Alkaloids in food: a review of toxicity, analytical methods, occurrence and risk assessments

Comparison of the Potential of "Green" Classical and Natural Deep Eutectic Solvents in the Production of Natural Food Colorant Extracts from the Roots of Alkanna tinctoria (L.)

Alkanna tinctoria L. Tausch ("alkanet" or "alkanna") is a medicinal plant. Extracts from alkanet roots have applications as natural food coloring agents. In addition, they have proven antioxidant effects. Three classical solvents (ethanol and acidified ethanol/water) and four natural eutectic solvents (NADES)-choline chloride/urea; choline chloride/citric acid; choline chloride/lactic acid; and sodium acetate/formic acid-were compared for their effectiveness as "green" solvents for the extraction of the alkanet pigment. Notably, this study is the first to apply choline chloride-based NADESs for alkanet extraction, providing a comprehensive profile of key bioactive compounds and their contributions to antioxidant activity using UV/Vis and FT-IR spectrometry, GC-MS, and HPLC-PDA-MS. Among the classical solvents, 50% acidified ethanol showed the highest extraction capacity, as indicated by its total flavonoid (708 ± 32 mgCE/L) and total phenolic (1318 ± 63 mgGAE/L) content. However, this extract exhibited the highest total alkaloid content (256 ± 15 µg/L) compared to the other classical extraction solvents. Consequently, absolute ethanol was identified as a more suitable alternative. Among the NADES, the sodium acetate/formic acid (1:2 mol/mol, NADES4) extract was the only one to show the presence of alkannins. This extract also contained high levels of phenols (355 ± 21 mg GAE/L) and tannins (163 ± 10 mg CE/L), exhibited strong antioxidant potential (DPPH: 131 µmol TE/g dw, FRAP: 7.49 mg Fe(II)/mg dw), and contained significantly lower alkaloid levels (7.0 ± 0.5 µg/L). Comparative analyses indicated that the sodium acetate/formic acid extract outperformed those prepared with ethanolic solvents and other NADES.

The definition of chemical contaminants in food: Ambiguity and consequences

Consumers may be exposed via foods to a diverse range of substances that could be considered as contaminants. However, it is not always straightforward to understand the definition of a 'contaminant'. The present review evaluates how various categories of food-relevant substances are considered in terms of being 'contaminants'. To this end these categories of food borne constituents are evaluated against the various criteria encountered in the available definitions of a food contaminant, including unintentional presence, harmful, existence of regulatory limits, and stakeholder perception. The categories of chemicals considered include: phytotoxins, mycotoxins, (heavy) metals, persistent organic pollutants (POPs), processing aids, process related contaminants, food contact materials (FCMs), pesticides and veterinary drugs. The evaluation revealed that usage of the term appears complex, and may differ between stakeholders. A common proposed definition of the term 'contaminant' could be 'a substance considered to require control measures due to the unacceptability of its context within a food'. Use of a dimension of harm results in equivocal outcomes because risk depends on the level of exposure. As the term 'contaminant' has influence on risk management including public policy, the motivations for applying the term should be subject to more detailed analysis and understanding.

Alkaloids solenopsins from fire ants display in vitro and in vivo activity against the yeast Candida auris

The urgency surrounding Candida auris as a public health threat is highlighted by both the Center for Disease Control (CDC) and World Health Organization (WHO) that categorized this species as a priority fungal pathogen. Given the current limitations of antifungal therapy for C. auris, particularly due to its multiple resistance to the current antifungals, the identification of new drugs is of paramount importance. Some alkaloids abundant in the venom of the red invasive fire ant (Solenopsis invicta), known as solenopsins, have garnered attention as potent inhibitors of bacterial biofilms, and there are no studies demonstrating such effects against fungal pathogens. Thus, we herein investigated the antibiotic efficacy of solenopsin alkaloids against C. auris biofilms and planktonic cells. Both natural and synthetic solenopsins inhibited the growth of C. auris strains from different clades, including fluconazole and amphotericin B-resistant isolates. Such alkaloids also inhibited matrix deposition and altered cellular metabolic activity of C. auris in biofilm conditions. Mechanistically, the alkaloids compromised membrane integrity as measured by propidium iodide uptake in exposed planktonic cells. Additionally, combining the alkaloids with AMB yielded an additive antifungal effect, even against AMB-resistant strains. Finally, both extracted solenopsins and the synthetic analogues demonstrated protective effect in vivo against C. auris infection in the invertebrate model Galleria mellonella. These findings underscore the potent antifungal activities of solenopsins against C. auris and suggest their inclusion in future drug development. Furthermore, exploring derivatives of solenopsins could reveal novel compounds with therapeutic promise.

Non-targeted metabolomics reveals the characteristics of the unique bitterness substances in quinoa

Bitterness is a key factor that affects the consumption of quinoa products, even if they are nutritious. In this study, a non-targeted metabolomics approach based on UHPLC-Orbitrap-MS was applied to comprehensively profile the characteristic metabolites of twenty-two quinoas. A total of twenty key metabolites were identified correlated with bitterness, among which, fifteen were triterpenoid saponins. In addition, these metabolites bind to the active site of the human bitter taste receptor and are the main compounds that produce the bitter taste of quinoa. Our results contribute to a deeper understanding of the origin of quinoa bitterness and provide directions for optimizing its flavor to improve market acceptance.

Modeling HepaRG metabolome responses to pyrrolizidine alkaloid exposure for insight into points of departure and modes of action

The new challenges in toxicology demand novel and innovative in vitro approaches for deriving points of departure (PODs) and determining the mode of action (MOA) of chemicals. Therefore, the aim of this original study was to couple in vitro studies with untargeted metabolomics to model the concentration-response of extra- and intracellular metabolome data on human HepaRG cells treated for 48 h with three pyrrolizidine alkaloids (PAs): heliotrine, retrorsine and lasiocarpine. Modeling revealed that the three PAs induced various monotonic and, importantly, biphasic curves of metabolite content. Based on unannotated metabolites, the endometabolome was more sensitive than the exometabolome in terms of metabolomic effects, and benchmark concentrations (BMCs) confirmed that lasiocarpine was the most hepatotoxic PA. Regarding its MOA, impairment of lipid metabolism was highlighted at a very low BMC (first quartile, 0.003 µM). Moreover, results confirmed that lasiocarpine targets bile acids, as well as amino acid and steroid metabolisms. Analysis of the endometabolome, based on coupling concentration-response and PODs, gave encouraging results for ranking toxins according to their hepatotoxic effects. Therefore, this novel approach is a promising tool for next-generation risk assessment, readily applicable to a broad range of compounds and toxic endpoints.

Review on toxicology and activity of tomato glycoalkaloids in immature tomatoes

Owing to the lack of selection and limited intelligence in mechanical picking, some immature tomatoes that contain alkaloids are thrown away. Tomatine alkaloids are steroidal alkaloids naturally present in Solanaceae plants, which are distributed in small amounts in immature tomato fruits and decrease as the fruits ripen. Tomato glycoalkaloids are harmful to human health. However, in small quantities, there is some evidence that these compounds might be beneficial, as other non-antioxidant bioactivities. This article considers recent research on the biological effects of tomato glycoalkaloids in immature tomatoes, providing reference value for the potential development of these compounds.

Structural Characterization and Electrochemical Studies of Selected Alkaloid N-Oxides

In this work, we synthesized and confirmed the structure of several alkaloid N-oxides using mass spectrometry and Fourier-transform infrared spectroscopy. We also investigated their reduction mechanisms using voltammetry. For the first time, we obtained alkaloid N-oxides using an oxidation reaction with potassium peroxymonosulfate as an oxidant. The structure was established based on the obtained fragmentation mass spectra recorded by LC-Q-ToF-MS. In the FT-IR spectra of the alkaloid N-oxides, characteristic signals of N-O group vibrations were recorded (bands in the range of 928 cm⁻1 to 971 cm⁻1), confirming the presence of this functional group. Electrochemical reduction studies demonstrated the reduction of alkaloid N-oxides at mercury-based electrodes back to the original form of the alkaloid. For the first time, the products of the electrochemical reduction of alkaloid N-oxides were detected by mass spectrometry. The findings provide insights into the structural characteristics and reduction behaviors of alkaloid N-oxides, offering implications for pharmacological and biochemical applications. This research contributes to a better understanding of alkaloid metabolism and degradation processes, with potential implications for drug development and environmental science.

Promising Role of Alkaloids in the Prevention and Treatment of Thyroid Cancer and Autoimmune Thyroid Disease: A Comprehensive Review of the Current Evidence

Thyroid cancer (TC) and thyroid autoimmune disorders (AITD) are among the most common diseases in the general population, with higher incidence in women. Chronic inflammation and autoimmunity play a pivotal role in carcinogenesis. Some studies, indeed, have pointed out the presence of AITD as a risk factor for TC, although this issue remains controversial. Prevention of autoimmune disease and cancer is the ultimate goal for clinicians and scientists, but it is not always feasible. Thus, new treatments, that overcome the current barriers to prevention and treatment of TC and AITD are needed. Alkaloids are secondary plant metabolites endowed with several biological activities including anticancer and immunomodulatory properties. In this perspective, alkaloids may represent a promising source of prophylactic and therapeutic agents for TC and AITD. This review encompasses the current published literature on alkaloids effects on TC and AITD, with a specific focus on the pathways involved in TC and AITD development and progression.

Maternal Mediterranean-Style Diet Adherence during Pregnancy and Metabolomic Signature in Postpartum Plasma: Findings from the Boston Birth Cohort

BACKGROUND

The health benefits of a Mediterranean-style diet (MSD) are well observed, but the underlying mechanisms are unclear. Metabolomic profiling offers a systematic approach for identifying which metabolic biomarkers and pathways might be affected by an MSD.

OBJECTIVES

This study aimed to identify postpartum plasma metabolites that are associated with MSD adherence during pregnancy and to further test whether these identified metabolites may vary by maternal characteristics.

METHODS

We analyzed data from 1410 mothers enrolled in the Boston Birth Cohort (BBC). A maternal food frequency questionnaire (FFQ) was administered and epidemiologic information was obtained via an in-person standard questionnaire interview within 24-72 h postpartum. Maternal clinical information was extracted from electronic medical records. A Mediterranean-style diet score (MSDS) was calculated using responses to the FFQ. Metabolomic profiling in postpartum plasma was conducted by liquid chromatography-MS. Linear regression models were used to assess the associations of each metabolite with an MSDS, adjusting for covariates.

RESULTS

Among the 380 postpartum plasma metabolites analyzed, 24 were associated with MSDS during pregnancy (false discovery rate < 0.05). Of 24 MSDS-associated metabolites, 19 were lipids [for example, triacylglycerols, phosphatidylcholines (PCs), PC plasmalogen, phosphatidylserine, and phosphatidylethanolamine]; others were amino acids (methionine sulfoxide and threonine), tropane (nor-psi-tropine), vitamin (vitamin A), and nucleotide (adenosine). The association of adenosine and methionine sulfoxide with MSDS differed by race (P-interaction = 0.033) and maternal overweight or obesity status (P-interaction = 0.021), respectively.

CONCLUSIONS

In the BBC, we identified 24 postpartum plasma metabolites associated with MSDS during pregnancy. The associations of the 2 metabolites varied by maternal race and BMI. This study provides a new insight into dietary effects on health under the skin. More studies are needed to better understand the metabolic pathways underlying the short- and long-term health benefits of an MSD during pregnancy.