Xanthohumol impairs glucose uptake by a human first-trimester extravillous trophoblast cell line (HTR-8/SVneo cells) and impacts the process of placentation.

In this study, we aimed to investigate modulation of glucose uptake by the HTR-8/SVneo human first-trimester extravillous trophoblast cell line by a series of compounds and to study its consequences upon cell proliferation, viability and migration. We observed that uptake of (3)H-deoxy-d-glucose ((3)H-DG; 10 nM) was time-dependent, saturable, inhibited by cytochalasin B (50 and 100 µM), phloretin (0.5 mM) and phloridzin (1 mM), insulin-insensitive and sodium-independent. In the short term (30 min), neither 5-HT (100-1000 µM), melatonin (10 nM) nor the drugs of abuse ethanol (100 mM), nicotine (100 µM), cocaine (25 µM), amphetamine (10-25 µM) and 3,4-methylenedioxy-N-methamphetamine (10 µM) affected (3)H-DG uptake, while dexamethasone (100-1000 µM), fluoxetine (100-300 µM), quercetin, epigallocatechin-3-gallate (30-1000 µM), xanthohumol (XH) and resveratrol (1-500 µM) decreased it. XH was the most potent inhibitor [IC50 = 3.55 (1.37-9.20) µM] of (3)H-DG uptake, behaving as a non-competitive inhibitor of (3)H-DG uptake, both after short- and long-term (24 h) treatment. The effect of XH (5 µM; 24 h) upon (3)H-DG uptake involved mammalian target of rapamycin, tyrosine kinases and c-Jun N-terminal kinases intracellular pathways. Moreover, XH appeared to decrease cellular uptake of lactate due to inhibition of the monocarboxylate transporter 1. Additionally, XH (24 h; 5 µM) decreased cell viability, proliferation, culture growth and migration. The effects of XH upon cell viability and culture growth, but not the antimigratory effect, were mimicked by low extracellular glucose conditions and reversed by high extracellular glucose conditions. We thus suggest that XH, by inhibiting glucose cellular uptake and impairing HTR-8/SVneo cell viability and proliferation, may have a deleterious impact in the process of placentation.

Biotransformation of phloretin by amylosucrase yields three novel dihydrochalcone glucosides.

Glycosylation is one of the most important tailoring reactions for natural products. It typically exerts profound direct or indirect effects on their biological activity. The dihydrochalcone phloretin and its known sugar derivatives, particularly phlori(d)zin, have been shown to influence various cellular processes. We found that a non-Leloir glycosyltransferase, amylosucrase from Neisseria polysaccharea, is an excellent catalyst for the stereospecific glucosylation of phloretin at the 4' position. Three novel phloretin derivatives were obtained, the first ones in which the sugar-aglycone bond possesses the configuration. A first biological characterization in a cell viability assay showed that each sugar attachment reduced the compound toxicity approximately two-fold.

Haematological and histopathological effects of apigenin, phloretin and myricetin based on uterotrophic assay in immature Wistar female albino rats.

In this study, it is aimed to determine the histopathological and haematological effects of apigenin, phloretin and myricetin on Wistar immature female rats using Tier 2 of the uterotrophic assay. The female rats were divided into 17 groups with 6 rats in each group. There was a negative control group and positive control dose groups that contained 0.07 µg/kg/day, 0.7 µg/kg/day and 7 µg/kg/day of ethinyl estradiol (EE), 0.7 µg/kg/day 17α-ethinyl estradiol + 1 mg/kg/day tamoxifen and genistein. The other dose groups contain 1 mg/kg/day, 10 mg/kg/day and 100 mg/kg/day of apigenin, myricetin and phloretin. All chemicals had been given to Wistar immature female rats with oral gavage for three consecutive days. At the end of the study, blood samples were analysed for haematological parameters. Tissue samples that were taken from the liver, kidney, spleen and thyroid were histopathologically and histomorphometrically examined. There were no significant differences between oil control and other dose groups for glomerular histomorphometry. However, there were significant differences for thyroid histomorphometry. Especially, 10 and 100 mg/kg/day of phloretin dose groups had a significant increase in colloid surface area in thyroid compared with the 1 mg/kg/day of phloretin and oil control groups. Significant histopathological changes (congestion, degeneration, fibrosis and mononuclear cell infiltration) were noted in the tissue specimens obtained from the treatment groups compared with the control group. According to the results of the haematological analysis of the groups, especially the values of erythrocytes and haematocrit were increased significantly in most of the dose groups according to the oil control group.

The estrogenic effects of apigenin, phloretin and myricetin based on uterotrophic assay in immature Wistar albino rats.

Chemicals that occur in vegetal food and known as phytoestrogens, because of their structures similarity to estrogen, have benefits on chronic diseases. Despite this, when they are taken at high amounts, they can cause harmful effects on endocrine system of human and animals. In this study, it has been intended to determine the estrogenic potencies of phytoestrogens apigenin, phloretin and myricetin whose affinities for estrogen receptors in vitro. The female rats divided into 17 groups, each containing six rats. There was a negative control group and there were positive control dose groups which contains ethinyl estradiol, ethinyl estradiol+tamoxifen and genistein. The other dose groups which were tested for estrogenic activity contains apigenin, myricetin and phloretin All chemicals have been given to Wistar immature female rats with oral gavage for 3 consecutive days. By using uterotrophic analysis, uterus wet and blotted weights, vaginal opening, uterus length of female rats has been recorded at the end of the experiment. For detect of cell response, luminal epithelium height, gland number and lactoferrin intensity in luminal epithelium of uterus were evaluated. Biochemical analysises in blood were performed. Relative uterus weights of rats in 100 mg/kg/day dose group of myricetin were statistically increased according to vehicle control and positive control groups. In dose groups of apigenin and phloretin it was found that there were cell responses in uterus. All treatment groups had a significant difference in the high intensity of lactoferrin and uterine gland count compared to oil control group. There was no difference between phloretin and apigenin treatment groups in uterine weight statictically. Uterine heights were increased in positive control groups and 100 mg/kg/day dose group of myricetin. Epithelial cell heights were increased in treatment groups except apigenin and phloretin dose groups. There was no difference between all treatment groups in vaginal opening values according to positive control.

The responses of zebrafish (Danio rerio) to high external ammonia and urea transporter inhibition: nitrogen excretion and expression of rhesus glycoproteins and urea transporter proteins.

While adult zebrafish, Danio rerio, possess ammonia and urea transporters (Rh and UT proteins, respectively) in a number of tissues, they are most heavily concentrated within the gills. UT has a diffuse expression pattern within Na+-K+-ATPase (NKA)-type mitochondrion-rich cells and Rh proteins form a network similar to the arrangement seen in pufferfish gills (Nakada et al., 2007b). Rhag expression appeared to be limited to the pillar cells lining the blood spaces of the lamellae while Rhbg was localized to the outer layer of both the lamellae and the filament, upon the pavement cells. Exposure to high external ammonia (HEA) or phloretin increased tissue levels of ammonia and urea, respectively, in adult and juvenile zebrafish; however, the responses to these stressors were age dependent. HEA increased mRNA levels for a number of Rh proteins in embryos and larvae but did not elicit similar effects in adult gills, which appear to compensate for the unfavourable ammonia excretory gradient by increasing expression of V-type H+-ATPase. Phloretin exposure increased UT mRNA levels in embryos and larvae but was without effect in adult gill tissue. Surprisingly, in both adults and juveniles, HEA increased the mRNA expression of UT and phloretin increased the mRNA expression of Rh proteins. These results imply that, in zebrafish, there may be a tighter link between ammonia and urea excretion than is thought to occur in most teleosts.

Antimicrobial natural products as beta-ketoacyl-acyl carrier protein synthase III inhibitors.

Beta-ketoacyl-acyl carrier protein synthase III (KAS III) initiates bacterial fatty acid biosynthesis, making it one of the most promising condensing enzymes. In a previous study, we developed three pharmacophore maps from receptor-oriented pharmacophore-based in silico screening and proposed a potent antimicrobial inhibitor for KAS III. Using these pharmacophore maps, we examined a natural product database and chose 4 natural compounds as possible KAS III inhibitors. Here, we propose that YKAF01 (3,6-dihydroxyflavone) and YKAF04, 3-(4-hydroxyphenyl)-1-(2,4,6-tri-hydroxyphenyl)propan-1-one (or 4,2',4',6'-tetra-hydroxychalcone, phloretin) are potent antimicrobial inhibitors of KAS III with high binding affinity. In particular, these compounds display an excellent antimicrobial effect against Staphylococcus aureus and MRSA in the range of 16-32 microM.

Comparative quantitative structure toxicity relationships for flavonoids evaluated in isolated rat hepatocytes and HeLa tumor cells.

Quantitative structure activity relationship (QSAR) equations were obtained to describe the cytotoxicity of 22 polyphenols using toxicity (logLD50) representing the concentration for 50% cell survival in 2 h for isolated rat hepatocytes, log P representing octanol/water partitioning, and/or E(p/2) representing redox potential. One- and two-parameter equations were derived for the quantitative structure toxicity relationships (QSTR) for polyphenol induced hepatocyte cytotoxicity: e.g. log C(hepatocyte) (microM)=-0.65(-0.08)log P+4.12(-0.15) (n=19, r(2)=0.80, s=0.33, P<1 x 10(-6)). One- and two-parameter QSAR equations were also derived to describe the inhibitory effects of 13 polyphenols on tumor cell growth when incubated with HeLa cells for 3 days: e.g. log C(tumor) (microM)=-0.34(+/-0.04)log P+2.40(+/-0.07) (n=11, r(2)=0.90, s=0.13, P<1 x 10(-5)). These findings point to lipophilicity as a major characteristic determining polyphenol cytotoxicity. The E(p/2) also played a significant role in polyphenol cytotoxicity towards both cell types: e.g. log C(hepatocyte) (microM)=-0.60(+/-0.06)log P+2.01(+/-0.43)E(p/2) (V)+3.86(+/-0.12) (n=9, r(2)=0.96, s=0.15, P<0.005). The involvement of log P and E(p/2) could be explained if polyphenol cytotoxicity involved the formation of radicals, which interacted with the mitochondrial inner membrane resulting in a disruption of the membrane potential.

The efficacy of phloridzin and phloretin on tumor cell growth.

This study utilized phloridzin (P1) and its aglucone phloretin (P2), two known inhibitors of glucose transmembrane transport, to inhibit tumor cell growth in vivo. The efficacy of hydrazine sulfate as an anticachexic agent was also evaluated. Utilizing the rat mammary adenocarcinoma and Fischer bladder cell carcinoma cell lines, it has been shown that the i.p. administration of P1 and P2 can produce significant differences in mean tumor diameters as compared to the untreated controls.