New water-soluble carbamate ester derivatives of resveratrol

Low bioavailability severely hinders exploitation of the biomedical potential of resveratrol. Extensive phase-II metabolism and poor water solubility contribute to lowering the concentrations of resveratrol in the bloodstream after oral administration. Prodrugs may provide a solution—protection of the phenolic functions hinders conjugative metabolism and can be exploited to modulate the physicochemical properties of the compound. We report here the synthesis and characterization of carbamate ester derivatives of resveratrol bearing on each nitrogen atom a methyl group and either a methoxy-poly(ethylene glycol)-350 (mPEG-350) or a butyl-glucosyl promoiety conferring high water solubility. Ex vivo absorption studies revealed that the butyl-glucosyl conjugate, unlike the mPEG-350 one, is able to permeate the intestinal wall. In vivo pharmacokinetics confirmed absorption after oral administration and showed that no hydrolysis of the carbamate groups takes place. Thus, sugar groups can be attached to resveratrol to obtain soluble derivatives maintaining to some degree the ability to permeate biomembranes, perhaps by facilitated or active transport

Cytotoxicity of a mitochondriotropic quercetin derivative: Mechanisms

AbstractThe mitochondriotropic compound 7-O-(4-triphenylphosphoniumbutyl)quercetin iodide (Q-7BTPI) in the μM concentration range caused necrotic death of cultured cells by acting as a prooxidant, with generation of superoxide anion in the mitochondria. Externally added membrane-permeating superoxide dismutase or catalase largely prevented death. Rescue by permeant catalase indicates that the toxicant is H2O2, or reactive species derived from it. Rescue by permeant dismutase suggests the possibility of a chain mechanism of H2O2 production, in which dismutation of superoxide constitutes a termination step. Oxidative stress was due to the presence of free phenolic hydroxyls and to accumulation in mitochondria, since the analogous mitochondriotropic per-O-methylated compound -3,3′,4′,5-tetra-O-methyl,7-O-(4-triphenylphosphoniumbutyl) quercetin iodide (QTM-7BTPI)—or Quercetin itself induced no or little superoxide production and cell death. Q-7BTPI did not cause a significant perturbation of the mitochondrial transmembrane potential or of respiration in cells. On the other hand its presence led to inhibition of glutathione peroxidase, an effect expected to accentuate oxidative stress by interfering with the elimination of H2O2. An exogenous permeable glutathione precursor determined a strong increase of cellular glutathione levels but did not rescue the cells. Death induction was selective for fast-growing C-26 tumoral cells and mouse embryonic fibroblasts (MEFs) while sparing slow-growing MEFs. This suggests a possible use of Q-7BTPI as a chemotherapeutic agent

MONIKULTTUURINEN KASVATUSKUMPPANUUS VARHAISKASVATUKSESSA : Monikulttuuristen perheiden vanhempien näkemyksiä

Opinnäytetyön tarkoituksena on kuvailla monikulttuuristen perheiden vanhempien kokemuksia ja toiveita kasvatuskumppanuudesta varhaiskasvatuksessa. Opinnäytetyö on kvalitatiivinen ja se on toteutettu teemahaastatteluiden avulla. Haastattelut on tehty yksilöhaastatteluina. Opinnäytetyön toimeksiantajana toimi oululainen päiväkoti. Teoreettinen viitekehys opinnäytetyössä pohjautuu vahvasti kasvatuskumppanuuden periaatteisiin, joita ovat kuuleminen, kunnioitus, luottamus ja dialogi. Lisäksi opinnäytetyössä on teoriaa kulttuurista ja monikulttuurisuudesta. Haastattelurunko sisälsi lähinnä avoimia kysymyksiä, jotka pohjautuivat tietoperustaan. Haastattelut on analysoitu teemoittelun avulla. Teemat olivat samat kuin tietoperustassa. Opinnäytetyön pääteemoja ovat kasvatuskumppanuus ja monikulttuurisuus, jotka sisältävät vielä alateemoja. Tuloksissa nousee esiin pääosin positiiviset kokemukset kasvatuskumppanuudesta varhaiskasvatuksessa. Kasvatuskumppanuus koetaan tärkeänä ja kasvatusvastuuta jaetaan mielellään. Kulttuurieroja ei arjessa huomata juurikaan, mutta perheen kulttuuritausta toivotaan huomioitavan hienovaraisesti, liikaa korostamatta. Johtopäätöksenä voidaan sanoa, että varhaiskasvatukseen ja kasvatuskumppanuuden toteutumiseen ollaan tyytyväisiä.The purpose of this thesis is to describe experiences and wishes of parents of multicultural families about educational partnership in early childhood education. This thesis is qualitative and the material for it was collected with individual theme interviews. The thesis was commissioned by a certain kindergarten from Oulu. The theoretical frame of this thesis includes principles of educational partnership such as hearing, respect, trust and dialog. There is also theory of culture and multiculturalism in this thesis. Open questions of the interview were based on the theoretical frame. The interviews were analyzed by thematic analyzing. Themes were same as in theoretical frame. The main themes of this thesis are educational partnership and multiculturalism which includes subthemes. The results of our thesis show positive experiences in educational partnership and early childhood education. The parents feel the importance of educational partnership and responsibility of raising a child is shared gladly. The parents do not feel cultural differences in everyday life, but there is a wish for sensitive consideration of culture which does not overemphasize the culture. In summary it can be said, that the parents are satisfied with educational partnership and early childhood education

Inhibition of PI-3-K and AKT Amplifies Kv1.3 Inhibitor-Induced Death of Human T Leukemia Cells

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Impaired Mitochondrial ATP Production Downregulates Wnt Signaling via ER Stress Induction.

Wnt signaling affects fundamental development pathways and, if aberrantly activated, promotes the development of cancers. Wnt signaling is modulated by different factors, but whether the mitochondrial energetic state affects Wnt signaling is unknown. Here, we show that sublethal concentrations of different compounds that decrease mitochondrial ATP production specifically downregulate Wnt/β-catenin signaling in vitro in colon cancer cells and in vivo in zebrafish reporter lines. Accordingly, fibroblasts from a GRACILE syndrome patient and a generated zebrafish model lead to reduced Wnt signaling. We identify a mitochondria-Wnt signaling axis whereby a decrease in mitochondrial ATP reduces calcium uptake into the endoplasmic reticulum (ER), leading to endoplasmic reticulum stress and to impaired Wnt signaling. In turn, the recovery of the ATP level or the inhibition of endoplasmic reticulum stress restores Wnt activity. These findings reveal a mechanism that links mitochondrial energetic metabolism to the control of the Wnt pathway that may be beneficial against several pathologies

Synthesis of resveratrol sulfates: turning a nightmare into a dream

Abstract The growing interest in the bioactivity of natural polyphenols and of their metabolites requires pure metabolites to be used in bioassays and as standards in analytical protocols. We report here the synthesis of all five resveratrol sulfates achieved using a known approach of selective protection via silyl ether and sulfation but new reaction conditions and isolation procedures, which result in simplified protocols and greatly improved yields. A rationale for the problems so far encountered in handling and isolating resveratrol sulfates is provided as well as a solution based on avoidance of low pressure conditions during purification/isolation. These conclusions are probably of more general scope and might be usefully taken into consideration for obtaining other phenolic sulfates in high yield

Determination of Quercetin and Resveratrol in Whole Blood-Implications for Bioavailability Studies

Resveratrol (trans-3,4',5-trihydroxystilbene) and quercetin (3,3',4',5,7-pentahydroxyflavone) are two naturally occurring polyphenols with the potential to exert beneficial health effects. Since their low bioavailability is a major obstacle to biomedical applications, efforts are being made to improve their absorption and slow down phase II metabolism. An accurate evaluation of the corresponding levels in the bloodstream is important to assess delivery strategies, as well as to verify claims of efficacy based on in vitro results. In the present work we have optimized a simple method ensuring complete stabilization and extraction of resveratrol and quercetin from whole blood. The suitability of different protocols was evaluated by measuring the recovery of polyphenol and internal standard from spiked blood samples via HPLC/UV analysis. The optimized procedure ensured a satisfactory recovery of both internal standards and compounds. Comparing plasma and whole blood, up to 76% of the analyte, being associated with the cellular fraction, was unaccounted for when examining only plasma. This indicates the importance of analysing whole blood rather than plasma to avoid underestimating polyphenol absorption in bioavailability studies

N-Monosubstituted Methoxy-oligo(ethylene glycol) Carbamate Ester Prodrugs of Resveratrol

Resveratrol is a natural polyphenol with many interesting biological activities. Its pharmacological exploitation in vivo is, however, hindered by its rapid elimination via phase II conjugative metabolism at the intestinal and, most importantly, hepatic levels. One approach to bypass this problem relies on prodrugs. We report here the synthesis, characterization, hydrolysis, and in vivo pharmacokinetic behavior of resveratrol prodrugs in which the OH groups are engaged in an N-monosubstituted carbamate ester linkage. As promoiety, methoxy-oligo(ethylene glycol) groups (m-OEG) (CH3–[OCH2CH2]n–) of defined chain length (n = 3, 4, 6) were used. These are expected to modulate the chemico-physical properties of the resulting derivatives, much like longer poly(ethylene glycol) (PEG) chains, while retaining a relatively low MW and, thus, a favorable drug loading capacity. Intragastric administration to rats resulted in the appearance in the bloodstream of the prodrug and of the products of its partial hydrolysis, confirming protection from first-pass metabolism during absorption

Ester-based precursors to increase the bioavailability of quercetin

Plant polyphenols exhibit a variety of potentially useful biochemical properties in vitro, but their evaluation and clinical exploitation in vivo is hampered by their limited bioavailability. Precursors exhibiting resistance to phase II metabolism during absorption are therefore desirable. We report here the synthesis as well as stability and solubility studies of several ester derivatives of quercetin (3,3',4',5,7-pentahydroxy flavone), most of which comprise an aminoacyl group. To model transepithelial absorption, we tested transport across supported tight monolayers of MDCK-1, MDCK-2, and Caco-2 cells. Quercetin itself was extensively conjugated by all three types of cells. A few of our precursors did not cross the monolayers, but others did, undergoing partial deacylation. No phase II conjugation was observed during transport of these compounds across MDCK or some Caco-2 clones. With other Caco-2 lines complete deacylation occurred, followed by metabolism of quercetin. Since elimination of residual acyl groups is expected to take place in vivo, ester derivatives of polyphenols may constitute a useful method to increase systemic aglycone concentrations