[Polymethoxylated flavonoids activate cystic fibrosis transmembrane conductance regulator chloride channel].

Cystic fibrosis transmembrane conductance regulator (CFTR), a cAMP-dependent chloride channel, plays key roles in fluid secretion in serous epithelial cells. Previously, we identified two polymethoxylated flavonoids, 3',4',5,5',6,7-hexamethoxyflavone (HMF) and 5-hydroxy-6,7,3',4'-tetramethoxyflavone (HTF) which could potentiate CFTR chloride channel activities. The present study was aimed to investigate the potentiation effects of HMF and HTF on CFTR Cl(-) channel activities by using a cell-based fluorescence assay and the short circuit Ussing chamber assay. The results of cell-based fluorescence assay showed that both HMF and HTF could dose-dependently potentiate CFTR Cl(-) channel activities in rapid and reversible ways, and the activations could be reversed by the CFTR blocker CFTRinh-172. Notably, HMF showed the highest affinity (EC50 = 2 µmol/L) to CFTR protein among the flavonoid CFTR activators identified so far. The activation of CFTR by HMF or HTF was forskolin (FSK) dependent. Both compounds showed additive effect with FSK and 3-Isobutyl-1-methylx (IBMX) in the activation of CFTR, while had no additive effect with genistein (GEN). In ex vivo studies, HMF and HTF could stimulate transepithelial Cl(-) secretion in rat colonic mucosa and enhance fluid secretion in mouse trachea submucosal glands. These results suggest that HMF and HTF may potentiate CFTR Cl(-) channel activities through both elevation of cAMP level and binding to CFTR protein pathways. The results provide new clues in elucidating structure and activity relationship of flavonoid CFTR activators. HMF might be developed as a new drug in the therapy of CFTR-related diseases such as bronchiectasis and habitual constipation.

Nobiletin suppresses cell viability through AKT pathways in PC-3 and DU-145 prostate cancer cells.

BACKGROUND: Nobiletin is a non-toxic dietary flavonoid that possesses anti-cancer properties. Nobiletin has been reported to reduce the risk of prostate cancer, but the mechanism is not well understood. In this study, we investigated the effects of nobiletin in prostate cancer cell lines PC-3 and DU-145. METHODS: Nobiletin was isolated from a polymethoxy flavonoid mixture using HPLC, cell viability was analyzed with MTS-based assays. Protein expression was examined by ELISA and western blotting. Gene expression was examined by luciferase assay. And the pathways were examined by manipulating genetic components with plasmid transfection. RESULTS: Data showed that nobiletin decreased cell viability in both prostate cell lines, with a greater reduction in viability in PC-3 cells. HIF-1α expression and AKT phosphorylation were decreased in both cell lines. The VEGF expression was inhibited in PC-3 but not DU-145 cells. cMyc expression was decreased in DU-145 cells. Nobiletin down-regulated NF-κB (p50) expression in nuclei of DU145 cells but not whole cells. It also suppressed NF-κB expression in both whole cells and nuclei of PC-3 cells. Increasing HIF-1α levels reversed nobiletin's inhibitory effects on VEGF expression, and up-regulating AKT levels reversed its inhibitory effects on HIF-1α expression. We speculate that AKT influences cell viability probably by its effect on NF-κB in both prostate cells. The effect of nobiletin on VEGF expression in PC-3 cell lines was through the AKT/HIF-1α pathway. CONCLUSION: Taken together, our results show that nobiletin suppresses cell viability through AKT pathways, with a more profound effect against the more metastatic PC-3 line. Due to this enhanced action against a more malignant cell type, nobiletin may be used to improve prostate cancer survival rates.

In vitro and in vivo evaluation of a novel antiherpetic flavonoid, 4'-phenylflavone, and its synergistic actions with acyclovir.

The development of therapeutic agents for preventing herpes simplex virus (HSV) infections has become urgently necessary because of the increasing incidence of this virus and its role as a cofactor in the transmission of human immunodeficiency virus infection. We have evaluated the antiviral activities of a series of natural and synthetic flavonoids and found that a synthetic flavonoid, 4'-phenylflavone, showed the highest activity against acyclovir (ACV)-sensitive and ACV-resistant strains of HSV-1, as well as HSV-2, with a selectivity index of 213, 35 and 55, respectively. Although the attachment and penetration of HSV-1 to host cells and the synthesis of viral proteins were not inhibited, the infectivity of the virus and the amount of progeny virus released were reduced by 4'-phenylflavone treatment in a dose-dependent manner. 4'-Phenylflavone plus ACV synergistically inhibited the replication of HSV-1. This flavonoid also showed efficacy in vivo and potentiated the antiherpetic effect of ACV in a mouse model of genital herpes. Our results suggest that 4'-phenylflavone might be useful as a candidate for the development of novel antiherpetic therapeutics.

Higher dietary flavone, flavonol, and catechin intakes are associated with less of an increase in BMI over time in women: a longitudinal analysis from the Netherlands Cohort Study.

BACKGROUND: Dietary flavonoids are suggested to have antiobesity effects. Prospective evidence of an association between flavonoids and body mass index (BMI) is lacking in general populations. OBJECTIVE: We assessed this association between 3 flavonoid subgroups and BMI over a 14-y period in 4280 men and women aged 55-69 y at baseline from the Netherlands Cohort Study. DESIGN: Dietary intake was estimated at baseline (1986) by a validated food-frequency questionnaire. BMI was ascertained through self-reported height (in 1986) and weight (in 1986, 1992, and 2000). Analyses were based on sex-specific quintiles for the total intake of 6 catechins and of 3 flavonols/flavones. Linear mixed effect modeling was used to assess longitudinal associations in 3 adjusted models: age only, lifestyle (age, energy intake, physical activity, smoking status, alcohol intake, type 2 diabetes, and coffee consumption), and lifestyle and diet (vegetables, fruit, fiber, grains, sugar, dessert, and dieting habits). RESULTS: After adjustment for age and confounders, the BMI (kg/m(2)) of women with the lowest intake of total flavonols/flavones and total catechins increased by 0.95 and 0.77, respectively, after 14 y. Women with the highest intake of total flavonols/flavones and total catechins experienced a significantly lower increase in BMI of 0.40 and 0.31, respectively (between group difference: P < 0.05). This difference remained after additional adjustment for dietary determinants and after stratification of median baseline BMI. In men, no significant differences in BMI change were observed over the quintiles of flavonoid intake after 14 y. CONCLUSION: Our results suggest that flavonoid intake may contribute to maintaining body weight in the general female population.

Involvement of extracellular signal-regulated kinase in nobiletin-induced melanogenesis in murine B16/F10 melanoma cells.

Nobiletin contributes to pharmacological activities such as anti-cancer and anti-inflammatory effects, but little is known about its effect on melanogenesis. In this study, we found that nobiletin increased melanin content and tyrosinase activity in murine B16/F10 melanoma cells. Furthermore, inhibition of the extracellular signal-regulated kinase (ERK) pathway with U0216 resulted in inhibition of nobiletin-induced melanin synthesis and tyrosinase expression.

Isolation and syntheses of polymethoxyflavones and hydroxylated polymethoxyflavones as inhibitors of HL-60 cell lines.

Fifteen polymethoxyflavones (PMFs) and hydroxylated PMFs were isolated from sweet orange (Citrus sinensis) peel extract and synthesized to investigate their biological activity. All obtained compounds were tested in HL-60 cancer cell proliferation and apoptosis induction assays. While some PMFs and hydroxylated PMFs had moderate anti-carcinogenic activities, 5-hydroxy-6,7,8,3',4'-pentamethoxyflavone and 5-hydroxy-3,6,7,8,3',4'-hexamethoxyflavone showed strong inhibitory activities against the proliferation and induced apoptosis of HL-60 cell lines.

Phenolic constituents of Celosia cristata L. susceptible to spinach root rot pathogen Aphanomyces cochlioides.

Cochliophilin A (5-hydroxy-6,7-methylenedioxyflavone, 1), known as a host-specific attractant towards the zoospores of Aphanomyces cochlioides, a cause of root rot and damping-off diseases of Chenopodiaceae, was found in the Amaranthaceae plant, Celosia cristata, that is susceptible to the pathogen. The content of 1 in Celosia seedlings was quantified as 1.4 microg/g fresh weight. A new isoflavone, cristatein (5-hydroxy-6-hydroxymethyl-7,2'-dimethoxyisoflavone, 2), and five known flavonoids were also identified.