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Artificial pigmentation of apple fruits has been intensely evaluated to generate less pigmented red apples, which are profitable because of the changes in fruit quality. In this study, we analyzed the diversity of flavonoids and the patterns of flavonoid metabolic gene expression under light irradiation with or without methyl jasmonate (MeJA) treatment in immature (S1) and color-turning (S2) staged ‘Fuji’ apples. Further, we assessed the metabolic regulation at the gene level between anthocyanin and flavonol in light-responsive apple skins. UV-B exposure within 3 days was found to significantly stimulate anthocyanin accumulation in apple skin compared to other light exposure. S1 skin was more sensitive to UV-B and MeJA treatment, in the aspect of indaein accumulation. The enhancement of apple pigmentation following treatment with adequate levels of UV-B and MeJA was maximized at approximately 72 h. Red (range from 4.25 to 17.96 µg·g−1 DW), blue (range from 4.59 to 9.17 µg·g−1 DW) and UV-A (range from 3.98 to 19.12 µg·g−1 DW) lights contributed to the induction of idaein content. Most genes related to the flavonoid pathways increased their expression under UV-B exposure, including the gene expression of the transcription factor, MdMYB10, a well-known upstream factor of flavonoid biosynthesis in apples. The boosted upregulation of MdMYB10, MdCHS, MdF3H MdLDOX, and MdUFGT genes due to MeJA in UV-B was found and may contribute the increase of idaein. UV-A and UV-B caused higher quercetin glycoside content in both S1 and S2 apple skins than longer wavelengths, resulting in significant increases in quercetin-3-O-galactoside and quercetin-3-O-glucoside. These results suggest that the application of adequate UV-B with MeJA in less-pigmented postharvest apples will improve apple color quality within a short period.

Highlights • The article describes the apple fruit peel color and various factors responsible for it. • Factors like light, temperature, mineral nutrition, growth regulators, and carbohydrate availability effect anthocyanin accumulation. • Anthocyanins are the main pigments for apple peel colouration and Cyanidin 3- galactoside commonly named idaein is the prime one. Abstract Apple is one of the most important and popular fruits in the world. Among the various fruit quality traits, skin color is the preferred one which determines a cultivar's market acceptance. Fruit color in apple is dogged primarily by the ground color of the skin and secondarily by the imposed anthocyanin pigmentation, if present. The prime anthocyanin pigment in apple is Cyanidin 3- galactoside commonly named idaein. However, Cyanidin 3- pentoside was also identified in two species. Cyanidin arabinosylgalactoside has also been mentioned from the flesh of Komsomeletes apples but has not been reported elsewhere and is either specific to this cultivar having arisen from a mutation or is a mis-identification. Various factors like light, temperature, mineral nutrition, growth regulators, and carbohydrate availability etc. effect anthocyanin accumulation. The intensity of light and low temperature is crucial for the accumulation of anthocyanins in the skin of apple fruit. The light intensity especially UV-B, could activate anthocyanin synthesis pathway through photoreceptor and finally promote the accumulation of anthocyanins. In apple, low temperature could promote anthocyanin synthesis and high temperature could inhibit accumulation of the same. MdMYB1, the light responsive regulatory factor was found to control the transcription of apple flavonoid genes. Transcription of MdMYBA, MdDFR, MdCHS, MdLDOX and MdUFGluT in apple peel has also been found to be regulated by light particularly UV-B radiation. Optimum temperature for anthocyanin accumulation was found to be 25 °C. Application of Urea increases the Chlorophyll and Carotenoid concentration in fruit skin and reduces anthocyanins concentration in the blush side of fruit at maturity. Ethylene is a key factor in the regulation of anthocyanins biosynthesis and color development in apples. It has been found that the accumulation of anthocyanins is clearly stimulated by ethephon (an ethylene releasing agent) and delayed by ABG-3168 (a likely inhibitor of ethylene production). Anthocyanin reddening in apple fruit skin has been a topic of genetic studies since the 1930's. Several studies have indicated a monogenic approach of inheritance and a single dominant gene Rf was proposed to control anthocyanin reddening on apple fruit skin. Recent molecular genetic studies strongly support the hypothesis of a major gene inheritance as has been reported in the earlier literature. However, there has been much controversy among researchers and many of the studies have been questionable. It therefore requires a thorough analysis and understanding of the development of over color in apple so as to increase the apple trade in national and international market. In this view, an updated summary of published reports on the peel color in apple has been attempted but the experimental groundwork still needs to be done to overcome the misconception. [ABSTRACT FROM AUTHOR]

Glycation, the nonenzymatic reaction between proteins and excess blood sugar, is implicated in multiple disorders and occurs via the formation and accumulation of advanced glycation end products (AGEs). In our previous studies, we demonstrated that the red-leaf variant of the Persicaria hydropiper sprout (Japanese red water pepper, Benitade) is one of the potent plants that inhibit formation of AGEs. In this study, we aimed to identify antiglycative compounds in Benitade. Benitade extracts were prepared with hot water, then fractionated by using high-performance liquid chromatography (HPLC). The antiglycative efficacy of each fraction was evaluated by measuring the formation of fluorescent AGEs (Ex 370 nm/Em 440 nm). Two fractions, which contained peaks at 26.4 min and 31.8 min, showed potent antiglycative efficacy. When we hydrolyzed these peaks, they shifted to 32.5 and 41.4 min, which are the same retention times as cyanidin and quercetin, respectively. Based on thin-layer chromatography, both compounds contained galactose. Finally, ultrahigh-performance liquid chromatography/quadrupole-time of flight mass spectrometry (UHPLC-QqTOF-MS) analyses were performed to determine the structure of those compounds. Overall, we identified two glycosides, cyanidin 3-O-galactoside (idaein) and quercetin 3-O-galactoside (hyperin), as representative antiglycative compounds in Benitade. [ABSTRACT FROM AUTHOR]

Artificial pigmentation of apple fruits has been intensely evaluated to generate less pigmented red apples, which are profitable because of the changes in fruit quality. In this study, we analyzed the diversity of flavonoids and the patterns of flavonoid metabolic gene expression under light irradiation with or without methyl jasmonate (MeJA) treatment in immature (S1) and color-turning (S2) staged 'Fuji' apples. Further, we assessed the metabolic regulation at the gene level between anthocyanin and flavonol in light-responsive apple skins. UV-B exposure within 3 days was found to significantly stimulate anthocyanin accumulation in apple skin compared to other light exposure. S1 skin was more sensitive to UV-B and MeJA treatment, in the aspect of indaein accumulation. The enhancement of apple pigmentation following treatment with adequate levels of UV-B and MeJA was maximized at approximately 72 h. Red (range from 4.25 to 17.96 µg·g−1 DW), blue (range from 4.59 to 9.17 µg·g−1 DW) and UV-A (range from 3.98 to 19.12 µg·g−1 DW) lights contributed to the induction of idaein content. Most genes related to the flavonoid pathways increased their expression under UV-B exposure, including the gene expression of the transcription factor, MdMYB10, a well-known upstream factor of flavonoid biosynthesis in apples. The boosted upregulation of MdMYB10, MdCHS, MdF3H MdLDOX, and MdUFGT genes due to MeJA in UV-B was found and may contribute the increase of idaein. UV-A and UV-B caused higher quercetin glycoside content in both S1 and S2 apple skins than longer wavelengths, resulting in significant increases in quercetin-3-O-galactoside and quercetin-3-O-glucoside. These results suggest that the application of adequate UV-B with MeJA in less-pigmented postharvest apples will improve apple color quality within a short period. [ABSTRACT FROM AUTHOR]

Abstract: The polyphenolic content of two cell suspension lines (red and yellow) initiated from the ovarian wall of Crataegus monogyna flower and their antioxidative potencies against ABTS +, DPPH , and human LDL oxidation were compared to those of red fresh and dry fruits, flower buds and flowering tops. Maximal phenolics and proanthocyanidins contents were found in red suspension extracts displaying high antioxidative effects. In contrast, yellow cell extracts were always the poorest in both phenolics and activity. Flower buds and flowering tops have significant phenolic yields and effects. Both fresh and dried fruits are less active. The amounts in some major phenolic compounds were determined in all tested samples: again, the most antioxidant samples were richer, the red cell line showing particularly high amounts in epicatechin and chlorogenic acid, whilst dried flower buds contained mainly hyperoside and chlorogenic acid. (−)-Epicatechin was confirmed to be more efficient as an antioxidant compound than hyperoside and chlorogenic acid in all assays and more generally, proanthocyanidins were found to be more clearly related to antioxidant activity than other classes of phenolics. The major anthocyanin characterising the red cells of C. monogyna was isolated and identified as cyanidin-3-O-galactoside. [Copyright &y& Elsevier]

Glycation, the nonenzymatic reaction between proteins and excess blood sugar, is implicated in multiple disorders and occurs via the formation and accumulation of advanced glycation end products (AGEs). In our previous studies, we demonstrated that the red-leaf variant of the Persicaria hydropiper sprout (Japanese red water pepper, Benitade) is one of the potent plants that inhibit formation of AGEs. In this study, we aimed to identify antiglycative compounds in Benitade. Benitade extracts were prepared with hot water, then fractionated by using high-performance liquid chromatography (HPLC). The antiglycative efficacy of each fraction was evaluated by measuring the formation of fluorescent AGEs (Ex 370 nm/Em 440 nm). Two fractions, which contained peaks at 26.4 min and 31.8 min, showed potent antiglycative efficacy. When we hydrolyzed these peaks, they shifted to 32.5 and 41.4 min, which are the same retention times as cyanidin and quercetin, respectively. Based on thin-layer chromatography, both compounds contained galactose. Finally, ultrahigh-performance liquid chromatography/quadrupole-time of flight mass spectrometry (UHPLC-QqTOF-MS) analyses were performed to determine the structure of those compounds. Overall, we identified two glycosides, cyanidin 3- O -galactoside (idaein) and quercetin 3- O -galactoside (hyperin), as representative antiglycative compounds in Benitade.