Natriuretic peptide receptor-C releases and activates guanine nucleotide-exchange factor H1 in a ligand-dependent manner.

Although natriuretic peptide receptor-C (NPR-C) is involved in the clearance of natriuretic peptides from plasma, it also possesses other physiological functions, such as inhibition of adenylyl cyclase activity through Gαi. However, the physiological roles and intracellular signaling pathways of NPR-C have yet been not fully elucidated. In this study, we identified a RhoA-specific guanine nucleotide-exchange factor, GEF-H1, as a novel binding protein of NPR-C. We demonstrated that endogenous NPR-C interacted with GEF-H1 in HeLa cells, and that the interaction between NPR-C and GEF-H1 was dependent on a 37-amino acid cytoplasmic region of NPR-C. In contrast, another natriuretic peptide receptor, NPR-A, which includes the kinase homology and guanylyl cyclase domains in the intracellular region, did not interact with GEF-H1. We also revealed that the ligands of NPR-C (i.e., ANP, CNP, and osteocrin) caused dissociation of GEF-H1 from NPR-C. Furthermore, osteocrin treatment induced phosphorylation of GEF-H1 at Ser-886, enhanced the interaction of GEF-H1 with 14-3-3, and increased the amount of activated GEF-H1. These findings strongly supported that NPR-C may be involved in diverse physiological roles by regulating GEF-H1 signaling.

Degradation Index for quality evaluation of commercial dietary supplements of bilberry extract.

In recent years, many anthocyanin-containing dietary supplements of various dosages and formulations have been sold through advertising their large number of beneficial effects. On the other hand, there is an increased risk of distributing deteriorated supplements to consumers due to lax regulations, because in Japan these supplements are classified as food. Spectrophotometric methods are commonly used to control the quality of supplements. However, these methods have limitations with regard to assessing deterioration. In this study, we evaluated a new index for detection of deteriorated products. The stability of 3 formulations and the quality of 20 supplements were investigated by ultra-high performance liquid chromatography, which is superior to spectrophotometry for identifying and quantifying individual anthocyanins. The stability was not only affected by storage temperature but also by formulation. We defined "Degradation Index" (DI) as an indicator of the deterioration of supplements. Of 20 supplements investigated, the DI of 5 supplements was more than 3-fold the value of Bilberon-25, and the worst one was 12.7-fold. These results suggest that DI could be a useful quality control index for detecting deteriorated supplements.

Protective effects of natsumikan (Citrus natsudaidai) extract on acetaminophen-induced lethal hepatotoxicity in mice.

BACKGROUND: Like other citrus fruits, natsumikan (Citrus natsudaidai) contains several antioxidative nutrients which occur in higher concentrations in the peel than in the pulp. A high dose of acetaminophen (APAP) generates highly reactive intermediates and causes fatal liver injury. In this study, we examined whether an extract from immature natsumikan peel prevents lethal hepatotoxicity induced by a lethal dose of APAP in mice. MATERIALS AND METHODS: Male ICR mice were treated orally with natsumikan extract (300 and 1,000 mg/kg) 2, 26, and 50 h before single oral APAP (300 mg/kg) administration. Mice were fasted for 18 h before APAP treatment, but given tap water ad libitum. Survival was assessed for 24 h after APAP treatment. RESULTS: Following administration of 300 mg/kg APAP, all mice died within 6 h. However, pretreatment with natsumikan extract (300 and 1,000 mg/kg) or silymarin (300 and 1,000 mg/kg) increased the survival rate to 16.7%, 33.3%, 16.7%, and 50%, respectively, at 24 h. CONCLUSION: The results suggest that natsumikan has a protective effect on APAP-induced lethal hepatotoxicity.

Anthocyanins, but not anthocyanidins, from bilberry (Vaccinium myrtillus L.) alleviate pruritus via inhibition of mast cell degranulation.

We have previously reported that bilberry anthocyanins exhibit an anti-pruritic effect in a mouse model of allergic contact dermatitis. It has been reported that anthocyanins are particularly sensitive to thermal treatment and are easily hydrolyzed to anthocyanidins when exposed to high temperatures. The objective of this study was to compare the anti-pruritic effect of anthocyanin-rich quality-controlled bilberry extract and anthocyanidin-rich degraded extract using a mouse model of allergic contact dermatitis. BALB/c mice with allergic contact dermatitis induced by 4 weeks of repeated application of 2,4,6-trinitro-1-chlorobenzene (TNCB) were administered Bilberon-25 orally for 4 weeks after sensitization with TNCB. The effect of Bilberon-25 on pruritus was evaluated by measurement of scratching behavior. RBL-2H3 mast cells were used to investigate the effect of Bilberon-25 on degranulation in 48/80-stimulated mast cells. Compared with nonheated Bilberon-25, the proportion of anthocyanins in heated Bilberon-25 decreased, and the proportion of anthocyanidins was increased in heated-time dependent manner. Treatment with non-heated Bilberon-25 significantly attenuated the TNCB-induced increase in scratching behavior, whereas treatment with 2 h-heated Bilberon-25 did not. Moreover, 300 µg/mL nonheated Bilberon-25 showed significant inhibition of degranulation in RBL-2H3 mast cells, whereas 2 h-heated Bilberon-25 had no effect at any concentration studied. It is assumed that the inhibitory effect of bilberry anthocyanins on pruritus might be mediated, at least in part, by its inhibitory effect on mast cell degranulation. In conclusion, the anthocyanin-rich but not anthocyanidin-rich bilberry extract may be a useful dietary supplement for skin diseases involving pruritic symptoms, such as chronic allergic contact dermatitis, atopic dermatitis, and rhinitis.

Antidepressant-like effects of young green barley leaf (Hordeum vulgare L.) in the mouse forced swimming test.

BACKGROUND: Young green barley leaf is one of the richest sources of antioxidants and has been widely consumed for health management in Japan. In this study, we examined whether oral administration of young green barley leaf has an antidepressant effect on the forced swimming test in mice. MATERIALS AND METHODS: Mice were individually forced to swim in an open cylindrical container, one hour after oral administration of young green barley leaf (400 or 1000 mg / kg) or imipramine (100 mg / kg). Expression of mRNA for nerve growth factor (NGF), brain-derived neurotrophic factor, and glucocorticoid receptor in the brain was analyzed using real-time quantitative polymerase chain reaction (PCR). RESULTS: There was a significant antidepressant-like effect in the forced swimming test; both 400 and 1000 mg / kg young green barley leaves, as well as the positive control imipramine (100 mg / kg), reduced the immobility duration compared to the vehicle group. The expression of mRNA for NGF detected in the hippocampus immediately after the last swimming test was higher than that in the non-swimming group (Nil). Oral administration of imipramine suppressed this increase to the level of the Nil group. Young green barley leaf (400 and 1000 mg / kg) also showed a moderate decrease in the expression of mRNA for NGF, in a dose-dependent manner. CONCLUSION: Oral administration of young green barley leaf is able to produce an antidepressant-like effect in the forced swimming test. Consequently it is possible that the antidepressant-like effects of the young green barley leaf are, at least in part, mediated by an inhibition of the increase in the hippocampus levels of NGF.

Extract from peel of Citrus natsudaidai alleviates experimental chronic allergic dermatitis in mice.

BACKGROUND: Citrus natsudaidai (natsumikan) is a typical citrus fruit containing several antioxidative nutrients which are found in higher concentration in the peel than in the pulp of the fruit. In this study, we examined whether extract from immature natsumikan peel prevents development of chronic allergic dermatitis in mice. MATERIALS AND METHODS: Chronic allergic dermatitis was induced by repeated application of 2, 4, 6-trinitro-1-chlorobenzene in BALB/c mice and natsumikan was administrated orally for 30 days. Ear swelling and dermatitis score were measured after each challenge. The level of derivative-reactive oxygen metabolites (d-ROM) in serum was measured on day 30. RESULTS: Treatment of natsumikan significantly attenuated the increase in ear swelling and improved dermatitis scores. In addition, increases in serum d-ROM were attenuated by a treatment of natsumikan. Although the routine treatment with dexamethasone resulted in a clear and significant reduction in body weight, natsumikan treatment did not have such effects. CONCLUSION: Immature natsumikan peel is beneficial for the treatment of chronic allergic dermatitis.

Anthocyanins from bilberry (Vaccinium myrtillus L.) alleviate pruritus in a mouse model of chronic allergic contact dermatitis.

BACKGROUND: Bilberry (Vaccinium myrtillus L.) is one of the richest sources of anthocyanins which are known to have anticancer, wound healing and anti-allergic effects. Here, we examined whether bilberry extract (Bilberon-25) alleviates pruritus in a mouse model of chronic allergic contact dermatitis. MATERIALS AND METHODS: BALB/c mice with chronic allergic contact dermatitis induced by 3 weeks of repeated application of 2,4,6-trinitro-1-chlorobenzene (TNCB) were administered Bilberon-25 orally for 3 weeks after sensitization with TNCB. The effects of Bilberon-25 on pruritus and inflammation were evaluated by measurement of scratching behaviour and ear swelling, respectively. RESULTS: Treatment with Bilberon-25 significantly attenuated the TNCB-induced increase in scratching behaviour, but dexamethasone did not. In contrast, ear swelling was ameliorated by dexamethasone treatment, and significantly decreased by Bilberon-25. Repeated application of TNCB induced a shift in the cutaneous cytokine milieu from a T helper cell type (Th)1 to a Th2 profile; Bilberon-25 and dexamethasone alleviated this Th2 predominance of the lesional skin. CONCLUSION: Anthocyanins from bilberry might be beneficial for the treatment of chronic pruritus which can occur in patients with inflammatory skin diseases such as atopic dermatitis.

Stereoselective multimodal transformations of planar chiral 9-membered diallylic amides.

Intermolecular reactions of planar chiral 9-membered diallylic amides provide a variety of bicyclic compounds with central chiralities in a stereospecific fashion with high group selectivity. Lewis-acid-promoted intramolecular reactions of the obtained bicyclic compounds provide transannular products in a stereospecific fashion. Furthermore, a direct transannular reaction of diallylic amide involving sequential intermolecular-intramolecular reactions has been developed.

Protective effects of goldenseal (Hydrastis canadensis L.) on acetaminophen-induced hepatotoxicity through inhibition of CYP2E1 in rats.

BACKGROUND: Goldenseal (Hydrastis canadensis L.) inhibits various cytochrome P450 (CYP) isoforms such as CYP2C9, CYP2C19, CYP2D6, CYP2E1, and CYP3A in vitro. High doses of acetaminophen (APAP) generate the highly reactive intermediate, N-acetyl-p-benzoquinone imine (NAPQI), catalyzed mainly by CYP2E1. The aim of this study was to investigate the hepatoprotective effects of orally administrated goldenseal against APAP-induced acute liver failure (ALF) via inhibition of CYP2E1. MATERIALS AND METHODS: Male Wistar rats were treated orally with goldenseal (300 and 1000 mg/kg) 2, 18, and 26 h before and 6 h after oral APAP (400 mg/kg) administration. Serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities as well as serum APAP concentration were evaluated. RESULTS: Goldenseal extract inhibited CYP1A2, CYP2D6, CYP2E1, and CYP3A activity, and the inhibitory effect on CYP2E1 was the strongest (IC(50) 4.32 µg/mL). Treatment with goldenseal (300 mg/kg) significantly attenuated the APAP-induced increase in serum AST and ALT, and the hepatoprotective effect of goldenseal was stronger than that of silymarin (200 mg/kg). Moreover, serum APAP concentration was increased by goldenseal treatment, presumably as a result of the inhibitory effect of goldenseal on the metabolism of APAP to NAPQI. CONCLUSION: These results suggest that goldenseal ameliorates APAP-induced ALF and that this protection can likely be attributed to the inhibition of CYP2E1 activity, which generates the highly reactive intermediate of APAP.

Histological protection by cilnidipine, a dual L/N-type Ca(2+) channel blocker, against neurotoxicity induced by ischemia-reperfusion in rat retina.

Although a blockade or lack of N-type Ca(2+) channels has been reported to suppress neuronal injury induced by ischemia-reperfusion in several animal models, information is still limited regarding the neuroprotective effects of a dual L/N-type Ca(2+) channel blocker, cilnidipine. We histologically examined the effects of cilnidipine on neuronal injury induced by ischemia-reperfusion, intravitreous N-methyl-D-aspartate (NMDA) (200nmol/eye) and intravitreous NOC12 (400nmol/eye), an nitric oxide donor, in the rat retina, and compared its effects with those of omega-conotoxin MV IIA, an N-type Ca(2+) channel blocker and amlodipine, an L-type Ca(2+) channel blocker. Morphometric evaluation at 7 days after ischemia-reperfusion showed that treatment with cilnidipine (100microg/kg, i.v. or 0.5pmol/eye, intravitreous injection) prior to ischemia dramatically reduced the retinal damage. Treatment with omega-conotoxin MV IIA before ischemia (0.1pmol/eye, intravitreous injection) significantly reduced the retinal damage. However, amlodipine (30-100microg/kg, i.v. or 0.1-1pmol/eye, intravitreous injection) did not show any protective effects. Treatment with cilnidipine (100microg/kg, i.v.) reduced the retinal damage induced by intravitreous NMDA, but not NOC12. These results suggest that cilnidipine reduces Ca(2+) influx via N-type Ca(2+) channels after NMDA receptors activation and then protects neurons against ischemia-reperfusion injury in the rat retina in vivo. Cilnidipine may be useful as a therapeutic drug against retinal diseases which cause neuronal cell death, such as glaucoma and central retinal vessel occlusion.

Planar chiral cyclic amine and its derivatives: synthesis and stereochemical behavior.

Nine-membered diallylic cyclic amines and amides have remarkably stable planar chirality. The transformation of enantiomerically enriched amides provides optically active nitrogen heterocycles containing stereogenic centers in a stereospecific fashion.