Current Drug Metabolism - Volume 23, Issue 12, 2022

Orphan cytochromes P450 (CYP) are enzymes whose biological functions and substrates are unknown. However, the use of new experimental strategies has allowed obtaining more information about their relevance in the metabolism of endogenous and exogenous compounds. Likewise, the modulation of their expression and activity has been associated with pathogenesis and prognosis in different diseases. In this work, we review the regulatory pathways and the possible role of orphan CYP to provide evidence that allow us to stop considering some of them as orphan enzymes and to propose them as possible therapeutic targets in the design of new strategies for the treatment of diseases associated with CYP-mediated metabolism.

Background: Salt-processed product of cuscutae semen (SCS), which is documented in Chinese pharmacopoeia (2020 edition), is one of the processed products of cuscustae semen. SCS possesses hepatoprotective effects. However, Pharmacokinetic/Pharmacodynamic (PK-PD) study of SCS with intervening acute liver injury (ALI) has not been reported yet. Effective constituents are still not well addressed. Objective: This study was performed to study PK-PD properties with the purpose of linking SCS hepatoprotective effects to key therapeutic outlines to guide therapeutic use in clinical settings. Methods: Rats were orally administered SCS after the acute liver injury model was established. Plasma biochemical analysis, antioxidative analysis, and liver histopathology were measured to evaluate the hepatoprotective effects of SCS. Blood samples were collected at different time points (0 h, 0.083 h, 0.25 h, 0.5 h, 1 h, 1.5 h, 2 h, 3 h, 4 h, 8 h, 12 h, 24 h) for PK/PD study after SCS administration. Contents of chlorogenic acid, hyperoside and astragalin were estimated by UHPLC-ESI-MS. The relationship between concentrations of chlorogenic acid, hyperoside, and astragalin and hepatoprotective effects was assessed by PK-PD modeling. Results: The results showed that SCS ameliorated liver repair and decreased the serum levels of alanine aminotransferase (ALT), aspartate transaminase (AST) markedly. Hepatic oxidative stress was inhibited by SCS, as evidenced by a decrease in malondialdehyde (MDA) and an increase in glutathione (GSH) and superoxide dismutase (SOD) in the liver. PK-PD correlation analysis indicated that concentrations of chlorogenic acid, hyperoside, and astragalin were negatively correlated with level of AST and ALT. Conclusion: The encouraging finding indicates that SCS has beneficial effects on CCl4-induced liver damage. Chlorogenic acid, hyperoside, and astragalin are three effective constituents to exert hepatoprotective effects while astragalin may have maximum pharmacological activity. PK-PD study reveals the positive relationship between drug concentration and action intensity of SCS against liver injury. This research provides a robust foundation for future studies.

Background: Tangeretin, present in citrus fruits, is a polymethoxy flavone with extensive pharmacological effects. It has been widely used in the clinic, but there were no detailed studies on the in vivo metabolism of tangeretin. Objective: This study aimed to establish a rapid and effective strategy to identify the metabolites of tangeretin and evaluate the biotransformation pathways of tangeretin in rats. Methods: The ultra-high performance liquid chromatography (UHPLC) equipped with a Q-Exactive Orbitrap mass spectrometer was used to identify the metabolites of tangeretin in plasma, urine and faeces of rats after intragastric administration. Based on high-resolution extracted ion chromatograms (HREICs) and parallel reaction monitoring mode (PRM), metabolites of tangeretin were identified by comparing the accurate mass, chromatographic retention times, diagnostic product ions (DPIs) and neutral loss fragments (NLFs) with those of tangeretin reference standard. Isomers were distinguished by ClogP values. Results: An efficient and integrated strategy was established for the comprehensive screening and characterizing of tangeretin metabolites through Rapid Profiling. Based on this strategy, a total of 52 metabolites were detected and identified, among which 25 metabolites were found in rat plasma, while 48 and 16 metabolites were characterized from rat urine and faeces, respectively. These metabolites were produced by demethylation, demethoxylation, hydroxylation, methoxylation, glucuronidation, glycosylation, sulfation, and their composite reactions. Interestingly, tangeretin is easy to lose methyl in vivo and becomes an intermediate product, and then other phase I and phase II reactions occur. Moreover, the characteristic fragmentation pathways of tangeretin were summarized for the subsequent metabolite identification. Conclusion: The analytical method based on UHPLC-Q-Exactive mass spectrometer has the ability to quickly clarify unknown metabolism. And the the comprehensive metabolism study of tangeretin provided an overall metabolic profile, which will be of great scientific basis for further studies on tangeretin in determining its pharmacokinetics, the bioactivity of the metabolites, and clinical applications.

Background: Despite CoQ10 being a powerful antioxidant and its redox state that may characterize the body’s antioxidant system, the latter remains unstudied in patients with cardiovascular diseases. Objective: This prospective case-control study aimed to investigate the concentrations of ubiquinol, ubiquinone, total CoQ10 and its redox state in patients with ischemic heart disease (IHD) and arterial hypertension (AH) during standard therapy and with the additional prescription of CoQ10. Methods: The study included 54 healthy individuals and 26 patients, who were divided into a control group receiving standard therapy and a test group receiving CoQ10 in addition to standard therapy. Quantitative determination of COQ10, ubiquinone and ubiquinol was carried out by HPLC-MS/MS. Results: It was found that the CoQ10 level in patients was significantly lower than in healthy individuals (on average -32Δ%). In the test group, after treatment, the concentrations of ubiquinol (+53 Δ%), ubiquinone (-28 Δ%), total CoQ10 (+27 Δ%) and redox state (+112 Δ%) were significantly different from the baseline, while in the control group no significant differences were noticed. In the test group after treatment, the levels of total CoQ10 (+25 Δ%), ubiquinol (+43 Δ%), and redox state (+86 Δ%) were statistically significantly higher than in the control group and total CoQ10 concentration did not significantly differ from that in healthy individuals (-12 Δ%). Conclusion: The additional prescription of CoQ10 for patients with IHD significantly increases the level of total CoQ10, which leads to the increase of body antioxidant potential.

Background: Irinotecan is widely used to treat various types of solid and metastatic cancer. It is an ester prodrug and its hydrolytic metabolite (SN-38) exerts potent anticancer activity. Irinotecan is hydrolyzed primarily by carboxylesterase-2 (CES2), a hydrolase abundantly present in the intestine such as the duodenum. We have identified several potent and covalent CES2 inhibitors such as remdesivir and sofosbuvir. Remdesivir is the first small molecule drug approved for COVID-19, whereas sofosbuvir is a paradigm-shift medicine for hepatitis C viral infection. Irinotecan is generally well-tolerated but associated with severe/life-threatening diarrhea due to intestinal accumulation of SN-38. Objective: This study was to test the hypothesis that remdesivir and sofosbuvir protect against irinotecan-induced epithelial injury associated with gastrointestinal toxicity. Methods: To test this hypothesis, formation of organoids derived from mouse duodenal crypts, a robust cellular model for intestinal regeneration, was induced in the presence or absence of irinotecan +/- pretreatment with a CES2 drug inhibitor. Results: Irinotecan profoundly inhibited the formation of intestinal organoids and the magnitude of the inhibition was greater with female crypts than their male counterparts. Consistently, crypts from female mice had significantly higher hydrolytic activity toward irinotecan. Critically, remdesivir and sofosbuvir both reduced irinotecan hydrolysis and reversed irinotecan-reduced formation of organoids. Human duodenal samples robustly hydrolyzed irinotecan, stable CES2 transfection induced cytotoxicity and the cytotoxicity was reduced by CES2 drug inhibitor. Conclusion: These findings establish a therapeutic rationale to reduce irinotecan-gastrointestinal injury and serve as a cellular foundation to develop oral formulations of irinotecan with high safety.