Chemical Studies on Amino—Carbonyl Reaction

When N-n-butyl-D-xylosylamine was heated with acetic acid in methanol at 55~70°G, it decomposed to N-n-butyIpyrrole-2-aldehyde,** through 3-deoxy-d-pentosulose as an intermediate. d-Xylose and methylamine in neutralized aqueous solution at 65~100°C also formed N-methylpyrrole-2-aldehyde. N-n-Butyl-l-rhamnosylamine, in a mixture of methanol and acetic acid, formed the corresponding pyrrolealdehyde, l-n-butyl-5-methylpyrrole-2- aldehyde, at the almost same rate as did N-xyloside. On the contrary, N-n-butyl-d-glucosylamine, under the same condition, did not form any detectable amount of the corresponding pyrrolealdehyde, but formed complicated products. A formation mechanism of the pyrrolealdehydes from 3-deoxyosulose and amine was proposed.     

Chemical Studies on “Clover Sickness”

Two new isoflavonoids were isolated from red clover as germination inhibitors for the same plant and their structures were determined as a glucoside of biochanin A (7-d-β-glucosyl-5,7-dihydroxy-4′-methoxyisoflavone) (II) and its 5-malonate (I), respectively. Besides these compounds the following substances were also isolated as inhibitors: trifolirhizin (III), ononin (IV), daidzein (V) and its 7-glucoside (VI), formononetin (VII), genistein (VIII) and biochanin A (IX).     

Studies on γ-Radiolysis of Sulfur Containing Amino Acids

In connection with flavor deterioration accompanied by food irradiation, the effect of γ-irradiation on sulfoxide amino acids in air free aqueous system was investigated. The major radiolysis products from S-n-propyl-l-cysteine sulfoxide (PCSO) were alanine, cysteic acid, dipropyl disulfide, etc., and from S-allyl-l-cysteine sulfoxide (ACSO) were S-allyl-l-cysteine, cystine, cysteic acid, etc., which were isolated chromatographycally and identified by using IR and mass spectrometry. The sulfoxide in ACSO was more easily reduced to sulfide than that of in PCSO, and the bond of S-C (β-carbon in alanine moiety) in ACSO was difficult to cleave. These differences observed between PCSO and ACSO in the radiolysis products and their yields indicate that the radiolysis degradation is considerably influenced by the structure of alkyl group. From the experiments with N₂O or KBr addition during irradiation, principal roles of the active species in irradiated water in the degradation processes were partly elucidated.     

Chemical Studies on Smelling Compounds in Hen’s Egg

Volatile smelling compounds of freezed egg white, freshness of which was kept by freezed storage, were collected by steam-distillation. After DNP-hydrazones of volatile carbonyl compounds were separated into four classes by column chromatography, DNP-hydrazones contained in each class were separated by thin layer chromatography. Rf and melting point of recrystalized compounds were compared with those of authentic compounds. Volatile basic compounds were collected as hydrochlorides and detected by paper and thin layer chromatography.

Acetone, acetaldehyde, formaldehyde, 2-pentanone, 2-butanone diacetyl except two unknown compounds as volatile carbonyl compounds, and ammonia, methylamine, dime-thylamine and putrescine as volatile basic compounds were tentatively identified.

Correlations between these compounds and smell of freezed egg white were discussed.     

Chemical Studies on Components of Dried Bonito, “Katsuobushi”

The flavor concentrate obtained by the extraction of “Katsuobushi” of bonito (Katsuwonus pelamis) with 80% ethanol and by the subsequent steam distillation of the extract was fractionated by the usual method and the resulting neutral, non-carbonyl oxygenated fraction was investigated by gas chromatography. The following components were tentatively identified: 2-pentanol and 2-methyl-1-heptanol as free alcohols, and 4 alcohols of n- and isobutanol, n-pentanol and n-dodecanol and 9 carboxylic acids of propanoic, n-butanoic, n-pentanoic, n-octanoic, n-nonanoic n-decanoic, n-dodecanoic, n-tetradecanoic and n-hexadecanoic acid as the constituents of esters. A constituent alcohol existing in the largest amount was isolated by gas chromatography and identified as 2-methyl-1-heptanol by elemental analysis, NMR, IR, and MS. A constituent acid existing in large amount was also isolated and investigated similarly, and the structure was partially estimated. 2-Methyl-1-heptanol holds a fresh woody aroma and seems to have a major effect on “Katsuobushi” flavor.     

Chemical Studies on Components of Dried Bonito, “Katsuobushi”

Volatile components obtained by the extraction of “Katsuobushi” with 80% ethanol and by the subsequent steam distillation of the extract were fractionated by the usual methods, and the resulting hydrocarbon fraction was investigated. Gas chromatographic study on this fraction originated from “Katsuobushi” of bonito (Katsuwonus pelamis) revealed 9 hydrocarbons, including n-tetradecane, n-pentadecane, n-hexadecane, n-heptadecane, n-octadecane, n-nonadecane, n-eicosane, n-heneicosane and n-docosane, which were tentatively identified by the retention times with the aid of authentic hydrocarbons. n-Pentadecane and n-heptadecane that were main components among these hydrocarbons were identified further by NMR and IR spectrometry. “Katsuobushi” of frigate mackerel (Auxis thazard), mackerel (Scomber Japonicus Houttuyn) or muroaji (Decapterus muroadsi) also contained n-penta-decane and n-heptadecane in large amounts, but did other hydrocarbons in negligible amounts.

Possible mechanisms of the hydrocarbon formation during the processing of “Katsuobushi” were discussed.     

γ-Irradiation Effects on the Antioxidative Activity Developing in the Amino Acid-Sugar Reaction

The effects of γ-irradiation on the antioxidative activity developing in the amino acid-sugar reaction were investigated. The antioxidative activity of the nondialyzable melanoidin prepared from glycine and d-glucose was not much affected by γ-irradiation. However, the development of the antioxidative activity of an l-leucine-d-glucose solution on heating was markedly accelerated when the mixture had been preirradiated with γ-rays, and the development of the activity was more prominent than that of the brown color. The irradiation of a glucose solution alone accelerated the antioxidative activity development when heated with leucine, but the irradiation of a leucine solution alone did not cause a similar effect when heated with glucose. Except an l-cysteine-glucose combination, all combinations of amino acids and sugars tested gave rise to almost similar antioxidative effects.     

Studies on the Chemical Components of the Tacca chanteraeri André

A steroidal saponin has been isolated from the roots of Taccachanteraeri Andre', a folk medicine in Yunnan, which identified as diosgenin 3β-O-α-L-rhamnopyranosyl-(1→2)- O-α-L-rhamnopyranosyl-( 1 → 3 )-O-β-D-glucopyranoside ( 1 ) with stigmasterol (2) and daucosterin (3). Our studies support I. H. Burkill and A. Takhtajan's idea according to which Taccaceae would be the closest to Dioscoreaceae and be included in Liliales.     

Steady-state Inhibitory Kinetic Studies on Almond β-Glucosidase-catalyzed Reaction——Binding Sites of Monosaccharides

Steady-state inhibitory kinetic studies on almond β-glucosidase-catalyzed reactions were done to elucidate the binding subsite of several monosaccharides on this enzyme.

Glucono-1,5-Iactone (a transition-state analog), glucose, 2-deoxy glucose, fucose, and methyl α-glucoside showed mixed-type inhibition, but galactose, galactosamine, mannose, N-acetyl glucosamine, and glucosamine showed pure competitive inhibition on the hydrolysis of P-nitrophenyl β-glucoside.

These results are reasonably accounted for by assuming that the former monosaccharides (the mixed type inhibitors) bind to subsite 1 (the nonreducing-end side subsite to which the nonreducing-end glucose residue of a substrate binds in a productive binding mode), and that the latter (the competitive inhibitors) bind to subsite 2, the adjacent subsite to subsite 1.

The binding affinity ( — ΔG°) of glucono-1,5-lactone (— ΔG° = 6.7 kcal mol ¹ at pH 5.0, 25°C) was significantly greater than those of the others (0.3 ~ 1.6 kcal mol^-1).     

The Chemical Studies on Corydalis hendersonii Hemsl（ =C. nepalensis Kitamura——

Five alkaloids were isolated from the whole plants of Corydalis hendersonii Hemsl (= C. nepalensis Kitamura) by means of centrifugal TLC method. Alkaloids Cn-20(I) was assigned as a new alkaloid named henderine. Alkaloids Cn-1, Cn-2, Ch-16 and Cn- 19 were identified as β-allocryptopine, protopine, stylopine and Cheilanthifoline, respectively, based on mp. UV. IR. MS and 1H-NMR spectra.     

Studies on the Kinetic Properties of Photosystem Ⅱ Primary Reaction Using Fluorescence Spectroscopy with 470 fs Time Resolution

The primary reaction kinetics of the isolated photosystem Ⅱ particles and photosystem Ⅱ core complexes from spinach ( Spinacia deracea Mill. ) was investigated using the time-resolved fluorescence spectroscopy with 470 fs time resolution. 2 to 4 lifetime components were detected by the multi-exponential curve fining method. These components were analyzed and discussed in terms of different kinetic processes. It is suggested that 3 ps component is attributed to the charge separation and 0.8 ps, 12 ps, 25 ps and 100 ps components are related to the energy transfer processes. A possible kinetic scheme in photosystem Ⅱ reaction center was proposed based upon the reported previously result.     

Comparative Biochemical Studies on α-Glucosidases

The substrate specificity of Schizosaccharomyces pombe α-glucosidase has been investigated.

The range of opt. pH was 4.0~4.4 and opt. temp. 45°C. The enzyme lost almost all the enzymatic activity at 55°C for 15 min. and the range of pH-stability was 3.2~6.8 at 30 °C for 20 hrs.

The enzyme was active especially on maltose in comparison with other α-glucosides. The rate of hydrolysis decreased in the following order: maltose, isomaltose, phenyl-α-glucoside, panose and turanose. Therefore, the substrate specificity of the enzyme was quite different from that of brewer’s yeast (Saccharomyces cerevisiae) α-glucosidase, though similar to that of mold α-glucosidase.