Rapid bioluminescence assay for monitoring rat CES1 activity and its alteration by traditional Chinese medicines

Discovery of natural anthraquinones as potent inhibitors against pancreatic lipase: structure-activity relationships and inhibitory mechanism

Obesity is acknowledged as a significant risk factor for various metabolic diseases, and the inhibition of human pancreatic lipase (hPL) can impede lipid digestion and absorption, thereby offering potential benefits for obesity treatment. Anthraquinones is a kind of natural and synthetic compounds with wide application. In this study, the inhibitory effects of 31 anthraquinones on hPL were evaluated. The data shows that AQ7, AQ26, and AQ27 demonstrated significant inhibitory activity against hPL, and exhibited selectivity towards other known serine hydrolases. Then the structure-activity relationship between anthraquinones and hPL was further analysed. AQ7 was found to be a mixed inhibition of hPL through inhibition kinetics, while AQ26 and AQ27 were effective non-competitive inhibition of hPL. Molecular docking data revealed that AQ7, AQ26, and AQ27 all could associate with the site of hPL. Developing hPL inhibitors for obesity prevention and treatment could be simplified with this novel and promising lead compound.

Identification of the first selective bioluminescent probe for real-time monitoring of carboxylesterase 2 in vitro and in vivo

Carboxylesterase (CES), a main hydrolysis enzyme family in the human body, plays a crucial role in drug metabolism. Among them, CES1 and CES2 are the primary subtypes, and each exhibits distinct distribution and functions. However, convenient and non-invasive methods for distinguishing them and the real-time monitoring of CES2 are relatively rare, hindering the further understanding of physiological functions and underlying mechanisms. In this study, we have designed, synthesized, and evaluated the first selective bioluminescent probe (CBP 1) for CES2 with high sensitivity, high specificity and rapid reactivity. This probe offers a promising approach for the real-time detection of CES2 and its dynamic fluctuations both in vitro and in vivo.

Potential herb‒drug interactions between anti-COVID-19 drugs and traditional Chinese medicine

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has spread worldwide. Effective treatments against COVID-19 remain urgently in need although vaccination significantly reduces the incidence, hospitalization, and mortality. At present, antiviral drugs including Nirmatrelvir/Ritonavir (PaxlovidTM), Remdesivir, and Molnupiravir have been authorized to treat COVID-19 and become more globally available. On the other hand, traditional Chinese medicine (TCM) has been used for the treatment of epidemic diseases for a long history. Currently, various TCM formulae against COVID-19 such as Qingfei Paidu decoction, Xuanfei Baidu granule, Huashi Baidu granule, Jinhua Qinggan granule, Lianhua Qingwen capsule, and Xuebijing injection have been widely used in clinical practice in China, which may cause potential herb-drug interactions (HDIs) in patients under treatment with antiviral drugs and affect the efficacy and safety of medicines. However, information on potential HDIs between the above anti-COVID-19 drugs and TCM formulae is lacking, and thus this work seeks to summarize and highlight potential HDIs between antiviral drugs and TCM formulae against COVID-19, and especially pharmacokinetic HDIs mediated by metabolizing enzymes and/or transporters. These well-characterized HDIs could provide useful information on clinical concomitant medicine use to maximize clinical outcomes and minimize adverse and toxic effects.

Carboxylesterase 1 family knockout alters drug disposition and lipid metabolism

The mammalian carboxylesterase 1 (Ces1/CES1) family comprises several enzymes that hydrolyze many xenobiotic chemicals and endogenous lipids. To investigate the pharmacological and physiological roles of Ces1/CES1, we generated Ces1 cluster knockout (Ces1 ^-/- ) mice, and a hepatic human CES1 transgenic model in the Ces1 ^-/- background (TgCES1). Ces1 ^-/- mice displayed profoundly decreased conversion of the anticancer prodrug irinotecan to SN-38 in plasma and tissues. TgCES1 mice exhibited enhanced metabolism of irinotecan to SN-38 in liver and kidney. Ces1 and hCES1 activity increased irinotecan toxicity, likely by enhancing the formation of pharmacodynamically active SN-38. Ces1 ^-/- mice also showed markedly increased capecitabine plasma exposure, which was moderately decreased in TgCES1 mice. Ces1 ^-/- mice were overweight with increased adipose tissue, white adipose tissue inflammation (in males), a higher lipid load in brown adipose tissue, and impaired blood glucose tolerance (in males). These phenotypes were mostly reversed in TgCES1 mice. TgCES1 mice displayed increased triglyceride secretion from liver to plasma, together with higher triglyceride levels in the male liver. These results indicate that the carboxylesterase 1 family plays essential roles in drug and lipid metabolism and detoxification. Ces1 ^-/- and TgCES1 mice will provide excellent tools for further study of the in vivo functions of Ces1/CES1 enzymes.

Inhibition of Radix Scutellariae flavones on carboxylesterase mediated activations of prodrugs

AIMS

Carboxylesterase (CES) plays an essential role in the hydrolysis of ester prodrugs. Our study explored the inhibitions of Radix Scutellariae flavones, including baicalein (B), baicalin (BG), wogonin (W), wogonoside (WG), oroxylin A (OXA) and oroxylin A-7-O-glucuronide (OAG), on CES-mediated hydrolysis of seven prodrugs (capecitabine, clopidogrel, mycophenolate mofetil, dabigatran etexilate, acetylsalicylic acid, prasugrel and irinotecan).

MAIN METHODS

In vitro screenings were developed by incubating the flavones with prodrugs in rat plasma, intestine S9 and liver S9. Docking simulations were conducted using AMDock v1.5.2. In vivo evaluations were performed in rats co-administered with the selected flavone and prodrug via oral gavage/intravenous administration for five consecutive days.

KEY FINDINGS

The in vitro investigation showed that B and OXA demonstrated strongest inhibitions on the hydrolysis of irinotecan followed by dabigatran in rat plasma, intestine S9 and liver S9. Consistent results showed in the molecular docking analyses. Additionally, in rats receiving irinotecan, B/OXA intravenous and oral pre-treatments both led to reduction trends on the active metabolite SN-38 formation in plasma. Besides, significant decreases of SN-38/irinotecan plasma concentration ratios were found in the B/OXA oral pre-treatment group with quicker and stronger inhibition potential in OXA pre-treatment than that from B pre-treatment. OXA oral pre-treatment was also found to be able to significantly inhibit intestinal CES2 activities at 0.5 h and 5 h after irinotecan administration.

SIGNIFICANCE

Our current findings for the first time alert on potential CES-mediated HDIs between RS flavones and prodrugs, which provide a constructive information referring to rational drug combinations in clinical practice.

Development of a Novel Bioluminescence Pyrophosphate Assay for the High-Sensitivity Detection of Hepatitis B Virus

The transmission of bloodborne viruses through transfusion remains a major blood supply-related safety concern, with hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus (HIV) being the most important pathogens in this context. Real-time bioluminescent pyrophosphate testing has been developed as a means of readily detecting bacterial cells within particular sample types without requiring the use of expensive or complex instrumentation. The sensitivity of this approach, however, is often limited such that it is not compatible with many potential applications. In this study, we sought to overcome the limitations of this pyrophosphate bioluminescent assay format by using 2-deoxyadenosine-5-(α-thio)-triphosphate (dATPαS) in place of dATP for PCR amplification, thereby dramatically reducing background signal levels. We leveraged this combination PCR and bioluminescent pyrophosphate assay approach to facilitate HBV detection. This assay yielded a limit of detection of 500 copies/mL, making it more sensitive than traditional bioluminescent assays, about 1000 times more sensitive than that of PCR product analysis by agarose gel electrophoresis, and roughly as sensitive as qPCR as a means of detecting viral DNA. We then used this assay to analyze 100 serum samples, with qPCR being used for result validation. The assay required 100 min to complete, and was able to detect as few as 500 copies/mL of viral DNA. Overall, our approach was rapid, sensitive, and simple, enabling users to readily detect HBV in a reliable and efficient manner.

Novel O-[11C]-methylated derivatives of the neprilysin inhibitor sacubitril: Radiosynthesis, autoradiography and plasma stability evaluation

INTRODUCTION

The O-[11C]methylated derivatives of the clinically used neprilysin inhibitor (NEPi) sacubitril ([11C]SacOMe, (2R,4S)-ethyl 5-([biphenyl]-4-yl)-4-(4-[11C]methoxy-4-oxobutanamido)-2-methylpentanoate) and LBQ657 ([11C]MeOLBQ, (2R,4S)-5-(biphenyl-4-yl)-4-[(3-carboxypropionyl)amino]-2-methylpentanoic acid [11C]methyl ester and [11C]LBQOMe, (2R,4S)-5-(biphenyl-4-yl)-4-[(4-[11C]methoxy-4-oxobutanamido)]-2-methylpentanoic acid) were evaluated to determine their potential as PET imaging tracers and investigate the effect of such labeling esterification on neprilysin (NEP) binding.

METHODS

[11C]MeOLBQ, [11C]SacOMe and [11C]LBQOMe were synthesized by O-[11C]methylation using [11C]methyl triflate. Binding of these radiolabeled derivatives (5 nM) were assessed by autoradiography on rat neprilysin rich kidney slices with or without 10 μM NEPi (thiorphan or sacubitril) for 20 min at 37 °C. [11C]LBQOMe was further tested for binding selectivity in the presence of 10 μM of angiotensin-converting enzyme inhibitor (ACEi, captopril) or angiotensin II AT1 receptor blocker (AT1R, losartan). Radioligands were evaluated for their in vitro stability up to 20 min after incubation at 37 °C in rat and human plasma by reverse-phase column-switch HPLC. Non-radioactive SacOMe incubated in rat and human plasma was analyzed by HPLC-coupled with high resolution mass spectrometry (HRMS) to confirm the metabolites' identity. [11C]SacOMe main labeled metabolite was further analyzed by HPLC after incubation in rat kidney slices at 37 °C.

RESULTS

The novel [11C]SacOMe and [11C]LBQOMe were produced in 32 ± 3% RCY and 15 ± 6% at EOS (decay-corrected from [11C]CO2, n = 3), high molar activity (407 ± 92 GBq/μmol and 260 ± 92 GBq/μmol), and high chemical (≥90%) and radiochemical (≥99%) purities in a total synthesis time of 31 and 34 min, respectively. High accumulation of [11C]SacOMe and [11C]LBQOMe in kidneys was completely blocked (>99.9%) by pre-incubation with NEPi, whereas [11C]MeOLBQ displayed negligible uptake in autoradiography studies. [11C]LBQOMe binding was not affected by saturating doses of losartan or captopril indicating binding selectivity for NEP. While [11C]SacOMe and [11C]LBQOMe were stable in human plasma (>92%) even after 20 min incubation at 37 °C, rat plasma analyses exhibited >95% biotransformation of [11C]SacOMe, 40% of [11C]LBQOMe and >80% loss of the 11C-methyl group of [11C]MeOLBQ after 5 min of incubation. Comparable results using the non-radioactive SacOMe were obtained by HPLC-HRMS. Radio-HPLC analysis of the extracted activity of rat kidney slices incubated with [11C]SacOMe demonstrated that >95% of the radioactive signal corresponded to [11C]LBQOMe as the main metabolite.

CONCLUSION

The desethyl active metabolite of [11C]SacOMe, [11C]LBQOMe, displayed stability in human plasma, binding selectivity for neprilysin over ACE or AT1R in rat kidney slices. Rapid plasmatic dealkylation at the 2-methylbutanoic acid position is in line with the necessity of incorporating the labeling group on oxobutanoic acid side in the strategy to develop a stable O-alkylated labeled derivative of sacubitril.