Asymmetric total syntheses of some biologically active natural products are reviewed. The present methods rely on the novel application of the readily available optically active compounds as a chiral synthons that are used as a chiral source in the asymmetric induction and as a carbon framework of the target molecules. Asymmetric syntheses of some Amaryllidaceae alkaloids, maritidine and galanthamine by the use of L-tyrcsine, and the antitumor lignans, steganacin and related lignans by the use of (S)-γ-hydroxymethyl γ-butyrolactone as a chiral synthon are described.
Optical density (OD), as an index for the suspension stability of hydroxyapatite (HAP ; 5g/dl), was measured at 550 nm in an aqueous solution of CaCl2 mixed with sodium chondroitin-6-sulfate (Na2Chs). The contour lines for OD with respect to concentrations of CaCl2 and Na2Chs were obtained. It was found that the suspension stability of HAP decreases with an increase in concentration of CaCl2, but increases with an increase in concentration of Na2Chs. It was concluded that HAP suspension is stabilized mainly by virtue of steric hindrance effect and inter-particle electrostatic repulsion effect of negatively charged segments of adsorbed Chs, even though ionic strength is high and the net charge of HAP particles becomes positive (i.e., the amount of adsorbed Ca2+ is larger than that of adsorbed Chs).
Chemical constituents in the alkaloidal fraction of the bark of Formosan X. nitidum (ROXB.) D.C. (F. nitida ROXB.) (Japanese name : Teriha-Zansho), Rutaceae, which was collected in the area of Ping-Tung Hsien, were examined. Twelve alkaloids [nitidine (1), oxynitidine (2), 6-methoxy-5, 7-dihydrochelerythrine (4), oxychelerythrine (6), des-N-methyl-chelerythrine (7), chelerythrine (14), arnottianamide (24), liriodenine (25), bocconoline (26), decarine (27), integriamide (28), and isoarnottianamide (13)] and three lignans [l-asarinin (20), l-sesamin (21), and l-syringaresinol (29)], a coumarin, aesculetin dimethyl ether (22), together with β-sitosterol (23) were isolated. Other than the above seventeen known compounds a new phenolic benzo [c] phenanthridone alkaloid designated as oxyterihanine (30a) was also isolated as a minor component. While the past three groups reported that nitidine (1) was a sole quaternary benzo-[c] phenanthridine alkaloid in the same plants collected in the areas of Hong-Kong and of China mainland (Gauanx and Gauantung), in our case, chelerythrine (14) was isolated as a major component. Nitidine (1) was isolated from the plant collected at March as a second component, but chelecythrine (14) was essentially a sole benzo [c] phenanthridine alkaloid in the case of the plant collected at July and at September. The seasonal variation of the contents of the quaternary benzo [c] phenanthridine alkaloids is discussed.
New saponins, named gypenosides XLII (1), XLIII (2), XLIV (3), XLV (4) and XLVI (5), besides the known gynosaponin TN-1 (6), -2 (7), gypenoside I (8), II (9), V (10) and VII (11) were isolated from the aerial parts of Gynostemma pentaphyllum MAKINO collected in Tokushima pref. On enzymatic hydrolysis 1, 2, 3, 4 and 5 yielded 20-O-β-D-glucopyranoside of dammar-24-ene-2α, 3β, 12β, 20 (S)-tetraol (6) as a prosapogenin. The configuration of the sugar linkages in each saponin was established on the basis of chemical and spectroscopic evidence.
The effects of aqueous extracts of 18 herbs used for Oketsu, blood coagulation, in Chinese medicine were investigated. Plasma recalcification time on mice was employed for the bioassay. It was found that all of 18 herbs have an inhibiting blood coagulative activity.
A method was developed for the determination of taurine in whole blood and plasma by gas-liquid chromatography. The method involves a deproteinization, conversion of taurine into its N-isobutyloxycarbonyl di-n-butylamide derivative and chromatography on a 5.0% SE-54 column with hydrogen flame ionization detection. 3-Amino-1-propanesulfonic acid was used as an internal standard. The average recoveries of taurine added to whole blood and plasma samples were 97.6 and 98.3%, respectively. The mean values of taurine content in whole blood and plasma of thirty normal subjects were 163.9±35.8 and 45.3±7.4 nmol/ml, respectively.
Aqueous extracts prepared from porcine spleens were found to inhibit colony growth in agar cultures of mouse bone marrow cells stimulated by L-cell conditioned medium (LCM). The inhibitory activity in the extracts was heat stable and was not ether extractable. Preincubation of the spleen extracts with LCM failed to inhibit colony formation in subsequent agar cultures. This suggests that if inhibitor-colony stimulating factor (CSF) complexes exist in culture system, they must be readily dissociable and/or inhibitors can not bind to the active site (s) of CSF. Two highly purified inhibitors were obtained from the extracts by a combination of gel filtration, silica gel column chromatography, paper electrophoresis and cellulose thin layer chromatography. Analytical procedures suggested that these inhibitors had an apparent molecular weight of 300 and 400, respectively, and were not peptides.
7-(Hydroxyamino)-5, 8-quinolinedione (7-HAQD), a simple mimetic compound of Streptonigrin in whose chemical structure an aminoquinone moiety has been recognized to be significant for the appearance of its antitumor activity, was investigated for antitumor activities. 7-HAQD showed difference spectra toward deoxyribonucleic acid (DNA), and inhibited their precursor incorporation into DNA and ribonucleic acid (RNA) in Ehrlich ascites carcinoma cells. Also, 7-HAQD inhibited against the proliferation of L1210 leukemia cells in vitro. 7-HAQD exhibited distinct antineoplastic effects against Ehrlich mouse ascites carcinoma and P388 leukemia. However, its inhibitory effects against the solid carcinomas of Ehrlich and Sarcoma 180 were weaker than those against the ascites carcinomas.
The values of Km and Vmax of the citrus esterase for the hydrolysis of p-nitrophenyl acetate were 1.9×10-3M and 250μmol/min·mg, respectively. The enzyme was stable in the pH range from 4.5 to 6.0 and temperature range from 0 to 30°C but was quickly denatured at pH values below 4.5 or over 6.0. Its activity considerably decreased on lyophilization. The enzyme was completely inactivated by sodium dodecylsulfate. It was also inhibited by cetyltrimethylammonium bromide, Brij-35, Tween 80, and Triton X-100, and the enzymatic activity decreased with their increasing concentrations. It was strongly inhibited by diisopropylfluorophosphate and HgCl2. N-Ethylmaleimide, p-chloromercuribenzoic acid, phenylmethanesulfonyl fluoride, p-bromophenacyl bromide, phenylglyoxal, N-tosyl-L-phenylalanyl chloromethyl ketone, N-tosyl-L-lysyl chloromethyl ketone, and ethylenediaminetetraacetic acid showed no significant effect on the enzymatic activity at pH 5.5. The enzyme was inactivated with incorporation of 0.96 mol 208HgCl2 per mol enzyme but did not react with p-[208H] chloromercuribenzoic acid.
The inclusion complexations of flurbiprofen (FP) with three cyclodextrins (α-, β-, and γ-CyD) were assessed by solubility method, optical rotatory dispersion (ORD), ultraviolet spectra (UV) and circular dichroism (CD) in aqueous solution. FP was included with β-CyD or γ-CyD in the molecular ratio of 1 : 1. Their stability constants and mutual effects were in the order of β-, >γ-, >α-CyD. To improve the local irritation induced by intramuscular injection or eye dropping of FP, CyD complexation was utilized. CyDs were found to protect the erythrocytes from the hemolysis and shape changes induced by FP in vitro. Their protective effects on whole blood of human and rabbit increased in the order of β-, >γ-CyD. The irritative effects of FP or its CyD complexes on the M. vastus lateralis of rabbits were studied on the gross examination. The irritation of β-CyD complex was found to be the mildest in all other CyD complexes. The effects of FP aqueous ophthalmic solution was studied for the reduction of local irritation and the inhibition of the increase of aqueous humor protein induced by the paracentesis to rabbit eyes. The complexation of FP with β-CyD was found to be the mildest in all FP ophthalmic solution studied on the eye irritation. Furthermore, the aqueous ophthalmic solution of 0.1% FP containing β-CyD indicated the inhibition about 75% of increasing protein in the intraocular surgery.
Inhibitory activities of four bile salts, deoxycholate, chenodeoxycholate, ursodeoxy-cholate and cholate on the cholecystokinin (CCK)- and acetylcholine (ACh)-induced contraction of the isolated guinea-pig gallbladder were compared. Ki values of bile salts for the CCK-induced contraction were not different from those of the corresponding bile salts for ACh-induced contraction. Deoxycholate inhibited the maximum response of the gallbiadder to CCK and ACh in a similar manner. Potassium chloride-induced contraction was also inhibited by these bile salts. These findings indicate that bile salts exert a nonspecific inhibitory effect on the contractility of gallbladder. Anti-CCK activities of conjugated bile salts were also examined but their activities were found to be much lower than those of the corresponding bile salts. Imidazole, a phosphodiesterase (PDE) activator, significantly reduced the anti-CCK action of deoxycholate. Inhibitory actions of deoxycholate and dibutyryl cyclic adenosine monophosphate (c-AMP) on the potassium chlorideinduced contraction disappeared in the absence of external sodium ion but were readily restored by the addition of 10mM sodium ion to the bathing solution. These facts suggest that bile salts exert their spasmolytic action in gallbladder by inhibiting PDE and resulting accumulation of cyclic AMP, as proposed by Uruno et al. in rat uterus. Meanwhile, imidazole supra-additively enhanced the contractile action of CCK. This findings may argue against the concept proposed by Amer that CCK induces contraction of gallbladder via activating PDE of the muscle.
Gastric acid secretion was repeatedly measured in the same rats which were conscious and unoperated. A vescical catheter for female use (No. 4) was introduced into the stomach of fasted rats via the oesophagus. Two milliliters of saline were injected through this tube and about 1.5ml was rapidly aspirated. Acid in the aspirate was titrated with 1/100 N NaOH. This procedure were repeatedly at 15, 30 or 60 min intervals. It was possible that gastric acid secretion was measured repeatedly 4 times in 2 weeks in the same rats. Antisecretory activities of atropine and cimetidine, and secretagogue actions of tetragastrin and histamine, but not bethanechol and carbachol, were detected by this method. This method should be available for the study of the pharmacological evaluation of antiulcerative drugs as well as the gastric acid secretory mechanisms.
Effects of cinnamaldehyde on general behaviour, locomotor activity, body temperature and striatal levels of dopamine, serotonin and their metabolites were studied in mice. Cinnamaldehyde produced a decrease in the spontaneous activity at higher doses than 30 mg/kg, i.p., and produced a transient excitation or running fit prior to marked depression at higher doses than 100 mg/kg, i.p. Cinnamaldehyde at doses of 125 and 250 mg/kg, i.p., suppressed locomotor activity produced by apomorphine or methamphetamine. In reserpine-pretreated mice, running fit was produced with cinnamaldehyde at lower doses than those in normal mice. Cinnamaldehyde markedly reversed reserpine-induced hypothermia as did imipramine. Cinnamaldehyde at a dose of 500 mg/kg, i.p., significantly increased the striatal levels of 3, 4-dihydroxyphenylacetic acid, homovanillic acid and 5-hydroxyindoleacetic acid. These results suggest that cinnamaldehyde has central inhibitory and excitatory effects which may be derived from interaction with monoaminergic neurons in the central nervous system.
We developed a simultaneous detection method of 9 kinds of diuretics in the urine by using thin-layer chromatographic (TLC) method and/or high-performance liquid chromatographic (HPLC) method. The diuretic drugs were extracted from the urine according to modified Tisdall et al. method by use of 1M phosphate buffer and ethylacetate. The TLC method was performed with a commercially available chromatographic plate containing mixed fluorescent substance and isopropyl alcohol-ammonia mixture as a development solvent. The HPLC method was accomplished with UV detection at 271nm. To examine the limit of detection of the methods, normal subjects were individually administered with commercially available tablets of 11 kinds of diuretics, 9 drugs were detected from 24 h urine of normal subjects. However, 2 drugs were not detected. By applying these methods to urine samples of female patients with hypokalemia, furosemide (FD) and trichlormethiazide (TCT) were detected. The chromatographic peak of FD on HPLC method was further assigned by mass spectrometry. The quantitative determination of TCT in the urine was also developed by HPLC method, and the urine concentration in a patient with self-administration of TCT was 0.80μg/ml.