Discovery of a Bacterial Gene Cluster for Deglycosylation of Toxic Potato Steroidal Glycoalkaloids α-Chaconine and α-Solanine.

Potato juice is a byproduct of starch processing currently used as feed. However, potato proteins are an untapped source of high-protein food for human nutrition if harmful constituents notably glycoalkaloids (GAs) are detoxified. The two principle GAs found in potato are α-chaconine and α-solanine, both consisting of a solanidine aglycone with a carbohydrate side chain. The first step in the detoxification of these compounds is the removal of the trisaccharide. Whole-genome sequencing of a bacterial isolate, Arthrobacter sp. S41, capable of completely degrading α-chaconine and α-solanine, revealed the presence of a gene cluster possibly involved in the deglycosylation of GAs. Functional characterization confirmed the enzymatic activity of the gene cluster involved in the complete deglycosylation of both α-chaconine and α-solanine. The novel enzymes described here may find value in the bioconversion of feed proteins to food proteins suitable for human nutrition.

Potato leaf extract and its component, α-solanine, exert similar impacts on development and oxidative stress in Galleria mellonella L.

Plants synthesize a broad range of secondary metabolites that act as natural defenses against plant pathogens and herbivores. Among these, potato plants produce glycoalkaloids (GAs). In this study, we analyzed the effects of the dried extract of fresh potato leaves (EPL) on the biological parameters of the lepidopteran, Galleria mellonella (L.) and compared its activity to one of the main EPL components, the GA α-solanine. Wax moth larvae were reared from first instar on a diet supplemented with three concentrations of EPL or α-solanine. Both EPL and α-solanine affected survivorship, fecundity, and fertility of G. mellonella to approximately the same extent. We evaluated the effect of EPL and α-solanine on oxidative stress in midgut and fat body by measuring malondialdehyde (MDA) and protein carbonyl (PCO) contents, both biomarkers of oxidative damage. We evaluated glutathione S-transferase (GST) activity, a detoxifying enzyme acting in prevention of oxidative damage. EPL and α-solanine altered MDA and PCO concentrations and GST activity in fat body and midgut. We infer that the influence of EPL on G. mellonella is not enhanced by synergistic effects of the totality of potato leaf components compared to α-solanine alone.

Compositional and toxicological analysis of a GM potato line with reduced α-solanine content--a 90-day feeding study in the Syrian Golden hamster.

Steroidal glycoalkaloids (GAs) are toxins, produced by plants of the Solanaceae family. The potato plant (Solanum tuberosum L.) and its tubers predominantly contain the two GAs α-chaconine and α-solanine. These compounds are believed to act in synergy, and the degree of toxicity may therefore depend on their ratio in the potato. To determine the influence of α-solanine: α-chaconine ratio in potatoes on toxicity, a GM potato line (SGT 9-2) with reduced α-solanine content, and the parental control line (Desirée wild-type) having a traditional α-solanine: α-chaconine ratio were (1) studied for compositional similarity by analysing for a range of potato constituents, and (2) used in a 90-day feeding trial with the Syrian Golden hamster to study differential toxicity. The animal feeding study used diets with up to 60% freeze-dried potato powder from either line. Whilst data indicated some compositional differences between the GM line and its wildtype control these did not raise concerns related to nutritional value or safety. Results of the feeding trials showed a low number of significant differences between potato lines with different α-solanine: α-chaconine ratio but none were considered to raise safety concerns with regard to human (or animal) consumption.

A literature review on the safety assessment of genetically modified plants.

In recent years, there has been a notable concern on the safety of genetically modified (GM) foods/plants, an important and complex area of research, which demands rigorous standards. Diverse groups including consumers and environmental Non Governmental Organizations (NGO) have suggested that all GM foods/plants should be subjected to long-term animal feeding studies before approval for human consumption. In 2000 and 2006, we reviewed the information published in international scientific journals, noting that the number of references concerning human and animal toxicological/health risks studies on GM foods/plants was very limited. The main goal of the present review was to assess the current state-of-the-art regarding the potential adverse effects/safety assessment of GM plants for human consumption. The number of citations found in databases (PubMed and Scopus) has dramatically increased since 2006. However, new information on products such as potatoes, cucumber, peas or tomatoes, among others was not available. Corn/maize, rice, and soybeans were included in the present review. An equilibrium in the number research groups suggesting, on the basis of their studies, that a number of varieties of GM products (mainly maize and soybeans) are as safe and nutritious as the respective conventional non-GM plant, and those raising still serious concerns, was currently observed. Nevertheless, it should be noted that most of these studies have been conducted by biotechnology companies responsible of commercializing these GM plants. These findings suggest a notable advance in comparison with the lack of studies published in recent years in scientific journals by those companies. All this recent information is herein critically reviewed.

Degradation of the potato glycoalkaloids--alpha-solanine and alpha-chaconine in groundwater.

The potato glycoalkaloids alpha-chaconine and alpha-solanine are produced in high amounts in potato plants from where release to soil takes place. Degradation of the compounds in groundwater was investigated, as their fate in the terrestrial environment is unknown. Abiotic and microbial degradation were followed in groundwater sampled from below a potato field and spiked with the glycoalkaloids (115 nmol/l). Degradation was primarily microbial and the glycoalkaloids were degraded within 21-42 days. The metabolites beta(1)-solanine, gamma-solanine, and solanidine were formed from alpha-solanine, while beta-chaconine, gamma-chaconine and solanidine were detected from alpha-chaconine. Thus, indigenous groundwater microorganisms are capable of degrading the glycoalkaloids.

Toxicity studies of genetically modified plants: a review of the published literature.

According to the information reported by the WHO, the genetically modified (GM) products that are currently on the international market have all passed risk assessments conducted by national authorities. These assessments have not indicated any risk to human health. In spite of this clear statement, it is quite amazing to note that the review articles published in international scientific journals during the current decade did not find, or the number was particularly small, references concerning human and animal toxicological/health risks studies on GM foods. In this paper, the scientific information concerning the potential toxicity of GM/transgenic plants using the Medline database is reviewed. Studies about the safety of the potential use of potatoes, corn, soybeans, rice, cucumber, tomatoes, sweet pepper, peas, and canola plants for food and feed were included. The number of references was surprisingly limited. Moreover, most published studies were not performed by the biotechnology companies that produce these products. This review can be concluded raising the following question: where is the scientific evidence showing that GM plants/food are toxicologically safe?

La acrilamida, contaminante químico de procesado: revisión / Acrylamide formation in foods: a review Acrylamide

La acrilamida, 'probable carcinógeno para los humanos',mutágeno de categoría 2 y tóxico para la reproducción de categoría 3según la UE, se comporta como neurotóxico tras exposiciones agudas. A pesar de que se recomienda disminuir los niveles de exposición, el tabaquismo, la exposición ocupacional y la exposición dietética son fuentes de acrilamida para el hombre. De entre todos los alimentos, son los ricos en carbohidratos y los elaborados a altas temperaturas, los que mayores niveles de este tóxico presentan. En la presente revisión se explica la formación de acrilamida en los alimentos, se describen sus efectos tóxicos, se citan los métodos analíticos usados en su determinación, se recopilan datos sobre los niveles detectados en distintos alimentos y se enumeran los datos más recientes sobre la ingesta en distintas poblaciones (AU)

Acrylamide formation in foods: A review Acrylamide,'probable carcinogenic for humans', mutagenic type 2 and toxic for reproduction type 3 for the European Union, produces neurotoxicity after acute expositions. Although recommendations are given to minimize the exposition levels to this compound, smoking and occupational and dietary exposures are important acrylamide sources. Among foods, those rich in carbohydrates and those cooked at high temperatures present the highest acrylamide concentrations. The present revision points out the acrylamide formation in foods, its toxic effects and the analytical methods used in its determination. Moreover, data are given about acrylamide levels in foods and dietary intakes in different populations (AU)

A study of the toxic hazard that might be associated with the consumption of green potato tops.

Eating green potatoes has reportedly led to poisoning attributed to potato glycoalkaloids (PGA), primarily alpha-solanine and alpha-chaconine. Concentrations of PGA increase during the greening of potatoes but are reportedly much higher in potato tops (leaves). As it is known that members of the UK Bangladeshi community consume potato tops, a study of the toxic hazard that may be associated with the consumption of green potato tops has been carried out. PGA in seven potato varieties were determined by HPLC. Tubers protected from light contained 0.05-0.65 mg/100 g alpha-solanine and 0.3-0.63 mg/100 g alpha-chaconine. Concentrations in leaf samples ranged from 0.64 to 22.6 mg alpha-solanine/100 g and 0.06 to 55.7 mg alpha-chaconine/100 g. Aqueous leaf extracts were cytotoxic to Chinese hamster ovary cells and lysed human, rat and hamster blood cells with no difference in sensitivity among species. Oral administration of potato tops to rats, mice and Syrian hamsters had no adverse effects at the highest practicable dose. A mixture of alpha-solanine and alpha-chaconine (1:1, w/w) given orally at doses of up to 50 mg/kg body weight to hamsters had no effect, but a single ip injection of 25 mg/kg body weight or greater was lethal, with bleeding in the gut. High concentrations of cytotoxic PGA were found in some potato tops, but their effect in laboratory animals was minimal. It is concluded that the consumption of moderate quantities of potato tops (2-5 g/kg body weight/day) is unlikely to represent an acute health hazard to humans.

Induction of terata in hamsters by solanidane alkaloids derived from Solanum tuberosum.

The potential induction of terata by solanidanes has been of public health concern since a report in 1972 hypothesized that certain birth defects in humans could be attributed to ingestion of blighted potatoes. The potential teratogenicity of solanidane alkaloids from potatoes and tomatoes in domestic livestock had been considered even earlier. In the present report, oral administration of the steroidal alkaloid glycosides alpha-solanine and alpha-chaconine and their aglycone solanidine is shown to induce craniofacial malformations (exencephaly, encephalocele, and anophthalmia) in Syrian hamsters. All three alkaloids, that were either isolated or obtained by hydrolysis from Solanum tuberosum (var. Kennebec) sprouts, possessed the 22-(R),25(S)-configuration in the indolizidine moiety with no other isomers present. Toxicity constraints precluded administration of dosages high enough to induce statistically significant levels of terata in litters dosed with alpha-chaconine and permitted the attainment of only marginal statistical significance for alpha-solanine. However, malformation induction at p < 0.005 was observed in litters upon dosing both the nontoxic aglycone solanidine and the derivative solanidine N-oxide at higher levels. The relatively high teratogenicity of nontoxic solanidine, compared to the glycosides, demonstrates that terata induction by solanidanes is not due to maternal toxicity nor is the oligosaccharide portion of steroidal alkaloid glycosides required to facilitate passage of the teratogen to the fetus. The teratogenicity of solanidine N-oxide, a putative metabolite, suggests that N-oxidation is not an effective mammalian detoxification pathway. Relative teratogenic potencies (RTP) were assigned to solanidanes by conversion of literature data to equimolar doses compared to the powerful Veratrum teratogen jervine and the nonteratogenic spirosolane tomatidine. RTP values are as follows: jervine (100), 22(S),-25(R)-solanidanes (50), alpha-chaconine (43), alpha-solanine (32), 22(R),25(S)-solanidine (32), solanidine N-oxide (32), 5 alpha,6-dihydrosolanidine (9), and tomatidine (0).

Efecto de los glicoalcaloides totales parcialmente purificados de flor de papa sobre las lesiones gástricas producidas por etanol en ratas albinas

El presente trabajo se realizó con la finalidad de determinar la diferencia del grado de lesiones gástricas entre el grupo de animales tratados con TGA y el grupo que no recibe tratamiento. Se llevó a cabo un estudio experimental, ciego, randomizado, comparativo y controlado por placebo en el Laboratorio de Fisiología de la Facultad de Medicina de la UNSA; utilizando ratas de la especie Novergicus, de la cepa Holtzman, de ambos sexos, sanos, con pesos de 178 gr. a 289 gr. en ayunas de 12h(grupo D) y de 16h(grupos A-B-C), mantenidas con agua "adlibitum" hasta dos horas antes del experimento. Las ratas fueron distribuídas aleatoriamente en cuatro grupos, con igual número de especímenes. El primer grupo(A) recibió sólo TGA(33mg/Kg); el grupo B(Control) recibió Etanol(5ml/Kg) y posteriormente agua; el grupo C(Tratamiento) recibió etanol + TGA y el grupo D(Prevención) recibió primero TGA y después Etanol. Todos los animales fueron sacrificados a las 6 horas de haber administrado el etanol, se les extrajo el estomago y se determinó el grado de daño de la mucosa gástrica con la ayuda de un microscópio estereoscópico a través de lectura ciega. Fueron guardados los estómagos en formol al 10 por ciento, siendo procesados por metodología convencional de H-E y luego, observados microscópicamente para determinar el daño de la mucosa. La comparación del grado de daño de la mucosa gástrica se realizó con las pruebas no paramétricas de Kruskall Wallis y Mann Whitney con ajuste de Bonferroni; encontrando diferencia significativa entre el grupo control(B) y el grupo tratamiento (C); siendo iguales el grupo control con el grupo de prevención (D). Se concluye que los TGA de la papa a dosis de 33mg/Kg tienen efecto terapeútico en las lesiones gástricas producidas por etanol en ratas albinas

The mysterious potato.

Even though it comes from a potentially toxic family and may contain solanine-type alkaloids, the potato has risen from a wild food stuff of South American Indians to one of the world's most useful plants and important food source. Toxicity of the tuber commonly seen today is low, with the sprouts and green skin most often involved in toxic exposures. New cultivars may bring about more disease resistance, new tastes, and possibly a smaller solanine content.

Arsénico en tubérculos de papa de las zonas de Junín (Valle de Mantaro) y Lima / Arsenic

Se ha cuantificado arsénico por el método espectrofotométrico de Vasac y Sedivec en tubérculos de papas de cultivos expuestos. Las muestras proceden del Valle del Mantaro (Junín) y de las zonas de Cañete, Barranca, Puente Piedra y Huachipa (Lima). La investigación se realizó en 50 tubérculos de diferentes variedades y formas de riego. El nivel medio de Arsénico en las muetras fue de 0,2572 ppm ñ 0,0132, con una desviación standard de 0,0927ñ0,0093 y cifras extremas de 0,095-0.500 ppm. Los valores promedios obtenidos de arsenico en los tubérculos es menos que los valores máximos aceptables de Canadá ya que solo constituyen el 25,72 por ciento de 1ppn, que es la cantidad máxima de arsénico aceptada en la papa, ya que a partir de ella produce efectos nocivos y tóxicos.

[The hygienic evaluation of potato treated with the preparation Polikar made from the byproducts of soda manufacture]. / Gigienicheskaia otsenka kartofelia, obrabotannogo preparatom iz otkhodov sodovogo proizvodstva Polikarom.

It has been shown that Polycar prepared from sodium carbonate byproducts, intended for the treatment of potatoes before its storage, makes for an increase in solanine content, and a decrease in the level of ascorbic acid in potato. Such potato produces a toxic effect on the rat body. A conclusion has been made that Polycar could not be used as an agent for potato treatment.

Mutagenicity of deep-frying fat, and evaluation of urine mutagenicity after consumption of fried potatoes.

Mutagen formation during deep-frying was evaluated using standard frying conditions. Portions of pre-fried, sliced potatoes were fried in a commercial brand of hydrogenated vegetable frying fat, which was used repeatedly and for a prolonged period of time. Concentrations of polar oxidation and degradation products, and of dimeric and polymeric triglycerides, were found to increase in the frying fat as well as in fried potatoes with prolonged use of the fat. Thiobarbituric acid-reactive substances were detectable neither in the frying fat nor in the fried potatoes. Polar fractions of repeatedly used frying fat significantly increased the number of revertants in Salmonella typhimurium strain TA97 without S-9 mix. In the presence of S-9 mix mutagenic activity was reduced. As a consequence of ongoing formation of polar degradation and oxidation products, the mutagenicity of the fat increased after repeated use. Polar fractions of lipids extracted from commercially obtained pre-fried potatoes, as well as from fried potatoes, marginally increased the number of revertants in strain TA97 without S-9 mix. The mutagenicity of the lipid fractions of fried potatoes was not related to the heating time of the fat. Methanol extracts of fat-free residues of fried potatoes significantly increased numbers of revertants in strain TA97 after metabolic activation, which indicated that a different class of mutagens had been isolated. The mutagenicity of methanol extracts was not increased after either prolonged or repeated use of the fat. Urine samples of six healthy, non-smoking volunteers, collected during the 24 hr following consumption of portions of potatoes fried in repeatedly used fat, showed no increase in mutagenicity compared with control samples. Since the exact identity of mutagens formed during deep-frying, as well as their metabolic fate in man, is unclear at present, evaluation of possible adverse biological effects associated with consumption of fried foods will require strictly controlled metabolic studies.