Cycads and their association with certain neurodegenerative diseases

Metals and Metalloids Increase in Cycas micronesica Seed Gametophyte Tissue in Shaded Growth Conditions

Exposure to environmental toxins may be partly responsible for mammal neurodegenerative disorders. Consumption of seeds from Guam's cycad tree has been linked to the disorder known as amyotrophic lateral sclerosis-parkinsonism dementia complex (ALS-PDC). The unambiguous identification of causal agents of ALS-PDC has been elusive. We have examined the levels of eight metals and metalloids in cycad seeds as a function of the ambient shade in which the plants were grown. Of these metals, the data strongly suggest that aluminum (Al) and selenium (Se) are present in washed flour prepared from southern Guam's cycad seed tissues at elevated levels, especially when the trees are grown in shade. Previous authors have speculated that Al and Se are involved in various ALS outcomes, and our results support this interpretation.

Toxicidad aguda oral y actividad antioxidante de la harina de las semillas de teosinte (Diion mejiae)

Antecedentes. En Honduras, el teosinte (Dioon mejiae) se cultiva desde épocas prehistóricas y su uso como alimento de consumo humano ha sido aislado y reducido. Sin embargo, sus semillas son prometedoras por altos contenidos en carbohidratos, proteínas y minerales en el afrontamiento de la inseguridad alimentaria. Objetivos. Se propuso elaborar una harina de teosinte para almacenarla a dos temperaturas en los días 0, 30, 60 y 90 después de su preparación para determinar estabilidad. Asimismo, se preparó un extracto hidroalcohólico para determinar la capacidad antioxidante y toxicidad aguda oral. Métodos. Se midieron los valores de pH de las harinas almacenadas a diversas temperaturas y tiempos. Se utilizó la técnica de DPPH para la determinación de la capacidad antioxidante del extracto y ratas wistar para evaluar la toxicidad aguda oral. Resultados. La harina de teosinte no sufrió cambios físicos después de tres meses de almacenamiento y el valor promedio de pH obtenido fue de 6.80. El mayor porcentaje de inhibición fue del 94% para una concentración de 25.00 mg/mL del extracto y no se observaron efectos tóxicos agudos en los animales de experimentación. Conclusión. La harina de teosinte es un potencial alimento funcional, por su actividad antioxidante y su nula toxicidad aguda. Palabras clave: harina, capacidad antioxidante, toxicidad aguda oral, DPPH.

Effects of Cassava Juice (Manihot esculenta Crantz) on Renal and Hepatic Function and Motor Impairments in Male Rats

Cassava (Manihot esculenta Crantz) is a plant that contains neurotoxins such as linamarin and lotaustraline. Its long-term consumption is associated with neuronal damage and contributes to the development of motor impairment in humans and rats. We investigated the effects of the consumption of cassava juice on renal and hepatic function and motor impairments in male rats. The rats received the vehicle, non-toxic and toxic doses of cassava juice, or linamarin as a pharmacological control, over 35 consecutive days. The effects were evaluated in an open field test, rotarod, and swim test. The toxic cassava dose and linamarin resulted in motor impairments in the rotarod and swim test from day 7 of treatment. The toxic cassava dose and linamarin increased the parameters that indicate renal and hepatic damage, with the exception of total protein and albumin levels. Behavioral variables that show motor incoordination (i.e., latency to fall in the rotarod) were negatively correlated with biochemical parameters of renal and kidney damage, whereas spin behavior was positively correlated. Our data indicate that chronic oral consumption of cassava juice caused renal and hepatic damage that was correlated with motor coordination impairment in rats, similarly to their principal neurotoxic compound, linamarin.

Preclinical and clinical research on the toxic and neurological effects of cassava (Manihot esculenta Crantz) consumption

Cassava (Manihot esculenta Crantz) is a tropical plant that is used as fresh food, processed food, or raw material for the preparation of flours with high nutritional value. However, cassava contains cyanogenic glycosides, such as linamarin and lotaustralin, that can trigger severe toxic effects and some neurological disorders, including motor impairment, cognitive deterioration, and symptoms that characterize tropical ataxic neuropathy and spastic epidemic paraparesis (Konzo). These alterations that are associated with the consumption of cassava or its derivatives have been reported in both humans and experimental animals. The present review discusses and integrates preclinical and clinical evidence that indicates the toxic and neurological effects of cassava and its derivatives by affecting metabolic processes and the central nervous system. An exhaustive review of the literature was performed using specialized databases that focused on the toxic and neurological effects of the consumption of cassava and its derivatives. We sought to provide structured information that will contribute to understanding the undesirable effects of some foods and preventing health problems in vulnerable populations who consume these vegetables. Cassava contains cyanogenic glycosides that contribute to the development of neurological disorders when they are ingested inappropriately or for prolonged periods of time. Such high consumption can affect neurochemical and neurophysiological processes in particular brain structures and affect peripheral metabolic processes that impact wellness. Although some vegetables have high nutritional value and ameliorate food deficits in vulnerable populations, they can also predispose individuals to the development of neurological diseases.

Identification of β-phenylalanine as a non-protein amino acid in cultivated rice, Oryza sativa

Non-protein amino acids, often analogs of the standard 20 protein amino acids, have been discovered in many plant species. Recent research with cultivated rice (Oryza sativa) identified (3R)-β-tyrosine, as well as a tyrosine amino mutase that synthesizes (3R)-β-tyrosine from the protein amino acid (2S)-α-tyrosine. Gas chromatography-mass spectrometry (GC-MS) assays and comparison to an authentic standard showed that β-phenylalanine is also a relatively abundant non-protein amino acid in rice leaves and that its biosynthesis occurs independently from that of β-tyrosine.