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group of phytochemicals as a result of their great abundance in plant foods and consist chiefly of phenolic acids and flavonoids ( Dillard and German, 2000 ; Manach et al., 2004 ). Dietary phenolic compounds significantly contribute to the antioxidant

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Gawlik-Dziki, 2007 ) of Rosa species, but studies targeted at identification of individual phenolic compounds are limited. The aim of the present study was to identify and quantify phenolic compounds in petals of several indigenous rose species in

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of bioactive substances that together provide high antioxidant capacity ( Fratianni et al., 2018 ). Phenolic compounds in apricot are represented primarily by gallic acid, chlorogenic acid, neochlorogenic acid, caffeic acid, pcoumaric acid, ferulic

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’s capability to eliminate free radicals by the consumption of foods high in antioxidants may be beneficial, and studies have implicated phenolic compounds to be important phytochemicals because of their antioxidant activities ( Boyer and Liu, 2004 ; Rice

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( Brandt et al., 2004 ; Pennington and Fisher, 2009 ). In particular, phenolic compounds, which are one of the most widely occurring groups of phytochemicals, exhibit various types of physiological properties, including antioxidant activity ( Balasundram

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Sweetpotatoes may be potentially high in concentration of certain phytochemical compounds, including phenolics. Low temperature stress-induced phenolic compounds may enhance the nutraceutical value of sweetpotatoes. However, extended exposure to low temperature results in chilling injury. Cured and non-cured roots of `Beauregard' sweetpotatoes were exposed to low temperature storage (5 °C) for up to 4 weeks. The total phenolics and individual phenolic acid contents were determined at weekly intervals using Folin-Denis reagent and reversed-phase HPLC, respectively. Total phenolics and individual phenolic acids increased with length of low temperature exposure. Non-cured roots had a higher phenolic content than cured roots after 4 weeks. A 3-day exposure period to room temperature (22 °C) following removal from low temperature storage typically resulted in increased phenolics. In a comparison of different tissue locations, the highest phenolic content was found in peel tissue and the lowest in the pith tissue. The major individual phenolic acid in all root tissues was chlorogenic acid.

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Abstract

The interaction between Cytospora leucostoma (causal agent of peach canker) and host-phenolic compounds in dormant peach trees [Prunus persica (L.) Batsch] was examined. Initially, inoculated samples had significantly higher phenolic levels than uninoculated samples. The levels in inoculated samples decreased dramatically in tissues closest to the point of inoculation, however, while the phenolic levels in uninoculated samples remained relatively stable through time. The data suggested that C. leucostoma degraded host-phenolic compounds. Maximum phenolic enrichment was observed in the branch collar region of the main stem of inoculated samples. It was concluded that the presence of C. leucostoma in host tissue played a significant role, over and above the wounding response, in establishing levels of host-phenolic compounds. Levels of phenolics in host tissue seemed to increase in advance of the fungus and this increase may function as a mechanism that slows the pathogen's advance.

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Abstract

Rhododendron leaf disks (Rhododendron L., cv. Jean Marie de Montague) release water-soluble phenolic compounds when subjected to lethal freezing stress. Following low-temperature exposure, the levels of phenolic compounds leached from the disks are assessed by spectrophotometric measurement (260 nm). The increase in phenolics is highly correlated with other viability tests—electrolyte leakage, visual browning, ethane production, and TTC reduction have r values of 0.99, 0.99, 0.95, and −0.88, respectively. Chemical names used: Trichloroacetic acid (TCA), polyvinylpolypyrrolidone (PVPP), 2,3,5-triphenyl tetrazolium chloride (TTC).

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Abstract

Extracts from flowers of 5 Cineraria cultivars contained 4 major phenolic compounds: 2 anthocyanidins (cyanidin and delphinidin), the flavone apigenin2, and caffeic acid. The flavone and the phenolic acid were present in all cultivars. The color variations among the cultivars is apparently caused by variations in the relative concn of the 2 anthocyanidins. The presence of delphinidin is of particular interest because of its rare occurrence in Compositae.

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Abstract

The effects of catechol, juglone, phloridzin, phloroglucinol, and tannic acid were tested on tobacco callus growth and on axillary shoot proliferation and rooting of blackberry. Juglone (500 μM) promoted tobacco (Nicotiana tabacum L. ‘McNair 944’) callus growth, whereas catechol and phloroglucinol (500 μM) increased adventitious shoot formation, but not callus growth. Tannic acid increased the frequency of vitreous shoots. No phenolic compounds stimulated axillary shoot proliferation in blackberry (Rubus sp. ‘Dirkson Thornless’), and phloroglucinol (1 mM) inhibited shoot elongation. Auxin increased rooting of blackberry shoots irrespective of the presence or absence of incorporated phenols. On shoots derived from proliferation media void of phenols, root number and percent rooting were greater if they were treated with the phenolic auxin P-ITB compared to IBA. In contrast, shoots originating from proliferation media containing phenols rooted the same with both auxins. Chemical names used: 1,2-benzenediol (catechol); 5-hydroxy-1,4-naphthalendedione (juglone); 1-[2-(β-D-glycopyranosloxy)-4,6-dihydroxyphenyl-3-[4-hydroxyphenyl)-1-propanone (phloridzin); 1,3,5-benzenetriol (phloroglucinol); 1H-indole-3-butanoic acid (IBA); N-(phenylmethyl)-1H-purin-6-amine (BA): phenyl indole-3-thiolobutyrate (P-ITB); (1α,2β,4aα,4bβ,10β)-2,4a,7-trihydroxy-1-methyl-8-methylenegibb-3-ene-1, 10-dicarboxylic acid 1,4a-Iactone (GA3).

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