Effect Of Plant Flavonoids Research Articles

Effect of plant flavonoids on the volume regulation of rat thymocytes under hypoosmotic stress.

Cell volume regulation and volume-regulated anion channels are critical for cell survival in non-isosmotic conditions, and dysregulation of this system is detrimental. Although genes and proteins underlying this basic cellular machinery were recently identified, the pharmacology remains poorly explored. We examined effects of 16 flavonoids on the regulatory volume decrease (RVD) of thymocytes under hypoosmotic stress assessed by light transmittance and on the activity of volume-sensitive chloride channel by patch-clamp technique. Comparison of effects of flavonoids on RVD revealed a group of four active substances with lehmannin being the strongest inhibitor (IC50 = 8.8 μM). Structure-functional comparison suggested that hydrophobicity brought about by methoxy, prenyl or lavandulyl groups as well as by the absence of glucosyl fragment together with localization of the phenyl ring B at the position C2 (which is at C3 in totally inactive isoflavones) are important structural determinants for the flavonoids activity as volume regulation inhibitors. All active flavonoids suppressed RVD under Gramicidin D-NMDG hypotonic stress conditions when cationic permeability was increased by an ionophore, gramicidin D, with all extracellular monovalent cations replaced with bulky NMDG+ suggesting that they target volume-sensitive anionic permeability. While effects of hispidulin and pulicarin were only partial, lehmannin and pinocembrin completely abolished RVD under Gramicidin D-NMDG conditions. In direct patch-clamp experiments, lehmannin and pinocembrin produced a strong inhibiting effect on the swelling-induced whole-cell chloride conductance in a voltage-independent manner. Lehmannin, pinocembrin, and possibly hispidulin and pulicarin may serve as leads for developing effective low-toxic immunomodulators.

Elucidation of signaling pathways involved in effects of plant flavonoids in human primary macrophages

Elucidation of signaling pathways involved in effects of plant flavonoids in human primary macrophages

New Insights Into the Pharmacological Potential of Plant Flavonoids in the Catecholamine System

Flavonoids are biologically active polyphenolic compounds widely distributed in plants. Recent research has focused on high dietary intake of flavonoids because of their potential to reduce the risks of diseases such as cardiovascular diseases, diabetes, and cancers. We report here the effects of plant flavonoids on catecholamine signaling in cultured bovine adrenal medullary cells used as a model of central and peripheral sympathetic neurons. Daidzein (0.01 – 1.0 μM), a soy isoflavone, stimulated 14C-catecholamine synthesis through plasma membrane estrogen receptors. Nobiletin (1.0 – 100 μM), a citrus polymethoxy flavone, enhanced 14C-catecholamine synthesis through the phosphorylation of Ser19 and Ser40 of tyrosine hydroxylase, which was associated with 45Ca2+ influx and catecholamine secretion. Treatment with genistein (0.01 – 10 μM), another isoflavone, but not daidzein, enhanced [3H]noradrenaline uptake by SK-N-SH cells, a human noradrenergic neuroblastoma cell line. Daidzein as well as nobiletin (≥ 1.0 μM) inhibited catecholamine synthesis and secretion induced by acetylcholine, a physiological secretagogue. The present review shows that plant flavonoids have various pharmacological potentials on the catecholamine system in adrenal medullary cells, and probably also in sympathetic neurons.

1-(4-Chlorophenyl)cyclopropyl](piperazin-1-yl)methanone

The title compound, [1-(4-chlorophenyl)cyclopropyl](piperazin-1-yl)methanone, was synthesized and characterized by elemental analysis, IR, 1H NMR, 13C NMR and mass spectral data.

Effects of plant flavonoids on fecundity, survival, and feeding of the Formosan subterranean termite.

Fecundity, mortality, and food consumption of the Formosan subterranean termite, Coptotermes formosanus Shiraki, were evaluated in response to five plant flavonoids (genistein, biochanin A, apigenin, quercetin, and glyceollin). Apigenin fed at 50 microg/primary reproductive pair proved to be the most toxic flavonoid. Biochanin A was most effective in reducing fecundity. Subsequently, these two flavonoids were tested through oral feeding and topical application at 100-microg dose. Significant reduction in the numbers of progeny was evident for biochanin A in both treatment methods. Choice feeding tests with termite workers showed that initially termites were attracted to filter paper treated with biochanin A, but over a period of 72 hr, consumed significantly less material when compared to controls. Biochanin A is a promising phytochemical with ability to reduce fecundity in primary reproductives of the Formosan subterranean termite, but it does not elicit phagostimulant activity.

Flavonoids differentially regulate IFNγ-induced ICAM-1 expression in human keratinocytes: molecular mechanisms of action

The effect of plant flavonoids on intercellular adhesion molecule-1 (ICAM-1) expression in human keratinocyte was investigated. ICAM-1 is known to mediate skin inflammation. Among the flavonoids tested, taxifolin was the most potent in inhibiting interferon γ (IFNγ)-induced ICAM-1 protein as well as mRNA expression in human keratinocytes. Much smaller dosages of taxifolin were required in primary keratinocytes compared to HaCaT (immortalized cell) to achieve similar levels of inhibition in the inducible ICAM-1 expression. Regulation of inducible ICAM-1 expression by taxifolin was at transcriptional level by inhibiting the activation of signal transducers and activators of transcription (STAT)1 and protein tyrosine phosphorylation of Janus kinase (JAK)1 suggesting that the JAK–STAT pathway may be the molecular site of action of taxifolin. Finally, taxifolin pre-treatment also potently inhibited IFNγ-induced ICAM-1 expression in a reconstructed human skin equivalent suggesting therapeutic potential of taxifolin in skin pathological conditions related to increased cell adhesion and inflammation.

Effect of plant flavonoids on immune and inflammatory cell function.

The flavonoids are a large group of naturally occurring phenylchromones found in fruits, vegetables, grains, bark, roots, stems, flowers, tea, and wine. Up to several hundred milligrams are consumed daily in the average Western diet. Only limited information is available on the absorption, distribution, metabolism, and excretion of these compounds in man. Some compounds are absorbed, however, and measurable plasma concentrations are achieved which could have pharmacological relevance. A variety of in vitro and in vivo experiments have shown that selected flavonoids possess antiallergic, antiinflammatory, antiviral and antioxidant activities. Moreover, acting by several different mechanisms, particular flavonoids can exert significant anticancer activity including anticarcinogenic properties and even a prodifferentiative activity, amongst other modes of action. Certain flavonoids possess potent inhibitory activity against a wide array of enzymes, but of particular note is their inhibitory effects on several enzyme systems intimately connected to cell activation processes such as protein kinase C, protein tyrosine kinases, phospholipase A2, and others. Evidence suggests that only activated cells are susceptible to the modulating effects of flavonoids, i.e. cells which are responding to a stimulus. The stimulated activities of numerous cell types, including mast cells, basophils, neutrophils, eosinophils, T & B lymphocytes, macrophages, platelets, smooth muscle, hepatocytes, and others, can be influenced by particular flavonoids. On balance, a considerable body of evidence suggests that plant flavonoids may be health-promoting, disease-preventing dietary compounds.

Effects of plant flavonoids and other allelochemicals on insect cytochrome P-450 dependent steroid hydroxylase activity

The plant flavonoids flavone, chrysin, apigenin, kaempferol, morin, quercetin, myricetin and phloretin were found to inhibit in a dose-dependent manner the cytochrome P-450 dependent ecdysone 20-monooxygenase activity associated with adult female Aedes aegypti, wandering stage larvae of Drosophila melanogaster, and fat body and midgut from prewandering and wandering stage last instar larvae of Manduca sexta. The concentrations of these flavonoids required to elicit a 50% inhibition of the steroid hydroxylase activity in all the insects ranged from ca 1 × 10 −5 to 1 × 10 −3 M. In addition, lower concentrations (1 × 10 −6 to 1 × 10 −5 M) of the flavonols kaempfenol, morin, quercetin and myricetin significantly stimulated (50–100% above control) M. sexta fat body ecdysone 20-monooxygenase activity. Other plant allelochemicals examined and found to significantly inhibit insect ecdysone 20-monooxygenase activity include corynanthine, quinidine, and quinine; whereas, indican and mimosine were found to significantly stimulate M. sexta fat body steroid hydroxylase activity. Several allelochemicals were without effect at all concentrations tested. Although none of the compounds tested in this study elicited effects at very low concentrations (1 × 10 −9 to 1 × 10 −8 M), the in vitro monooxygenase radioassay does hold considerable promise as a screening tool for the detection and identification of plant allelochemicals which may function as biopesticides affecting insect ecdysteroidogenesis.

571 The effect of plant flavonoids on eosinophil degranulation

571 The effect of plant flavonoids on eosinophil degranulation

Effect of plant flavonoids on microsome catalyzed reactions of aflatoxin B 1 leading to activation and DNA adduct formation

Twenty-six plant phenolic flavonoids were tested for their ability to modulate microsome mediated activation of aflatoxin B 1 (AFB 1) and covalent adduct formation of activated metabolites with DNA. Some of the flavonoids were observed to inhibit both the reactions very significantly. A few of these showed inhibition of these reactions at varying degrees while others were inactive. Structurally, polyhydroxy flavonols such as robinetin, quercetin, fisetin and morin were found to be very active. Methylation and glycosylation usually rendered the flavonoid less active or inactive. With active flavonoids DNA adduct formation appeared to be modulated through their action on microsomal enzymes, and this could form a basis to counteract the carcinogenic action of aflatoxin B 1.