Glycoalkaloid Levels Research Articles

Induced mutations for reduced tuber glycoalkaloid content in potatoes

AbstractMutation breeding was used to produce mutants of the potato breeding selection NDA1725‐1 with reduced levels of tuber glycoalkaloids. Excised tuber eye‐pieces were exposed to 35 Gy of gamma rays from a 60Co source. In the M1V1, leaf tissue was screened using high‐performance thin layer chromatography and each plant given a relative score based on a subjective rating of band intensity. Tubers were harvested from all plants that produced leaves with relatively low levels of glycoalkaloids. Tuber glycoalkaloids were quantified in the M1V2 and M1V3 using high‐performance liquid chromatography, and 35% and 23% of clones with the lowest glycoalkaloid content were selected for further evaluation in each generation, respectively. In the M1V4, M1V5 and M1V6, selection was based on statistically significant differences between the mutant clones and the controls for glycoalkaloid content, as determined using a gravimetric quantification method, as well as on agronomic and quality characteristics. At the end of six clonal generations three selections exhibited acceptable levels of tuber glycoalkaloids and retained enough of the parent clone's exceptional traits to have potential in the commercial potato chip (crisp) industry.

Development of cell culture techniques for assessment of the toxicity of plant products

Plant products consumed by humans contain a wide variety of both beneficial and toxic compounds. Studies have been undertaken to explore the utility of cell culture techniques in testing plant products for toxicity and antitoxicity. Preliminary results are reported on the cytotoxic effects of aqueous and methanol extracts of a range of conventional and herb teas and a variety of vegetables. The teas were tested in primary cultures of rat hepatocytes, using lactate dehydrogenase release and inhibition of protein synthesis as endpoints of cytotoxicity. Toxicity was detected in aqueous preparations but not in methanol extracts. Korean green tea and a conventional black tea were more toxic than herb teas such as comfrey and ragwort, which are thought to contain hepatotoxic pyrrolizidine alkaloids. Extracts of five vegetables were tested using the same assays and also the MTT assay in hepatocytes and the Kenacid blue assay in Chinese hamster ovary (CHO) cells. Toxicity to hepatocytes was low but most extracts were more toxic to CHO cells. The toxicity of cabbage was reduced by cooking and that of potato was increased by greening, which increases the levels of glycoalkaloids and other toxins in the tubers. The results suggest a number of ways in which cell culture tests may be useful for detecting and assessing the effects of toxins and antitoxins in plant products.

The effect of sterols on phytoalexin, steroid glycoalkaloid, and sterol accumulation in potato tuber discs inoculated with Phytophthora infestans or treated with arachidonic acid

Potato tuber discs contain low levels of steroid glycoalkaloids (SGA) and free sterols at 0 h after slicing. Aging the discs increased SGA and free sterol levels in the outer 3 mm of disc surface. Inoculating the discs with incompatible races of Phytophthora infestans or treatment with arachidonic acid (AA) caused a hypersensitive reaction (HR), which included the accumulation of sesquiterpenoid phytoalexins and a marked reduction in the accumulation of steroid glycoalkaloids (SGA) and free sterols, largely β-sitosterol and stigmasterol. Inoculation with a compatible race elicited little and delayed phytoalexin accumulation, modest reductions in SGA and little or no reduction of free sterol accumulation. Treatment of tuber discs with 1 or 2 μg/disc stigmasterol or β-sitosterol before inoculation with an incompatible race allowed colonization by the fungus, markedly decreased phytoalexin accumulation and decreased the suppression of SGA and free sterol accumulation. Treatment with AA did not prevent colonization by either compatible or incompatible races of P. infestans in the sterol-treated discs. Neither sterol elicited phytoalexin accumulation, nor significantly affected SGA and free sterol accumulation in the absence of the fungus. The sterols also did not affect AA-elicited phytoalexin accumulation the suppression of SGA nor free sterol accumulation in the absence of the fungus.

High levels of glycoalkaloids in the established swedish potato variety magnum bonum

AbstractIn 1986, potentially toxic levels of the glycoalkaloids α‐solanine and α‐chaconine were unexpectedly found in tubers of the established Swedish consumer potato variety Magnum Bonum, leading to the imposition of a conditional sales ban on such potatoes. The combined amounts of α‐solanine and α‐chaconine in more than 300 commercial lots of Magnum Bonum potatoes analysed as a consequence of the ban ranged from 61 to 665 mg kg−1 fresh weight with an average of 254 mg kg−1. Sixty‐six percent of the samples exceeded a temporary maximum residue limit of 200 mg kg−1, 8% were above 400 mg kg−1. Peeling did not significantly remove the glycoalkaloids in tubers with a high content. The occasional glycoalkaloid elevation was initially attributed to the unusually cold and rainy conditions during the late part of the season in 1986, but subsequent investigations have failed to confirm this hypothesis. Varietal characteristics are likely to have been involved since most other common Swedish varieties seemed to have had normal glycoalkaloid levels in 1986. There were no indications of serious or widespread adverse health effects in consumers due to the high glycoalkaloid levels, although there was circumstantial evidence that a few cases of temporary gastrointestinal disturbances were caused by consumption of Magnum Bonum potatoes with glycoalkaloid concentrations in the range 310–1000 mg kg−1.

Glycoalkaloid content in tubers of hybrid and backcross populations from aSolanum tuberosumx s. chacoense cross

The glycoalkaloid contents of foliage were measured in populations derived from a cross ofSolanum chacoense Bitter (PI 472810) with a composite sample of genotypes from a randomly matedSolanum tuberosum L. population. The mean total glycoalkaloid contents of the parent PI 472810 andtuberosum populations, and the F2 and F4 populations were 856, 121, 286, and 279 mg/100g fresh weight, respectively. The total glycoalkaloid content of the first backcross population, F2 xtuberosum, was 290 mg/100 g, close to the content of the F2. In a second backcross totuberosum, the mean total content was 148 mg/100 g, close to the content of the parenttuberosum population. Only the glycoalkaloids α-solanine and α-chaconine were found in PI 472810, whereas in the parenttuberosum, hybrid, and backcross populations, the glycoalkaloids α & β-solamarine also were found in a small number of genotypes. The ratios of chaconine to solanine contents were significantly (P≤.05) different in the parent PI 472810 andtuberosum populations, 2.55 and 2.12, respectively. The ratios in the F2 and F4 populations were similar to that of PI 472810, whereas the ratios in the backcross populations were closer to that of thetuberosum parent. The levels of foliage glycoalkaloids in the hybrid and backcross populations paralleled the levels of potato leafhopper,Empoasca fabae Harris, resistance measured in a previous study.

Genotypic differences in susceptibility to wireworm attack in potato: mechanisms and implications for plant breeding

AbstractThe influence of different tuber compounds on susceptibility to wire‐worms (Agriotes obscurus) was studied in experiments with 10–13 potato genotypes. Both greenhouse and field experiments showed that the susceptibility to wireworm attack was negatively correlated with the concentration of glycoalkaloids and positively correlated with the concentration of reducing sugars in the outer 2 mm of the tubers. Varietal differences in chlorogenic acid had no effect on susceptibility. Breeding for high levels of glycoalkaloids in the extreme periphery, but very low levels in the rest of the tuber, will protect the tubers from wireworms and yet result in acceptable glycoalkaloid levels for food safety.

Influence of packaging materials and temperature on the glycoalkaloid content of potato tubers

The potato variety BEATE was packed in different coloured paper, polyester mesh and polyethylene bags. The samples were stored for 1 and 2 weeks at 5 and 23 °C. High storage temperature increased the solanine content significantly in all packaging variables. The highest content of glycoalkaloids was found in a blue polyethylene bag with high light transmission and the lowest glycoalkaloid content occurred in a paper bag coated with black polyethylene inside. To avoid high levels of glycoalkaloids, potato tubers should be kept cool during marketing.

Glycoalkaloid Content and in vitro Glycoalkaloid Solubility of Extruded Potato Peels

Potato peelings from French fry production are a potential source of dietary fiber, but the presence of naturally occurring glycoalkaloids could limit their use as a food additive. Potato peels were twin-screw extruded at 110 or 150 o C and 30 or 35% feed moisture to potentially reduce levels of glycoalkaloids. Individual glycoalkaloids were measured by HPLC. Neither α-chaconine nor α-solanine decreased on a dry weight basis from nonextruded peels (3.9 and 8.0 mg/10g, respectively). Extrusion did not change α-chaconine/α-solanine ratios. Only 3-5% of total glycoalkaloids were solubilized during in vitro digestion

Chlorophyll, Chlorogenic Acid, Glycoalkaloid, and Protease Inhibitor Content of Fresh and Green Potatoes

Exposure of commercial White Rose potatoes to fluorescent light for 20 days induced a time-dependent greening of potato surfaces; an increase in chlorophyll, chlorogenic acid, and glycoalkaloid content (α-chaconine and α-solanine); and no changes in the content of inhibitors of the digestive enzymes trypsin, chymotrypsin, and carboxypeptidase A. The minimum chlorophyll level of the light-stored potatoes was 0.5 mg/100 g of fresh potato weight. Unstored potatoes contained no chlorophyll. Storing potatoes in the dark did not result in greening or chlorophyll formation. Chlorogenic acid and glycoalkaloid levels of dark-stored potatoes did increase but less than in the light-stored potatoes

Determination of glycoalkaloids in potato tubers by reversed-phase high-performance liquid chromatography

A relatively fast and simple method for the determination of the glycoalkaloids α-solanine and α-chaconine in potato tubers is described. The glycoalkaloids are concentrated from potato samples by solid-phase extraction with a disposable C 18 cartridge column. The recovery, determined by addition of glycoalkaloid standard to a potato sample, was found to be better than 90%. The relative standard deviation of the measured glycoalkaloid levels was less than 4%. For the reversed-phase (RP) HPLC analysis of basic compounds, e.g., glycoalkaloids, too strong an interaction with the residual silanol groups of the stationary phase can be disadvantageous. In this work, acetonitrile-water was used as eluent with an RP-HPLC column with a reduced amount of residual silanol groups. The absence of buffer in the eluent increases the lifetime of the column and makes this system very suitable for the routine determination of glycoalkaloids.

Performance of potato peels in muffins and cookies

Potato peels produced as a by-product of potato processing have potential use as a dietary fiber supplement in baked foods. Both extruded and unextruded potato peels were used as a 25% weight replacement for wheat flour in cinnamon muffins. Muffins with peels were darker, lower in height, and more resistant to compression. An experienced sensory panel found no significant differences between types of peels for shape, color, odor, and flavor, but muffins with extruded peeels were less cohesive. Oatmeal cookies with 10% or 15% peels (w/w) were darker, harder and smaller in diameter than control cookies. Although sensory panelists detected differences in color and flavor between cookies with no peels and those with 10% peels, there was no difference between types of peels. During 4 weeks of storage at 21°C, all cookie formulations became harder, although differences between control cookies and those with peels decreased with time. Lower peroxide values were found for cookies with peels throughout the storage period, particularly those with 15% extruded peels. Potato peels, particularly extruded peels which have reduced glycoalkaloid levels, offer bakers the ability to prolong shelf-life while increasing dietary fiber content.

Interactive antifungal activity of the glycoalkaloids α-solanine and α-chaconine

The antifungal activity of the major potato glycoalkaloids, α-solanine and α-chaconine, against Ascobolus crenulatus, Alternaria brassicicola, Phoma medicaginis and Rhizoctonia solani has been examined. Both compounds showed reduced activity at lower pH (6 cf 7) and, in all cases, chaconine was the more inhibitory of the two compounds. A 1 : 1 mixture of solanine and chaconine produced marked synergistic effects, the magnitude of which varied with the fungus, concentration and pH. While individual glycoalkaloid activity declined substantially with decreasing pH and concentration, in most cases the inhibitory effect of the glycoalkaloid combination showed only a small reduction. In some cases, major inhibition was achieved with mixtures, the levels of individual glycoalkaloids in which showed no antifungal activity at all. The synergism between solanine and chaconine extended over a wide range of glycoalkaloid ratios with as little as 10–20% of either compound in the mixture causing a pronounced enhancement of the effect of any single glycoalkaloid, especially chaconine. The generally reduced sensitivity of R. solani to solanine and chaconine, both individually and in combination, is in keeping with this fungus being a serious pathogen of potato.

Evaluation of wild tuber-bearingSolanum accessions for foliar glycoalkaloid level and composition

Six hundred forty-five accessions of 70Solanum species and six natural hybrids were screened for foliar glycoalkaloids. Total foliar glycoalkaloid (TFGA) level and glycoalkaloid composition of one or more accessions of each species were determined by TLC and GLC analyses. Of the more than 12 different glycoalkaloids found in the wild species in this survey, solanine and chaconine account for more than 60% of the TFGA found in the foliage of these plants. There was wide variation in the total glycoalkaloid levels among the species.S. neocardenasii had the highest average TFGA value of the 70 species, 222 mg/100 g fresh wt (222 mg %) and an accession ofS. chacoense had the highest TFGA value recorded in the survey, 486 mg %. Of the 70 species, only 11 had average TFGA levels of more than 100 mg %. However, one or more accessions in 27 of the species synthesized more than 100 mg %. Forty-five species synthesized an average level of less than 50 mg %. The level usually found in the foliage of commercial potato cultivars is about 50 mg %. Therefore, most of theSolanum species in the potato germplasm collection can be considered low glycoalkaloid species.

The effect of light intensity on Colorado potato beetle resistance and foliar glycoalkaloid concentration of fourSolanum chacoense clones

Controlled environment experiments were used to determine the effect of light intensity on levels of glycoalkaloids and resistance to the Colorado potato beetle (CPB),Leptinotarsa decemlineata Say, inSolanum chacoense Bitter clones that synthesized acetylated glycoalkaloids, the leptines. Plants were grown under two light intensities, 50 or 250 ώmol m-2S-1, and bioassayed for CPB resistance by placing neonate larvae on excised foliage. Larval development stage and mortality were recorded after four days. The leptine-synthesizing clones responded to the increase in light intensity with a 2–4 fold increase in level of foliar leptines. Larval development rate on foliage from plants grown under high light intensity was reduced and larval mortality increased. Results showed a significant (p>0.05) effect of light on glycoalkaloid synthesis and CPB resistance.

With bitter herbs they shall eat it: chemical ecology and the origins of human diet and medicine

People have always been attracted to foods rich in calories, fat and protein, yet the biblical admonition that meat be eaten bitter herbs suggests that unpalatable plants play an important role in our diet. So-called primitive peoples show a surprisingly sophisticated understanding of how their bodies interact with plant chemicals, which may allow us to rediscover the origins of diet by retracing the paths of biology and culture. The domestication of the potato serves as the focus of Timothy Johns' interdisciplinary study, which forges a synthesis of ethnobotany and chemical ecology. The Aymara of highland Bolivia have long used varieties of potato containing potentially toxic levels of glycoalkaloids, and Johns proposes that such plants can be eaten without harm, owing to human genetic modification and cultural manipulation. Drawing on additional fieldwork in Africa, he considers the evolution of the human use of plants, the ways in which humans obtain foods from among the myriad poisonous and unpalatable plants in the environment, and the consequences of this history for understanding the basis of the human diet.

Evaluation of Solanum laciniatum press-cake silage as roughage for growing-finishing cattle

The green plant Solanum laciniatum contains various levels of steroid glycoalkaloids of which solasonine is used for the industrial synthesis of a wide range of steroid hormones. The residue of the industrial process, based on pressing extraction, provides a press-cake by-product that we have employed in the present trial. In vitro dry matter (DM) digestibility was 59.22%; in vivo DM digestibility was 60.39 and residual solasonine content in the ensiled press-cake was < 0.1%. A feeding trial was carried out with the objective of studying the effect of diets based on S. laciniatum press-cake (SLPC) versus cereal straw as a fibre source for rumen function and supplemented with different levels of concentrates. The response to concentrates and SLPC DM intake and weight increase have been studied, as well as the general behaviour of the animals and possible digestive disorders, carcass quality (conformation, colour and fattening) and the characteristics of the liver, lungs, spleen and genitals. Twenty-four cross-breed young bulls were randomly allotted to three pens of eight head each and three treatments were then assigned: (A) restricted intake of concentrates amounting to 1.6% of live weight (LW) and SLPC ad libitum; (B) 2 kg of concentrates per head per day up to 300 kg LW and then 1.6% of LW of concentrates and in both cases SLPC ad libitum; (C) concentrates and cereal straw both ad libitum. The bulls were slaughtered when the average LW of one group reached 500 kg. Voluntary intake of DM and crude protein (CP) was significantly higher for Treatment C. From Day 63 of the feeding trial, the weight of animals undergoing Treatment C was significantly higher than those of Treatments A and B ( P < 0.01). The use of SLPC silage allows a saving of concentrates up to 400 kg LW, the ratio of forages to concentrates of 50:50 being the most favourable with our traditional method of fattening and the concentrates being fed at 1.5% of LW throughout the fattening period.

Varietal and environmental effect on the glycoalkaloid content of potato (Solanum tuberosum L.).

The tubers of 14 potato varieties were analysed for glycoalkaloids. The level of glycoalkaloids in tubers of all the varieties analysed are within the safe limits for human consumption. The peels of tuber contained about 60-70% of the total glycoalkaloids present in the whole tuber. The levels of glycoalkaloids in leaves and tubers were correlated (r = 0.865). There was a significant increase in the content of glycoalkaloids in peels of tubers exposed to sunlight. Glycoalkaloid contents increased at the rate of 1.9 mg/100 g fresh weight per day in peels of "Kufri Jyoti" tubers exposed to diffused sunlight.

Utilization of potatoes in bioregenerative life support systems

Data on the tuberization, harvest index, and morphology of 2 cvs of white potato ( Solanum tuberosum L.) grown at 12, 16, 20, 24 and 28°C, 250, 400 and 550 μmol s −1 m −2 photosynthetic photon flux (PPF), 350, 1000 and 1600 μ1 1 −1 CO 2 will be presented. A productivity of 21.9 g m −2 day −1 of edible tubers from a solid stand of potatoes grown for 15 weeks with continuous irradiation at 400 μmol s −1 m −2, 16°C and 1000 μ1 1 −1 CO 2 has been obtained. This equates to an area of 34.3 m 2 being required to provide 2800 kcal of pototoes per day for a human diet. Separated plants receiving side lighting have produced 32.8 g m −2 day −1 which equates to an area of 23.6 m 2 to provide 2800 kcal. Studies with side lighting indicate that productivities in this range should be realized from potatoes. Glycoalkaloid levels in tubers of controlled-environment-grown plants are within the range of levels found in tubers of field grown plants. The use and limitation of recirculating solution cultures for potato growth is discussed.

Untersuchungen des Glykoalkaloidgehalts von Kartoffelhybriden mit Resistenz gegen die Kartoffelnematoden Globodera rostochiensis und Globodera pallida

Glycoalkaloid content in tubers of 77 F 1 -hybrids derived from Solanum tuberosum ssp. tuberosum and 6 different wild species depends to a high degree on the wild species used for crossing. In most cases offsprings from crosses with S. aracc-papa , S. vernei and S. sparsipilum produced more glycoalkaloids (12–168 mg/100 g fresh weight) than offsprings from crosses with S. oplocense and S. spegazzinii (6–56 mg/100 g fresh weight). I3ackcrosses with cultivars on the basis of this F 1 -hybrids resulted in a significant decrease of glycoalkaloid level after the second backcross. However, it is possible that even after the 4th backcross clones with a high content of glycoalkaloids can be found. No relationship existed between the degree of resistance to G. rostochiensis and G. pallida and the glycoalkaloid content of tubers in the investigated populations.

Taste evaluation of potato glycoalkaloids by the Aymara: A case study in human chemical ecology

A chemical ecological model can be the basis for defining testable hypotheses concerning human interactions with plants. Selection by Aymara subsistence cultivators against toxic glycoalkaloids in the ongoing domestication of the Bolivian potato cultigen Solanum X ajanhuiriwas used as a specific case study of human interactions with phytochemicals. In taste perception tests, Aymara subjects were able to discriminate between concentrations of pure glycoalkaloids in solution only above 20 mg/100 ml. Taste panel tests of potato clones indicated that glycoalkaloid levels are important to the Aymara in determining quality only as part of a decision-making process involving two character states: too high or acceptable. Glycoalkaloids in potatoes are regarded as toxic to humans above 20 mg/100 g fresh weight. Among the Aymara, a breakpoint in the curve for glycoalkaloid preference appears to occur between 20–38 mg/100 g. This distinction is evident in the Aymara potato taxonomy which distinguishes bitter (luq'i ch'oke) from nonbitter (ch'oke) potatoes.