New otonecine-type pyrrolizidine alkaloid from Petasites japonicus

Mass spectrometric analysis strategies for pyrrolizidine alkaloids

Pyrrolizidine alkaloids (PAs) in food and natural preparations have received widespread attention due to their hepatotoxicity, genotoxicity, and embryotoxicity. Mass spectrometry (MS), as a high resolution, high sensitive, and high throughput detection tool, has been the most commonly used technique for the determination of PAs. The continuous advancement of new technologies, methods, and strategies in the field of MS has contributed to the improvement of the analytical efficiency and methodological enhancement of PAs. This paper provides an overview of the structure, toxicity properties and commonly employed analytical methods, focusing on the concepts, advances, and novel techniques and applications of MS-based methods for the analysis of PAs. Additionally, the remaining challenges, future perspectives, and trends for PA detection are discussed. This review provides a reference for toxicological studies of PAs, content monitoring, and the establishment of quality control and safety standards for herbal and food products.

A review on the ethnobotany, phytochemistry, pharmacology and toxicology of butterbur species (Petasites L.)

ETHNOPHARMACOLOGICAL RELEVANCE

Petasites (butterbur, Asteraceae) species have been used since Ancient times in the traditional medicine of Asian and European countries to treat central nervous system (migraine), respiratory (asthma, allergic rhinitis, bronchitis, spastic cough), cardiovascular (hypertension), gastrointestinal (ulcers) and genitourinary (dysmenorrhea) disorders.

AIM OF THE REVIEW

This study summarized and discussed the traditional uses, phytochemical, pharmacological and toxicological aspects of Petasites genus.

MATERIALS AND METHODS

A systematic search of Petasites in online databases (Scopus, PubMed, ScienceDirect, Google Scholar) was performed, with the aim to find the phytochemical, toxicological and bioactivity studies. The Global Biodiversity Information Facility, Plants of the World Online, World Flora Online and The Plant List databases were used to describe the taxonomy and geographical distribution.

RESULTS

The detailed phytochemistry of the potentially active compounds of Petasites genus (e.g. sesquiterpenes, pyrrolizidine alkaloids, polyphenols and essential oils components) was presented. The bioactivity studies (cell-free, cell-based, animal, and clinical) including the traditional uses of Petasites (e.g. anti-spasmolytic, hypotensive, anti-asthmatic activities) were addressed and followed by discussion of the main pharmacokinetical and toxicological issues related to the administration of butterbur-based formulations.

CONCLUSIONS

This review provides a complete overview of the Petasites geographical distribution, traditional use, phytochemistry, bioactivity, and toxicity. More than 200 different sesquiterpenes (eremophilanes, furanoeremophilanes, bakkenolides), 50 phenolic compounds (phenolic acids, flavonoids, lignans) and volatile compounds (monoterpenes, sesquiterpenes) have been reported within the genus. Considering the phytochemical complexity and the polypharmacological potential, there is a growing research interest to extend the current therapeutical applications of Petasites preparations (anti-migraine, anti-allergic) to other human ailments, such as central nervous system, cardiovascular, malignant or microbial diseases. This research pathway is extremely important, especially in the recent context of the pandemic situation, when there is an imperious need for novel drug candidates.

Plasma concentration profiles for hepatotoxic pyrrolizidine alkaloid senkirkine in humans extrapolated from rat data sets using a simplified physiologically based pharmacokinetic model

AIM

The main aim of the current study was to obtain forward dosimetry assessments of pyrrolizidine alkaloid senkirkine plasma and liver concentrations by setting up a human physiologically based pharmacokinetic (PBPK) model based on the limited information available.

BACKGROUND

The risks associated with plant-derived pyrrolizidine alkaloids as natural toxins have been assessed.

OBJECTIVE

The pyrrolizidine alkaloid senkirkine was investigated because it was analyzed in a European transcriptomics study of natural hepatotoxins and in a study of the alkaloidal constituents of traditional Japanese food plants Petasites japonicus. The in silico human plasma and liver concentrations of senkirkine were modeled using doses reported for acute-term toxicity in humans.

METHODS

Using a simplified PBPK model established using rat pharmacokinetic data, forward dosimetry was conducted. Since in vitro rat and human intrinsic hepatic clearances were similar; an allometric scaling approach was applied to rat parameters to create a human PBPK model.

RESULTS

After oral administration of 1.0 mg/kg in rats in vivo, water-soluble senkirkine was absorbed and cleared from plasma to two orders of magnitude below the maximum concentration in 8 h. Human in silico senkirkine plasma concentration curves were generated after virtual daily oral administrations of 3.0 mg/kg senkirkine (the dose involved in an acute fatal hepatotoxicity case). A high concentration of senkirkine in the culture medium caused in vitro hepatotoxicity as evidenced by lactate dehydrogenase leakage from human hepatocyte-like HepaRG cells.

CONCLUSION

Higher virtual concentrations of senkirkine in human liver and plasma than those in rat plasma were estimated using the current rat and human PBPK models. Current simulations suggest that if P. japonicus (a water-soluble pyrrolizidine alkaloid-producing plant) is ingested daily as food, hepatotoxic senkirkine could be continuously present in human plasma and liver.

Metabolic profiles for the pyrrolizidine alkaloid neopetasitenine and its metabolite petasitenine in humans extrapolated from rat in vivo and in vitro data sets using a simplified physiologically based pharmacokinetic model

Naturally occurring food substances may constitute safety hazards. The risks associated with plant-derived pyrrolizidine alkaloids have been extensively evaluated. Petasites japonicus (common Japanese name, fuki) is a widely consumed water-soluble pyrrolizidine alkaloid-producing plant. In this study, neopetasitenine (acetylfukinotoxin) was selected as a model food substrate (for which human pharmacokinetics were estimated) because of its high concentration in fuki, along with petasitenine (fukinotoxin), its carcinogenic deacetylated metabolite. Although neopetasitenine was rapidly absorbed and converted to petasitenine after oral administration of 1.0 mg/kg in rats, petasitenine was slowly cleared from plasma. Forward dosimetry was conducted using in silico simplified physiologically based pharmacokinetic (PBPK) modeling formulated on experimental pharmacokinetic rat data. From ~2 hr after the oral administration of neopetasitenine in rats, the plasma concentrations of petasitenine were higher than those of neopetasitenine under the present conditions. A human PBPK model was established following an allometric scaling approach applied to rat parameters (without considering interspecies factors) to estimate human intrinsic hepatic clearances from empirical rat values. Human in silico neopetasitenine and petasitenine plasma concentration curves were simulated after daily oral administrations of 3.0 and 1.3 mg/kg neopetasitenine. These doses were taken from reported acute/short-term cases of pyrrolizidine alkaloid toxicity. In vitro hepatotoxicity of neopetasitenine and petasitenine was caused by their high concentrations in the medium for human hepatocyte-like cell line HepaRG cells as an index of lactate dehydrogenase leakage. Neopetasitenine was estimated to be rapidly absorbed and converted to deacetylated carcinogenic petasitenine, even after hepatotoxic doses of 1.0 mg/kg in humans. If the water-soluble pyrrolizidine alkaloid-producing plant P. japonicus were daily consumed as food, current simulation results suggest that dangerous amounts of deacetylated petasitenine could be continuously present in human plasma.

Petatewalide B alleviates oxygen‑glucose deprivation/reoxygenation‑induced neuronal injury via activation of the AMPK/Nrf2 signaling pathway

Neuronal injury is a common, and critical, occurrence in clinical ischemic strokes, and can cause irreversible brain damage. However, the precise pathological mechanisms underlying this condition and effective treatment remain unclear. Increasing evidence shows that the nuclear factor erythroid 2‑related factor 2 (Nrf2)/activated protein kinase (AMPK) signaling pathway serves a significant role in neuronal injury and is involved in neuroprotection. The present study demonstrated that petatewalide B, the active constituent of Petasites japonicus, otherwise known as butterbur, can alleviate oxygen‑glucose deprivation/reoxygenation (OGD/R)‑induced neuronal death via the adenosine monophosphate‑AMPK/glycogen synthase kinase (GSK)‑3/β/Nrf2/antioxidant response element (ARE) signaling pathways in human neuroblastoma SH‑SY5Y cells. A neuronal injury model was established by depriving SH‑SY5Y cells of oxygen and glucose for 8 h, followed by 24 h of reoxygenation (OGD/R). The results indicated that the OGD/R model exhibited reduced cell viability but increased lactate dehydrogenase (LDH) release, reactive oxygen species (ROS) production and apoptosis. These were accompanied by increased levels of cleaved PARP, cleaved caspase‑9, cleaved caspase‑3, p53, Bax and p21, as well as decreased Bcl‑2 levels. Treatment with petatewalide B was able to strengthen cell viability but reduced LDH release, ROS production and the expression levels of apoptosis‑related proteins. Additionally, treatment with petatewalide B activated AMPK in the OGD/R‑exposed SH‑SY5Y cells and upregulated activation of the downstream transcription factor Nrf2, which accompanied heme oxygenase 1 (HO‑1) and NAD(P)H quinone dehydrogenase 1 (NQO1) expression. Furthermore, silencing AMPK, Nrf2, HO‑1 and NQO1 expression inhibited petatewalide B's protective effect against apoptosis in the OGD/R‑exposed SH‑SY5Y cells. Therefore, petatewalide B protected human neuroblastoma cells against OGD/R‑induced injury by downregulating apoptosis and oxidative stress via upregulation of the AMPK/Nrf2 signaling pathway, suggesting that petatewalide B may be a prospective protector against neuronal injury, having possible therapeutic and medical implications.