Hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂ ; HAP) is a major component of mammalian hard tissues and one of the components of pathological and undesirable concretion, such as urolithiasis. In the present review, the interaction of biologically significant ions with HAP is discussed from the view point of physical and colloid chemistry. It was found that the concurrent adsorption of the lattice ions of HAP (OH^-and Ca²⁺, for example) onto the surface of HAP was similar to the crystal growth of HAP. Pyrophosphate ion (PPi) showed specific behaviors, such as a retarding effect on the crystal growth of HAP and a dispersing effect on the HAP secondary particles, owing to the adsorption of the terminal phosphate group of PPi to the surface of HAP. PPi was hydrolyzed to orthophosphate ion in the presence of Ca²⁺ and/or on the surface of HAP. These effects are important to understand the inhibiting effect of PPi against biological calcification and calculus formation. When organic ions, such as dodecyl sulfate ion and chondroitin sulfate ion, were adsorbed on HAP, some phosphate ions were released from the surface of HAP by a mechanism of ion-exchange. It was shown that this phenomenon is of great importance in connection with the binding affinity of biopolymers in the connective tissues to the biological HAP of the hard tissues and to the synthesized HAP of the artificial bones.

View full abstract

The relationship between the chemical structure and the color of riboflavin tetrabutylate (RTB) in the solid state was studied. The RTB of orange crystals obtained from methanol solvent and dark-yellow powders from isopropanol gave identical results in nuclear magnetic risonance, thin-layer chromatography and high performance liquid chromatography. The difference in emission spectra around 500-650 nm explained the color of RTB ; the orange crystals showed a maximum at 595 nm and the dark-yellow powders at 565nm, respectively. The reflection and exitation spectra also supported the difference in color between them. Powder X-ray diffraction showed that the crystal structure of orange RTB gave a pattern different from that of dark-yellow one. A strong electron spin resonance signal in dark-yellow RTB suggested the presence of charge-transfer complexes. Infrared spectra of RTB showed a difference in the hydrogen bond of NH which caused a change in the mode of the arrangement of RTB.

View full abstract

By the reaction of 4-imino-4H-pyrido [1, 2-α] pyrimidine (7) with dimethyl acetylenedicarboxylate (DMAD), or methyl acetylenecarboxylate (MAC) with Pd-C as dehydrogenatic reagent, the corresponding 1, 4-diazacycl [3. 3. 3] azine derivatives (10, 11) were obtained. 1, 4-Diazacycl [3. 3. 3] azine (3), which was a very unstable free base, was prepared by the degradation of 11. The ¹H-nuclear magnetic resonance spectral data of 3 may be interpreted in terms of a paramagnetic ring current.

View full abstract

Four acylated glycosides, named syringalide-A, syringalide-A-3'-α-L-rhamnoside, isosyringalide-3'-α-L-rhamnoside and syringalide-B, have been isolated together with acteoside, cis-acteoside and echinacoside from the fresh leaves of Syringa reticulata (BLUME) HARA. The structure were elucidated on the basis of carbon-13 nuclear magnetic resonance, circular dichroism spectra and some other physicochemical evidence.

View full abstract

New saponins, named gypenosides LXV (1), LXVI (2), LXXII (3), LXXIII (4) and LXXIX (5), were isolated from the aerial parts of Gynostemma pentaphyllum MAKINO (Cucurbitaceae) collected in Wakayama pref., together with the known saponins, gypenosides II, VII, XLV (6) and gynosaponin TN-2. On the basis of chemical and physicochemical evidence, they were characterized as follows. 1, 3β, 12β, 19, 20 (S)-tetrahydroxydammar-24-ene 20-O-β-primeveroside : 2, 3β, 12β, 19, 20 (S)-tetrahydroxydammar-24-ene 20-O-β-rutinoside : 3, 3β, 12β, 19, 20 (S)-tetrahydroxydammar-24-ene 3-O-β-rutinoside-20-O-β-D-glucopyranoside : 4, 2α, 3β, 20 (S)-trihydroxydammar-24-ene 3-O-β-D-glucopyranoside-20-O-β-rutinoside : 5, 3β, 19, 20 (S)-trihydroxydammar-24-ene 3-O-β-D-glucopyranoside-20-O-β-D-glucopyranoside.

View full abstract

Saponins of plants of Gynostemma pentaphyllum MAKINO (Cucurbitaceae), collected at Sodegaura, Chiba Pref. and Oozu, Ehime Pref., were investigated. From the aerial parts of the specimen collected at Sodegaura, three new dammaran-saponins, gypenosides LXXIV (1), LXXV (2) and LXXVI (3) were isolated together with the known saponins, gypenosides IX (8), XIII (9) and LXV (6). From the aerial parts of the specimen collected at Oozu, two new dammaran-saponins, gypenosides LXXVII (4) and LXXVIII (5) were isolated together with the known saponins, 3, 6, gypenoside VII (10), gynosaponins TN-1 (11) and TN-2 (12). On the basis of chemical and physicochemical evidence, they were characterized as follows : 1, 2α, 3β, 12β, 20 (S)-tetrahydroxydammar-24-ene 20-O-β-gentiobioside : 2, 3β, 12β, 20 (S)-trihydroxydammar-24-ene 20-O-β-gentiobioside : 3, 3β, 12β, 19, 20 (S)-tetrahydroxydammar-24-ene 20-O-β-D-glucopyranoside : 4, 2α, 3β, 12β, 30 (S)-tetrahydroxydammar-24-ene 20-O-β-primeveroside : 5, 2α, 3β, 20 (S)-trihydroxydammar-24-ene 20-O-β-primeveroside.

View full abstract

The supercritical fluid extraction was applied to the components of Cnidium formosanum fruits by use of carbon dioxide gas, and the effects of temperature, pressure and time on the extraction were examined to establish the way of applying this new technique to crude drugs. The optimum temperature and pressure for the extraction of furocoumarins such as columbianadin, bergapten, O-acetylcolumbianetin, edultin and columbianetin, with supercritical carbon dioxide were 40°C and 400 bar, respectively. Although the amounts of extractives increased with prolonging extraction times, the increments after 80 min were small. Effects of entrainers were examined, and compared with those of the ordinary liquid extraction.

View full abstract

A new method for simultaneous determination of ephedrine, pseudoephedrine and methylephedrine in the decoction of Ephedrae Herba by normal phase high-performance liquid chromatography is reported. By using silica gel column and the mixture of n-hexane, ethanol and ammonia (125 : 75 : 1) as a mobile phase, each alkaloid was well separated within 10 min. Optimal wavelength for detection was found to be 220 nm by three dimensional observation. Reproduceble peak area calculation was achieved by the peak smoothing technique.

View full abstract

Granulation processes in high speed mixer granulator were divided into 4 zones to study the granulation mechanism in each zone. This study showed the importance of evaluating the granulation processes from the view of power consumption change and not from the view of granulation time. It was found that the granulation end-point at which a high yield of well-compacted, spherical small grains was obtained, corresponded to the early phase of zone IV during which the power consumption and granule temperature gained stability. Measurement of the granule temperature is, therefore, helpful for determining the granulation end-point. It was further found that the binder content where a high yield of small grains was obtained, resulted in production of well-compacted, spherical small grains. In granulation with a water-ethanol solution as a binder, the grain sphericity tended to become poorer and the small grains coarser as compared with granulation with purified water as a binder.

View full abstract