Antioxidant compounds and antioxidant activity in "early potatoes"

Plant-derived and dietary phenolic cinnamic acid derivatives: Anti-inflammatory properties

Cinnamic acids are aromatic acids primarily found in plants and plant-derived food. Phenolic cinnamic acids, with one or more hydroxyl groups in the aromatic ring, often contribute to the biological activities attributed to these compounds. The presence of hydroxyl groups and a carboxyl group makes cinnamic acids very hydrophilic, preventing them from crossing biological membranes and exerting their biological activities. To alleviate this condition, a panel of synthetic modifications have been made leading to a diverse set of phenolic cinnamic structures. In this review, an overview of the natural phenolic cinnamic acid derivatives and their plant sources (more than 200) is described. The synthetic approaches to obtain the referred derivatives (more than 200) namely esters and amides are reviewed. Further, their anti-inflammatory activity (more than 70 compounds) is scrutinized. Finally, future directions will be indicated to translate the research on phenolic cinnamic derivatives into potentially effective anti-inflammatory drugs.

How physicochemical and nutritional traits of potatoes may vary under field conditions over long periods

BACKGROUND

Potato is the most important non-grain crop worldwide, whose quality characteristics are always affected by temporal and spatial variability. Knowledge of the performance consistency of quality characteristics over long periods could prove very important to identify which quality traits are less variable over time, and therefore provide greater guarantees of stability. In this research, variations in physicochemical and nutritional traits of tubers over five consecutive growing seasons of two potato genotypes (Arizona and Vogue) were monitored in two locations.

RESULTS

Although qualitative performances of genotypes fluctuated across the seasons in both locations, two physicochemical traits (pH and dry matter content) and starch content showed less variability throughout the five seasons compared to total soluble solids and most of the nutritional traits (namely reducing sugars, citric acid, vitamin C, total phenolics and antioxidant capacity), which were considerably influenced by weather conditions.

CONCLUSION

The results suggest that pH, dry matter content and starch content traits could be used advantageously in studies of temporal stability in potatoes. This approach could prove useful in providing scientific support for the setup of potato protected geographical identifications. © 2024 Society of Chemical Industry.

Metabolite profiling and cytotoxic activity of Andean potatoes: Polyamines and glycoalkaloids as potential anticancer agents in human neuroblastoma cells in vitro

Andean potatoes (Solanum tuberosum L. ssp. andigena) are a good source of dietary antioxidant polyphenols. We have previously demonstrated that polyphenol extracts from Andean potato tubers exerted a dose-dependent cytotoxic effect in human neuroblastoma SH-SY5Y cells, being skin extracts more potent than flesh ones. In order to gain insight into the bioactivities of potato phenolics, we investigated the composition and the in vitro cytotoxic activity of total extracts and fractions of skin and flesh tubers of three Andean potato cultivars (Santa María, Waicha, and Moradita). Potato total extracts were subjected to liquid-liquid fractionation using ethyl acetate solvent in organic and aqueous fractions. We analyzed both fractions by HPLC-DAD, HPLC-ESI-MS/MS, and HPLC-HRMS. Results corroborated the expected composition of each fraction. Organic fractions were rich in hydroxycinnamic acids (principally chlorogenic acid isomers), whereas aqueous fractions contained mainly polyamines conjugated with phenolic acids, glycoalkaloids, and flavonoids. Aqueous fractions were cytotoxic against SH-SY5Y cells and even more potent than their respective total extracts. Treatment with a combination of both fractions showed a similar cytotoxic response to the corresponding extract. According to correlation studies, it is tempting to speculate that polyamines and glycoalkaloids are crucial in inducing cell death. Our findings indicate that the activity of Andean potato extracts is a combination of various compounds and contribute to the revalorization of potato as a functional food.

Development of Ready-to-Eat Organic Protein Snack Bars: Assessment of Selected Changes of Physicochemical Quality Parameters and Antioxidant Activity Changes during Storage

Novel organic high-protein bars (HPB) were developed and produced from organic ingredients such as prebiotic and pro-healthy additives or whey protein concentrate (WPC-80). The influence of temperature and time on the selected physicochemical parameters and antioxidant activity of three formulations of HPBs when stored (at 4 °C and 22 °C for 3 months) was investigated. The fresh products varied on the basis of available carbohydrates, crude lipids, amino acid profile, and fatty acid profile resulting from the used formulations. A total of 17 amino acids (AA), including 10 essential amino acids (EAA), were identified in HPBs. The concentrations of all essential amino acids determined by EAA scores (AAS), except Histidine (His), were higher than the FAO/WHO/UNU (2007) pattern; for the WPC-80 however, in the case of the developed HPB, the scores were lower (0.21-0.48). The first limiting amino acid in HPB was Val (Valine). The temperature and time of storage significantly affected the proximate chemical composition and an assessment of the products' antioxidant activity. The amino acid and fatty acid composition of stored products slightly changed. However, stored HPBs had a low content of trans fatty acids (TFAs). The optimal method of storage for the investigated bars was at the temperature of 4 °C for 3 months.

Genetic Diversity and Health Properties of Polyphenols in Potato

Polyphenol is one of the most essential phytochemicals with various health benefits. Potato (Solanum tuberosum L.) is known as a potential source of polyphenols, and also has health benefits in which phenolic acids, such as chlorogenic, ferulic acid, caffeic acid, and flavonoids, such as anthocyanins, sustainably play the most significant role. Almost every polyphenol contributes to various biological activities. In this review, we collected comprehensive information concerning the diversity of polyphenols in potatoes, and the effects of post-harvest processing and different cooking methods on the bioavailability of polyphenols. To achieve maximum health benefits, the selection of potato cultivars is necessary by choosing their colors, but various cooking methods are also very important in obtaining the maximum concentration of polyphenolic compounds. The health properties including major biological activities of polyphenols, such as antioxidant activity, anticarcinogenic activity, anti-inflammatory activity, anti-obesity activity, and antidiabetic activity, have also been summarized. All these biological activities of polyphenols in potatoes might be helpful for breeders in the design of new varieties with many health benefits, and are expected to play a vital role in both pharmaceutical and nutraceutical industries.

Influence of potato variety on polyphenol profile composition and glycoalcaloid contents of potato juice

The results of studies published in recent years indicate the broad biological activity of potato juice (PJ), which is a byproduct of the starch production process. Among the most frequently described activities are anti-inflammatory, antioxidant, and cytotoxic effects. Nevertheless, this waste juice is produced by the processing of many varieties of potatoes with different proportions, which does not allow to conclude on the biological activity of individual varieties. This article is a report on the antioxidant activity of PJ from seven selected potato varieties, their profile of polyphenolic compounds, and the content of glycoalkaloids (GAs). The use of similar cultivation conditions allowed to eliminate the influence of environmental factors on the content of the analyzed compounds. The influence of PJ on the growth of probiotic, commensal, and pathogenic bacteria was also assessed. It was shown that the varieties significantly influenced the differences in antioxidant activity as well as the content of GAs, but despite the observed differences, none of them showed antimicrobial activity. Therefore, it can be concluded that an appropriately selected variety will make it possible to obtain PJ that will be characterized by high antioxidant activity and, at the same time, will be safe from the toxicological point of view.

Antioxidative Characteristics and Sensory Acceptability of Bread Substituted with Purple Yam (Dioscorea alata L.)

In this study, plain bread was made by substituting wheat flour with purple yam flour (Dioscorea alata, L). The addition of 0, 10, 15, 20, and 30% purple yam flour aims to increase the functional value of plain bread as a source of natural antioxidants. The bread produced with two baking temperatures (170°C and 180°C) was tested for anthocyanin levels, total phenol, antioxidant activity (DPPH free radical scavenging), volume expansion, color, and preference test. The results showed that the temperatures of the bread baking did not affect anthocyanin levels, total phenol, antioxidant activity, volume expansion, and bread color (p > 0.05). The substitution of purple yam flour had a significant effect on anthocyanin levels, total phenol, antioxidant activity, volume, and bread color (p < 0.05). The levels of anthocyanins, total phenol, antioxidant activity, and darker color increased with the addition of purple yam flower whereas the rate of expansion reduced. However, the addition of purple yam flour did not affect the level of preference for the bread produced. Purple yam flour can be added to the manufacture of bread made from wheat flour as much as 30% with a baking temperature of 180°C. The resulting bread contained total anthocyanins 54.62 mg/100 g db, total phenol 391.14 mg EAG/100 g db, antioxidant activity 48.53% and volume expansion 64.85%, color L^∗ = 53.06, a^∗ = 6.52, b^∗ = 13.32, C = 14.87, H = 64.06, and sensory score = 3.24 (preferred).

Effect of Cooking Methods on Bioactivity of Polyphenols in Purple Potatoes

Purple-fleshed potato (Solanum tuberosum L.) is a good dietary source of anthocyanins, flavonols, and polyphenolic acids, mostly chlorogenic acid. The objective of this study was to examine the impacts of cooking methods including boiling, steaming, and the newly developed vacuum-sealed boiling (VSBoil) on extractability and bioactivity of polyphenolic compounds in a purple potato (PP) cultivar, Purple Pelisse. Data showed that boiling and steaming reduced the total polyphenolic content in PP. High-performance liquid chromatography analysis showed that steaming slightly reduced the extractable chlorogenic acid content, while VSBoil increased it. For DPPH free radical scavenging activities, VSBoil and steaming effectively preserved the antioxidant activity of a polyphenol-rich extract of PP, while boiling resulted in a significant reduction compared to raw potato extract. All extracts effectively suppressed bursts of intracellular reactive oxygen species in human colonic epithelial cells upon hydrogen peroxide induction, of which the extract from the VSBoil group showed the highest antioxidant potential. In addition, all extracts showed anti-inflammatory effects in Caco-2 cells induced with tumor necrosis factor-α. In conclusion, the content and bioactivity of extractable polyphenols were largely retained in PP subjected to different cooking processes. VSBoil resulted in the highest content of extractable polyphenolic compounds and bioactivity among tested cooking methods.

Antioxidant and Pro-Oxidant Capacities as Mechanisms of Photoprotection of Olive Polyphenols on UVA-Damaged Human Keratinocytes

A wide variety of polyphenols are reported to have considerable antioxidant and skin photoprotective effects, although the mechanisms of action are not fully known. Environmentally friendly and inexpensive sources of natural bioactive compounds, such as olive mill wastewater (OMWW), the by-product of olive-oil processing, can be considered an economic source of bioactive polyphenols, with a range of biological activities, useful as chemotherapeutic or cosmeceutical agents. Green strategies, such as the process based on membrane technologies, allow to recover active polyphenols from this complex matrix. This study aims to evaluate the antioxidant, pro-oxidant, and photoprotective effects, including the underlying action mechanism(s), of the ultra-filtered (UF) OMWW fractions, in order to substantiate their use as natural cosmeceutical ingredient. Six chemically characterized UF-OMWW fractions, from Italian and Greek olive cultivar processing, were investigated for their antioxidant activities, measured by Trolox Equivalent Antioxidant Capacity (TEAC), LDL oxidation inhibition, and ROS-quenching ability in UVA-irradiated HEKa (Human Epidermal Keratinocytes adult) cultures. The photoprotective properties of UF-OMWW were assayed as a pro-oxidant-mediated pro-apoptotic effect on the UVA-damaged HEKa cells, which can be potentially involved in the carcinogenesis process. All the UF-OMWW fractions exerted an effective antioxidant activity in vitro and in cells when administered together with UV-radiation on HEKa. A pro-oxidative and pro-apoptotic effect on the UVA-damaged HEKa cells were observed, suggesting some protective actions of polyphenol fraction on keratinocyte cell cultures.

Emerging Processing Technologies for the Recovery of Valuable Bioactive Compounds from Potato Peels

Potato peel (PP) is the major underutilised by-product in the potato-processing industry and a potential source of valuable bioactive molecules. Among them, glycoalkaloids and polyphenols are important precursors for steroid hormones and natural antioxidants, respectively. Moreover, the huge quantities of industrial potato-peel waste that are produced are a rich source of primary metabolites, which principally include starch as well as non-starch polysaccharides, proteins, lipids, lignin and cellulose. All carbohydrates are prone to undergo fermentation to produce ethanol, lactic and acetic acid. Finally, the main portion of PP is made up of alcohol-insoluble matter with a dietary fibre content of approximatively 40%. The present review summarises the recent advances and emerging technologies in potato-peel extraction and further valorisation processing in the food industry.

Analysis of Environmental Conditions Effect in the Phytochemical Composition of Potato (Solanum tuberosum) Cultivars

Crop productivity and food quality are affected by environmental conditions. The objective of this work was to evaluate the effect of the environment on the concentration of phytochemical components in several potato (Solanum tuberosum) cultivars. The content of vitamin C (ascorbic acid, AA), the total carotenoids content (TCC), the total polyphenols content (TPC), and the total anthocyanins content (TAC) of 11 potatoes varieties grown in Ecuador (Cutuglahua, Pujilí, and Pilahuín) was measured by the spectrophotometric method. The antioxidant capacity (AC) of potato cultivars was evaluated by the ABTS method. The AA concentration ranged between 12.67 to 39.49 mg/100g fresh weight (FW), the TCC ranged between 50.00 and 1043.50 μg/100g FW, the TPC ranged between 0.41 and 3.25 g of gallic acid equivalents (GAE)/kg dry weight (DW), the TAC ranged between 2.74 and 172.53 μg/g FW and finally the AC ranged between 36.80 and 789.19 μg of trolox equivalents (TE)/g FW. Genotypes (G), location (L), and interaction (G x L) were significant at p < 0.01. The genotype (G) showed a greater variation in the phytochemical contents. AA and TPC showed the highest correlation with the AC. A selection of genotypes with these characteristics can be used to develop germplasms with a high AC.

The Impact of Fertilization Regime on the Crop Performance and Chemical Composition of Potato (Solanum tuberosum L.) Cultivated in Central Greece

Potato cultivation is quite demanding in inorganic nutrients and adequate fertilization is a key factor for maximizing yield and producing tubers of high quality. In the present study, a field experiment was carried out to evaluate the effect of various forms of fertilization on crop performance and the nutritional value and chemical composition of two potato varieties (cv. Spunta and cv. Kennebec). For this purpose, five different fertilizer treatments were applied namely: control (C), standard fertilizer (T1), standard fertilizer + zeolite (T2), manure (T3) and slow release nitrogen fertilizer (T4). According to the results, it was observed that slow release treatment (T4) achieved the highest yield for both varieties, while the control treatment presented significantly lower yield compared to the studied fertilization regimes. The dry matter of leaves and shoots was higher in T1 treatment for cv. Kennebec and in T2 and T4 treatments for cv. Spunta, whereas the control treatment presented the highest dry matter content in tubers for cv. Kennebec and T2 and T3 treatments for cv. Spunta. A significant effect of the fertilization regime was also observed on the nutritional value of tubers and more specifically the protein, ash and fat content was increased by treatments T1 and T4, while carbohydrate content was also increased by T3 and T4 treatments for both varieties. Similarly, the total sugars, organic acids, β-carotene and lycopene content was increased in T3 treatment for the Spunta variety, while the antioxidant capacity showed a varied response depending on the fertilizer regime and the tested variety. In conclusion, the fertilization regime has a significant effect not only on the tuber yield but also on the quality of the final product and should be considered as an effective tool to increase the added value of potato crop.

Areca nut procyanidins prevent ultraviolet light B-induced photoaging via suppression of cyclooxygenase-2 and matrix metalloproteinases in mouse skin

Chronic exposure to solar ultraviolet (UV) light induces photoaging in human skin. Our previous results have shown that areca nut procyanidins (ANPs) have antioxidant capacity and possess potential anti-inflammatory effects. Here, we aimed to investigate the effect of ANPs on UVB-induced photoaging. In the present study, dorsal skin of CD-1 mice was exposed to UVB at a minimal erythema dose (130 mJ/cm²) throughout a 3-week period. The effects of ANPs and epigallocatechin-3-gallate (EGCG), a polyphenolic constituent of green tea, on UVB-induced photoaging were compared. The results show that oral administration of ANP prevented UVB-induced photoaging, indicated by epidermal thickness and collagen disorientation, and inhibited UVB-induced expression of cyclooxygenase-2 and matrix metalloproteinases (MMPs), such as MMP-2, MMP-9, and TIMP1. The protective potential of ANP on UVB-induced photodamage was comparable to that of EGCG. These data suggest that ANP could be useful as a dietary supplement to attenuate solar UVB-induced premature skin aging.

Antioxidant properties of potato tubers (Solanum tuberosum L.) as a consequence of genetic potential and growing conditions

The concentrations of the bioactive compounds in potato tubers are determined by both genetic potential and environmental factors. The purpose of the experiment was to determine the influence of organic and integrated production on the expression of the genetic potential with respect to the antioxidant properties of potato tubers and to evaluate its stability under different environmental conditions. This phenotyping was performed on seven new breeding lines (tetraploid clones) and three modern cultivars: Jelly, Satina and Tajfun. The results indicated that production system and location significantly influenced the antioxidant capacity measured by FRAP method. Organic farming and the location Chwałowice were characterized by higher values. Furthermore, anitioxidative capacity measured by FRAP method was correlated with chlorogenic acid content (r = 0.590**) and glutathione fractions, especially with the reduced form (GSH, r = 0.692**). Multidimensional comparative analysis (MCA) proved a better development of antioxidant properties of potato tubers in the organic cultivation system when compared with the integrated. Especially favorable were growing conditions at Boguchwała (organic) and worst at Młochów (integrated). From all investigated varieties, the best antioxidant properties were found in ‘Satina’ and ‘Jelly’. Clones TG-97-403 and 13-VIII-45 developed the weakest health promoting traits.

Potatoes and risk of chronic disease: a systematic review and dose-response meta-analysis

PURPOSE

We aimed to synthesize the evidence on the relation between different types of potato consumption with risk of all-cause mortality, coronary heart disease (CHD), stroke, type 2 diabetes (T2D), colorectal cancer (CRC), and hypertension.

METHODS

Systematic searches until May 2018 were conducted in PubMed, Scopus, and Web of Science. Random effects meta-analyses comparing extreme categories, linear and non-linear dose-response analyses were conducted.

RESULTS

Twenty-eight reports were identified. Only total potato consumption was available for some endpoints which showed no associations with all-cause mortality (RR: 0.88, 95% CI 0.69-1.12), CHD (RR: 1.03, 95% CI 0.96-1.09), stroke (RR: 0.98, 95% CI 0.93-1.03), and CRC (RR: 1.05, 95% CI 0.92-1.20) per one daily/serving (150 g/day) increase. Consumption of one daily serving of boiled/baked/mashed-potatoes was not associated with risk of hypertension (RR: 1.08, 95% CI 0.96-1.21), but slightly with the risk of T2D (RR: 1.09, 95% 1.01-1.18). Positive associations for the risk of T2D (RR: 1.66, 95% CI 1.43-1.94) and hypertension (RR: 1.37, 95% CI 1.15-1.63) were observed for each 150 g/day increase in French-fries consumption. The quality of evidence was rated mostly low (moderate quality of evidence for the risk-associations of French-fries).

CONCLUSION

Total potato consumption is not related to risk for many chronic diseases but could pose a small increase in risk for T2D if consumed boiled. A clear risk relation was found between French-fries consumption and risk of T2D and hypertension. For several outcomes, the impact of different preparation procedures could not be assessed.

Pro-Apoptotic Effect of Grape Seed Extract on MCF-7 Involves Transient Increase of Gap Junction Intercellular Communication and Cx43 Up-Regulation: A Mechanism of Chemoprevention

Growing evidence suggests dietary antioxidants reduce the risk of several cancers. Grape seeds extracts (GSE) are a rich source of polyphenols known to have antioxidant, chemopreventive and anticancer properties. Herein, we investigated the in vitro effects and putative action mechanisms of a grape seed extract (GSE) on human breast cancer cells (MCF-7). The effects of GSE were evaluated on cell proliferation, apoptosis and gap-junction-mediated cell-cell communications (GJIC), as basal mechanism involved in the promotion stage of carcinogenesis. GSE (0.05-100 μg/mL) caused a significant dose- and time-dependent inhibition of MCF-7 viability and induced apoptotic cell death, as detected by Annexin-V/Propidium Iodide. Concurrently, GSE induced transient but significant enhancement of GJIC in non-communicating MCF-7 cells, as demonstrated by the scrape-loading/dye-transfer (SL/DT) assay and an early and dose-dependent re-localization of the connexin-43 (Cx43) proteins on plasma membranes, as assayed by immunocytochemistry. Finally, real-time-PCR has evidenced a significant increase in cx43 mRNA expression. The results support the hypothesis that the proliferation inhibition and pro-apoptotic effect of GSE against this breast cancer cell model are mediated by the GJIC improvement via re-localization of Cx43 proteins and up-regulation of cx43 gene, and provide further insight into the action mechanisms underlying the health-promoting action of dietary components.

Effect of Thermal Processing on Antioxidant Activity and Cytotoxicity of Waste Potato Juice

Potato juice (PJ), commonly considered a burdensome waste, is rich in various compounds with bioactive properties. It has long been considered a remedy for gastric problems in traditional folk medicine. If valorization of PJ through implementation in the production of functional foods is to be considered, stabilization methods must be developed to allow long-term storage of this seasonal product. It is important that such methods are chosen with regard to their effect on the bioactive value of the obtained product. In this study, the impact of four stabilization methods on the antioxidant and cytotoxic activities of PJ was investigated. Elevated temperatures were used in thermal deproteinization used to obtain DPJW (deproteinated potato juice water) and spray-drying of FPJ (fresh potato juice) that resulted in SDPJ. Freeze drying and cryoconcentration were the low temperature processing methods that yielded PJL (potato juice lyophilisate) and CPJ (cryocorncentrated potato juice), respectively. All processed materials were characterized chemically and compared with raw materials in terms of phenolic compounds content, antioxidant activity as well as cytotoxicity to human tumor cells isolated from the gastric mucosa (Hs476T cell line), colon (Caco-2 and HT-29 cell lines), and normal cells isolated from the small intestine and colon epithelium (IEC-6 and NCM460 cell lines). It was stated that high-temperature processes – thermal deproteinization and spray-drying – yielded products with increased antioxidant potential (TEAC) that also showed increased cytotoxic activity towards intestinal cancer cells. At the same time the cytotoxicity towards normal cells remained on par with that of fresh PJ (IEC-6 cells) or decreased (NCM460 cells). Thermal deproteinization significantly decreased the content of glycoalcaloids in the juice, while spray drying did not have such an effect. The two low-temperature processes investigated – cryoconcentration and freeze drying – did not affect the PJ cytotoxic activity towards any of the cell lines used in the tests, whereas they did affect the antioxidant properties and glycoalcaloids content of PJ.

Bactericidal and Cytotoxic Activities of Polyphenol Extracts from Solanum tuberosum spp. tuberosum and spp. andigena Cultivars on Escherichia coli and Human Neuroblastoma SH-SY5Y Cells In Vitro

Potatoes (Solanum tuberosum L.) are a good source of dietary antioxidant polyphenols. This study investigated the potential antioxidant, bactericidal, and cytotoxic activities in vitro of the phenolic compounds present in tubers of one S. tuberosum spp. tuberosum (Summerside), and three S. tuberosum spp. andigena (landraces Moradita, Waicha, and Santa María) cultivars. Both the content of phenolic acids, chlorogenic acids (CGAs) being the most abundant, and the antioxidant activity were higher in extracts from skin than from flesh. Extracts from Moradita flesh and Summerside skin showed bactericidal activity against Escherichia coli ATCC 25922 but failed to inhibit pathogenic E. coli O157. Both extracts lack pigmentation but do contain 5-CGA, caffeic, and ferulic acids. Positive control with gentamicin and commercial 5-CGA resulted in a complete inhibition of bacterial growth. In addition, all potato extracts and commercial 5-CGA diminished dose-dependently human neuroblastoma SH-SY5Y cell viability. Skin extracts were more potent than flesh extracts. Among flesh extracts, Moradita was the most potent. Together, our results suggest that Moradita flesh could provide a desirable source of important health-promoting substances. Findings indicate that the biological activity of potato extracts is a combination of various bioactive compounds and contribute to the revalorization of potato as a functional food.

Phenolic Compounds in the Potato and Its Byproducts: An Overview

The potato (Solanum tuberosum L.) is a tuber that is largely used for food and is a source of different bioactive compounds such as starch, dietary fiber, amino acids, minerals, vitamins, and phenolic compounds. Phenolic compounds are synthetized by the potato plant as a protection response from bacteria, fungi, viruses, and insects. Several works showed that these potato compounds exhibited health-promoting effects in humans. However, the use of the potato in the food industry submits this vegetable to different processes that can alter the phenolic content. Moreover, many of these compounds with high bioactivity are located in the potato's skin, and so are eliminated as waste. In this review the most recent articles dealing with phenolic compounds in the potato and potato byproducts, along with the effects of harvesting, post-harvest, and technological processes, have been reviewed. Briefly, the phenolic composition, main extraction, and determination methods have been described. In addition, the "alternative" food uses and healthy properties of potato phenolic compounds have been addressed.

Levels of potential bioactive compounds including carotenoids, vitamin C and phenolic compounds, and expression of their cognate biosynthetic genes vary significantly in different varieties of potato (Solanum tuberosum L.) grown under uniform cultural conditions

BACKGROUND

In addition to their high carbohydrate content, potatoes are also an important dietary source of vitamin C and bioactive secondary metabolites, including phenolic compounds and carotenoids, which have been suggested to play a role in human health. The expression of genes encoding key enzymes involved in the synthesis of these compounds was assessed by reverse transcription-quantitative polymerase chain reaction and compared to the accumulation of the corresponding product in seven potato varieties showing contrasting levels of metabolite accumulation.

RESULTS

Strong positive correlations were found between phenolic content in the flesh of tubers and transcript levels of phenylalanine ammonia lyase (PAL) and chalcone synthase (CHS) genes. The expression of PAL and CHS was also related to that of AN1, a transcription factor involved in the synthesis of anthocyanins, suggesting that these genes are regulated in a coordinated manner. No clear relationship was found between transcript levels of phytoene synthase (PSY) or L-galactono-1,4-lactone dehydrogenase (GLDH) genes and total carotenoid or vitamin C accumulation, respectively.

CONCLUSION

Data indicate that levels of total phenolic and flavonoid compounds in potato are controlled primarily by PAL and CHS gene expression. Transcript levels of PSY and GLDH did not control accumulation of carotenoids or vitamin C.

Plant derived and dietary phenolic antioxidants: anticancer properties

In this paper, a review of the literature on the phenolic compounds with anticancer activity published between 2008 and 2012 is presented. In this overview only phenolic antioxidant compounds that display significant anticancer activity have been described. In the first part of this review, the oxidative and nitrosative stress relation with cancer are described. In the second part, the plant-derived food extracts, containing identified phenolic antioxidants, the phenolic antioxidants isolated from plants and plant-derived food or commercially available and the synthetic ones, along with the type of cancer and cells where they exert anticancer activity, are described and summarized in tables. The principal mechanisms for their anti-proliferative effects were also described. Finally, a critical analysis of the studies and directions for future research are included in the conclusion.

Effect of exogenous amylolytic enzymes on the accumulation of chlorogenic acid isomers in wounded potato tubers

Potato tubers under wounding stress synthesize chlorogenic acid isomers, which are phenolic compounds that prevent chronic diseases. The biosynthesis of phenolic compounds in plants requires aromatic amino acids that are produced from sugars. Therefore, in this study, we hypothesized that the wound-induced accumulation of chlorogenic acid isomers in potatoes could be enhanced if the availability of sugars is increased by exogenous amylolytic enzymes applied to the surface of the site of wounding. To test this hypothesis, wounded potatoes stored at 20 °C were treated with amylolytic enzymes (pullulanase and amyloglucosidase, 282 units/mL, 10 mL/kg) after being stored for 0 (E0h), 48 (E48h), or 96 h (E96h). The highest level of accumulation of total chlorogenic acid isomers (∼210% higher than that of time 0 h samples) was observed after storage for 120 h for the E96h treatment. The results suggest that increasing the availability of carbon sources needed for the biosynthesis of phenolic compounds would trigger their accumulation in wounded plants.

Dietary intake of natural antioxidants: vitamins and polyphenols

Oxidative stress is a condition in which oxidant metabolites exert their toxic effect because of an increased production or an altered cellular mechanism of protection; oxidative stress is rapidly gaining recognition as a key phenomenon in chronic diseases. Antioxidants terminate these chain reactions by removing free radical intermediates, and inhibit other oxidation reactions by being oxidized themselves. Endogenous defence mechanisms are inadequate for the complete prevention of oxidative damage, and different sources of dietary antioxidants may be especially important. This article calls attention to the dietary antioxidants, such as vitamins A, C, and E and polyphenols. Compelling evidence has led to the conclusion that diet is a key environmental factor and a potential tool for the control of chronic diseases. More specifically, fruits and vegetables have been shown to exert a protective effect. The high content of minerals and natural antioxidant as vitamins A, C, and E and polyphenols in fruits and vegetables may be a main factor responsible for these effects.

The role of potatoes and potato components in cardiometabolic health: a review

Potatoes (Solanum tuberosum) are an important food crop worldwide and contribute key nutrients to the diet, including vitamin C, potassium, and dietary fiber. Potatoes and potato components have been shown to have favorable impacts on several measures of cardiometabolic health in animals and humans, including lowering blood pressure, improving lipid profiles, and decreasing markers of inflammation. A range of glycemic index (GI) values have been reported for potatoes, and data are sparse regarding the impact of potato consumption on the postprandial glycemic response, especially when potatoes are consumed with other foods. There is a lack of clinical trial data regarding the impact of potatoes on weight management. A small number of human cohort studies have reported beneficial associations between potato consumption as part of a healthy lifestyle and cardiometabolic health. Another small number of human population studies have included potatoes as part of a dietary pattern with other calorie-dense foods and have not reported cardiometabolic benefits. The epidemiological literature should be interpreted with caution due to lack of consistency in both defining dietary patterns that include potatoes and in control for potential confounding variables. Controlled clinical trials are needed to define the impact of potatoes on cardiometabolic health.

The rate of decolorization of a radical ion reagent was used to determine the phenolic content of various food extracts

Polyphenols are among the most valuable and widely studied food components. In the laboratory, they are readily extractable with aqueous alcohol. An aliquot rapidly decolorizes a measured portion of ABTS, a stable deep blue radical ion. The semilog plot of light absorption versus time is typically a straight line, and an immediately evident slope provides rapid classification in terms of gallic acid equivalents. Experimental data are presented to show general agreement with the literature. The disproportionate concentration of antioxidant in the skins and peels of fruits, vegetables, and nuts is given special attention.

Anti-wrinkle and anti-inflammatory effects of active garlic components and the inhibition of MMPs via NF-κB signaling

Skin aging is a multisystem degenerative process caused by several factors, such as, UV irradiation, stress, and smoke. Furthermore, wrinkle formation is a striking feature of photoaging and is associated with oxidative stress and inflammatory response. In the present study, we investigated whether caffeic acid, S-allyl cysteine, and uracil, which were isolated from garlic, modulate UVB-induced wrinkle formation and effect the expression of matrix-metalloproteinase (MMP) and NF-κB signaling. The results obtained showed that all three compounds significantly inhibited the degradation of type І procollagen and the expressions of MMPs in vivo and attenuated the histological collagen fiber disorder and oxidative stress in vivo. Furthermore, caffeic acid and S-allyl cysteine were found to decrease oxidative stress and inflammation by modulating the activities of NF-κB and AP-1, and uracil exhibited an indirect anti-oxidant effect by suppressing cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) expressions levels and downregulating transcriptional factors. These results suggest that the anti-wrinkle effects of caffeic acid, S-allyl cysteine, and uracil are due to anti-oxidant and/or anti-inflammatory effects. Summarizing, caffeic acid, S-allyl cysteine, and uracil inhibited UVB-induced wrinkle formation by modulating MMP via NF-κB signaling.

Microwave-assisted extraction of phenolic antioxidants from potato peels

A response surface method was used to optimize the microwave-assisted extraction parameters such as extraction time (t) (min), solvent (methanol) concentration (S) (v/v) and microwave power level (MP) for extraction of antioxidants from potato peels. Max. total phenolics content of 3.94 mg g⁻¹ dry weight (dw) was obtained at S of 67.33%, t of 15 min and a MP of 14.67%. For ascorbic acid (1.44 mg g⁻¹ dw), caffeic acid (1.33 mg g⁻¹ dw), ferulic acid (0.50 mg g⁻¹ dw) max contents were obtained at S of 100%, t of 15 min, and MP of 10%, while the max chlorogenic acid content (1.35 mg g⁻¹ dw) was obtained at S of 100%, t of 5 min, and MP of 10%. The radical scavenging activity of the extract was evaluated by using the DPPH assay and optimum antioxidant activity was obtained at S of 100%, t of 5 min, and MP of 10%.

Influence of the cultivar on the organic acid and sugar composition of potatoes

BACKGROUND

Citric, malic, tartaric, oxalic, ascorbic, aconitic and fumaric acids, and sucrose, fructose and glucose, were determined in ten potato cultivars (Azucena negra, Bonita, Bonita negra, Borralla, Colorada de baga, Mora, Negra, Palmera lagarteada, Peluca blanca and Terrenta) from the Canary Islands in order to differentiate them. The influence of the production zone was also considered.

RESULTS

Citric acid and sucrose were the most abundant organic acid and sugar, respectively. There were significant differences in all the analysed sugars and organic acids between the potato cultivars, except for oxalic and malic acids. Differences associated with the production zone were found in the contents of organic acids for some cultivars. Linear discriminant analysis is a useful tool to differentiate the potato samples according to the cultivar and the zone of production.

CONCLUSIONS

Seven organic acids (citric, oxalic, malic, tartaric, aconitic, fumaric, and ascorbic acids) were identified and quantified in potatoes. The main sugars (sucrose, glucose and fructose) were also determined. The genetic information of the cultivars determines marked differences in sugars and organic acid contents among the analysed potato cultivars. The soil and climatic conditions affect the organic acid and sugar contents of some potato cultivars.

Supercritical CO(2)-extracted tomato Oleoresins enhance gap junction intercellular communications and recover from mercury chloride inhibition in keratinocytes

A nutritionally relevant phytochemical such as lycopene, found in tomatoes and other fruits, has been proposed to have health-promoting effects by modulating hormonal and immune systems, metabolic pathways, and gap junction intercellular communication (GJIC). This work analyzes lycopene extracts, obtained from tomato and tomato added with grape seeds by using a safe and environmentally friendly extraction process, based on supercritical carbon dioxide technology (S-CO(2)). Analysis of the innovative S-CO(2)-extracted oleoresins showed peculiar chemical composition with high lycopene concentration and the presence of other carotenoids, lipids, and phenol compounds. The oleoresins showed a higher in vitro antioxidant activity compared with pure lycopene and beta-carotene and the remarkable ability to enhance the GJIC and to increase cx43 expression in keratinocytes. The oleoresins, (0.9 microM lycopene), were also able to overcome, completely, the GJIC inhibition induced by 10 nM HgCl(2), mercury(II) chloride, suggesting a possible action mechanism.

Medicinal use of potato-derived products: a systematic review

In the traditional medicine of Europe, raw potatoes are used for gastrointestinal disorders, and topical potato preparations as a hot pack for pain or for softening furuncles. The aim of this study was to review the literature and summarize the data on the medicinal use of potato-derived products. Several databases and other sources were searched to identify clinical trials investigating potato-derived preparations. The trials were analysed for quality. Five trials were identified; two open uncontrolled studies, two open controlled studies and one double-blind study. These results stimulate further investigation of oral potato juice concentrate in patients with dyspeptic complaints, of potato proteinase inhibitor II for weight reduction, and of topical potato proteins for preventing protease-induced perianal dermatitis. We recommend that future studies have a confirmatory design.