The Ultraviolet Spectra of Flavones and Flavonols
01 Jan 1970-pp 41-164
TL;DR: The methanol spectra of flavones and flavonols exhibit two major absorption peaks in the region 240 - 400 nm1 as discussed by the authors, and these two peaks are commonly referred to as Band I (usually 300 − 380 nm, Table V-1 records the λmaxvalues for Band I for all flavones examined in the present investigation), and Band II (usually 240 - 280 nm).
Abstract: The methanol spectra of flavones and flavonols exhibit two major absorption peaks in the region 240 – 400 nm1. These two peaks are commonly referred to as Band I (usually 300 – 380 nm, Table V-1 records the λmaxvalues for Band I for all flavones and flavonols examined in the present investigation), and Band II (usually 240 – 280 nm). Band I is considered to be associated with absorption due to the B-ring cinnamoyl system, and Band II with absorption involving the A-ring benzoyl system (see III) [1].
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TL;DR: Analytical techniques for the characterization of juices from different Citrus fruits regarding their flavonoid content (even if present in only trace amounts), concentrating on the most widely used methods (LC-MS and LC-MS-MS).
Abstract: In the early nineties the presence of flavonoids in Citrus juices began to attract the attention of a number of researchers, as a result of their biological and physiological importance. This short review will explore two different aspects. The first part will focus on analytical techniques for the characterization of juices from different Citrus fruits regarding their flavonoid content (even if present in only trace amounts), concentrating on the most widely used methods (LC-MS and LC-MS-MS). The second part analyzes data reported in the literature regarding the composition of Citrus juices. The main components that have been detected so far are flavanone-O-glycosides and flavone-O- or -C-glycosides. The presence of such derivatives in various hand-squeezed and industrial juices is discussed, with special emphasis on their correlation to different species.
584 citations
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TL;DR: Copper and simulated solar radiation (SSR, a light source containing photosynthetically active radiation (PAR) and UV radiation) induced similar responses in the plants, and the potential of ROS being a common signal for acclimation to stress by both copper and UV can be considered.
Abstract: Metals and ultraviolet (UV) radiation are two environmental stressors that can cause damage to plants. These two types of stressors often impact simultaneously on plants and both are known to promote reactive oxygen species (ROS) production. However, little information is available on the potential parallel stress responses elicited by metals and UV radiation. Using the aquatic plant Lemna gibba, we found that copper and simulated solar radiation (SSR, a light source containing photosynthetically active radiation (PAR) and UV radiation) induced similar responses in the plants. Both copper and SSR caused ROS formation. The ROS levels were higher when copper was combined with SSR than when applied with PAR. Higher concentrations of copper plus PAR caused toxicity as monitored by diminished growth and chlorophyll content. This toxicity was more pronounced when copper was combined with SSR. Because the generation of ROS was also higher when copper was combined with SSR, we attributed this enhanced toxicity to elevated levels of ROS. In comparison to PAR-grown plants, SSR treated plants exhibited elevated levels of superoxide dismutase (SOD) and glutathione reductase (GR). These enzyme levels were further elevated under both PAR and SSR when copper was added at concentrations that generated ROS. Interestingly, copper treatment in the absence of SSR (i.e. copper plus PAR) induced synthesis of the same flavonoids as those observed in SSR without copper. Finally, addition of either dimethyl thiourea or GSH (two common ROS scavengers) lowered in vivo ROS production, alleviated toxicity and diminished induction of GR as well as accumulation of UV absorbing compounds. Thus, the potential of ROS being a common signal for acclimation to stress by both copper and UV can be considered.
182 citations
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TL;DR: LC-DAD-ESI/MS was used to identify 23 flavonoid glycosides in the extract of Mexican oregano, the first report of detection of over 20 flavonoids, including chalcones, in this plant material.
147 citations
Cites background from "The Ultraviolet Spectra of Flavones..."
...Therefore, this compound was tentatively identified as scutellarein 7-O-hexoside (I-3-A) (Mabry et al., 1970)....
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...The similarity of the UV spectra between the glycosides and their aglycones indicated that the sugars of these glycosylated flavones were located at the 7-position (Mabry et al., 1970)....
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TL;DR: This is the first report of the isolation and identification of nonvolatile constituents and as well as antioxidant activities from cinnamon fruits.
Abstract: Defatted cinnamon fruit powder was successively extracted with benzene ethyl acetate, acetone, MeOH, and water. The concentrated water extract contained the maximum amount of phenolics and showed the highest antioxidant activities. Hence, it was fractionated by Diaion HP-20SS, Diaion HP-20, and Sephadex LH-20 column chromatographies. It gave five purified compounds, the purities of which were analyzed by HPLC. Compounds 1-5 were identified as 3,4-dihydroxybenzoic acid (protocatechuic acid), epicatechin-(2beta-->O-7,4beta-->8)-epicatechin-(4beta-->8)-epicatechin (cinnamtannin B-1), 4-[2,3-dihydro-3-(hydroxymethyl)-5-(3-hydroxypropyl)-7-(methoxy)benzofuranyl]-2-methoxyphenyl beta-d-glucopyranoside (urolignoside), quercetin-3-O-(6-O-alpha-l-rhamnopyranosyl)-beta-d-glucopyranoside (rutin), and quercetin-3-O-alpha-l-rhamnopyranoside by using extensive spectral studies. The antioxidant activities of purified compounds were screened for their antioxidative potential using beta-carotene-linoleate and 1,1-diphenyl-2-picrylhydrazyl model systems. All of the compounds showed antioxidant and radical scavenging activities. This is the first report of the isolation and identification of nonvolatile constituents and as well as antioxidant activities from cinnamon fruits.
146 citations
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TL;DR: In this article, the synthesis of chalcones and their biological activities with focus on structure-activity relationships are discussed, and the properties, biosynthesis and structural diversity of natural chalcone are reviewed.
Abstract: Chalcone is an aromatic ketone that forms the central core of many important biological compounds, which are known as chalcones. Chalcones are the biogenetic precursors of flavonoids and isoflavonoids, which are abundant in plants. Chalcones are active lead molecules in medicinal chemistry for the discovery of new drugs. Here, we review properties, biosynthesis and structural diversity of natural chalcones. Then, we present the synthesis of chalcones and their biological activities with focus on structure–activity relationships. Pharmaceutically important and patented chalcones are also discussed.
142 citations
References
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TL;DR: In this article, a Hypothese uber die Entstehung des Hypericins in der pflanze wird diskutiert, das sie 4.5.7.4.
Abstract: Durch reduzierende Acetylierung des Hypericins wurde eine blaue, kristallisierte Verbindung dargestellt. Es wird gezeigt, das sie 4.5.7.10.4′.5′.7′-Heptaacetoxy-2.2′-dimethyl-meso-naphthodianthren ist und damit der endgultige Beweis fur die Konstitution des Hypericins erbracht. Eine Hypothese uber die Entstehung des Hypericins in der pflanze wird diskutiert.
49 citations
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TL;DR: In this paper, a spectroscopic procedure using anhydrous AlCl 3 and AlCl3 /HCl was described for the detection of ortho-dihydroxyl groups in flavonoids.
42 citations