There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Flavonoids, a group of natural substances with variable phenolic structures, are found in fruits, vegetables, grains, bark, roots, stems, flowers, tea and wine. These natural products are well known for their beneficial effects on health and efforts are being made to isolate the ingredients so called flavonoids. Flavonoids are now considered as an indispensable component in a variety of nutraceutical, pharmaceutical, medicinal and cosmetic applications. This is attributed to their anti-oxidative, anti-inflammatory, anti-mutagenic and anti-carcinogenic properties coupled with their capacity to modulate key cellular enzyme function. Research on flavonoids received an added impulse with the discovery of the low cardiovascular mortality rate and also prevention of CHD. Information on the working mechanisms of flavonoids is still not understood properly. However, it has widely been known for centuries that derivatives of plant origin possess a broad spectrum of biological activity. Current trends of research and development activities on flavonoids relate to isolation, identification, characterisation and functions of flavonoids and finally their applications on health benefits. Molecular docking and knowledge of bioinformatics are also being used to predict potential applications and manufacturing by industry. In the present review, attempts have been made to discuss the current trends of research and development on flavonoids, working mechanisms of flavonoids, flavonoid functions and applications, prediction of flavonoids as potential drugs in preventing chronic diseases and future research directions.

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Flavonoids: an overview

Anthocyanins are colored water-soluble pigments belonging to the phenolic group. The pigments are in glycosylated forms. Anthocyanins responsible for the colors, red, purple, and blue, are in fruits and vegetables. Berries, currants, grapes, and some tropical fruits have high anthocyanins content. Red to purplish blue-colored leafy vegetables, grains, roots, and tubers are the edible vegetables that contain a high level of anthocyanins. Among the anthocyanin pigments, cyanidin-3-glucoside is the major anthocyanin found in most of the plants. The colored anthocyanin pigments have been traditionally used as a natural food colorant. The color and stability of these pigments are influenced by pH, light, temperature, and structure. In acidic condition, anthocyanins appear as red but turn blue when the pH increases. Chromatography has been largely applied in extraction, separation, and quantification of anthocyanins. Besides the use of anthocyanidins and anthocyanins as natural dyes, these colored pigments are potential pharmaceutical ingredients that give various beneficial health effects. Scientific studies, such as cell culture studies, animal models, and human clinical trials, show that anthocyanidins and anthocyanins possess antioxidative and antimicrobial activities, improve visual and neurological health, and protect against various non-communicable diseases. These studies confer the health effects of anthocyanidins and anthocyanins, which are due to their potent antioxidant properties. Different mechanisms and pathways are involved in the protective effects, including free-radical scavenging pathway, cyclooxygenase pathway, mitogen-activated protein kinase pathway, and inflammatory cytokines signaling. Therefore, this review focuses on the role of anthocyanidins and anthocyanins as natural food colorants and their nutraceutical properties for health. Abbreviations: CVD: Cardiovascular disease VEGF: Vascular endothelial growth factor.

/pdf/anthocyanidins-and-anthocyanins-colored-pigments-as-food-7f8c92tmit.pdf

Anthocyanidins and anthocyanins: colored pigments as food, pharmaceutical ingredients, and the potential health benefits.

The normal biochemical reactions in our body, increased exposure to the environment, and higher levels of dietary xenobiotic's result in the generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS). The ROS and RNS create oxidative stress in different pathophysiological conditions. The reported chemical evidence suggests that dietary antioxidants help in disease prevention. The antioxidant compounds react in one-electron reactions with free radicals in vivo/in vitro and prevent oxidative damage. Therefore, it is very important to understand the reaction mechanism of antioxidants with the free radicals. This review elaborates the mechanism of action of the natural antioxidant compounds and assays for the evaluation of their antioxidant activities. The reaction mechanisms of the antioxidant assays are briefly discussed (165 references). Practical applications: understanding the reaction mechanisms can help in evaluating the antioxidant activity of various antioxidant compounds as well as in the development of novel antioxidants.

https://pubs.rsc.org/en/content/articlepdf/2015/RA/C4RA13315C

Free radicals, natural antioxidants, and their reaction mechanisms

A critical review of methods for characterisation of polyphenolic compounds in fruits and vegetables.

Chemical studies of anthocyanins: A review

Spectroscopy study of 5-amino-1,10-phenanthroline.

UV-visible spectroscopic and electrochemical study of the complex formation between Fe(II) and 5-amino-1,10-phenantroline (5-Aphen) in aqueous solution.

A quantitative methodology to determine formation con- stants that takes into consideration the 27 Al-NMR signals of Al(III)- H2O systems has been analyzed, where area fractions beneath the peaks recorded were associated with the corresponding species frac- tions. The values of the formation constants were compared with the model obtained by potentiometric studies. In agreement with previ- ous reports, the -log*β values obtained by NMR and potentiometry, at 0.020 M ≤ (Al(III))total ≤ 0.500 M are 12.96 ± 0.02 for Al(OH)3, 13.50±0.02 for Al3(OH)4 5+ , and 109.70±0.09 for Al13(OH)32 7+ , by assuming that Al(OH) 2+ has a value of 5.29. Additionally the equi- librium constant values obtained allowed fitting of the conductimetry titrations in the 6.00(10- 3 ) M ≤ (Al(III))total ≤ 0.120 M. The algorithm presented in this work gives a support to establish that the area frac- tions of NMR signals are proportional to the species concentration fractions.

/pdf/equilibrium-constants-determination-of-the-species-formation-2scgkes59y.pdf

Equilibrium Constants Determination of the Species Formation in the Al(III)-H2O System by Integration of 27Al-NMR Signals and Fitting with Species Fractions

Ma de Lourdes Pacheco-Hernández

Papers

Chemical studies of anthocyanins: A review

Spectroscopy study of 5-amino-1,10-phenanthroline.

UV-visible spectroscopic and electrochemical study of the complex formation between Fe(II) and 5-amino-1,10-phenantroline (5-Aphen) in aqueous solution.

Equilibrium Constants Determination of the Species Formation in the Al(III)-H2O System by Integration of 27Al-NMR Signals and Fitting with Species Fractions