Dissipation pattern and conversion of pyrrolizidine alkaloids (PAs) and pyrrolizidine alkaloid N-oxides (PANOs) during tea manufacturing and brewing

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.

Recent advances and challenges in the analysis of natural toxins

Natural toxins (NTs) are poisonous secondary metabolites produced by living organisms developed to ward off predators. Especially low molecular weight NTs (MW<∼1 kDa), such as mycotoxins, phycotoxins, and plant toxins, are considered an important and growing food safety concern. Therefore, accurate risk assessment of food and feed for the presence of NTs is crucial. Currently, the analysis of NTs is predominantly performed with targeted high pressure liquid chromatography tandem mass spectrometry (HPLC-MS/MS) methods. Although these methods are highly sensitive and accurate, they are relatively expensive and time-consuming, while unknown or unexpected NTs will be missed. To overcome this, novel on-site screening methods and non-targeted HPLC high resolution mass spectrometry (HRMS) methods have been developed. On-site screening methods can give non-specialists the possibility for broad "scanning" of potential geographical regions of interest, while also providing sensitive and specific analysis at the point-of-need. Non-targeted chromatography-HRMS methods can detect unexpected as well as unknown NTs and their metabolites in a lab-based approach. The aim of this chapter is to provide an insight in the recent advances, challenges, and perspectives in the field of NTs analysis both from the on-site and the laboratory perspective.

Uptake, accumulation, translocation and transformation of seneciphylline (Sp) and seneciphylline-N-oxide (SpNO) by Camellia sinensis L

Pyrrolizidine alkaloids (PAs) and their N-oxide (PANOs), as emerging environmental pollutants and chemical hazards in food, have become the focus of global attention. PAs/PANOs enter crops from soil and reach edible parts, but knowledge about their uptake and transport behavior in crops is currently limited. In this study, we chose tea (Camellia sinensis L.) as a representative crop and Sp/SpNO as typical PAs/PANOs to analyze their root uptake and transport mechanism. Tea roots efficiently absorbed Sp/SpNO, utilizing both passive and active transmembrane pathways. Sp predominantly concentrated in roots and SpNO efficiently translocated to above-ground parts. The prevalence of SpNO in cell-soluble fractions facilitated its translocation from roots to stems and leaves. In soil experiment, tea plants exhibited weaker capabilities for the uptake and transport of Sp/SpNO compared to hydroponic conditions, likely due to the swift degradation of these compounds in the soil. Moreover, a noteworthy interconversion between Sp and SpNO in tea plants indicated a preference for reducing SpNO to Sp. These findings represent a significant stride in understanding the accumulation and movement mechanisms of Sp/SpNO in tea plants. The insights garnered from this study are pivotal for evaluating the associated risks of PAs/PANOs and formulating effective control strategies.

Effects of thermal and nonthermal treatments on microorganisms, pyrrolizidine alkaloids and volatile compounds in oregano (Origanum vulgare L.)

Effects of steam sterilization, gamma-irradiation, UV-irradiation and ozonation on microbial inactivation, pyrrolizidine alkaloid degradation and volatile compound profile in oregano were investigated. Steam sterilization and gamma-irradiation were the most effective treatments in inactivating microorganisms. These treatments resulted in 0.87-2.15 log reductions in total aerobic mesophilic bacteria counts and reduced yeast-mold and Enterobacteriaceae counts below the detectable level. Steam sterilization caused increased levels of pyrrolizidine alkaloids (PAs) and decreased levels of their N-oxide forms (PANOs) demonstrating a simultaneous conversion of PANOs into the corresponding PAs. Ozone treatment caused significant decreases in the levels of individual and total PAs/PANOs. After ozone treatment, decreases of 54.4, 53.9, 61.6 and 61.4% were observed in the levels of europine-N-oxide, europine, lasiocarpine-N-oxide and lasiocarpine, respectively. Steam sterilization, UV-irradiation and ozone treatments significantly altered the composition of the volatile compounds of oregano as evidenced by decreased levels of major components and the formation of some new compounds.

Levels, Toxic Effects, and Risk Assessment of Pyrrolizidine Alkaloids in Foods: A Review

Pyrrolizidine alkaloids (PAs) are naturally occurring secondary metabolites of plants. To date, more than 660 types of PAs have been identified from an estimated 6000 plants, and approximately 120 of these PAs are hepatotoxic. As a result of PAs being found in spices, herbal teas, honey, and milk, PAs are considered contaminants in foods, posing a potential risk to human health. Here, we summarize the chemical structure, toxic effects, levels, and regulation of PAs in different countries to provide a better understanding of their toxicity and risk assessment. With recent research on the risk assessment of PAs, this review also discusses the challenges facing this field, aiming to provide a scientific basis for PA toxicity research and safety assessment.