Central and peripheral des-acyl ghrelin regulates body temperature in rats

In the present study using rats, we demonstrated that central and peripheral administration of des-acyl ghrelin induced a decrease in the surface temperature of the back, and an increase in the surface temperature of the tail, although the effect of peripheral administration was less marked than that of central administration. Furthermore, these effects of centrally administered des-acyl ghrelin could not be prevented by pretreatment with [D-Lys3]-GHRP-6 GH secretagogue receptor 1a (GHS-R1a) antagonists. Moreover, these actions of des-acyl ghrelin on body temperature were inhibited by the parasympathetic nerve blocker methylscopolamine but not by the sympathetic nerve blocker timolol. Using immunohistochemistry, we confirmed that des-acyl ghrelin induced an increase of cFos expression in the median preoptic nucleus (MnPO). Additionally, we found that des-acyl ghrelin dilated the aorta and tail artery in vitro. These results indicate that centrally administered des-acyl ghrelin regulates body temperature via the parasympathetic nervous system by activating neurons in the MnPO through interactions with a specific receptor distinct from the GHS-R1a, and that peripherally administered des-acyl ghrelin acts on the central nervous system by passing through the blood–brain barrier, whereas it exerts a direct action on the peripheral vascular system.     

Heme-binding properties of heme detoxification protein from Plasmodium falciparum

The heme detoxification protein of the malaria parasite Plasmodium falciparum is involved in the formation of hemozoin, an insoluble crystalline form of heme. Although the disruption of hemozoin formation is the most widely used strategy for controlling the malaria parasite, the heme-binding properties of heme detoxification protein are poorly characterized. In this study, we established a method for the expression and purification of the non-tagged protein and characterized heme-binding properties. The spectroscopic features of non-tagged protein differ from those of the His-tagged protein, suggesting that the artificial tag interferes with the properties of the recombinant protein. The purified recombinant non-tagged heme detoxification protein had two heme-binding sites and exhibited a spectrum typical of heme proteins. A mechanism for hemozoin formation is proposed.     

Structure–activity relationships of bisphenol A analogs at estrogen receptors (ERs): Discovery of an ERα-selective antagonist

Our multi-template approach for drug discovery, focusing on protein targets with similar fold structures, has yielded lead compounds for various targets. We have also shown that a diphenylmethane skeleton can serve as a surrogate for a steroid skeleton. Here, on the basis of those ideas, we hypothesized that the diphenylmethane derivative bisphenol A (BPA) would bind to the ligand-binding domain of estrogen receptors (ERs) in a similar manner to estradiol and act as a steroid surrogate. To test this idea, we synthesized a series of BPA analogs and evaluated their structure-activity relationships, focusing on agonistic/antagonistic activities at ERs and ERα/ERβ subtype selectivity. Among the compounds examined, 18 was found to be a potent ERα-antagonist with high selectivity over ERβ and androgen receptor under our assay conditions. A computational docking study suggested that 18 would bind to the antagonistic conformation of ERα. ERα-selective antagonists, such as 18, are candidate agents for treatment of breast cancer.     

Structure–activity studies on the side chain of a simplified analog of aplysiatoxin (aplog-1) with anti-proliferative activity

We have recently developed a simplified analog of aplysiatoxin (aplog-1) as an activator of protein kinase C (PKC) with anti-proliferative activity like bryostain 1. To identify sites in aplog-1 that could be readily modified to optimize therapeutic performance and to develop a molecular probe for examining the analog’s mode of action, substituent effects on the phenol ring were systematically examined. Whereas hydrophilic acetamido derivatives were less active than aplog-1 in inhibiting cancer cell growth and binding to PKCδ, introduction of hydrophobic bromine and iodine atoms enhanced both biological activities. The anti-proliferative activity was found to correlate closely with molecular hydrophobicity, and maximal activity was observed at a log P value of 4.0–4.5. On the other hand, an induction test with Epstein–Barr virus early antigen demonstrated that these derivatives have less tumor-promoting activity in vitro than aplog-1 regardless of the hydrophobicity of their substituents. These results would facilitate rapid preparation of molecular probes to examine the mechanism of the unique biological activities of aplog-1.     

Excitotoxicity-induced immediate surge in hippocampal prostanoid production has latent effects that promote chronic progressive neuronal death

Excitotoxicity is involved in neurodegenerative conditions. We investigated the pathological significance of a surge in prostaglandin production immediately after kainic acid (KA) administration [initial phase], followed by a sustained moderate elevation in prostaglandin level [late phase] in the hippocampus of juvenile rats. Numerous pyknotic hippocampal neurons were observed 72 h after KA treatment; this number remained elevated on days 10 and 30. Gross hippocampal atrophy was observed on days 10 and 30. Pre-treatment with indomethacin ameliorated neuronal death on days 10 and 30, and prevented hippocampal atrophy on day 30. Microglial response was moderated by the indomethacin pre-treatment. Blockade of only late-phase prostaglandin production by post-treatment with indomethacin ameliorated neuronal death on day 30. These findings suggest a role for initial-phase prostaglandin production in chronic progressive neuronal death, which is exacerbated by late-phase prostaglandin production. Blockade of prostaglandin production has therapeutic implications in preventing long-term neurological sequelae following excitotoxic brain damage.     

Biochemical Characterization of Lipoxygenase Lacking Mutants,L-l-less,L-2-less,and L-3-less Soybeans

In this paper, lipoxygenase lacking mutants were characterized in comparison with normal soybeans. The three lipoxygenase isozymes (L-l, L-2, and L-3) in crude seed extracts of normal soybeans were resolved clearly by an improved SDS-polyacrylamide gel electrophoresis. As expected, the three mutant types, L-l-less (P. I. 408251 and 133226), L-2-less (P. I. 86023), and L-3 less (Wasenatsu and Ichigowase) soybeans did not give L-l, L-2, and L-3 protein bands, respectively on a single dimension SDS gel.

An anti L-2 serum obtained from a rabbit reacted not only with the purified L-2 protein, but also partially with the purified L-l and L-3 proteins. By double immunodiffusion and immuno-disc gel electrofocusing analyses using the anti L-2 serum, L-l, L-2, and L-3 isozymes could not be detected in crude seed extracts from P.I. 408251, P. I. 86023, and Wasenatsu soybeans, respectively.

Three lipoxygenase activity peaks (L-l, L-2, and L-3 enzyme peaks) and a small unknown activity peak eluted right after the L-l peak were fractionated by DEAE-Sephacel column chromatography of crude seed extracts of Raiden (normal) soybeans. The chromatographic analyses have demonstrated that both the L-l and the unknown enzyme activities disappear completely in the L-l-less type soybean seeds, and that the L-2 and L-3 enzyme activities disappear completely in P. I. 86023 and the L-3-less type soybean seeds, respectively.     

Volatile Flavor Components of ZINGIBERIS RHIZOMA (Zingiber officinale Roscoe)

The toxicity of dimethyl sulfoxide (Me₂SO) was examined in HeLa cells cultured at 37°C for up to 72 hr. The growth of the cells was measured by a colorimetric method with the use of 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), which gave good correlation between the cell number and the color development from the reduction of MTT under suitable conditions. When the initial number of cells was 3 × 10⁴/ml, Me₂SO at 1% or less had no apparent effect on prolifiration for up to 48 hr of incubation, but in longer incubations, cell growth was repressed. When the initial number of cells was 3 × 10⁵/ml, the effect of Me₂SO was similar.     

Isolation of Cerebroside from Pea Seeds

Cerebroside was isolated from pea (Pisum sativum L.) seeds by solvent extraction, mild alkaline hydrolysis and silicic acid column chromatography. The purified material was identified as cerebroside by thin-layer chromatography and infrared spectrometry. Hydrolysates of the cerebroside were divided into fatty acid, sphingosine base and sugar fractions, and analysed, mainly by gas-liquid chromatography. The major fatty acid components were hydroxytricosanoic, hydroxydocosanoic and hydroxytetracosanoic acids. Dihydrosphingosine was the predominant sphingosine base. Only glucose was detected in the sugar fraction. Based on these results, one of the major species of pea cerebroside is suggested to be N-hydroxytricosanoyl-glucopyranosyl-dihydrosphingosine.     

Inhibition of malaria parasite growth by quinomycin A and its derivatives through DNA-intercalating activity

Quinomycin A and its derivatives were identified as potent antimalarial (Plasmodium falciparum) agents in a screen of the RIKEN NPDepo chemical library. IC₅₀ values of quinomycin A and UK-63,598 were approximately 100 times lower than that of the antimalarial drug chloroquine. This activity was mitigated by the addition of plasmid DNA, suggesting that these compounds act against parasites by intercalating into their DNA.