Influence of environment and genotype on polyphenol compounds and in vitro antioxidant capacity of native Andean potatoes (Solanum tuberosum L.)

The influence of environment and genetics on total phenolic content and hydrophilic antioxidant capacity (H-ORAC) of potato tubers was evaluated using 13 native Andean genotypes. Cultivars were grown at two highland locations in Peru: Huancayo and Huancani. Environmental conditions significantly affected the total phenolic contents and H-ORAC values in a cultivar-dependent manner. However, the potato genotype was the most determining factor of the observed variations. The effects of environment on individual phenolic compounds were also significant in terms of quantity, whereas the chemical profile remained stable across environmental conditions. To gain an insight into the observed antioxidant capacity of potato extracts, the individual and combined antioxidant effects of the main potato phenolic compounds were investigated. The ORAC values of reconstituted polyphenol mixtures reflecting the authentic phenolic composition of potato extracts were higher than expected from the summing of the ORAC values of individual phenolic compounds, indicating synergistic effects. The authentic potato extracts showed either a higher or a lower ORAC value than their reconstituted counterparts, suggesting positive or negative interactions with other compounds. Taken together, our results lead us to the following conclusions: (i) the hydrophilic antioxidant capacity observed in potato extracts is the result of various and complex interactions that could be attributed to phenolic compounds, to other non-identified molecules, and to synergistic as well as antagonistic effects between all these components and (ii) the high stability of the ranking of cultivars across environment in terms of phenolic content and antioxidant capacity indicates that the native Andean cultivars could be confidently used within breeding programs aiming at improving the health-promoting value of potato.     

Functional food characteristics of potato cultivars (Solanum tuberosum L.): Phytochemical composition and inhibition of 1-methyl-1-nitrosourea induced breast cancer in rats

Effects of freeze-dried potato powder, prepared from baked potato with skin and incorporated into a purified diet, on the post-initiation phase of chemically induced breast carcinogenesis in rats, were evaluated for both dose dependence and variation in anticancer activity among cultivars. Associations among anticancer activity, select phytochemicals, and antioxidant capacity were investigated. No adverse effects were observed in rats fed diets containing between 5% and 50% (w/w) freeze-dried potato powder. While Russet Burbank potato (RB) (5%, w/w) had marginal effects on the carcinogenic response, feeding a range of dietary concentrations (12.5%, 25%, and 50%, w/w), of a red pigmented cultivar, cv. Mountain Rose (MR), with higher content of chlorogenic acid derivatives and anthocyanin content than RB, showed greater inhibition of carcinogenesis. Overall, MR-fed rats had a 23% reduction in cancer incidence (p = 0.009) and a 49% reduction in cancer multiplicity (2.1 vs. 4.0 cancers per rat, p = 0.004) with evidence of a dose dependent effect on cancer multiplicity. Evaluation of additional cultivars showed significant variation for anticancer activity that is likely to be sufficient to build upon for crop breeding and improvement.     

Determination of total phenol content, antioxidant activity and acetylcholinesterase inhibition in selected mushrooms from Turkey

In the present study, we investigated the acetylcholinesterase (AChE) inhibitory activity of the ethanolic extracts of a number of mushroom species growing in Turkey, including mainly Polyporus species (Polyporus gilvus, Polyporus sulphureus, Polyporus annosus, Polyporus radiatus, Polyporus pinicola, Polyporus volvatus, Polyporus fomentarius, Polyporus stevenii, Polyporus badius), as well as Cantharellus cibarius, Lactarius deliciosus, and Trametes versicolor. The analyses were carried out using the spectrophotometric method of Ellman in ELISA microplate reader at 500 μg/ml. Since Alzheimer's disease (AD) is associated with oxidative degeneration of cells, several methods of antioxidant activity were applied to the mushroom extracts such as 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, ferrous ion-chelating effect, ferric-reducing antioxidant power (FRAP), and beta-carotene bleaching tests. Total phenol contents of the extracts were also determined by Folin-Ciocalteu reagent. In anti-AChE assay, the most active one was P. sulphureus having 31.44% of inhibition. P. voluatus showed the best scavenging effect against DPPH, while all of the extracts exerted low capacity in chelating ferrous ions and reducing ferric ion.     

A study on degradation kinetics of niacin in potato (Solanum tuberosum L.)

The kinetics of niacin degradation in potato (Solanum tuberosum L.) as well as in pure niacin solutions at initial concentrations present in potato has been studied over a temperature range of 50–120 °C (isothermal process). Niacin degradation followed first-order kinetics, where the rate constant increased with an increase in the temperature. The temperature dependence of degradation was adequately modeled by the Arrhenius equation. The degradation kinetics of niacin in normal open pan cooking, pressure-cooking and a newly developed and patented fuel-efficient “EcoCooker” has also been studied (non-isothermal process). A mathematical model has been developed using the isothermal kinetic parameters obtained to predict the losses of niacin from the time–temperature data of the non-isothermal heating/cooking process. The results obtained indicate a niacin degradation of a similar magnitude in all three modes of cooking used in the study.     

Total and individual carotenoid profiles in Solanum phureja of cultivated potatoes: I. Concentrations and relationships as determined by spectrophotometry and HPLC

Total and individual carotenoid concentrations were determined by spectrophotometry and HPLC, in raw tubers of a sample of 23 accessions of Solanum phureja potatoes taken at random from the world germplasm collection following its stratification on tuber flesh color. Lutein, zeaxanthin, violaxanthin, antheraxanthin and β-carotene were detected in all accessions and three distinct patterns of carotenoid accumulation were evidenced by cluster analysis. Accessions in group 1 showed the highest concentrations of total carotenoids (1258–1840 μg 100 g⁻¹ FW) comprised largely of zeaxanthin (658–1290 μg 100 g⁻¹ FW) with very low or no presence of β-carotene (below 5.4 μg 100 g⁻¹ FW). Accessions in group 2 presented moderate total carotenoid concentrations with violaxanthin, antheraxanthin, lutein and zeaxanthin as the major carotenoids. Accessions in group 3 showed low concentrations of total carotenoids (97–262 μg 100 g⁻¹ FW) and very low or no zeaxanthin, with lutein and violaxanthin as the predominant carotenoids and relatively high concentrations of β-carotene (up to 27 μg 100 g⁻¹ FW). Five accessions with significant concentrations of zeaxanthin were identified with the accession 703566 showing the highest concentration (1290 μg 100 g⁻¹ FW). This value is to our knowledge higher than any value previously reported for potatoes, including those achieved through genetic modification. For the 23 S. phureja accessions, total carotenoid concentration was positively and significantly correlated with antheraxanthin and zeaxanthin concentrations, and negatively and significantly correlated with β-carotene concentration.     

Influence of harvest date on nitrate contents of three potato varieties for off-season production

The influence of potato variety and harvest date was investigated on tuber nitrate content for off-season production in three varieties: Arinda (mid-early), Spunta (mid-late) and Mondial (late). Samples of tubers were harvested at 90, 105 and 120 days after planting in winter–spring crop and at 80, 95 and 110 days after planting in summer–autumn crop. Tuber nitrate content was determined by ion selective electrode (ISE) method. Investigated varieties differed in nitrate content. In both off-season crops, the highest quantities of nitrate were contained in the late Mondial, with respect to the middle early Arinda variety and Spunta. After a delay of the harvest date, nitrate contents in the investigated tuber samples significantly decreased in winter–spring crop, whereas they increased in summer–autumn crop in the three varieties, but to the greatest extent in the case of late Mondial variety. Regardless of variety and harvest time, the content of nitrate in tubers was within the guidelines proposed by some European countries.     

Ascorbic acid concentration of native Andean potato varieties as affected by environment, cooking and storage

The ascorbic acid (AA) concentration of tubers was determined in 25 Andean potato varieties (Solanum tuberosum L.) grown in three environments, and the effect of cooking and storage time in subsets of samples was evaluated. Significant variation due to genotype, environment and genotype × environment (G × E) interaction was found. AA concentration in freshly harvested raw, peeled tubers ranged from 22.2 to 121.4 mg/100 g on a dry weight basis (DW) and from 6.5 to 36.9 mg/100 g on a fresh weight basis (FW) with the accession 704393 showing the highest levels of AA in all three locations. Differences in AA concentration were found among cooking methods and storage times; and significant non-crossover interactions with genotype were observed for both of these parameters. It was found that AA concentration of boiled tubers of the six varieties evaluated was higher than in oven and microwaved tubers and that AA concentration of tubers of the 23 varieties evaluated decreased with storage time. The variety 704393 retained 54 and 34% of its original AA concentration after boiling and storage during 26 weeks under farmer conditions. One hundred grams of fresh harvested boiled potatoes of this variety (704393) could provide adults with 17–20% of the recommended daily allowance (RDA) of AA.     

The influence of nitrogen and potassium fertilisation on the content of polyphenolic compounds and antioxidant capacity of coloured potato

The effect of fertilisation rates of nitrogen: 0 (control treatment—no soil fertilisation), 40, 80 and 120 kg/ha and potassium: 0 (control treatment), 120, 150 and 180 kg/ha on the content of anthocyanins, phenolic acids and antioxidant capacity in purple–blue potato cv. ‘Blue Congo’ was examined. Anthocyanins and phenolic acids were identified and quantified by LC–MS and UPLC–PDA. Nitrogen was more effective in increasing the anthocyanin content—their quantity in tubers after nitrogen application was twice as much as that found after potassium application. Among phenolic acids, the dominant one was chlorogenic acid, the content of which significantly increased after nitrogen fertilisation at 120 kg/ha, in line with the increase in total concentration of phenolic acids and antioxidant capacity. The adjustment of nitrogen and potassium fertilisation levels during the growth of purple–blue potatoes seems to be an effective way to increase the expression of polyphenolic compounds in these cultivars. Therefore, fertilisation with N at 120 kg/ha and K at 120 and 150 kg/ha is recommended as a way to improve the content of biologically active compounds and antioxidant properties, and consequently, to enhance the nutritional value and the functionality of purple–blue potatoes.     

The antioxidant and cytotoxic activities of Sonchus oleraceus L. extracts

This study investigated in vitro antioxidant activity of Sonchus oleraceus L. by extraction solvent, which were examined by reducing power, hydroxyl radical-scavenging activity(HRSA) and 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assays. 70% MeOH extract had the greatest reducing power while EtOH extract had the greatest HRSA. The antioxidant activity of S. oleraceus extracts was concentration dependent and its IC₅₀ values ranged from 47.1 to 210.5 µg/ml and IC₅₀ of 70% MeOH, boiling water and 70% EtOH extracts were 47.1, 52.7 and 56.5 µg/ml, respectively. 70% MeOH extract of S. oleraceus contained the greatest amount of both phenolic and flavonoid contents. The extracts tested had greater nitrite scavenging effects at lower pH conditions. The cytotoxic activity showed that EtOH extract had the best activity against the growth of stomach cancer cell. These results suggest that S. oleraceus extract could be used as a potential source of natural antioxidants.     

Variation and inheritance of oil content and fatty acid composition in niger (Guizotia abyssinica)

Niger (Guizotia abyssinica) is an economically important edible oilseed crop with a wide variation in seed oil content and fatty acid composition between populations. This study sought to determine the extent of this variation among the Ethiopian niger populations and to analyze the inheritance of high oil and oleic acid (C18:1) contents. The analysis of 153 niger populations revealed a twofold variation in seed oil content (27–56%) with 7% of the populations having more than 50% oil. These high oil content populations came from different regions and a wide altitudinal range (1400–2590 m asl). There was also a high variation in oleic acid content between populations (3.3–31.1%). Interestingly, the populations with more than 13% oleic acid were entirely collected from elevations of less than 2000 m asl. Breeding of selected genotypes for two generations revealed a highly significant positive correlation between the parents and their progenies both in oil and oleic acid contents. The study also suggests a significant contribution of environmental factors to the variation in both traits suggesting a moderate heritability. We conclude that there is a highly significant variation both in oil content and fatty acid composition in the niger populations that can be used for its improvement.     

Relationship between potato starch isolation methods and kinetic parameters of hydrolysis by free and immobilised α-amylase on alginate (from Laminaria digitata algae)

The kinetic study of the hydrolysis of starch, isolated by two methods (bisulphite and alkaline) from potatoes cultivated in the south of Algeria, was carried out by α-amylase (from Aspergillus oryzae). The enzyme used is free and immobilised by covalent bonds on alginate in the presence of the 1-ethyl-3-[3-(dimethylamino)-propyl]carbodiimide hydrochloride (EDCI). The kinetics of hydrolysis of the extracted starches obeys the Michaelis–Menten model. The values of k_m in g L⁻¹ and V_max in g L⁻¹ min⁻¹ for the starches isolated by the alkaline method are (40.7, 3.8) for free amylase and (70.8, 3.4) for the immobilised enzyme. For the starches extracted by the bisulphite method, the latter kinetic parameters values are (34.2, 2.8) for free amylase and (55.7, 1.7) for the immobilised enzyme. The results show that the kinetic parameters of the hydrolysis are dependent on the conditions of extraction and they are larger for the alkaline method for both the free and immobilised enzyme.     

Antioxidant capacity of underutilized Malaysian Canarium odontophyllum (dabai) Miq. fruit

This study aimed to evaluate the antioxidant capacities of various parts of the dabai (Canarium odontophyllum Miq.) fruit. The antioxidant capacities of C. odontophyllum were evaluated using a β-carotene bleaching assay, ferric reducing antioxidant power (FRAP) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assays. Total phenolic content of the dabai fruit was estimated using the Folin–Ciocalteu method. The antioxidant capacities ranked in the following order: skin > flesh + skin > flesh > kernel. Our findings show that a high correlation exists between total phenolic content and total antioxidant activity. This indicates that phenolic compounds could be the major contributors to the antioxidant capacity of C. odontophyllum fruit. Therefore, dabai fruit, especially the skin, can be recommended as a major source of natural antioxidants.     

Salvia leriifolia Benth (Lamiaceae) extract demonstrates in vitro antioxidant properties and cholinesterase inhibitory activity

The object of the present study was to investigate the in vitro antioxidant properties and cholinesterase inhibitory activity of Salvia leriifolia Benth extracts and fractions. The functional role of herbs and spices and their constituents is a hot topic in food-related plant research. Salvia species have been used since ancient times in folk medicine for cognitive brain function and have been subjected to extensive research. Thus, we hypothesize that S leriifolia, because of its functional properties, would be a good candidate to use as a nutraceutical product for improving memory in the elderly or patients affected by Alzheimer disease (ad). To test this hypothesis, we examined the cholinesterase inhibitory activity using the modified colorimetric Ellman's method against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). The n-hexane exhibited the highest activity, with inhibitory concentration 50% (IC₅₀) values of 0.59 and 0.21 mg/mL, for AChE and BChE, respectively. This extract was fractionated, and 9 of these fractions (A-I) were obtained and tested. Fraction G, characterized by the presence of sesquiterpenes as major components, was the most active against AChE (IC₅₀ = 0.05 mg/mL). Because oxidative stress is a critical event in the pathogenesis of AD, we decided to screen the antioxidant activity (AA) using 2,2-diphenyl-1-picrylhydrazyl test, β-carotene bleaching test, and bovine brain peroxidation (thiobarbituric acid) assay. The ethyl acetate extract showed the highest activity, with IC₅₀ values of 2 and 33 μg/mL on β-carotene bleaching test and thiobarbituric acid test, respectively. These results suggest potential health benefits of S leriifolia extracts. However, this finding requires additional investigation in vivo.     

Tuber quality and nutritional components of “early” potato subjected to chemical haulm desiccation

“Early” potato is a typical crop grown in most of the Mediterranean countries, and it is one of the most important horticultural crops exported towards the Northern European markets. In order to improve market value of early potatoes, growers are more and more involved in choosing new potato varieties and constantly looking for methods to improve the commercial quality of tubers. One of the most increasingly used agro-techniques is chemical haulm desiccation, which aims to simplify harvesting and can help to manipulate tuber size distribution and tuber skin-set. Its effect on yield and quality aspects of early potato remains to be better evaluated. This paper resumes results of trials and analysis conducted during 2007 concerning the effect of the application of a chemical desiccant (gluphosinate ammonium) on some relevant nutritional parameters of three early potato varieties (Spunta, Ditta, and Krone) grown in Southern Italy. Tubers from the trials were analyzed for tuber size distribution, flesh and skin colour, dry matter, nitrate, soluble carbohydrates, total and resistant starch, vitamin C, phenol content, and total antioxidant activity. Results indicate that chemical desiccation does not affect the levels of vitamin C and those of other molecules with antioxidant properties as well as those of total soluble carbohydrates. On the other hand, it induces a significant decrease in starch storage and an increase in the percentage of resistant starch (a component of dietary fibre).     

Antioxidant and cyclooxygenase inhibitory activity of sorrel (Hibiscus sabdariffa)

The antioxidant activity of the hexane, ethyl acetate and methanol extracts of three varieties of sorrel (Hibiscus sabdariffa), as well as their potential for reducing blood viscosity, were studied in vitro. The samples screened were two red [(traditional red (TRED) and early bearing red (ERED)] and one white (WHTE) mature Hibiscus varieties. Antioxidant activity was measured by fluorescence spectroscopy using a model liposome system. Cyclooxygenase inhibitory activity was measured using cyclooxygenase (COX-1 and COX-2) enzymes by monitoring the rate of oxygen uptake in prostaglandin synthesis. Antioxidant activity was the highest overall in the red varieties compared to the white. The methanol extract from the three varieties had the highest activity. The methanol and ethyl acetate extracts of the three varieties of sorrel showed higher COX-1 enzyme inhibition than COX-2 and therefore had high potential to decrease blood viscosity. There was no COX-1 or COX-2 inhibition in the hexane extract. These findings support the ethnomedicinal use of H. sabdariffa in Africa and the Caribbean for the treatment of cardiovascular disease and hypertension.     

The effect of frying on anthocyanin stability and antioxidant activity of crisps from red- and purple-fleshed potatoes (Solanum tuberosum L.)

Red- and purple-fleshed potatoes (Solanum tuberosum L.) are a good source of polyphenols, mainly anthocyanins as one of the most important components. The chemical composition with reducing sugars and the total polyphenol contents were analyzed in four purple potato varieties (Salad Blue, Vitelotte, Valfi, Blue Congo) and three red-fleshed potato varieties (Rosalinde, Herbie 26, Highland Burgundy Red). The anthocyanin composition of raw potato and potato crisps was characterized by high-performance liquid chromatography tandem mass spectrometry (HPLC–MS/MS) method. Moreover, the antioxidant activity was measured with the radical scavenging assays using 2,2′-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid (ABTS) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical as well as ferric reducing ability of plasma assay (FRAP). In addition, colour parameters in prepared potato crisps were evaluated. Both red and purple-fleshed potato varieties contained high levels of total polyphenols (227–845 mg 100 g⁻¹ dry weight) and anthocyanins (21–109 mg 100 g⁻¹ dry weight). The process of frying caused degradation of anthocyanin compounds (38–70%). The HPLC–MS/MS analysis showed that pelargonidin and malvidin derivates were more stable during frying than petunidin derivatives. Although frying process affected the anthocyanin and polyphenol levels, obtained potato crisps exhibited bright intensive colour and good antioxidant activity.     

Bioactive compounds and antioxidant activities of different watermelon (Citrullus lanatus (Thunb.) Mansfeld) cultivars as affected by fruit sampling area

This investigation reports the variability of antioxidant components and antioxidant activities of six watermelon cultivars (cvs) (four commercial cvs Aramis, Crimson Sweet, Dumara, Giza, and two new selections P503 and P403 produced by the National Agricultural Research Institute of Tunisia) as influenced by sampling area. All cvs were simultaneously grown in an open-field and subjected to identical horticultural practices in order to minimize the effects of environmental conditions and maximize those related to genotype. Significant differences were found between watermelon cvs for lycopene, phenolics, flavonoids, ascorbic acid (AsA), dehydroascorbic acid (DHA) and total vitamin C (AsA + DHA) contents, as well as in the antioxidant activity of their hydrophilic and lipophilic fractions. P503 cv showed the highest lycopene and flavonoid contents. Crimson Sweet and Giza cvs showed the highest HAA and LAA when TEAC was used as assay method, while the highest HAA and LAA were detected in Giza and Dumara cvs and in P503 cv, respectively, when FRAP assay was used. This study demonstrates that the amount of each specific antioxidant, as well as the HAA and LAA, were both influenced by genotype and sampling area, emphasizing the need to evaluate watermelon biodiversity in order to improve its nutritional value.     

Analysis of protein amino acids,non-protein amino acids and metabolites,dietary protein,glucose, fructose,sucrose, phenolic,and flavonoid content and antioxidative properties of potato tubers,peels, and cortexes (pulps)

The composition and antioxidative activity of whole potato tubers from five Korean cultivars, three peels from one cultivar, and eight pulps (cortexes) after peeling from six different cultivars were evaluated. Whole tubers were sectioned into three parts followed by analysis of the peels and pulps of each part. The following characteristics were determined: the dimensions and water content of whole tubers; nutritional protein content consisting of protein and free amino acids by an automated Kjeldahl nitrogen assay; free non-protein amino acids, metabolites, and fructose, glucose, and sucrose content by HPLC; phenolic compounds by HPLC and LC/MS; total phenolics and flavonoids by colorimetry; and antioxidative properties by ABTS, DPPH, and FRAP assays. The results demonstrate differences and similarities in the content of nutritional and bioactive compounds and in their bioactivities from whole potatoes, peels, and pulps. The present study reports for the first time the analysis of multiple potato nutrients and bioactive components as well the antioxidative properties of whole potatoes, peels, and pulps derived from the same tubers. The described methods are expected to facilitate the analysis of commercial and newly-developed potato cultivars, peels, and pulps and relate their composition and antioxidative activities to their reported nutritional, health-promoting, and industrial properties.     

Preliminary chemical and nutritional characterization of liver from longnose skates (Raja rhina)

Skates (Raja rhina) have recently become a small commercial fishery in Alaska and along the western United States coast. Most of the skate byproduct is discarded or made into meal; therefore, there is opportunity to enhance the utilization for skate byproducts. The objective of this research project was to chemically characterize longnose skate livers. Livers from five long nose skates, caught off the coast of Kodiak, Alaska, were obtained immediately after the fins (called “wings”) had been removed by a commercial processor. Each liver was subjected to the following analysis: proximate composition, minerals, amino acids, α-tocopherol, protein gel electrophoresis, fatty acid profiles, thiobarbituric acid reactive substances (TBARS) and biogenic amines (BA). Livers were composed of lipid (49.6%), moisture (41.0%), protein (10.9%) and ash (0.8%). High levels of α-tocopherol were found in the livers (142 μg/g oil). Fatty acid profile indicated that the lipids extracted from livers contained high concentrations of eicosapentaenoic acid (16.0%) and docosahexaenoic acid (17.7%). Average TBARS values were low at 1.5 μg malondialdehyde/g oil, indicating low levels of lipid oxidation. The lysine content as percent of total amino acids on a weight basis was 6.1% and methionine content was 2.8%. Analysis of BA found putrescine (31 mg/kg liver) and spermine (85 mg/kg liver) present. Preliminary results suggest long nose skate livers as an abundant source of n-3 fatty acids and amino acids.