Ultraviolet-Visible and Proton Magnetic Resonance Spectroscopy of Flavonoids
01 Jan 1975-pp 45-77
TL;DR: A number of reviews of ultraviolet and visible absorption spectroscopy have appeared in the past (Jurd, 1962; Mabry et al., 1970; Swain, 1965; MABry, 1969; Harborne, 1963) as discussed by the authors.
Abstract: A number of reviews of ultraviolet and visible absorption spectroscopy have appeared in the past (Jurd, 1962; Mabry et al., 1970; Swain, 1965; Mabry, 1969; Harborne, 1963) the most comprehensive being those of Jurd (1962) and Mabry et al., (1970). The article by Jurd summarizes the work in this field up to about 1960 and gives detailed references to the original spectroscopic work carried out with flavonoids. The book by Mabry et al (1970) updates Jurd’s chapter and in addition provides a detailed catalogue of the ultraviolet (UV) spectra of 175 flavonoids together with comprehensive data on reagent induced shifts for each flavonoid. The present article includes some of the more significant aspects of the earlier reviews and in addition brings them up to date.
Citations
More filters
••
01 Jan 1988
TL;DR: In this article, it was shown that the color signals emerging from flowers are messages interpretable by mammals as well as by birds and insects, and that colour is most likely a link between animals and plants, as are flower shape, scent and taste.
Abstract: Flower colour results from the preferential absorption of part of the visible light by one, or several, chemical compound(s) synthesized by higher plants. Since plants cannot ‘see’ their own colours, it is conceivable that the colour signals emerging from flowers are messages interpretable by mammals as well as by birds and insects (Harborne, 1976). Thus colour is most likely a link between animals and plants, as are flower shape, scent and taste. In particular, insects and birds attracted by colour pollinate the flowers and aid the survival of plant species. In contrast to man, some insects, especially bees, can perceive in the near ultraviolet (340–380 nm) as well as in the visible.
298 citations
••
TL;DR: In this article, high-pressure liquid chromatography with electrochemical, diode-array and/or mass spectrometric detection revealed concentrations ranging in foods as eaten from 4 to 801 milligrams for ascorbic acid and 172 to 905 milligram for citrus flavanones.
284 citations
••
TL;DR: These phenolic compounds were shown to be effective to protect biological systems against various oxidative stresses and protected red cells against oxidative hemolysis.
233 citations
••
TL;DR: The 4,4'-dihydroxy-2'-methoxychalcone induced nod genes at a concentration one order of magnitude lower than luteolin and is the first naturally released chalcone reported to have this function.
Abstract: Flavonoid signals from alfalfa (Medicago sativa L.) induce transcription of nodulation (nod) genes in Rhizobium meliloti. Previous investigations identified the flavone luteolin as an active inducer in alfalfa seed extracts, but the nature of nod inducers released from roots has not been reported. Root exudate from 3-day-old alfalfa seedlings was purified and then assayed for biological activity with a nodABC-lacZ fusion in R. meliloti. Indentities of major nod inducers were established by spectroscopic analyses (ultraviolet/visible, proton nuclear magnetic resonance, and mass spectroscopy) and comparison with authentic standards. Major nod inducers, which were identified as 4',7-dihydroxyflavone, 4'-7-dihydroxyflavanone, and 4,4'-dihydroxy-2'-methoxychalcone, were released from seedling roots at 54, 22, and 20 picomole.plant(-1).day(-1), respectively. Luteolin was not found in these root exudates. The 4,4'-dihydroxy-2'-methoxychalcone induced nod genes at a concentration one order of magnitude lower than luteolin and is the first naturally released chalcone reported to have this function. Moderate and weak nod-inducing activity was associated, respectively, with 4',7-dihydroxyflavone and 4',7-dihydroxyflavanone.
221 citations
••
TL;DR: The pearl millet flavonoids have been identified as C-glycosylflavones by the combined use of paper chromatography and UV spectroscopy and a correlation between dietary tannins and occurrence of esophageal cancer has been established.
Abstract: Polyphenols in cereals and legumes have been receiving considerable attention largely because of their adverse influence on color, flavor, and nutritional quality. These compounds belong to the flavonoid and tannin groups and are mostly located in the seed coat or pericarp of the grains. The pearl millet flavonoids have been identified as C-glycosylflavones by the combined use of paper chromatography and UV spectroscopy. Although nontoxic, physiological and nutritional significance of these compounds occurring in high amounts in the pearl millet grain are still not clearly understood. In view of aesthetic quality, bleaching of the millet grains in acidic solution is recommended. A large proportion of current assays involves spectrophotometry of tannin or its chromogen and tannin-protein interaction. Sorghum and legume tannins have been characterized as condensed tannins. Several factors such as plant type, age of the plant or plant parts, stage of development, and environmental conditions govern the polyphenol contents in plants. Polyphenols are known to interact with proteins and form tannin-protein complexes leading to either inactivation of enzymes or making proteins insoluble. These are implicated in decreasing the activities of digestive enzymes, protein and amino acid availabilities, mineral uptake, vitamin metabolism, and depression of growth. Polyphenols are known to cause certain ultrastructural changes in the different parts of experimental animals. A correlation between dietary tannins and occurrence of esophageal cancer has been established. Bird resistance and seed germination in food crops have been correlated to high contents of polyphenols. The antinutritional activity of polyphenols can be reduced by removing polyphenols from the grains by chemical treatments or removing pericarp and testa by pearling. Treatment of alkaline reagents and ammonia can remove 90% of the polyphenols. Supplementation of polyphenols-rich diet with protein can alleviate the growth-depressing effect of polyphenols.
171 citations
References
More filters
•
01 Jan 1976
TL;DR: This book will help you to understand the chemistry and biochemistry of plant pigments book much better and the system of this book of course will be much easier.
Abstract: Reading is a hobby to open the knowledge windows. Besides, it can provide the inspiration and spirit to face this life. By this way, concomitant with the technology development, many companies serve the e-book or book in soft file. The system of this book of course will be much easier. No worry to forget bringing the chemistry and biochemistry of plant pigments book. You can open the device and get the book by on-line.
1,754 citations
•
01 Jan 1962
TL;DR: The chemistry of flavonoid compounds will lead you to love reading starting from now and will guide you to even the prestige stage of the life.
Abstract: We may not be able to make you love reading, but the chemistry of flavonoid compounds will lead you to love reading starting from now. Book is the window to open the new world. The world that you want is in the better stage and level. World will always guide you to even the prestige stage of the life. You know, this is some of how reading will give you the kindness. In this case, more books you read more knowledge you know, but it can mean also the bore is full.
678 citations
••
413 citations