Detection of Cyanotoxins in Algae Dietary Supplements

Neurotoxin BMAA and its isomeric amino acids in cyanobacteria and cyanobacteria-based food supplements

Cyanobacteria are photosynthetic microorganisms distributed globally in aquatic and terrestrial environments. They are also industrially cultivated to be used as dietary supplements, as they have a high nutritional value; however, they are also known to produce a wide range of toxic secondary metabolites, called cyanotoxins. BMAA (β-methylamino-l-alanine) and its most common structural isomers, DAB (2,4-diaminobutyric acid) and AEG (N-2-aminoethylglycine) produced by cyanobacteria, are non-proteinogenic amino acids that have been associated with neurodegenerative diseases. A possible route of exposure to those amino acids is through consumption of food supplements based on cyanobacteria. The review critically discusses existing reports regarding the occurrence of BMAA, DAB and AEG in cyanobacteria and cyanobacteria-based food supplements. It is shown that inconsistencies in reported results could be attributed to performance of different methods of extraction and analysis applied and in ambiguities regarding determination of soluble and bound fractions of the compounds. The critical aspect of this review aims to grow awareness of human intake of neurotoxic amino acids, while results presented in literature concerning dietary supplements aim to promote further research, quality control as well as development of guidelines for cyanotoxins in food products.

Review of Two Popular Eating Plans within the Multiple Sclerosis Community: Low Saturated Fat and Modified Paleolithic

The precise etiology of multiple sclerosis (MS) is unknown but epidemiologic evidence suggests this immune-mediated, neurodegenerative condition is the result of a complex interaction between genes and lifetime environmental exposures. Diet choices are modifiable environmental factors that may influence MS disease activity. Two diets promoted for MS, low saturated fat Swank and modified Paleolithic Wahls Elimination (WahlsElim), are currently being investigated for their effect on MS-related fatigue and quality of life (NCT02914964). Dr. Swank theorized restriction of saturated fat would reduce vascular dysfunction in the central nervous system (CNS). Dr. Wahls initially theorized that detailed guidance to increase intake of specific foodstuffs would facilitate increased intake of nutrients key to neuronal health (Wahls™ diet). Dr. Wahls further theorized restriction of lectins would reduce intestinal permeability and CNS inflammation (WahlsElim version). The purpose of this paper is to review the published research of the low saturated fat (Swank) and the modified Paleolithic (Wahls™) diets and the rationale for the structure of the Swank diet and low lectin version of the Wahls™ diet (WahlsElim) being investigated in the clinical trial.

Genotoxic effects of neurotoxin ß-N-methylamino-l-alanine in human peripheral blood cells

The non-proteinogenic amino acid ß-N-methylamino-l-alanine (BMAA) is associated with the development of neurodegenerative diseases such as Alzheimer's disease, amyotrophic lateral sclerosis/parkinsonism-dementia complex (ALS-PDC) and amyotrophic lateral sclerosis. BMAA is known to induce neurotoxic effects leading to neurodegeneration via multiple mechanisms including misfolded protein accumulation, glutamate induced excitotoxicity, calcium dyshomeostasis, endoplasmic reticulum stress and oxidative stress. In the present study, for the first time, genotoxic activity of BMAA (2.5, 5, 10 and 20 μg/mL) was studied in human peripheral blood cells (HPBCs) using the comet and cytokinesis-block micronucleus cytome assays. In addition, the influence of BMAA on the oxidative stress was assessed. At non-cytotoxic concentrations BMAA did not induce formation of DNA strand breaks in HPBCs after 4 and 24 h exposure; however, it significantly increased the number of micronuclei after 24 and 48 h at 20 μg/mL and nucleoplasmic bridges after 48 h at 20 μg/mL. The frequency of nuclear buds was slightly though non-significantly increased after 48 h. Altogether, this indicates that in HPBCs BMAA is clastogenic and induces complex genomic alterations including structural chromosomal rearrangements and gene amplification. No influence on oxidative stress markers was noticed. These findings provide new evidence that environmental neurotoxin BMAA, in addition to targeting common pathways involved in neurodegeneration, can also induce genomic instability in non-target HPBCs suggesting that it might be involved in cancer development. Therefore, these data are important in advancing our current knowledge and opening new questions in the understanding of the mechanisms of BMAA toxicity, particularly in the context of genotoxicity.

Identifying aerosolized cyanobacteria in the human respiratory tract: A proposed mechanism for cyanotoxin-associated diseases

Cyanobacteria produce harmful toxins that have been associated with several acute conditions and chronic human diseases, like gastroenteritis, non-alcoholic liver disease, and amyotrophic lateral sclerosis. Aerosol from waterbodies appears to be a likely mechanism for exposure. We conducted a study of human biospecimens focused on the cyanobacterial aerosilization process by evaluating the extent to which cyanobacteria can invade the human respiratory tract. Our study suggests that humans routinely inhale aerosolized cyanobacteria, which can be harbored in the nostrils and the lungs. Using PCR, cyanobacteria were found at high frequencies in the upper respiratory tract (92.20%) and central airway (79.31%) of our study subjects. Nasal swabs were not predictive of bronchoalveolar lavage (BAL) when detecting inhaled cyanobacteria. Interestingly, we found no evidence that time of year was a significant factor for cyanobacteria positivity (BAL cytology p = 1.0 and PCR p = 1.0); (nasal swab cytology p = 0.051 and PCR p = 0.65). Additionally, we found that proximity to a waterbody was not a significant factor for cyanobacteria positivity in BAL and nasal swabs collected during cyanobacteria bloom season [May-October] (p = 0.46 and p = 0.38). These data suggest that cyanobacteria exposure may be a prevalent and chronic phenomenon not necessarily restricted to waterbodies alone. Sources of indoor exposure warrant future investigation. Given the widespread prevalence of cyanobacterial exposure in the airway, investigation of the aerosol spread of cyanotoxins, more specifically, is warranted. Our findings are consistent with the hypothesis that aerosol is a significant route for cyanobacteria exposure, and thus a likely route of transmission for cyanotoxin-associated human diseases.

Identification and Quantification of an Adulterant in a Dietary Supplement Marketed for Sexual Enhancement

In recent years, the consumption of dietary supplements (DS) has increased worldwide. In Argentina, approximately 14 million DS units were sold between 2015 and 2017. The adulteration of DS with active pharmaceutical ingredients or their analogues has been reported. This represents an alarming emerging risk to public health. The aim of this work was to detect the possible adulteration of a DS marketed in Argentina for the treatment of erectile dysfunction. Initially, thin layer chromatography analysis of the DS capsules content suggested the presence of a major compound. For the isolation and purification of this compound, an easy method consisted of a liquid-liquid extraction (water/CH2Cl2) followed by re-crystallisation from ethanol, is reported. Spectroscopic techniques such as mono- and bidimensional nuclear magnetic resonance, Fourier transform infrared spectroscopy and mass spectrometry allowed its identification as tadalafil. A rapid and reliable method was developed for the quantification of tadalafil in this DS by high performance liquid chromatography-mass spectrometry (HPLC-MS/MS). The mean content of tadalafil per capsule was 21.2 mg which represents a slightly higher value than that found in approved products in Argentina (5 or 20 mg per tablet). In addition, an undeclared alga was identified in the DS by microscopic techniques.

Spirulina platensis attenuates the associated neurobehavioral and inflammatory response impairments in rats exposed to lead acetate

Heavy metals are well known as environmental pollutants with hazardous impacts on human and animal health because of their wide industrial usage. In the present study, the role of Spirulina platensis in reversing the oxidative stress-mediated brain injury elicited by lead acetate exposure was evaluated. In order to accomplish this aim, rats were orally administered with 300 mg/kg bw Spirulina for 15 d, before and simultaneously with an intraperitoneal injection of 50 mg/kg bw lead acetate [6 injections through the two weeks]. As a result, the co-administration of Spirulina with lead acetate reversed the most impaired open field behavioral indices; however, this did not happen for swimming performance, inclined plane, and grip strength tests. In addition, it was observed that Spirulina diminished the lead content that accumulated in both the blood and the brain tissue of the exposed rats, and reduced the elevated levels of oxidative damage indices, and brain proinflammatory markers. Also, because of the Spirulina administration, the levels of the depleted biomarkers of antioxidant status and interleukin-10 in the lead-exposed rats were improved. Moreover, Spirulina protected the brain tissue (cerebrum and cerebellum) against the changes elicited by lead exposure, and also decreased the reactivity of HSP70 and Caspase-3 in both cerebrum and cerebellum tissues. Collectively, our findings demonstrate that Spirulina has a potential use as a food supplement in the regions highly polluted with heavy metals.

Exposure routes and health effects of microcystins on animals and humans: A mini-review

Microcystins (MCs) pollution has quickly risen in infamy and has become a major problem to public health worldwide. MCs are a group of monocyclic hepatotoxic peptides, which are produced by some bloom-forming cyanobacteria in water. More than 100 different MCs variants posing a great threat to animals and humans due to their potential carcinogenicity have been reported. To reduce MCs risks, the World Health Organization has set a provisional guideline of 1 μg/L MCs in human's drinking water. This paper provides an overview of exposure routes of MCs into the human system and health effects on different organs after MCs exposure including the liver, intestine, brain, kidney, lung, heart and reproductive system. In addition, some evidences on human poisoning and deaths associated with MCs exposure are presented. Finally, in order to protect human life against the health threats posed by MCs, this paper also suggests some directions for future research that can advance MCs control and minimize human exposure to MCs.

A Systematic Literature Review for Evidence of Aphanizomenon flos-aquae Toxigenicity in Recreational Waters and Toxicity of Dietary Supplements: 2000⁻2017

Previous studies of recreational waters and blue-green algae supplements (BGAS) demonstrated co-occurrence of Aphanizomenon flos-aquae (AFA) and cyanotoxins, presenting exposure risk. The authors conducted a systematic literature review using a GRADE PRISMA-p 27-item checklist to assess the evidence for toxigenicity of AFA in both fresh waters and BGAS. Studies have shown AFA can produce significant levels of cylindrospermopsin and saxitoxin in fresh waters. Toxicity studies evaluating AFA-based BGAS found some products carried the mcyE gene and tested positive for microcystins at levels ≤ 1 μg microcystin (MC)-LR equivalents/g dry weight. Further analysis discovered BGAS samples had cyanotoxins levels exceeding tolerable daily intake values. There is evidence that Aphanizomenon spp. are toxin producers and AFA has toxigenic genes such as mcyE that could lead to the production of MC under the right environmental conditions. Regardless of this ability, AFA commonly co-occur with known MC producers, which may contaminate BGAS. Toxin production by cyanobacteria is a health concern for both recreational water users and BGAS consumers. Recommendations include: limit harvesting of AFA to months when toxicity is lowest, include AFA in cell counts during visible blooms, and properly identify cyanobacteria species using 16S rRNA methods when toxicity levels are higher than advisory levels.

Using agro-industrial wastes for the cultivation of microalgae and duckweeds: Contamination risks and biomass safety concerns

Aquatic organisms, such as microalgae (Chlorella, Arthrospira (Spirulina), Tetrasselmis, Dunalliela etc.) and duckweed (Lemna spp., Wolffia spp. etc.) are a potential source for the production of protein-rich biomass and for numerous other high-value compounds (fatty acids, pigments, vitamins etc.). Their cultivation using agro-industrial wastes and wastewater (WaW) is of particular interest in the context of a circular economy, not only for recycling valuable nutrients but also for reducing the requirements for fresh water for the production of biomass. Recovery and recycling of nutrients is an unavoidable long-term approach for securing future food and feed production. Agro-industrial WaW are rich in nutrients and have been widely considered as a potential nutrient source for the cultivation of microalgae/duckweed. However, they commonly contain various hazardous contaminants, which could potentially taint the produced biomass, raising various concerns about the safety of their consumption. Herein, an overview of the most important contaminants, including heavy metals and metalloids, pathogens (bacteria, viruses, parasites etc.), and xenobiotics (hormones, antibiotics, parasiticides etc.) is given. It is concluded that pretreatment and processing of WaW is a requisite step for the removal of several contaminants. Among the various technologies, anaerobic digestion (AD) is widely used in practice and offers a technologically mature approach for WaW treatment. During AD, various organic and biological contaminants are significantly removed. Further removal of contaminants could be achieved by post-treatment and processing of digestates (solid/liquid separation, dilution etc.) to further decrease the concentration of contaminants. Moreover, during cultivation an additional removal may occur through various mechanisms, such as precipitation, degradation, and biotransformation. Since many jurisdictions regulate the presence of various contaminants in feed or food setting strict safety monitoring processes, it would be of particular interest to initiate a multi-disciplinary discussion whether agro-industrial WaW ought to be used to cultivate microalgae/duckweed for feed or food production and identify most feasible options for doing this safely. Based on the current body of knowledge it is estimated that AD and post-treatment of WaW can lower significantly the risks associated with heavy metals and pathogens, but it is yet unclear to what extent this is the case for certain persistent xenobiotics.

Assessing Environmental Exposure to β-N-Methylamino-L-Alanine (BMAA) in Complex Sample Matrices: a Comparison of the Three Most Popular LC-MS/MS Methods

β-N-Methylamino-L-alanine (BMAA) is a naturally occurring non-protein amino acid produced by cyanobacteria, accumulated through natural food webs, found in mammalian brain tissues. Recent evidence indicates an association between BMAA and neurological disease. The accurate detection and quantification of BMAA in food and environmental samples are critical to understanding BMAA metabolism and limiting human exposure. To date, there have been more than 78 reports on BMAA in cyanobacteria and human samples, but different methods give conflicting data and divergent interpretations in the literature. The current work was designed to determine whether orthogonal chromatography and mass spectrometry methods give consistent data interpretation from a single sample matrix using the three most common analytical methods. The methods were recreated as precisely as possible from the literature with optimization of the mass spectrometry parameters specific to the instrument. Four sample matrices, cyanobacteria, human brain, blue crab, and Spirulina, were analyzed as 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC) derivatives, propyl chloroformate (PCF) derivatives separated by reverse phase chromatography, or underivatized extracts separated by HILIC chromatography. The three methods agreed on positive detection of BMAA in cyanobacteria and no detected BMAA in the sample of human brain matrix. Interpretation was less clear for a sample of blue crab which was strongly positive for BMAA by AQC and PCF but negative by HILIC and for four spirulina raw materials that were negative by PCF but positive by AQC and HILIC. Together, these data demonstrate that the methods gave different results and that the choices in interpretation of the methods determined whether BMAA was detected. Failure to detect BMAA cannot be considered proof of absence.

BMAA and Neurodegenerative Illness

The cyanobacterial toxin β-N-methylamino-L-alanine (BMAA) now appears to be a cause of Guamanian amyotrophic lateral sclerosis/parkinsonism dementia complex (ALS/PDC). Its production by cyanobacteria throughout the world combined with multiple mechanisms of BMAA neurotoxicity, particularly to vulnerable subpopulations of motor neurons, has significantly increased interest in investigating exposure to this non-protein amino acid as a possible risk factor for other forms of neurodegenerative illness. We here provide a brief overview of BMAA studies and provide an introduction to this collection of scientific manuscripts in this special issue on BMAA.