Evidence for Polyamine, Biogenic Amine, and Amino Acid Adduction Resulting from Metabolic Activation of Diosbulbin B

Introduced paeoniflorin reduces the main toxicity induced by diosbulbin B, the major toxic compound of Dioscorea bulbifera L.: involved inhibiting inflammation and ferroptosis

Rhizoma Dioscoreae Bulbiferae (HYZ) is a widely utilized herb in clinical practice, known for its significant biological activities. However, the associated hepatotoxicity poses limitations to its application. Our previous research indicated that the effective mitigation of HYZ-induced hepatotoxicity through the concoction with Radix Paeoniae Alba medicinal juice involves the incorporation of paeoniflorin (Pae) and a reduction in diosbulbin B (DB), the primary toxic compound in HYZ. This finding suggests that the introduced Pae may exert a direct attenuating effect on DB. In light of this, this study represents the first investigation into Pae's detoxification effect against DB-induced hepatotoxicity after administration for 2 months in mice vivo while also exploring underlying mechanisms related to inflammation and ferroptosis based on network pharmacology results. Our findings demonstrate that Pae significantly alleviates DB-induced hepatotoxicity in a dose-dependent manner. Western blotting and ELISA analyses revealed that Pae effectively reversed elevated levels of hepatic inflammation-related markers-such as NF-κB, p38 MAPK, NLRP3, TNF-α, and IL-1β-as well as excessively high concentrations of ferroptosis-related MDA and Fe2+. Furthermore, it restored low levels of GSH, SOD, GPX4, and FTH1. In summary, introduced Pae substantially mitigated DB-induced hepatotoxicity by inhibiting both hepatocyte inflammation and ferroptosis.

Mechanism-based cytotoxicity trend prediction of furan-containing pollutants present in a mixture

Human exposure to furan-containing pollutants (FCPs) has raised concerns due to their high risk of toxicity. A substantial number of approximately 8500 recorded compounds containing a furan ring exist which have been analytically or in biologically studied. A significant portion of these compounds is found in the everyday environments of individuals, particularly when ingested through food. Consequently, there is a need for a universal approach to rapidly predict the potential toxicity trends of FCPs. In this study, we developed a bromine labeling-based platform that combines LC-ICP-MS and LC-ESI-MS techniques to absolutely quantify FCP-induced protein adduction. The LC-ESI-MS approach facilitated the identification of FCP-derived protein adducts and optimized liquid chromatographic conditions for analyte separation. By employing a well-designed bromine-containing compound as a general internal standard, LC-ICP-MS-based technique enabled to absolutely assess bromine-labeled protein adduction. The protein adduction efficiencies of furan, 2-methylfuran, and 2,5-dimethylfuran were found to be 2.68, 2.90, and 0.37 molecules per 10,000 FCP molecules that primary hepatocytes received, respectively. Furthermore, we observed that 2-methylfuran exhibited the highest cytotoxicity, followed by furan and 2,5-dimethylfuran, which aligned with the order of their protein adduction. Thus, the protein adduction efficiency of FCPs could serve as a potential index for predicting their toxicity trends.

Ferulic acid prevents Diosbulbin B-induced liver injury by inhibiting covalent modifications on proteins

Diosbulbin B (DIOB) has been reported to cause serious liver injury. However, in traditional medicine, DIOB-containing herbs are highly safe in combination with ferulic acid (FA)-containing herbs, suggesting potential neutralizing effect of FA on the toxicity of DIOB. DIOB can be metabolized to generate reactive metabolites (RMs), which can covalently bind to proteins and lead to hepatoxicity. In the present study, the quantitative method was firstly established for investigating the correlation between DIOB RM-protein adducts (DRPAs) and hepatotoxicity. Then, we estimated the detoxication effect of FA in combination with DIOB and revealed the underlying mechanism. Our data indicated that the content of DRPAs positively correlate with the severity of hepatotoxicity. Meanwhile, FA is able to reduce the metabolic rate of DIOB in vitro. Moreover, FA suppressed the production of DRPAs and decreased the serum alanine/aspartate aminotransferase (ALT/AST) levels elevated by DIOB in vivo. Thus, FA can ameliorate DIOB-induced liver injury through reducing the production of DRPAs.

Rapid separation and characterization of the in vitro metabolites of moscatilin by ultra-high performance liquid chromatography coupled to hybrid quadrupole orbitrap tandem mass spectrometry

Moscatilin, a bioactive ingredient isolated from Dendrobium moscatum, has been demonstrated to have excellent anti-cancer activity. The goals of the present study were to investigate the metabolic profiles of moscatilin and to identify and characterize its metabolites. In vitro studies were performed by incubating moscatilin (10 μM) with rat, dog, monkey, and human liver microsomes (0.5 mg protein/ml) to generate the metabolites. An analytical method of liquid chromatography combined with hybrid quadrupole orbitrap high-resolution mass spectrometry in full mass/data-dependent tandem mass spectrometry scan was utilized to separate and identify the metabolites in accordance with their accurate masses, formulas, and tandem mass spectrometry fragment ions determination. A total of six phase I metabolites were detected and structurally characterized. The phase I metabolic pathways of moscatilin were hydroxylation, demethylation, and dehydrogenation. In glutathione-supplemented liver microsomes, nine glutathione conjugates were detected and identified. Our results demonstrated that moscatilin was susceptible to bioactivation with the result of ortho quinone and quinone-methide intermediates. The present study provided an overview of the in vitro metabolic profiles of moscatilin, which will aid in the understanding of the efficacy and safety of this active compound.

Characterization and identification of the metabolites of dihydromethysticin by ultra-high-performance liquid chromatography orbitrap high-resolution mass spectrometry

Dihydromethysticin, a natural component from Piper methysticum Forst, has been reported to display pharmacological effects in mental disorders and some malignant tumors. However, the metabolism of this component remained unknown. The goal of this work was conducted to discover the metabolic profiles of dihydromethysticin. The in vitro incubation was performed by incubating dihydromethysticin with rat, monkey, and human liver microsomes and hepatocytes. An analytical assay of ultra-high performance liquid chromatography combined with Orbitrap high-resolution mass spectrometry was utilized to detect and identify the metabolites. With high resolution mass spectrometric determination, the accurate mass, elemental composition, and product ions of the metabolites were determined, which enabled structural characterization to become easy. Under the present conditions, four phase-I metabolites, as well as six phase-II metabolites, were detected and their tentative structures were characterized by mass spectra. M4 was found as the most abundant metabolite both in liver microsomes and hepatocytes. Cytochrome P450 1A2, 2C9, and 3A4 contributed to the formation of this metabolite by using human recombinant P450 enzymes. M4 can be oxidized into reactive ortho-quinone intermediate followed by conjugating with glutathione. M4 was also subject to glucuronidation (M1 and M2) and methylation (M5). Demethylenation, oxidation, hydroxylation, glucuronidation, glutathionylation, and methylation were the primary metabolic pathways of dihydromethysticin. This study provides in vitro metabolism data of dihydromethysticin, which is indispensable for understanding the disposition of this compound.

A Metabolic Activation-Based Chemoproteomic Platform to Profile Adducted Proteins Derived from Furan-Containing Compounds

Human exposure to widespread furan-containing compounds (FCCs) has drawn much attention due to the high risk of their toxicities. Identifying adducted proteins resulting from the metabolic activation of FCCs is the core to learning the mechanism of FCCs' toxic action. We succeeded in establishing a metabolic activation-based chemoproteomic platform to map FCC-derived protein adducts in cultured primary hepatocytes treated with FCCs and to pinpoint the modification sites, using click chemistry but without alkynylation or azidation of FCCs to be investigated. The proposed platform was systematically verified by biomimetic synthesis, liver microsomal incubation, and primary hepatocyte culture. A mixture of furan, 2-methylfuran, and 2,5-dimethylfuran as model was tested by use of the established platform. A total of hepatic 171 lysine-based adducted proteins and 145 cysteine-based adducted proteins by the reactive metabolites of the three FCCs were enriched and identified (Byonic score ≥ 100). The target proteins were found to mainly participate in ATP synthesis. The technique was also successfully applied to furan-containing natural products. The established platform made it possible to profile covalently adducted proteins, because of potential exposure to a vast inventory of over two million of FCCs documented.

Semisynthesis and Non-Small-Cell Lung Cancer Cytotoxicity Evaluation of Germacrane-Type Sesquiterpene Lactones from Elephantopus scaber

Two series of germacrane-type sesquiterpene lactones were produced by semisynthetic modulation of scaberol C, which was prepared by a standard chemical transformation from an Elephantopus scaber extract. Their inhibition activities against non-small-cell lung cancer cells were screened, and preliminary structure-activity relationships were also established. Among them, monomeric analog 1u and dimeric analog 3d exhibited superior anti-non-small-cell lung cancer cytotoxic potencies with IC₅₀ values of 4.3 and 0.7 μM against A549 cells, respectively, and were more active than cisplatin and the standard sesquiterpene lactones, parthenolide and scabertopin. Further studies revealed that compounds 1u and 3d cause G2/M phase arrest and induce apoptosis through the activation of mitochondrial pathways in A549 cells. Collectively, the results obtained suggest that compounds 1u and 3d are promising anti-non-small-cell lung cancer lead compounds.