Eliciting Polyphenols in Strawberry Leaves: Preliminary Experiments in Fragaria × ananassa cv. Festival.

Polyphenols are plant secondary metabolites that function mostly as a general stress-induced protective mechanism. Polyphenols have also gained interest due to their beneficial properties for human health. Strawberry leaves represent an agro-industrial waste material with relevant bioactive polyphenol content, which could be incorporated into circular economy strategies. However, due to the low quantities of polyphenols in plants, their production needs to be improved for cost-effective applications. The objective of this research was to compare polyphenol production in strawberry (Fragaria × ananassa cv. Festival) leaves in plants grown in greenhouse conditions and plants grown in vitro, using three possible elicitor treatments (UV irradiation, cold exposure, and cysteine). General vegetative effects were morphologically evaluated, and specific polyphenolic compounds were quantified by UHPLC-DAD-MS/MS. Gallic acid was the most abundant polyphenol found in the leaves, both in vivo and in vitro. The results showed higher amounts and faster accumulation of polyphenols in the in vitro regenerated plants, highlighting the relevance of in vitro tissue culture strategies for producing compounds such as polyphenols in this species and cultivar.

Strawberry Fragaria x ananassa cv. Festival: A Polyphenol-Based Phytochemical Characterization in Fruit and Leaf Extracts.

Berry fruits are an important dietary source of health-promoting antioxidant polyphenols. Interestingly, berry leaves of diverse species, including strawberries, have shown higher bioactive phytochemical content in the leaves than in the fruit. Moreover, the vegetative part of the plants is usually discarded, representing a presumably large source of underutilized bioactive biomass. In this investigation, the polyphenol profiles of tropical highland strawberry (Fragaria x ananassa cv. Festival) leaves and fruits were compared by high-performance liquid chromatography coupled with a diode array detector (UHPLC-DAD) and mass spectrometry (HPLC-MS). The total polyphenol strawberry leaf extracts exhibited a 122-fold-higher total polyphenol content and 13-fold higher antioxidant activity (ORAC) than strawberry fruits, and they showed evidence of possible photoprotective effects against UV damage in human melanoma cells (SK-MEL-28) and in murine embryo fibroblasts (NIH/3T3), together with promising anti-proliferative activities against the same melanoma cells. Seven polyphenols were confirmed by HPLC-DAD in the leaf extracts, with differences depending on fraction solubility. Moreover, three substituted quercetin derivatives, three substituted kaempferol derivatives, two anthocyanins, and catechin were confirmed in the soluble fraction by HPLC-MS. Given their higher total polyphenol content and bioactive activities, underutilized strawberry Festival leaves are a potential source of apparently abundant biomass with prospective bioactive applications.

Self-Emulsifying Micellization of Crude Extracts from Apple (Malus domestica cv. Anna), Plum (Prunus domestica cv. Satsuma), and Guava (Psidium guajava L.) Fruits.

Micellar microemulsions are thermodynamically stable self-emulsifying systems that have been used to successfully improve the low oral bioavailability of several bioactive phytochemicals, such as antioxidant polyphenols. However, most studies have reported the micellization of single-compounds or purified chemical fractions; thus, the stability, phytochemical-loading efficiency, and bioactivity of complex crude extracts remain largely unexplored. In this study, we evaluated the effects of micellar emulsification of tropical apple (Malus domestica cv. Anna), plum (Prunus domestica cv. Satsuma), and guava (Psidium guajava L.) extracts regarding particle size and stability, polyphenol-loading efficiency, antioxidant capacity, and cytotoxic activity in human and murine cells. Simple food-grade extraction protocols were implemented to obtain apple, plum, and guava extracts. Total polyphenols, flavonoids, and antioxidant activity (DPPH) were determined in the fruit extracts, and their polyphenol profile was further characterized by liquid chromatography (HPLC-DAD). The dried extracts were mixed into a food-grade, self-emulsifying system, and their cytotoxicity in human and murine cell lines was compared. Our research showed that complex fruit matrixes were successfully emulsified into thermodynamically stable polysorbate-based nanometric micelles with uniform size distribution and consistent pH stability, with potential applications in food and biomedical industries.

α-Tocomonoenol Is Bioavailable in Mice and May Partly Be Regulated by the Function of the Hepatic α­Tocopherol Transfer Protein.

Tocomonoenols are vitamin E derivatives present in foods with a single double bond at carbon 11' in the sidechain. The α-tocopherol transfer protein (TTP) is required for the maintenance of normal α-tocopherol (αT) concentrations. Its role in the tissue distribution of α-11'-tocomonoenol (αT1) is unknown. We investigated the tissue distribution of αT1 and αT in wild-type (TTP+/+) and TTP knockout (TTP-/-) mice fed diets with either αT or αT1 for two weeks. αT1 was only found in blood, not tissues. αT concentrations in TTP+/+ mice were in the order of adipose tissue > brain > heart > spleen > lungs > kidneys > small intestine > liver. Loss of TTP function depleted αT in all tissues. αT1, contrary to αT, was still present in the blood of TTP-/- mice (16% of αT1 in TTP+/+). Autoclaving and storage at room temperature reduced αT and αT1 in experimental diets. In conclusion, αT1 is bioavailable, reaches the blood in mice, and may not entirely depend on TTP function for secretion into the systemic circulation. However, due to instability of the test compounds in the experimental diets, further in vivo experiments are required to clarify the role of TTP in αT1 secretion. Future research should consider compound stability during autoclaving of rodent feed.

α-Tocopherol transfer protein does not regulate the cellular uptake and intracellular distribution of α- and γ-tocopherols and -tocotrienols in cultured liver cells.

Liver cells express a cytosolic α-tocopherol transfer protein (αTTP) with high binding affinity for α-tocopherol (αT) and much lower affinities for the non-αT congeners. The role of αTTP in the intracellular distribution of the different vitamin E forms is currently unknown. We therefore investigated the intracellular localization of αT, γ-tocopherol (γT), α-tocotrienol (αT3), and γ-tocotrienol (γT3) in cultured hepatic cells with and without stable expression of αTTP. We first determined cellular uptake of the four congeners and found the methylation of the chromanol ring and saturation of the sidechain to be important factors, with tocotrienols being taken up more efficiently than tocopherols and the γ-congeners more than the α-congeners, irrespective of the expression of αTTP. This, however, could perhaps also be due to an observed higher stability of tocotrienols, compared to tocopherols, in culture media rather than a higher absorption. We then incubated HepG2 cells and αTTP-expressing HepG2 cells with αT, γT, αT3, or γT3, isolated organelle fractions by density gradient centrifugation, and determined the concentrations of the congeners in the subcellular fractions. All four congeners were primarily associated with the lysosomes, endoplasmic reticulum, and plasma membrane, whereas only αT correlated with mitochondria. Neither the chromanol ring methylation or sidechain saturation, nor the expression of αTTP were important factors for the intracellular distribution of vitamin E. In conclusion, αTTP does not appear to regulate the uptake and intracellular localization of different vitamin E congeners in cultured liver cells.

Carotenoids and xanthophyll esters of yellow and red nance fruits (Byrsonima crassifolia (L.) Kunth) from Costa Rica.

Carotenoid profiles, by means of HPLC-PDA-MSn, and CIE-L*C*h° colour values of yellow and red nance fruits from Costa Rica were elucidated. Among 16 carotenoids detected, (all-E)-lutein was the most abundant accounting for >80% of the total carotenoids, followed by (all-E)-zeaxanthin (9-11%) and (all-E)-ß-carotene (2-9%). Minor constituents were (Z)-isomers of lutein and ß-carotene, as well as diverse lutein diesters. Among the esters, lutein dimyristate was the most abundant as substantiated by the comparison with a marigold flower extract. Total carotenoids in the peel (616.2 µg/100 g of FW in yellow nance and 174.2 µg/100 g of FW in red nance) were higher than in the pulp (39.4 µg/100 g of FW in yellow nance and 31.4 µg/100 g of FW in red nance). Since carotenoid profiles of yellow and red varieties were qualitatively similar, although the colour values showed significant differences (77.2 and 88.6 h° in peel and pulp of yellow nance, versus 32.7 and 67.3 h° in peel and pulp of red nance, respectively), pigments other than carotenoids may impart the colour of red nance. High lutein content renders nance fruit as a nutritionally relevant source of this micronutrient.

Tocopherols, Tocomonoenols, and Tocotrienols in Oils of Costa Rican Palm Fruits: A Comparison between Six Varieties and Chemical versus Mechanical Extraction.

Palm oil is one of the richest sources of tocotrienols and may contain other non-tocopherol vitamin E congeners. The vitamin E profiles of fully ripened fruit mesocarp of three Elaeis guineensis, two Elaeis oleifera, and one hybrid O × G palm fruit genotypes from Costa Rica were analyzed by high-performance liquid chromatography with fluorescence detection and gas chromatography-mass spectrometry after mechanical extraction by a screw press and chemical extraction with hexane. γ-Tocotrienol, α-tocotrienol, and α-tocopherol were the most abundant tocochromanols, while other tocopherols (ß-tocopherol, γ-tocopherol, and δ-tocopherol) and α-tocomonoenol were detected at minor concentrations. Significant differences in vitamin E profiles between genotypes were observed, and the variety E. oleifera Quepos (CB9204) had by far the highest content of total tocotrienols (890 µg/g of oil) and total vitamin E (892 µg/g of oil). Chemical extraction with hexane afforded up to 2.5-fold higher vitamin E yields than screw press extraction. α-Tocomonoenol co-eluted with γ-tocopherol in reversed-phase high-performance liquid chromatography analyses and is a possible source of error in the quantification of γ-tocopherol in foods.

Formación de acrilamida durante el procesamiento de alimentos. Una revisión / Acrylamide formation during the processing of food. A review

ResumenEn abril del 2002, un grupo de investigadores suecos dio a conocer que algunos alimentos ricos en almidón y pobres en proteínas, sometidos a procesos con temperaturas mayores a 120°C (fritura, horneado, asado y tostado) contenían el pro-cancerígeno conocido como acrilamida. A partir de ese momento, se desató una verdadera carrera investigativa en torno al tema, generando más de 7000 publicaciones científicas relacionadas con el tema, solo en los últimos 4 años.Al día de hoy, las investigaciones realizadas dejan en claro que la formación de acrilamida en los alimentos involucra al aminoácido asparragina y a azúcares reductores, los cuales mediante la reacción de Maillard dan como resultado el mencionado compuesto, denominado actualmente como un contaminante del proceso o un contaminante neo formado.La investigación realizada, se puede decir tiene tres vertientes claramente definidas, una es explicar porque se da la presencia de acrilamida en los alimentos, otra se enfoca en el desarrollo de protocolos y tecnología de punta para la detección de la sustancia en diversos alimentos y la tercera tiene que ver con las medidas a tomar para mitigar la aparición de acrilamida en sustratos alimenticios. Esta revisión tiene como objetivo, brindar al lector una visión actualizada sobre estas tres vertientes anteriormente citadas.

AbstractIn April 2002, a Swedish group or researches informed that some food products with high starch and low protein constitution and submitted to temperature processes above 120°C contained a pro cancerigenous substance known as acrylamide. From this moment on, and until actual times, a research race around the theme has been established.Up to the date, research done clearly describes the formation of acrylamide in food from asparagine and reducing sugars, through Maillard's reaction, and is known as a process contaminant or a neo formed contaminant.Actual research on the theme has three different approaches, one that explains the presence of acrylamide in food, a second one that focusses in the development of protocols and technology for its detection in food and a third one that tries to develop mitigating measures for the appearance of acrylamide in food substrates. The aim of this review is to bring to the reader an actualized vision of these three approaches.