Change in Some Glycoalkaloids of Potato under Different Storage Regimes

The potato (Solanum tuberosum L.) is an important food crop worldwide. Potato tubers can be stored to provide continuity of supply between production seasons, but it is important that they be stored under appropriate conditions as incorrect storage will result in deterioration in end user quality and may increase glycoalkaloid levels. We have investigated the effects of types of household storage on potato glycoalkaloid content (total glycoalkaloids [TGA]; α-solanine; α-chaconine) in Turkey. Tubers of potato cultivars (cvs.) Agria and Bettina were stored under four types of storage conditions (indirect sunlight for 10 h per day and dark storage for the remaining 14 h per day; storage under continuous fluorescent light; storage in constant darkness; storage in the dark in a refrigerator) for 56 days. Samples of tubers were taken at the beginning of the storage period and after 14, 28 and 56 days of storage for tuber glycoalkaloid measurement. Tubers stored in the three light environments showed an increase in glycoalkaloid levels; however, none of the cv. Agria tubers reached the critical level of 200 mg/kg tuber. On day 56 the TGA level of cv. Bettina tubers stored under fluorescent light reached 234.31 mg/kg.     

Determination of the glycoalkaloids α-solanine and α-chaconine levels in 18 varieties of potato (Solarium tuberosum L.) grown in Oman

Summary The glycoalkaloid content in 18 potato varieties grown in Oman was measured by HPLC using peel and flesh tissues. The total glycoalkaloid content of the tubers was found to be variety dependent and varied greatly between the 18 varieties. The total glycoalkaloid in the tubers of seven varieties was within the safe limit of ≤200 mg kg^{− 1} FW recommended for food safety, whereas the remaining 11 varieties exceeded this upper limit. The principal glycoalkaloids α-chaconine and σ-solanine were present in higher concentration in the peel than in the flesh of all varieties with the former being the principal alkaloid in the peel. The flesh of all of the 18 potato varieties contained total glycoalkaloid levels lower than the upper safety limit. The leaves of the 18 potato varieties were also analyzed for glycoalkaloids. The levels of glycoalkaloids in expanding leaves were higher than that of expanded leaves with the exception of six varieties. The principal glycoalkaloid in expanding and expanded leaves was α-chaconine. No correlation was observed between the glycoalkaloids levels of in the leaves and tubers.     

Glycoalkaloid content inSolanum species and hybrids from a breeding program for resistance to late blight (Phytophthora infestans)

As part of an effort to study the relationship between the “glycoalkaloid trait” and genetic resistance to late blight (Phytophthora infestans), glycoalkaloid content in tuber and foliar tissues from a wide genetic background withinSolanum, includingS. demissum, S. iopetalum and 15 hybrids selected from a backcrossing breeding scheme was determined. Analysis of variance indicated significant genotypic effect on total glycoalkaloid, solanidine, α-solanine, and α-chaconine content in both tubers and leaves. Tubers from wild potato species commonly contain glycoalkaloids in concentrations that exceed international health regulations for human consumption (20 mg/100 g fresh weight). In this study,S. demissum andS. iopetalum were highest in total tuber glycoalkaloids among all materials tested, with 70.4 and 76.2 mg/100 g fresh weight, respectively. In contrast, both commercial cultivars had the lowest concentration, both below the safety limit. Solanine was more abundant than chaconine in all but one genotype. All hybrids were intermediate to low in total glycoalkaloids. Except for the two wild species, glycoalkaloid concentration in leaves of all genotypes studied was at least twice that in tubers, with glycosylated forms accounting for more than 80% total glycoalkaloid content. Correlation between tuber and foliage alkaloids was poor. In view of the observed field resistance to late blight, it was concluded that tuber glycoalkaloid content may not be responsible for such resistance.     

Evaluation of Vitamins and Glycoalkaloids in Potato Genotypes Grown Under Organic and Conventional Farming Systems

Potato tubers provide people not only with carbohydrates but also with other essential compounds for human health. Several investigations have compared the quality of crops grown under organic and conventional farming systems. The aim of the present study was to evaluate the concentrations of vitamins C, B₁ and B₂ as well as glycoalkaloids (α-solanine and α-chaconine) in potato tubers of different genotypes and to estimate the farming system (conventional and organic) impact on the content of these compounds. Twenty potato genotypes were grown under organic and conventional farming systems in Priekuli (Latvia) during 2010 and 2011. The concentrations of vitamins C, B₁ and B₂ as well as glycoalkaloids (α-solanine and α-chaconine) were significantly influenced by the potato genotype. The vitamin B₁ concentration of potato genotypes grown in the organic field exceeded that of potato genotypes grown in the conventional field. A significant negative correlation was found between the vitamin C concentration and tuber yield only in the conventional field. No significant correlations were found between the other potato characteristics, such as starch content, tuber taste after boiling and glycoalkaloids, vitamins C, B₁ and B₂. The high broad-sense heritability for all tested traits (vitamin C 93%, vitamin B₁ 92%, α-solanine 88%, α-chaconine 84% and vitamin B₂ 70%) demonstrated that the high genetic diversity in the potato genotype population accounted for the phenotypic expression. The present study suggested that the breeding of new potato varieties with improved nutritional quality can be launched, and that the varieties that will be developed can be produced in an environmentally friendly way.     

Potato glycoalkaloids: Increases and variations of ratios in aged slices over prolonged storage

Four commercial cultivars of potatoes were maintained under normal storage conditions at 44 F for 34 weeks. Except for a final 10 week interval tubers were withdrawn at 6 week intervals. After slicing, a portion of the slices was immediately analyzed for total glycoalkaloid content. The remaining slices were aged for four days in the dark at room temperature, then similarly analyzed. The total glycoalkaloid content of the aged slices increased dramatically on aging. This increase on aging of slices reached a maximum early in storage then decreased gradually over the storage period. In determining the individual glycoalkaloids, α-solanine and α-chaconine both increased in these slices, but the greatest increase was in the former. Appearing solely in the aged slices of the Kennebec variety, α-and β-solamarine appeared early in the storage period and gradually decreased over the storage period. Analyses of the unaged slices indicated that the glycoalkaloid content and composition of the potato tubers was little affected by storage. Aging of potato sprouts did not change their glycoalkaloid content.     

Glycoalkaloid accumulation during tuber development of early potato cultivars

Summary Plants of early potato cultivars were sampled at successive harvests during tuber development and individual tubers were analysed for α-solanine and α-chaconine using high-performance liquid chromatography. Mean tuber total glycoalkaloid concentration (α-solanine plus α-chaconine) per plant decreased with time and statistically significant differences between cultivars were observed in the patterns of decline during tuber growth. The mean tuber ratio of α-chaconine to α-solanine increased during tuber development and was also affected by genotype. Total glycoalkaloid concentration for individual tubers of marketable sizes (up to 50 g fresh weight) exceeded the safety limit of 20 mg per 100 g fresh weight for cultivars Home Guard and British Queen but not for Rocket. These differences were attributable to differences in both rates and patterns of glycoalkaloid accumulation during tuber development, although in all cultivars results were consistent with glycoalkaloid accumulation occurring in the expanding peripheral cell layers of tubers for a considerable period after tuber initiation.     

The nutrient and glycoalkaloid content of a new potato meal

The nutrient and glycoalkaloid content of a new potato meal produced as a by-product of starch manufacture using low temperature dehydration was determined. Comparisons were made between the new potato meal and the previously manufactured meal which was prepared by high temperature dehydration. The glycoalkaloid content of the new potato meal was 15.53mg α-chaconine and 4.75mg α-solanine per 100g meal compared to 15.79mg α-chaconine and 7.83mg α-solanine in the potato meal produced by high temperature dehydration. The new potato meal contained 2% more protein and 1.9, 3.4 and 1.2 times more niacin, riboflavin and thiamin, respectively than the previous by-product. The potassium and phosphorus concentrations were approximately 2.0 and 0.2%, respectively. Other minerals were found in lesser concentrations with the sodium content being only 7.4mg/100g potato meal. A 28g serving would provide approximately 5, 7 and 4% of the RDA for protein, niacin and thiamin, respectively.     

Recovery of Protease Inhibitors from Potato Fruit Water by Expanded Bed Adsorption Chromatography in Pilot Scale

The current study was conducted to investigate the recovery of native potato protein from potato fruit water (PFW) by expanded bed adsorption (EBA) chromatography. The eluted proteins were concentrated by ultrafiltration and spray-dried into powder. The SDS-PAGE showed that the recovered proteins were potato protease inhibitors (PPIs). The trypsin and chymotrypsin inhibitor activities of the recovered PPIs were 377.93 ± 8.22 and 12.90 ± 0.03 mg g^?1 protein, respectively. The recovery yield of protease inhibitors was 74.88%. The glycoalkaloid assay showed that the recovered PPIs contained 30.31 ± 0.15 μg g^?1 of α-chaconine and 92.77 ± 0.52 μg g^?1 of α-solanine, and these values were much lower than those in potato protein concentrate (PPC) obtained by traditional thermal coagulation. The most abundant amino acid in the PPIs was serine. The results indicated that the EBA can be used to effectively recover native potato protein from PFW.     

Resistance to late blight and soft rot in six potato progenies and glycoalkaloid contents in the tubers

Glycoalkaloids are anti-nutritional compounds commonly found in wildSolanum species used as resistance sources to major potato pathogens. It is therefore important for breeding purposes to know whether selecting for resistance using such species necessarily selects also for high glycoalkaloid contents in the tubers. To test this hypothesis, we used six partial progenies from crosses betweenSolanum tuberosum and accessions ofS. andigena, S. berthaultii, S. phureja, andS. vernei to investigate the possible correlation between resistance toPhytophthora infestans and/or toErwinia carotovora subsp.atroseptica and the concentration of glycoalkaloids in tubers. Concentrations of α-solanine and α-chaconine in the tubers segregated in each progeny, as did resistance to each pathogen. Some, but not all, clones from each progeny showed hypersensitive reactions to the isolate ofP. infestans used. Furthermore, clones within each progeny also differed for components of partial resistance toP. infestans, suggesting that all four wild species could be used as sources of both race-specific and partial resistance to late blight. With the exception of low, but statistically significant, correlations between concentration of α-solanine and two late blight resistance components (incubation period and spore production per unit lesion area) in progenies derived fromS. vernei, and despite a trend towards higher glycoalkaloid concentrations in the tubers of the clones most resistant to soft rot within progenies derived fromS. berthaultii andS. vernei, no consistent relationship between resistance to either disease and concentrations of α-solanine and/or α-chaconine was observed. These results indicate that neither race-specific nor partial resistance to late blight and soft rot in the accessions used as progenitors of resistance depend on high solanine or chaconine concentrations. These resistance sources could thus prove useful in breeding programs for improved behaviour againstP. infestans and/orE. carotovora.     

The proximate composition and glycoalkaloid content of three potato meals

The proximate composition and glycoalkaloid content of a dried potato by-product meal (tater meal) and two dried potato pulp meals (potato meal and potato meal plus 10% molasses) were determined. All three feeds demonstrated variable compositions: the tater meal averaged 8.7% moisture, 9.1% crude protein, 5.4% ether extract, 5.0% crude fiber, 4.1% ash and 56.8% nitrogen-free extract; the potato meal averaged 14.5% moisture, 6.0% crude protein, 0.5% ether extract, 9.5% crude fiber, 2.2% ash and 57.1% nitrogen-free extract; the potato meal plus 10% molasses averaged 15.3% moisture, 6.4% crude protein, 0.3% ether extract, 8.0% crude fiber, 2.6% ash and 57.8% nitrogen-free extract. The phosphorus concentration was determined to be approximately 0.2% for the three samples. Other minerals were found in lesser concentrations. The riboflavin and thiamine concentrations of the three potato meals were less than 10% of the values reported for raw potato pulp and peel. The niacin concentration was approximately 40% of the values reported for raw potato pulp and peel. Tater meal contained 11.5 mg a-chaconine and 6.5 mg α-solanine per 100g meal. Analysis of potato meal gave 15.8 mg α-chaconine and 7.8 mg α-solanine per 100g meal while the potato meal plus 10% molasses was found to contain 13.2 mg α-chaconine and 7.3 mg α-solanine per l00g meal.     

Glycoalkaloid contents in tubers fromSolanum tuberosum populations selected for potato leafhopper resistance

Solanum tuberosum L. Gp. Tuberosum populations that had been improved for resistance to potato leafhopper,Empoasca fabae (Harris), by recurrent selection, were analyzed for tuber contents of the glycoalkaloids α-solanine and α-chaconine. The mean content of both glycoalkaloids was significantly higher in the more resistant populations compared with the unselected population. In a population generated from seven cycles of selection for resistance, the mean content of solanine + chaconine was 9.5 mg/100 g fresh weight compared with 4.0 mg/100 g in the original, unselected population; a 137% increase. Kennebec, in the same experiment, averaged 10.9 mg/100 g; Katahdin averaged 4.6 mg/100 g.     

Glycoalkaloid content in foliage of hybrid and backcross populations from aSolanum tuberosum X 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.     

Einfluss von Lagerung und Sorte auf die Verteilung der Glykoalkaloide in der Kartoffelknolle

Zusammenfassung Fünf Speisekartoffelsorten wurden w?hrend einer sechsmonatigen Lagerung fünfmal auf α-Solanin und α-Chaconin untersucht. Es wurden vier Gewebebereiche der Knolle getrennt überprüft. Der Gesamtglykoalkaloidgehalt betrug im Augenbereich 164, in der restlichen Schale 101 und in der Gef?ssbündelzone mit ?usserem Speichergewebe 8mg/100g. Trockensubstanz. Im restlichen Innenk?rper waren nur noch Spuren (0.164mg/100g TS) nachzuweisen. Zwischen den Sorten und diesen Gewebepartien traten statistisch gesicherte Wechselwirkungen auf, die im wesentlichen von einer Sorte verursacht wurden. W?hrend der Lagerung sind die Alkaloidgehalte leicht, aber statistisch nicht gesichert gesunken. α-Solanin und α-Chaconin kamen generell im Verh?ltnis von etwa 1∶1.5vor; die Korrelation zwischen beiden Formen ist sehr eng (r=0.865). Bezogen auf die gesamte Knolle lagen die Gesamtglykoalkaloide je nach Sorte zwischen 2.4 und 8mg/100g Frischsubstanz und damit im gesundheitlich unbedenklichen Bereich.

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Summary Five table potato cultivars (Erna, Granola, Gusto, Ulse, Margit) from the same source were examined for their content of α-solanine and α-chaconine during a sixmonths storage period. For the testing and subsequent analysis the tubers were dissected into four kinds of tissues: eye-zone, peel, vascular bundle region, medulla. The total glycoalkaloid content (TGA) in the total tuber mass varied between 2.4 and 8mg per 100g fresh matter depending on cultivar (Fig. 1). Despite significant differences between cultivars (Table 1), all potato cultivars remained within the safe range during the entire storage period. Remarkable differences in TGA per 100g dry matter could be noted in the tuber parts. For the eye-zones a TGA of 164mg was found; the peel region showed 101mg and the vascular bundle zone 8mg. The medulla of the tubers contained only traces of TGA (0.164mg/100g dry matter, Fig. 2). The statistical analysis only revealed significant interactions between cultivars and tuber parts (Table 1), mainly caused by the cultivar Gusto which showed higher contents of α-solanine and α-chaconine in its vascular bundle regions (Figs 3–5). The ratio between amounts of α-solanine and α-chaconine was approximately 1∶1.5, and after eliminating effects of cultivar, storage and tuber parts, the correlation coefficient between amounts was 0.865. This close correlation can be used for breeding. The non-significant, slightly negative effect of the six-months storage period on alkaloid content was noteworthy. It is assumed that only after long storage periods or through inappropriate storage (sprouting of tubers) a significantly higher glycoalkaloid content may be expected.

     

Modification of Potato Steroidal Glycoalkaloids with Silencing RNA Constructs

Steroidal glycoalkaloids (SGAs), while found in many solanaceous plants, can accumulate to unacceptably high levels in potato tubers. The two primary SGAs that occur in potatoes are the tri-glycosylated alkaloids, α-solanine and α-chaconine. The first glycosylation steps in their biosynthetic pathways are performed by the regulated enzymes SGT1, the UDP-galactose:solanidine galactosyltransferase, and SGT2, the UDP-glucose:solanidine glucosyltransferase, respectively. Using fragments of the Sgt1 and Sgt2 genes to produce small inhibitory RNAs (siRNA), we have been able to down-regulate each branch of the pathway. The use of the siRNA approach increases the efficiency of producing transgenic plant lines with reductions in individual SGAs but further research is required to achieve reductions in levels of total SGA accumulation.     

Identification and Quantification of Steroidal Alkaloids from Wild Tuber-Bearing <Emphasis Type="Italic">Solanum</Emphasis> Species by HPLC and LC-ESI-MS

Wild Solanum species are characterized by several types of glycoalkaloids (GAs), which are usually not found in commercial potato cultivars. These alkaloids serve as defence compounds against herbivores and microorganisms, especially fungi. In this study, the GA composition of tuber and leaf material of 17 wild Solanum species was analysed qualitatively by liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) and quantitatively by high-performance liquid chromatography. The GAs identified were α-solanine, α-chaconine, β-chaconine, solasonine, solamargine, demissine, dehydrodemissine, α-tomatine, dehydrotomatine, commersonine, dehydrocommersonine, leptine I and leptine II. Most species accumulated the common potato GAs α-solanine and α-chaconine in tubers and solasonine and solamargine additionally in leaves. In some species, such as S. acaule ssp. acaule, S. demissum and S. polyadenium, substantial amounts of unusual alkaloids were detected. By using LC-ESI-MS, we detected several minor alkaloids such as dehydrogenated forms of α-tomatine, demissine and commersonine for the first time. Total GA content, expressed as the sum of the four main alkaloids α-solanine, α-chaconine, solamargine and solasonine differed from species to species. In general, GA contents in leaf tissue were higher and GA patterns were more complex than those of tubers.     

Preparative isolation ofSolanum tuberosum L. glycoalkaloids by MPLC

Summary A new, efficient and economic method employing Medium Pressure Liquid Chromatography (MPLC) for the isolation of the two majorSolanum tuberosum L. glycoalkaloids (α-solanine and α-chaconine) is described. Potato peelings are homogenised with 5% acetic acid, the glycoalkaloids purified by filtration through an XAD-2 column and then by precipitation from the aqueous solution. The resulting glycoalkaloid fraction was purified by MPLC using a Silica Gel column and a CHCl₃:MeOH:2% NH₄OH mixture (70∶30∶5) as mobile phase to yield pure α-chaconine and a-solanine. This methodology can be used to obtain glycoalkaloids for enthomology and toxicological research where large amounts of these compounds are required.     

Segregation of leptine glycoalkaloids and resistance to Colorado potato beetle (Leptinotarsa decemlineata (Say)) in F2Solanum tuberosum (4x) ×S. chacoense (4x) potato progenies

Solanum chacoense Bitter is resistant to the Colorado potato beetle (CPB),Leptinotarsa decemlineata (Say). Resistance has been associated with the presence of a rare class of glycoalkaloids, the leptines. In this study, seven tetraploid, F2S. tuberosum xS. chacoense families were evaluated for foliar production of leptines I and II, leptinines I and II, and α-solanine and α-chaconine; and screened for resistance to CPB in the laboratory and field. Resistance was correlated with the concentrations of glycoalkaloids on a family and an individual basis. Leptine concentrations ranged from undetectable to a high of 18.0 mg/g dry weight. All of the progeny produced solanine and chaconine. Family 9623 had the highest mean leptine concentration and the lowest mean leaf disk feeding and CPB defoliation levels. Family 9616 had the lowest mean glycoalkaloid concentration and ranked as one of the most susceptible families. Regression analyses of solanine + chaconine, leptine I and II, and leptinine I and II foliar concentrations versus leaf disk consumption and field defoliation revealed that only increased foliar levels of leptines resulted in decreased CPB feeding. The regression models for leptines versus leaf disk consumption and field defoliation were highly significant, accounting for 17% and 26% of the variation in consumption and defoliation, respectively. To the best of our knowledge, this is the first work reporting the impact of leptine and leptinine concentrations on CPB feeding in tetraploid,S. tuberosum xS. chacoense potato hybrids. Results are discussed within the context of breeding for resistance to CPB.     

Glycoalkaloids in potato tubers grown under controlled environments

Tuber content of α-solanine, α-chaconine, and total glycoalkaloids (TGA) was determined for the potato cultivars, Norland, Russet Burbank, and Denali grown under different environmental conditions in growth chambers. The lowest TGA concentrations (0.30 to 0.35 mg g¹ dry tissue) were found in the cv. Norland with 400 μnol m^-2 s^-1 photosynthetic photon flux (PPF), 12 h day length, 16 C temperature, and 350 μmol mol^-1 carbon dioxide. The ratio of α-chaconine to α-solanine was close to 60:40 under all growing conditions, except that it was 50:50 under the low temperature of 12 C. Cultivars responded similarly to environmental conditions although TGA was about 20% greater in cv. Russet Burbank and about 30% greater in Denali compared to Norland. The largest changes in TGA occurred with changes in temperature. In comparison to 16 C, TGA were 40% greater at 12 C, 80% greater at 20 C, and 125% greater at 24 C (0.70 mgg ^-1 dry weight). The TGA concentratation increased from 10 to 25% with an increase in light from 400 to 800 μmol m^-2 s^-1 PPF for all three cultivars. TGA increased 20% with extension of the day length from 12 to 24 hr and also increased 20% when carbon dioxide was increased from 350 to 1000 umol mol^-1. TGA concentrations were not influenced by changes in relative humidity from 50 to 80%. TGA concentrations decreased only slightly in harvests made from 9 to 21 weeks after planting. Variations in TGA among the different growing conditions and cultivars were below 20 mg/100 g fresh weight (= 1.0 mg g^-1 dry weight) recognized as the upper concentration for food safety. However the results suggest that TGA should be considered when potatoes are grown at temperatures above 20 C.     

Performance of Colorado potato beetle larvae,Leptinotarsa decemlineata (Say), reared on synthetic diets supplemented withSolanum glycoalkaloids

Glycoalkaloids are a class of secondary compounds (nitrogenous, steroidal glycosides), ubiquitously distributed throughout the Solanaceae. Numerous studies (in planta) have shown that certain glycoalkaloids, e.g., α-tomatine, solanocardenine, and leptine, have a negative impact on performance of the Colorado potato beetle,Leptinotarsa decemlineata (Say). However, the presence of other secondary compounds, as well as the nutritional status of the plants used, are additional variables in such experiments. By rearing Colorado potato beetle, from egg to prepupal stage, on a synthetic diet supplemented with the glycoalkaloids α-tomatine, α-chaconine, α-solanine, leptine I and the steroidal aglycone solanidine, we have been able to further establish the effects (ex planta) of these compounds on the Colorado potato beetle. Leptine I displayed a dose-dependent negative activity against the Colorado potato beetle (as measured by larval weight gain and tune to molt), when assayed at 0.31, 0.62 and 1.23 mM concentrations; however, by the fourth stadium no effect was found. When Colorado potato beetle were fed a higher concentration of leptine I (2.4 mM), there was a sustained effect in all stadia. At 2.4 mM, leptine I displayed a greater negative impact on Colorado potato beetle growth and development than did α-tomatine. α-Chaconine at 2.4 mM did not impair Colorado potato beetle performance relative to Colorado potato beetle reared on control diets. α-Chaconine plus α-solanine, at concentrations commonly found inSolanum tuberosum L. foliage (0.6 and 0.3 mM respectively), did not impair Colorado potato beetle performance. The steroidal aglycone solanidine (2.4 mM) had a significant negative impact on Colorado potato beetle performance. Results are discussed in the context of host-plant resistance and insect-plant interactions.     

A rapid method for the quantification of steroidal glycoalkaloids by reversed phase HPLC

Summary Methods were developed for clean-up of potato tuber extracts on solid phase extraction CN-cartridges and for analysis of steroidal glycoalkaloids by reversed phase HPLC. The alkaloids α-solanine, α-chaconine, α-solasonine and α-solamargine could be separated on C₈ or C₁₈ reversed phase columns using a mobile phase of acetonitrile/Tris-buffer (3∶2, v/v). The analysis time of tuber extracts containing these alkaloids was less then 4 min, if the pH of the mobile phase was adjusted to 7.4 and run at a flow rate of 0.5 ml/min.