosaponin in vivo were also proposed.

In total, 30 metabolites were provisionally identified in feces, urine, and plasma. Analysis of metabolic pathways revealed isomerization, deglycosylation, oxidation, hydroxylation, sulfate conjugation, glucuronide conjugation, and other related reactions as the primary biotransformation reactions of sakurasosaponin in vivo.

The findings demonstrate that the designed research strategy effectively minimizes matrix interference, prevents the omission of low-concentration metabolites, and serves as a foundation for the discovery of active metabolites of sakurasosaponin.

Small heterocyclic compounds have been crucial in pioneering advances in type 2 diabetes treatment. There has been a dramatic increase in the pharmacological development of novel heterocyclic derivatives aimed at stimulating the activation of Glucokinase (GK). A pharmaceutical intervention for diabetes is increasingly targeting GK as a legitimate target. Diabetes type 2 compromises Glucokinase's function, an enzyme vital for maintaining the balance of blood glucose levels. Medicinal substances strategically positioned to improve type 2 diabetes management are used to stimulate the GK enzyme using heterocyclic derivatives.

The research endeavor aimed to craft novel compounds, drawing inspiration from the inherent coumarin nucleus found in nature. The goal was to evoke the activity of the glucokinase enzyme, offering a tailored approach to mitigate the undesired side effects typically associated with conventional therapies employed in the treatment of type 2 diabetes.

Coumarin, sourced from nature's embrace, unfolds as a potent and naturally derived ally in the quest for innovative antidiabetic interventions. Coumarin was extracted from a variety of botanical origins, including Artemisia keiskeana, Mallotus resinosus, Jatropha integerrima, Ferula tingitana, Zanthoxylum schinifolium, Phebalium clavatum, and Mammea siamensis. This inclusive evaluation was conducted on Muybridge's digital database containing 53,000 hit compounds. The presence of the coumarin nucleus was found in 100 compounds, that were selected from this extensive repository. Utilizing Auto Dock Vina 1.5.6 and ChemBioDraw Ultra, structures generated through this process underwent docking analysis. Furthermore, these compounds were accurately predicted online log P using the Swiss ADME algorithm. A predictive analysis was conducted using PKCSM software on the primary compounds to assess potential toxicity.

Using Auto Dock Vina 1.5.6, 100 coumarin derivatives were assessed for docking. Glucokinase (GK) binding was significantly enhanced by most of these compounds. Based on superior binding characteristics compared with Dorzagliatin (standard GKA) and MRK (co-crystallized ligand), the top eight molecules were identified. After further evaluation through ADMET analysis of these eight promising candidates, it was confirmed that they met the Lipinski rule of five and their pharmacokinetic profile was enhanced. The highest binding affinity was demonstrated by APV16 at -10.6 kcal/mol. A comparison between the APV16, Dorzagliatin and MRK in terms of toxicity predictions using PKCSM indicated that the former exhibited less skin sensitization, AMES toxicity, and hepatotoxicity.

Glucokinase is most potently activated by 100 of the compound leads in the database of 53,000 compounds that contain the coumarin nucleus. APV12, with its high binding affinity, favorable ADMET (adjusted drug metabolic equivalents), minimal toxicity, and favorable pharmacokinetic profile warrants consideration for progress to in vitro testing. Nevertheless, to uncover potential therapeutic implications, particularly in the context of type 2 diabetes, thorough investigations and in-vivo evaluations are necessary for benchmarking before therapeutic use, especially experiments involving the STZ diabetic rat model.