Thymidylate synthase (TS) provides the only de novo source of thymidylate for deoxyribonucleic acid (DNA) synthesis and is a key target of cancer chemotherapeutic agents. Expression of its activity is strongly dependent on the cell cycle. Therefore, it is important for understanding the abnormal growth of cancer cells as well as for cancer chemotherapy to elucidate the structure of a TS gene and the regulatory mechanism of expression of its gene at the molecular level. From this point of view, genomic DNA segments partially coding for human TS were cloned from the mouse cell transformant obtained by gene transfer. By using them as a probe, functional cDNA and genomic DNA (approx. 18kb) clones for human TS were isolated, and the entire nucleotide sequence of these cloned DNAs including all the introns determined. On the basis of the sequence data, we revealed an amino acid sequence of human TS, and organization and several structural features of its gene were revealed. Then, multiple transcription initiation sites and transcriptional regulatory elements of the TS gene were identified. Furthermore, the importance of the post-transcriptional regulation in the cell-cycle dependent expression of the gene was shown. The results obtained so far have opened the way to elucidate the molecular mechanism regulating the TS gene expression entirely.
The synthesis of 7β-[(Z)-2-(aminothiazol-4-yl)-2-hydroxyiminoacetamido] cephalosporins (Ia-i) modified at the C-3 position of a cephem nucleus and the effect of the C-3 substituents on the antibacterial activity and oral absorbability are discussed. The cephems (Ie, h and i) having a C-3 substituent such as 1-propenyl, ethylthio and vinylthio group as well as FK482 (cefdinir) exhibited excellent antibacterial activities against both gram-positive and gram-negative bacteria. However, those compounds showed poor absorption rate after oral administration in rats. It is concluded that the vinyl moiety at the 3-position is necessary to display fairly oral absorptivity in a series of 7β-[(Z)-(2-aminothiazol-4-yl)-2-hydroxyiminoacetamido] cephems.
A carrier for a new tumor imaging agent, a bifunctional chelating agent (BCA)-coupled porphyrin (ATN-2), has been synthesized from protoporphyrin dimethyl ester in 4 steps. At first, the hydrobromination of protoporphyrin dimethyl ester is carried out to obtain a monobromo derivative. The derivative is treated with ethylene glycol. The resulting porphyrin has an ether group at the either 7-or 12-position of the ring. Metallation with GaCl3 of the porphyrin having a ethylene glycol residue affords Ga-metalloporphyrin. Final condensation of the metalloporphyrin with diethylenetriaminepentaacetic acid (DTPA) gave BCA-coupled porphyrin (ATN-2). The chelation of ATN-2 with 111InCl3 easily afforded [111In] ATN-2. This agent was used for imaging transplantable pancreatic carcinoma in Syrian golden hamster at 72 h after postinjection. The efficacy of the new agent was compared with that of [67Ga] citrate. The images with [111In] ATN-2 were found to be clearer than those with [67Ga] citrate. Therefore, ATN-2, a carrier for 111InCl3, seems to be more useful for tumor imaging agents.
A series of 6H-(1) benzothiopyrano [3, 4-e] [1, 2, 4] triazolo [4, 3-b] pyridazines and 6, 7-dihydro-(1) benzothiepino [4, 5-e] [1, 2, 4] triazolo [4, 3-b] pyridazines were prepared and tested for their ability to displace [3H] diazepam from rat brain membranes. An approximately planar shape of these molecules was essential for high affinity to the benzodiazepine receptor. Among them, 11-aryl compounds in the latter series were found to have high affinity to the benzodiazepine receptor. 11-Phenyl- and 11-thienyl-6, 7-dihydro-(1) benzothiepino [4, 5-e] [1, 2, 4] triazolo [4, 3-b] pyridazine (3b-5 and 3b-11 respectively) showed the potent affinity comparable to that of diazepam. The structure-activity relationships are also discussed.
During screening for the development of drugs from natural products, methanolic extract of tuber of Stachys sieboldii MIQ. (Labiatae) significantly inhibited the lethal induced by KCN in mice. The methanolic extract was fractionated by column chromatography to identify the active constituents. Acteoside and stachysoside C, phenylethanoid glycoside, have a significant effect on the KCN-induced anoxia model.
One of the important medicinal properties of ginger is known to remove chills caused by common cold and to warm body. In the present study, acetone extract of ginger at 100 mg/kg p.o. significantly inhibited serotonin (5-HT) induced hypothermia. Therefore, the active constituents of ginger were further examined. The acetone extract was functioned into 4 fractions by column chromatography. Fractions 1 and 2 showed significant activity. Fraction 2 was further purified and -shogaol which was obtained from fraction 2-2, at 10 mg/kg p.o. was shown to inhibit 5-HT induced hypothermia. Anticathartic activity is known to be one of the medicinal effects of ginger. In the present study, acetone extract of ginger at 75 mg/kg p.o., significantly inhibited 5-HT induced diarrhea. In order to clarify the active constituents, the acetone extract was fractionated into 4 fractions by silica gel chromatography. Fractions 2 and 3, which was especially effective, were further purified and -shogaol, -dehydrogingerdione, -and -gingerol were found to have an anticathartic action. -Shogaol was more potent than -dehydrogingerdione, -and -gingerol.
Tubeimosides I, II and III (cyclic bisdesmosides) have been isolated from Chinese cucurbitaceous crude drug Tu-bei-mu, a tuber of Bolbostemma paniculatum (MAXIM.) FRANQUET. Solubilizing effects of these cyclic bisdesmosides on water insoluble or lesssoluble compounds were examined. It was revealed that cyclic bisdesmosides were effective on increasing the solubility of Yellow OB, dl-α-tocopherol and saponin A from Sapindus mukurossi. The critical micell concentration (cmc) and association number as well as diameter of micell of tubeimoside I in water were also measured. The interaction of tubeimoside I with 1-anilino-8-naphthalene-sulfonate (ANS) in aqueous solution was investigated photometrically. It was observed that tubeimoside I strongly enhanced the intensity of fluorescence of ANS, suggesting the significant formation of inclusion complex.
The protective effects of 67 methanol extracts of crude drugs on rat hepatic injury by carbon tetrachloride (CCl4) were examined. In terms of the release of intrahepatic enzymes and bilirubin into the blood, 11 methanol extracts decreased these factors significantly. Among them methanol extracts of Caryophylli Flos, Angelicae Dahuricae Radix, Polygoni Avicularis Herba, Myricae Cortex and Forsythiae Fructus were newly found to have protective effects against acute hepatic injury induced by CCl4. And then these 11 extracts which protected hepatic injury by CCl4 were investigated for their membrane stabilizing and inhibitory effects of lipid peroxidation. The extract of Bupleuri Radix only decreased the hemolysis induced by hypotonic pressure. Nine kinds of extracts without those of Desmodii Herba and Bupleuri Radix suppressed the lipid peroxidation induced by CCl4 in rat hepatic microsomes. In addition, Scutellariae Radix, Caryophylli Flos and Myricae Cortex were shown to have inhibitory effects of nonenzymatic lipid peroxidation in rat hepatic mitochondria. This study reports that the methanol extracts of Caryophylli Flos, Angelicae Dahuricae Radix, Polygoni Avicularis Herba, Myricae Cortex and Forsythiae Fructus protect the hepatic injury by CCl4 and these protective effects are connected with the inhibitory effects of the lipid peroxidation in hepatic microsomes.
β-Glycosides of cleanolic acid and ursolic acid were synthesized by coupling methyl oleanolate and ursolate with per-O-acetylated glycosyl bromides of mono- and disaccharides by means of Koenigs-Knorr type condensation (Ag2CO3-I2-CH2Cl2). Sterically hindered methyl esters of these glycosides could be converted into the corresponding free acids by heating with lithium iodide in 2, 4, 6-trimethylpyridine. The anomeric configurations of newly formed glycoside linkages were determined as β on the basis of 1H and 13C nuclear magnetic resonance spectral data.
Anticholinergic action of Paeony root was examined in in vivo experiments with rat in order to substantiate the presence of analgesic, antispasmic and antidiarrheal properties. The 50% methanol extract of Paeony root was found to be effective. Fractionation of 50% methanol extract through column chromatography revealed that paeoniflorin was one of the active constituents in anticholinergic action in vivo, but in vitro, paeoniflorin had no effect on contractile responses of isolated rat proximal colon to the carbachol and KCl.
Twenty five Chinese herbal medicinal prescriptions containing gypsum, kaolin, longgu, oyster shell and sodium sulfate were studied for the inhibitory activity of adenosine 3', 5'-cyclic monophosphate phosphodiesterase. The inhibitory activity of 15 prescriptions without mineral drug was higher than that of each original prescription. On the contrary, four were lower and six were not recognized to be different. All 11 prescriptions containing gypsum with an exception increased the inhibitory activity by removing gypsum. The half prescriptions containing kaolin or sodium sulfate also increased the inhibitory activity by removing the mineral drug.