Simultaneous toxicokinetic studies of aristolochic acid I and II and aristolactam I and II using a newly-developed microdialysis liquid chromatography-tandem mass spectrometry

Long-term oral administration of Kelisha capsule does not cause hepatorenal toxicity in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Kelisha capsules (KLS) are often used to treat acute diarrhoea, bacillary dysentery, heat stroke, and other diseases. One of its components, Asarum, contains aristolochic acid I which is both nephrotoxic and carcinogenic. However, the aristolochic acid (AA) content in KLS and its toxicity remain unclear.

AIM OF THE STUDY

The aims of this study were to quantitatively determine the contents of five aristolochic acid analogues (AAAs) in Asarum and KLS, and systematically evaluate the in vivo toxicity of KLS in rats.

MATERIALS AND METHODS

Ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was used to determine the content of the five AAAs in Asarum and KLS. Sprague-Dawley rats were administered KLS at 0, 0.75, 1.5, and 3.0 g/kg respectively, and then sacrificed after 4 weeks of administration or after an additional 2 weeks of recovery. The endpoints assessed included body weight measurements, serum biochemistry and haematology indices, and clinical and histopathological observations.

RESULTS

The AAAs content in Asarum sieboldii Miq. (HB-ESBJ) were much lower than those of the other Asarums. The contents of AA I, AA IVa, and aristolactam I in KLS were in the ranges of 0.03-0.06 μg/g, 1.89-2.16 μg/g, and 0.55-1.60 μg/g, respectively, whereas AA II and AA IIIa were not detected. None of the rats showed symptoms of toxic reactions and KLS was well tolerated throughout the study. Compared to the control group, the activated partial thromboplastin time values of rats in the 1.5 and 3.0 g/kg groups significantly reduced after administration (P < 0.05). In addition, the serum triglycerides of male rats in the 0.75 and 1.5 g/kg groups after administration, and the 0.75, 1.5, 3.0 g/kg groups after recovery were significantly decreased (P < 0.01 or P < 0.001). No significant drug-related toxicological changes were observed in other serum biochemical indices, haematology, or histopathology.

CONCLUSIONS

The AA I content in KLS met the limit requirements (<0.001%) of the Chinese Pharmacopoeia. Therefore, it is safe to use KLS in the short-term. However, for safety considerations, attention should be paid to the effects of long-term KLS administration on coagulation function and triglyceride metabolism.

Catalpol from Rehmannia glutinosa Targets Nrf2/NF-κB Signaling Pathway to Improve Renal Anemia and Fibrosis

Rehmannia glutinosa is widely recognized as a prominent medicinal herb employed by practitioners across various generations for the purpose of fortifying kidney yin. Within Rehmannia glutinosa, the compound known as catalpol (CAT) holds significant importance as a bioactive constituent. However, the protective effects of CAT on kidneys, including ameliorative effects on chronic kidney disease - most prominently renal anemia and renal fibrosis - have not been clearly defined. In this study, the kidney injury model of NRK-52E cells and C57BL/6N male mice was prepared by exposure to aristolochic acid I (AA-I), and it was discovered that CAT could ameliorate oxidative stress injury, inflammatory injury, apoptosis, renal anemia, renal fibrosis, and other renal injuries both in vivo and in vitro. Further treatment of NRK-52E cells with Nrf2 inhibitors (ML385) and activators (ML334), as well as NF-κB inhibitors (PDTC), validated CAT's ability to target Nrf2 activation. Furthermore, the expression of phosphorylated NF-κB p65, IL-6, and Cleaved-Caspase3 protein was inhibited. CAT also inhibited NF-κB, and then inhibited the expression of IL-6, p-STAS3, TGF-β1 protein. Therefore, CAT can regulate Nrf2/NF-κB signaling pathway, significantly correct renal anemia and renal fibrosis, and is conducive to the preservation of renal structure and function, thus achieving a protective effect on the kidneys.

Establishment of enzyme-linked immunosorbent assay for aristolochic acid

In recent years, the nephrotoxicity and carcinogenicity of aristolochic acid have attracted worldwide attention, and the traditional Chinese medicine containing this ingredient has been banned in many places, affecting the TCM industry. To meet this challenge, researchers have developed various detection methods, such as high-performance liquid chromatography, gas chromatography-mass spectrometry and thin-layer chromatography. A rapid detection method must therefore be developed to ensure safety. A polyclonal antibody capable of recognizing aristolochic acid was prepared, and an indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) was established to detect the amount of aristolochic acid in the sample to be measured. Methods Using 1-(4-chlorophenyl) cyclobutylamine as a hapten, immunogens and coating antigens were obtained by coupling with bovine serum albumin (BSA) and chicken ovalbumin (OVA) using the active ester method. UV scanning confirmed the successful coupling of the conjugate, and New Zealand white rabbits were immunized. The obtained antibody serum was screened for the best antibody by ic-ELISA detection. Use the chessboard method to determine three optimal combinations of original coating concentration and antibody dilution ratio, establish a standard curve for each combination to obtain the best combination, and establish a rapid detection method. Finally, the standard aristolochic acid A was added to the purchased apple vinegar and canned coffee for recycling experiments to verify the detection method.By changing the antigen antibody concentration, the antibody showed the highest sensitivity to aristolochic acid standard at the original coating, 1000-fold dilution, IC50 of 24.88 ng/mL, limit of detection IC10 of 3.19 ng/mL, and detection range IC20-IC80 of 6.81-90.91 ng/mL. The recovery experiments under this conditions yielded a recovery rate of 92%-105%, within reasonable limits, indicating the success of the ELISA rapid detection method. Conclusion The enzyme-linked immunoassay method established in this paper can quickly detect the content of aristolochic acid in the sample to be tested, and the antibody prepared by this method has good broad-spectrum and can detect other aristolochic acid, such as aristolochic acid A, aristolochic acid B, aristolochic acid C, and aristolochic acid D.

Quantum Dot-Based Immunoassays: Unraveling Sensitivity Discrepancies and Charting Future Frontiers

The 2023 Nobel Prize in Chemistry honors the groundbreaking contributions of Alexei Ekimov, Louis Brus, and Moungi Bawendi to the field of quantum dots (QDs). In this spirit, we developed a direct competitive QD fluorescence immunoassay (dc-QD-FLISA) to detect aristolochic acid type I (AAI), a potent carcinogen found in herbal remedies. Unexpectedly, the dc-QD-FLISA exhibited lower sensitivity than that of an indirect competitive enzyme-linked immunosorbent assay (ic-ELISA), contrary to our initial expectations. This discrepancy in the sensitivity prompted a comprehensive analysis of the entire experimental process. We propose that steric hindrance between QDs and antigen-binding sites on antibodies may significantly diminish the binding efficiency, reducing sensitivity within the dc-QD-FLISA method. Furthermore, issues such as buffer conditions, antibody handling, and separation methods are also contributing factors. We recommend site-directed QD modification and stringent consideration of the experimental conditions. This study not only provides insights into QD-based immunoassays but also highlights the need for future advancements in immunoassay technology in terms of augmenting sensitivity and specificity, potentially revolutionizing disease diagnosis, biomarker discovery, and biomedical research.