Akira Yagi

Microencapsulation of ovalbumin in poly(lactide-co-glycolide) by an oil-in-oil (o/o) solvent evaporation method

The objective of this study was to produce biodegradable poly(lactide-co-glycolide) (PLGA; 50/50) microspheres by an oil-in-oil (o/o) solvent evaporation method to prolong the in vitro release of ovalbumin (OVA) as a model protein. The effects, on loading efficiency, microsphere yield, morphology and drug release, of two dispersing agents, aluminium tristearate and Span 80, in mineral oil were examined. PLGA 50/50 microspheres containing OVA powder (sieved through a 53 microns mesh) were prepared using an o/o solvent evaporation method. When aluminum tristearate was employed as a dispersing agent, the loading efficiency and yield of OVA had maximum values of 89 and 72% at 0.15% (w/v) aluminum tristearate, respectively. Morphology studies suggested that the obtained microspheres were spherical, and had a smooth surface. The diameters of the microspheres ranged between 100 and 200 microns. The loading efficiency, or yield, for microspheres decreased significantly above or below 0.15% (w/v) aluminum tristearate, and microspheres with irregular shapes were observed. The minimum sedimentation volume ratio (F) was obtained at a dispersity of carbon black particles in ethanol containing 0.15% (w/v) aluminum tristearate by a sedimentation study, and the cloudy supernatant suggested a deflocculated suspension. However, on the contrary, when Span 80 was added into the mineral oil as a dispersing agent, the concentration of Span 80 had little or no effect on the characteristics of the prepared microspheres. Drug loadings (60-70%) were obtained within the Span 80 concentrations employed in the present study (0.05-1.0% (w/v)). The yields were also in the same levels. The microspheres prepared in mineral oil containing Span 80 had an average diameter less than 50 microns in all cases. Sustained-release characteristics were demonstrated for PLGA microspheres prepared in mineral oil containing aluminum tristearate as a dispersing agent, even though a burst release at the initial phase was observed. This initial burst release from PLGA microspheres was reduced to some extent by micronization of the OVA powder using a planetary-type ball mill. However, PLGA microspheres prepared in mineral oil containing Span 80 as a dispersing agent, exhibited a large initial burst release. This burst release seems to be due to the smaller size of microspheres and the OVA powder adhering to the surface of PLGA microspheres (confirmed by scanning electron microscope (SEM) study).

Formation of tetrahydroanthracene glucosides by callus tissue of Aloe saponaria

Abstract Callus tissue of Aloe saponaria grown in the dark produced a new tetrahydroanthracene glucoside, 1-oxo-2-methoxy-4,8,9-trihydroxy-6-methyl-1,2,3,4-tetrahydroanthracene (aloesaponol IV) 8-O-β- D -glucoside, together with known tetrahydroanthracene glucosides. The effect of light on the formation of tetrahydroanthracene and anthraquinone glucosides is discussed.

Biosynthetic relations between protoberberine-, benzo(C)phenanthridine- and B-secoprotoberberine type alkaloids in Corydalis incisa

Abstract The biosynthetic relations between protoberberine-, benzo[C]phenanthridine- and B-secoprotoberberine type alkaloids were demonstrated by use of (±)-tetrahydrocoptisine-[8,14- 3 H HCl, (±)-tetrahydrocorysamine-[8,14- 3 H]HCl and corynoline-[6- 3 H]HCl in Corydalis incisa , and the following results were presented. (±)-Tetrahydrocoptisine was converted to corynoline, corydalic acid methyl ester and corydamine hydrochloride. (±)-Tetrahydrocorysamine was converted to corynoline and corydalic acid methyl ester. Evidence that N -methyl-3-[6′-(3′,4′-methylenedioxyphenethylalcohol)]-4-methyl-7,8-methylenedioxy-1,2,3,4-tetrahydroisoquinoline-[α- 3 H] HCl was incorporated into corynoline-[11- 3 H] indicates the occurrence of the ring fission at C 6 -N followed by linking ofthe C 6 and C 13 positions in (±)-tetrahydrocoptisine and (±)-tetrahydrocorysamine, and suggests the participation of one of two possible intermediates in the biosynthesis of these alkaloids.

Biosynthetic relationship between tetrahydroanthracene and anthraquinone in Aloe saponaria

Abstract The incorporation of Me 14 COONa into aloesaponol I, laccaic acid D methyl ester and aloesaponarin I was demonstrated. The biosynthetic relation between aloesaponol I and aloesaponarin I was established, but incorporation of aloesaponol I into laccaic acid D methyl ester, or vice versa was not demonstrated and this result was confirmed by an investigation using labelled laccaic acid D methyl ( 14 CH 3 ) ester. It was possible to show that aloesaponol I and laccaic acid D methyl ester were biosynthesized in parallel in Aloe saponaria .

Metabolism of phenylpropanoids in Hydrangea serrata var. thunbergii and the biosynthesis of phyllodulcin

Abstract DL -Phenylalanine-[3- 14 C] and cinnamic acid-[3- 14 C] were fed to this plant and the label from cinnamic acid was incorporated into gallic acid, phyllodulcin and quercetin. By feeding p - coumaric acid-[U- 3 H], caffeic acid-[U- 3 H] and hydrangea glucoside A-[U- 3 H], it was possible to show that hydroxylation at C-3′in phyllodulcin occurs after the ring closure of dihydroisocoumarin. The biosynthetic pathway of phyllodulcin in this plant is thus: phenylalanine → cinnamic acid → p - coumaric acid → hydrangenol → phyllodulcin.

Isolation and chemical properties of a haptenic substance from buckwheat dialysate

A haptenic substance was isolated from the dialysate of the aqueous extract of buckwheat. This substance, BWD II 22-3, which was composed of Asp(1), Thr(1), Ser(1), Gly(1), Gly(4), Ala(1), Val(1), Leu(1), Orn(2), Lys(1), Arg(1), Cys(1) and glucose was demonstrated to be homogeneous by gel filtration and paper electrophoretic analyses. The molecular weight was estimated to be 1600 by gel filtration on Sephadex G-50. The haptenic substance apparently has-SH group determinant caused about 50% inhibition at a concentration of 100 micrograms/disc in the RAST procedure using human serum sensitive to buckwheat. An active component, BWD II 22-3, might prove effective in the hyposensitization therapy of buckwheat-sensitive patients.