Flavonoids, bioactivity

Additionally, there are other factors such as age, interindividual and sex differences, biotransformation, and protein binding that may insert variations in xenobi-otic absorption between two different individuals. Here, the role of microbiota on biotransforming flavonoids has to be emphasized because it is critical for flavonoid bioactivity. This issue is developed later in this chapter. 

The inherent difficulties in the characterization, distribution, and localization of flavonoids within the body pose a major hurdle when attempting to investigate mechanisms of flavonoid bioactivity in vivo. Compounds reported to localize within brain structures include epigallocatechin gallate [21], a major polyphe-nolic in tea and to a lesser degree in wine, and the citrus flavonoids hesperetin... 

Bioactive sesquiterpenic y-lactones and flavonoids in plants of Inula L. genus 97MI20. 

Carmen Socaciu was bom in Cluj-Napoca, Romania and earned a BSc in chemistry in 1976, an MSc in 1977, and a PhD in 1986 from the University Babes-Bolyai in Cluj-Napoca, an important academic centre located in the Transylvania region. Dr. Socaciu worked as a researcher in medical and cellular biochemistry for more than 10 years, and became a lecturer in 1990 and full professor in 1998 in the Department of Chemistry and Biochemistry of the University of Agricultural Sciences and Veterinary Medicine (USAMV) in Cluj-Napoca. She extended her academic background in pure chemistry (synthesis and instrumental analysis) to the life sciences (agrifood chemistry and cellular biochemistry). Her fields of competence are directed especially toward natural bioactive phytochemicals (carotenoids, phenolics, flavonoids), looking to advanced methods of extraction and analysis and to their in vitro actions on cellular metabolism, their effects as functional food ingredients, and their impacts on health. 

Flavonoids and Anthocyanins in Plants, and Latest Bioactive Heterocycles I Volume Editor N. Motohashi Volume 15, 2008... 

Some of the bioactive phytochemicals found in fmits and vegetables are polyphenols, including flavonoids. This chapter provides a general overview of the relationship between flavonoids and health. The mechanisms of action believed to be behind the healthful effects of some compounds will also be mentioned. 

Phytochemicals or phytonutrients are bioactive substances that can be found in foods derived from plants and are not essential for life the human body is not able to produce them. Recently, some of their characteristics, mainly their antioxidant capacity, have given rise to research related to their protective properties on health and the mechanisms of action involved. Flavonoids are a diverse group of phenolic phytochemicals (Fig. 6.1) that are natural pigments. One function of flavonoids is to protect plants from oxidative stress, such as ultraviolet rays, environmental pollution, and chemical substances. Other relevant biological roles of these pigments are discussed in other chapters of this book. 

Flavonoids are a complex group of polyphenolic compounds with a basic C6-C3-C6 structure that can be divided in different groups flavonols, flavones, flavanols (or flavan-3-ols), flavanones, anthocyanidins, and isoflavones. More than 6,000 flavonoids are known the most widespread are flavonols, such as quercetin flavones, such as lu-teolin and flavanols (flavan-3-ols), such as catechin. Anthocyanidins are also bioactive flavonoids they are water-soluble vegetable pigments found especially in berries and other red-blue fruits and vegetables. 

Finally, it should also be considered that flavonoid-rich foods contain a great diversity of compounds with bioactive properties (for e.g., carotenoids, other phenolics, fiber, and minerals), and multiple interactions occur among all of them. There is also great diversity in the ingestion, absorption, and metabolism of these compounds in different populations, and all of these circumstances could camouflage any effect of flavonoids on disease prevention or treatment. 

Fig. 5.5 On-line HPLC bioactivity screening of a mixture of five flavonoids spiked with two cathepsin B inhibitors, E-64 and leupeptin using acetylcholinesterase as biological target. MS instrument Shimadzu LCMS-2010 single-stage quadrupole mass spectrometer, (a) TIC chromatogram of the mixture, scan range m/z 75-750 (b) mass chromatogram of AMC (m/z 176) (c) mass...

Chokchaisiri R, Suaisom C, Sriphota S, Chindaduang A, Chuprajob T, Suksamram A. (2009) Bioactive flavonoids of the flowers of Butea monosperma. Chem Pharm Bull 57 428 32. 

A herbal product contains multiple constituents that might be responsible for its therapeutic effects. It is thus necessary to define as many of the constituents as possible in order to understand and explain the bioactivity. The concept of phytoequivalence has been introduced in Germany to ensure consistency of phytotherapeuticals. According to this concept, a chemical profile for a herbal product is constructed and compared with the profile of a clinically proven reference product. Since many of these preparations contain flavonoids, it is essential to have adequate analytical techniques at hand for this class of natural product. 

Long, C. et ah. Bioactive flavonoids of Tanacetum parthenium revisited. Phytochemistry, 64, 567, 2003. 

Macias, F.A. et al.. Bioactive flavonoids from Helianthus annuus cultivars, Phytochemistry, 45, 683, 1997. 

Seo, E.-K. et ak. Bioactive prenylated flavonoids from the stem bark of Artocarpus kemando. Arch. Pharm. Res., 26, 124, 2003. 

Kofmas, C. et al., Flavonoids and bioactive coumarins of Tordylium apulum, Phytochemistry, 48, 637, 1998. 

Chang, L.C. et al., Absolute configuration of novel bioactive flavonoids from Tephrosia purpurea, Org. Lett., 2, 515, 2000. 

Yue, M.-E. and Shi, Y.-R, Application of l-alkyl-3-methylimidazolium-based ionic liquids in separation of bioactive flavonoids by capillary zone electrophoresis, /. Sep. Set., 29, 272-276,2006. 

To ensure lot-to-lot consistency, standardization of extracts often relies on constituents as biomarkers for plant identity and potency. SJW Hypericum perforatum), a perennial shrub traditionally used as a mood enhancer and mild antidepressant, has been tested in dozens of clinical trials, with mixed results for efficacy. Some of its purported bioactive constituents include naphthodianthrones, including hypericin flavonoids phloroglucinols, including hyperforin and essential oils. For many years, hypericin was presumed to be the active component. As a result most extracts were standardized based on hypericin concentration. Recent data, however, support other components such as hyperforin and the flavanoids, that may also contribute to the therapeutic efficacy of the SJW extracts (33-35). Because these secondary components were previously unaccounted for in the standardization of the former clinical test articles, and because these constituents are chemically unrelated to and their content within the plant varies independently of hypericin, it has been argued that the potency of these constituents in any particular batch was unlikely to be similar to that of other batches. This variability between batches could explain the observed differences in the clinical trial results (36). 

Nicolosi and coworkers have intensively investigated the exploitation of lipases for the selective deprotection of bioactive compounds [90]. For instance, as shown in Figure 6.8, the alternative use of the lipases from Candida antarctica (CalB) and Mucor miehei (Mml) enabled the preparation of different derivatives of the flavonoid quercetin (28) [91]. Similar results, this time exploiting the lipase from Pseudomonas cepacia, were obtained with the polyacetylated catechin 29 [92]. 

Several types of bioactive compounds have been reported from the genus Broussonetia including glycosidase inhibitory alkaloids and aromatase inhibitory or cytotoxic flavonoids. This chapter reviews the biologically active constituents from the genus Broussonetia reported by the end of 2001. 

The bioactive secondary metabolites reported from Broussonetia kazinoki can be classified into major two groups, alkaloids and flavonoids (Table 1), Fig. (1). The Kusano group at Osaka University of Pharmaceutical Sciences in Japan reported over 20 pyrrolidine alkaloids, broussonetines A-H, K-M, O-T, V-X, and Mi, and broussonetinines A and B, four pyrrolidinyl piperidine alkaloids, broussonetines I, J, Ji, and J2, two pyrroline alkaloids, broussonetines U and U, and one pyrrolizidine alkaloid, broussonetine N, from hot water extracts of B. kazinoki [16-24]. As shown in Table 1, some of these alkaloids exhibited strong... 

The major types of bioactive constituents reported from Broussonetia papyrifera are the prenylated flavonoids, which include compounds of the diphenylpropane, chalcone, flavan, flavanone, flavone, flavonol, and aurone classes (Table 2), Fig. (7). An early study on B. papyrifera resulted in the isolation of two diphenylpropanes, broussonins A (29) and B (30), and a coumarin, marmesin (52), with antifungal activity [39]. Also, a diprenylated diphenylpropane derivative, kazinol F (31) [40], was reported as an antioxidant and tyrosinase inhibitory constituent [34]. 

The isolation of flavonoids from the methanol extract of G. uralensis was carried out under non-basic conditions, because some flavonoids isomerize under basic conditions, e.g. racemization of flavanones and isoflavanones, ring-open reaction of flavanones etc. Bioactive fractions were separated by some chromatographic methods and each step was monitored with anti-H. pylori activity with the paper disk method. Eighteen compounds were isolated from these bioactive fractions and... 

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