A systematic review of pharmacokinetic studies on herbal drug Fuzi: Implications for Fuzi as personalized medicine.

BACKGROUND: Fuzi, which is the processed lateral roots of Aconitum carmichaeli Debx. (Ranunculaceae), is a traditional herbal medicine that is well known for its excellent pharmacological effects and acute toxicity. Aconitum alkaloids are responsible for its pharmacological activity and toxicity. Although a large number of studies on Fuzi have been reported, no comprehensive review on its pharmacokinetics has yet been published. PURPOSE: This paper seeks to present a comprehensive review regarding the phytochemistry, pharmacokinetic features and toxicity of Fuzi. The regulation of drug-metabolizing enzymes (DMEs) and efflux transporters (ETs) by Fuzi is also concluded. Additionally, the use of Fuzi as a personalized medicine based on the bioavailability barrier (BB), which mainly comprises DMEs and ETs, is discussed. METHODS: All available information on Fuzi was collected by searching for key words in PubMed, ScienceDirect, CNKI, Google Scholar, Baidu Scholar, and Web of Science. RESULTS: Aconitum alkaloids, which mainly include diester-diterpene alkaloids (DDAs), monoester-diterpene alkaloids (MDAs) and unesterified-diterpene alkaloids (UDAs), could be detected after Fuzi ingestion in vivo. The Aconitum alkaloids are rapidly absorbed in the intestine and extensively distributed in the body. DMEs, especially CYP3A4/5, are responsible for various types of metabolic reactions of the Aconitum alkaloids. ETs, including P-glycoprotein (P-gp), multidrug resistance-associated protein 2 (MRP2), and breast cancer resistance protein (BCRP), are involved in the efflux of the DDAs and MDAs. The kidney is the most important organ involved in the excretion of the Aconitum alkaloids. DDAs are the main toxic compounds present in Fuzi, and their acute toxicity is mainly due to their effects on the voltage-dependent sodium channels. Furthermore, Fuzi can substantially regulate DMEs and ETs. CONCLUSIONS: The toxicity of DDAs is acute. However, further investigations are necessary to determine the exact toxicological mechanisms. The significant impact of Fuzi on DMEs and ETs suggests that the co-administration of Fuzi with drugs that are substrates of DMEs and/or ETs may cause herb-drug interactions (HDIs). The BB network controlled exposure to the Aconitum alkaloids in vivo. Polymorphisms of DMEs and ETs in different individuals contribute to the differences in the efficacy and toxicity of Fuzi ingestion. In the future, the use of Fuzi as personalized medicine based on the BB network is necessary and practical to achieve ideal therapeutic efficacy with minimal toxicity.

Aconitum alkaloids, the major components of Aconitum species, affect expression of multidrug resistance-associated protein 2 and breast cancer resistance protein by activating the Nrf2-mediated signalling pathway.

BACKGROUND: Aconitum alkaloids from Aconitum species are often used to treat arthritis and rheumatic diseases but have the drawback of high toxicity. Identifying their pharmacokinetic behaviour is important for the safe clinical application of Aconitum species. Efflux transporters (ETs), including P-glycoprotein (P-gp), multidrug resistance-associated protein 2 (MRP2), and breast cancer resistance protein (BCRP), have important functions in regulating the pharmacokinetic behaviours of drugs and in herb-herb or herb-drug interactions (HDIs). The Aconitum alkaloids regulate P-gp expression and function, but their effects on MRP2 and BCRP expression remain unknown. PURPOSE: To determine the effects of three Aconitum alkaloids, aconitine (AC), benzoylaconine (BAC), and aconine, on MRP2 and BCRP. METHODS: The levels of the protein and mRNA expression of MRP2 and BCRP in vivo and in vitro were measured via Western blotting and real-time PCR, respectively. Fluorescence signals of MRP2 and BCRP were detected via confocal fluorescence microscopy. A reporter assay using HepG2-C8 cells, which were generated by transfecting plasmids containing the antioxidant response element (ARE)-luciferin gene into HepG2 cells, was used to examine the ARE-luciferin activity. The transport activities of MRP2 and BCRP were tested via flow cytometry using substrate probes. RESULTS: The Aconitum alkaloids significantly up-regulated MRP2 and BCRP expression, accompanied by a marked increase in nuclear factor E2-related factor-2 (Nrf2) expression in the jejunum, ileum, and colon of FVB mice, in the order AC < BAC < aconine. In the in vitro model, the Aconitum alkaloids increased MRP2 and BCRP expression in Caco-2 and LS174T cells, in the order AC < BAC < aconine. Additionally, these alkaloids promoted the translocation of Nrf2 from the cytoplasm to the nucleus and significantly increased ARE-luciferin activity in HepG2-C8 cells. Luteolin, a potent inhibitor of Nrf2, markedly prevented MRP2 and BCRP expression from being induced by the three Aconitum alkaloids. The efflux activity of MRP2 was also significantly increased in cells receiving the same treatment. CONCLUSIONS: The tested Aconitum alkaloids significantly increased the expression of MRP2 and BCRP by activating the Nrf2-mediated signalling pathway and enhanced the efflux activity of MRP2. The potential for herb-herb interactions or HDIs exists when Aconitum species are co-administered with substrate drugs that are transported via MRP2 and BCRP. Therefore, the Aconitum alkaloids may be used as quality indicators for the herbs of Aconitum species.