Pro-toxic dehydropyrrolizidine alkaloids in the traditional Andean herbal medicine "asmachilca"

A Machine Learning Approach for Predicting Caco-2 Cell Permeability in Natural Products from the Biodiversity in Peru

BACKGROUND

Peru is one of the most biodiverse countries in the world, which is reflected in its wealth of knowledge about medicinal plants. However, there is a lack of information regarding intestinal absorption and the permeability of natural products. The human colon adenocarcinoma cell line (Caco-2) is an in vitro assay used to measure apparent permeability. This study aims to develop a quantitative structure-property relationship (QSPR) model using machine learning algorithms to predict the apparent permeability of the Caco-2 cell in natural products from Peru.

METHODS

A dataset of 1817 compounds, including experimental log Papp values and molecular descriptors, was utilized. Six QSPR models were constructed: a multiple linear regression (MLR) model, a partial least squares regression (PLS) model, a support vector machine regression (SVM) model, a random forest (RF) model, a gradient boosting machine (GBM) model, and an SVM-RF-GBM model.

RESULTS

An evaluation of the testing set revealed that the MLR and PLS models exhibited an RMSE = 0.47 and R2 = 0.63. In contrast, the SVM, RF, and GBM models showcased an RMSE = 0.39-0.40 and R2 = 0.73-0.74. Notably, the SVM-RF-GBM model demonstrated superior performance, with an RMSE = 0.38 and R2 = 0.76. The model predicted log Papp values for 502 natural products falling within the applicability domain, with 68.9% (n = 346) showing high permeability, suggesting the potential for intestinal absorption. Additionally, we categorized the natural products into six metabolic pathways and assessed their drug-likeness.

CONCLUSIONS

Our results provide insights into the potential intestinal absorption of natural products in Peru, thus facilitating drug development and pharmaceutical discovery efforts.

Hepatotoxicity of Pyrrolizidine Alkaloid Compound Intermedine: Comparison with Other Pyrrolizidine Alkaloids and Its Toxicological Mechanism

Pyrrolizidine alkaloids (PAs) are common secondary plant compounds with hepatotoxicity. The consumption of herbal medicines and herbal teas containing PAs is one of the main causes of hepatic sinusoidal obstruction syndrome (HSOS), a potentially life-threatening condition. The present study aimed to reveal the mechanism underlying the cytotoxicity of intermedine (Im), the main PA in Comfrey. We evaluated the toxicity of the retronecine-type PAs with different structures to cell lines derived from mammalian tissues, including primary mouse hepatocytes, human hepatocytes (HepD), mouse hepatoma-22 (H₂₂) and human hepatocellular carcinoma (HepG2) cells. The cytotoxicity of Im to hepatocyte was evaluated by using cell counting kit-8 assay, colony formation experiment, wound healing assay and dead/live fluorescence imaging. In vitro characterization showed that these PAs were cytotoxic and induced cell apoptosis in a dose-dependent manner. We also demonstrated that Im induced cell apoptosis by generating excessive reactive oxygen species (ROS), changing the mitochondrial membrane potential and releasing cytochrome c (Cyt c) before activating the caspase-3 pathway. Importantly, we directly observed the destruction of the cell mitochondrial structure after Im treatment through transmission electron microscopy (TEM). This study provided the first direct evidence of Im inducing hepatotoxicity through mitochondria-mediated apoptosis. These results supplemented the basic toxicity data of PAs and facilitated the comprehensive and systematic evaluation of the toxicity caused by PA compounds.

Use of medicinal plants for COVID-19 prevention and respiratory symptom treatment during the pandemic in Cusco, Peru: A cross-sectional survey

BACKGROUND

The burden of the COVID-19 pandemic in Peru has led to people seeking alternative treatments as preventives and treatment options such as medicinal plants. This study aimed to assess factors associated with the use of medicinal plants as preventive or treatment of respiratory symptom related to COVID-19 during the pandemic in Cusco, Peru.

METHOD

A web-based cross-sectional study was conducted on general public (20- to 70-year-old) from August 31 to September 20, 2020. Data were collected using a structured questionnaire via Google Forms, it consisted of an 11-item questionnaire that was developed and validated by expert judgment using Aiken's V (Aiken's V > 0.9). Both descriptive statistics and bivariate followed by multivariable logistic regression analyses were conducted to assess factors associated with the use of medicinal plants for COVID-19 prevention and respiratory symptom treatment during the pandemic. Prevalence ratios (PR) with 95% Confidence Interval (CI), and a P-value of 0.05 was used to determine statistical significance.

RESULTS

A total of 1,747 respondents participated in the study, 80.2% reported that they used medicinal plants as preventives, while 71% reported that they used them to treat respiratory symptoms. At least, 24% of respondents used medicinal plants when presenting with two or more respiratory symptoms, while at least 11% used plants for malaise. For treatment or prevention, the multivariate analysis showed that most respondents used eucalyptus (p < 0.001 for both), ginger (p < 0.022 for both), spiked pepper (p < 0.003 for both), garlic (p = 0.023 for prevention), and chamomile (p = 0.011 for treatment). The respondents with COVID-19 (p < 0.001), at older ages (p = 0.046), and with a family member or friend who had COVID-19 (p < 0.001) used more plants for prevention. However, the respondents with technical or higher education used less plants for treatment (p < 0.001).

CONCLUSION

There was a significant use of medicinal plants for both prevention and treatment, which was associated with several population characteristics and whether respondents had COVID-19.

Development of a new LC-MS method for accurate and sensitive determination of 33 pyrrolizidine and 21 tropane alkaloids in plant-based food matrices

Setting of maximum limits for a number of plant alkaloids is under discussion in the EU. The novel method developed and optimized in this study enables simultaneous determination of 21 tropane alkaloids (TAs) and 33 pyrrolizidine (PAs) together with their N-oxides (PANOs). For analysis of aqueous-methanolic extract, reversed phase ultra-high-performance liquid chromatography and tandem mass spectrometry (RP-U-HPLC-MS/MS) was employed. The method was validated for frequently contaminated matrices (i) sorghum, (ii) oregano, and (iii) mixed herbal tea. The recoveries at two spiking levels were in the range of 82-115%, 80-106%, and 78-117%, respectively, and repeatabilities were less than 19% for all analyte/matrix combinations. As regards the achieved limits of quantification (LOQ), their values were in the range of 0.5-10 μg kg^-1. The crucial problem encountered during method development, co-elution of multiple groups of isomeric alkaloids, was overcome by subsequent sample separation in the second chromatographic system, hydrophilic interaction liquid chromatography (HILIC), providing different separation selectivity. Lycopsamine, echinatine, and indicine (co-elution group 1) and N-oxides of indicine and intermedine (co-elution group 2), which could not be resolved on the commonly used RP column, were possible to separate fully by using the HILIC system.

Potentially toxic pyrrolizidine alkaloids in Eupatorium perfoliatum and three related species. Implications for herbal use as boneset

INTRODUCTION

Pro-toxic dehydropyrrolizidine alkaloids are associated with liver disease in humans. The potential for long-term, low-level or intermittent exposures to cause or contribute to chronically-developing diseases is of international concern. Eupatorium perfoliatum is a medicinal herb referred to as boneset. While the presence of dehydropyrrolizidine alkaloids in some Eupatorium species is well-established, reports on Eupatorium perfoliatum are scant and contradictory.

OBJECTIVE

To investigate the presence of dehydropyrrolizidine alkaloids in a survey of boneset samples and related alcoholic tinctures, and hot water infusions and decoctions.

METHODS

Methanol, hot water or aqueous ethanol extracts of Eupatorium perfoliatum and three closely-related species were subjected to HPLC-ESI(+)MS and MS/MS analysis using three complementary column methods. Dehydropyrrolizidine alkaloids were identified from their MS data and comparison with standards.

RESULTS

Forty-nine samples of Eupatorium perfoliatum were shown to contain dehydropyrrolizidine alkaloids (0.0002-0.07% w/w), the majority dominated by lycopsamine and intermedine, their N-oxides and acetylated derivatives. Alcoholic tinctures and hot water infusions and decoctions had high concentrations of the alkaloids. Different chemotypes, hybridisation or contamination of some Eupatorium perfoliatum samples with related species were suggested by the co-presence of retronecine- and heliotridine-based alkaloids.

CONCLUSIONS

Sampling issues, low and high alkaloid chemotypes of Eupatorium perfoliatum or interspecies hybridization could cause the wide variation in dehydropyrrolizidine alkaloid concentrations or the different profiles observed. Concerns associated with dehydropyrrolizidine alkaloids provide a compelling reason for preclusive caution until further research can better define the toxicity and carcinogenicity of the dehydropyrrolizidine alkaloid content of Eupatorium perfoliatum. [Correction added on 12 July 2018, after first online publication: The 'Conclusions' section in the abstract has been added.].

Pyrrolizidine alkaloids: occurrence, biology, and chemical synthesis

Covering: 2013 up to the end of 2015This review covers the isolation and structure of new pyrrolizidines; pyrrolizidine biosynthesis; biological activity, including the occurrence of pyrrolizidines as toxic components or contaminants in foods and beverages; and formal and total syntheses of naturally-occurring pyrrolizidine alkaloids and closely related non-natural analogues.

The assessment of the chronic hepatotoxicity induced by Polygoni Multiflori Radix in rats: A pilot study by using untargeted metabolomics method

Polygoni Multiflori Radix is the dried root of Polygonum multiflorum Thunb officially recorded in the Chinese Pharmacopoeia as HeShouWu (HSW) in Chinese pinyin. The processed HSW are commonly used in TCM to treat liver disease and Chinese Pharmacopoeia has described the actions of it to tonify liver-kidney, replenish essence and blood, blacken beard and hair, strengthen sinew and bone, and resolve turbidity and lower lipid hence making it use not only as a herbal medicine in TCM but also as supplementary food in health care.

AIM OF THE STUDY

Concerns about the hepatotoxicity in association with Polygoni Multiflori Radix and its processed products have been reported in some countries. In the present study, we aim to investigate the potential hepatotoxicity of HSW in rats with oral administration of 95% ethanol-extracts of Polygoni Multiflori Radix by using metabolomics method.

MATERIALS AND METHODS

Here, male rats with 150-180g body weight were received vehicle control or Polygoni Multiflori Radix extracts (HSW-Ex) orally at 19.2 (low dose), 192 (medium dose), or 1920mg/kg/day (high dose), respectively, for 28 consecutive days. Signs of HSW-induced toxicity were monitored by traditional toxicity assessments (e.g., clinical pathology and histopathology). Metabolomics investigation of serum was performed to identify potential endogenous metabolites which may be relevant to liver injury.

RESULTS

Rats received High and Medium dose of HSW-Ex showed greater sign of liver injury with increased levels of ASP, ALT, and AST, as well as reduced SOD activity when compared to vehicle control. In contrast, there are no significant changes relevant to liver injury observed in rats by receiving the low dose of HSW-Ex. Metabolomics analyses have identified ten potential endogenous metabolites varied significantly among the treatment groups with varying doses of HSW-Ex, of which might be related to liver injury.

CONCLUSION

Our data has further suggested that liver damage resulting from HSW-Ex consumption is dosage dependent in rats. It is possible that disruption in amino acid and energy metabolism might lead to subsequent oxidative damage in the liver of rats. Because the clinic practice often use low dose in a short time, therefore HSW usage in TCM still keep safe currently, but we present a warning to the clinical doctors and make them has some concern about high dose of HSW usage in a long term that has potential danger to damage liver.

Dehydropyrrolizidine Alkaloid Toxicity, Cytotoxicity, and Carcinogenicity

Dehydropyrrolizidine alkaloid (DHPA)-producing plants have a worldwide distribution amongst flowering plants and commonly cause poisoning of livestock, wildlife, and humans. Previous work has produced considerable understanding of DHPA metabolism, toxicity, species susceptibility, conditions, and routes of exposure, and pathogenesis of acute poisoning. Intoxication is generally caused by contaminated grains, feed, flour, and breads that result in acute, high-dose, short-duration poisoning. Acute poisoning produces hepatic necrosis that is usually confirmed histologically, epidemiologically, and chemically. Less is known about chronic poisoning that may result when plant populations are sporadic, used as tisanes or herbal preparations, or when DHPAs contaminate milk, honey, pollen, or other animal-derived products. Such subclinical exposures may contribute to the development of chronic disease in humans or may be cumulative and probably slowly progress until liver failure. Recent work using rodent models suggest increased neoplastic incidence even with very low DHPA doses of short durations. These concerns have moved some governments to prohibit or limit human exposure to DHPAs. The purpose of this review is to summarize some recent DHPA research, including in vitro and in vivo DHPA toxicity and carcinogenicity reports, and the implications of these findings with respect to diagnosis and prognosis for human and animal health.

Pro-toxic 1,2-Dehydropyrrolizidine Alkaloid Esters, Including Unprecedented 10-Membered Macrocyclic Diesters, in the Medicinally-used Alafia cf. caudata and Amphineurion marginatum (Apocynaceae: Apocynoideae: Nerieae and Apocyneae)

INTRODUCTION

Within the Apocynoideae (Apocynaceae) pro-toxic dehydropyrrolizidine alkaloids have been reported only in Echiteae. However, attraction of pyrrolizidine alkaloid-pharmacophagous insects suggested their presence in Alafia cf. caudata Stapf (Nerieae: Alafiinae) and Amphineurion marginatum (Roxb.) D.J. Middleton (Apocyneae: Amphineuriinae), both used as medicinal plants.

OBJECTIVE

To confirm the presence of dehydropyrrolizidine alkaloids in Alafia cf. caudata and Amphineurion marginatum and identify their structures.

METHODS

Methanol extracts of air-dried roots, stems and leaves of non-flowering plants were analysed using HPLC-ESI(+)MS and MS/MS or collision-induced dissociation MS in low and/or high resolution modes. Pyrrolizidine alkaloids were tentatively identified based on the mass spectrometry data. Solid phase extraction combined with semi-preparative HPLC were used to isolate major alkaloids. Structures were elucidated using NMR spectroscopy.

RESULTS

Monoesters of retronecine with senecioic, hydroxysenecioic or syringic acids were identified in roots of Alafia cf. caudata. Two unprecedented 10-membered macrocyclic dehydropyrrolizidine alkaloid diesters were isolated from roots of Amphineurion marginatum. Pyrrolizidine alkaloids were detected in root and leaf material of Alafia cf. caudata at 0.34 and 0.01% dry weight (DW), and 0.13, 0.02 and 0.09% DW in root, leaf and stem material of Amphineurion marginatum.

CONCLUSIONS

The presence of pro-toxic dehydropyrrolizidine alkaloids suggests that medical preparations of these plants pose potential health risks to consumers. Dehydropyrrolizidine alkaloids are evidently more widespread in Apocynoideae than previously assumed, and it would seem rewarding to study other members of this family for the presence of pyrrolizidines, dehydropyrrolizidines and dihydropyrrolizines. Copyright © 2016 John Wiley & Sons, Ltd.