Naoko Morisaki

Sterol compositions in some green algae and brown algae

Abstract Compositions of the sterol in Chlorophyta and Phaeophyta were established quantitatively. Sterol content in Chlorophyta is more similar to higher plant, and it contains large amount of cholesterol. In Phaeophyta, fucosterol is the main sterol and small amounts of cholesterol, 24-methylene-cholesterol and saringosterol were identified.

Two flavonol glycosides from seeds of Camellia sinensis

Two novel flavonol triglycosides, camelliaside A and B, have been isolated from seeds of Camellia sinensis. The structures were determined to be kaempferol 3-O-[2-O-beta-D- galactopyranosyl-6-O-alpha-L-rhamnopyranosyl]-beta-D-glucopyranoside and kaempferol 3-O-[2-O-beta- D-xylopyranosyl-6-O-alpha-L-rhamnopyranosyl]-beta-D-glucopyranoside on the basis of spectroscopic, chemical and enzymatic studies. These types of interglycosidic linkages, Gal(1----2)[Rha(1----6)]Glc and Xyl(1----2)[Rha(1----6)]Glc, have not been reported previously in flavone and flavonol glycosides.

Different Rifampicin Inactivation Mechanisms in Nocardia and Related Taxa

Mycolic acid‐containing bacteria inactivate rifampicin in a variety of ways such as glucosylation, ribosylation, phosphorylation and decolorization. These inactivations were found to be a species‐specific phenomena in Nocardia and related taxa. Gordona, Tsukamurella and fast‐growing Mycobacterium modified rifampicin by ribosylation of the 23‐OH group of the antibiotic. Such ribosylation was not observed in Rhodococcus and Corynebacterium, but phosphorylation of the 21‐OH group of rifampicin was observed in one strain of Rhodococcus. Nocardia modified the antibiotic by glucosylation (23‐OH group) and phosphorylation, but ribosylation was not observed.

Mutagenicity of ptaquiloside, the carcinogen in bracken, and its related illudane-type sesquiterpenes I. Mutagenicity in Salmonella typhimurium

Ptaquiloside, a potent carcinogen of an illudane-type sesquiterpene glycoside isolated from Pteridium aquilinum, and its related compounds, hypolosides having the same nucleus isolated from the Pteridaceae, exhibited marked mutagenicity in the modified Ames test with Salmonella typhimurium TA98 and TA100 using a preincubation at pH 8.5. Illudins M and S, sesquiterpenes of the same illudane type from basidiomycetes, also exhibited mutagenicity. The structural requirements for mutagenicity are discussed.

Inactivation of the macrolide antibiotics erythromycin, midecamycin, and rokitamycin by pathogenic Nocardia species.

A survey of five Nocardia spp. with respect to susceptibility towards three macrolides (erythromycin, rokitamycin, and midecamycin) showed that the Nocardia spp. have different susceptibility profiles. Most of the resistance was due to the inactivation of the macrolides by phosphorylation, glycosylation, reduction, deacylation, or a combination thereof.

STRUCTURE OF LYDICAMYCIN, A NEW ANTIBIOTIC OF A NOVEL SKELETAL TYPE

Abstract The structure of a new antibiotic designated lydicamycin was elucidated as shown in Fig. 1 by NMR spectral analysis including a variety of two-dimensional techniques. Lydicamycin was found to possess a novel skeleton containing tetramic acid and amidinopyrrolidine moieties.

Identification of a major cytokinin in coconut milk

A major cytokinin found in coconut milk was isolted by using the tobacco callus growth-promoting assay as a guide during purification. The structure of the factor was determined to be 14-O-{3-O-[β-d-galactopyranosyl-(1→2)-α-d--galactopyranosyl-(1→3)-α-L-arabinofuranosyl]-4-O-(α-L-arabinofuranosyl)-β-d-galactopyranosyl}-trans-zeatin riboside [G3A2-ZR] by various NMR techniques, including heteronuclear multiple bond connectivity by 2D multiple quantum NMR (HMBC), as well as mass spectroscopy and sugar analysis. The optimum concentration of G3A2-ZR for cytokinin activity in the tobacco callus assay was estimated to be 5×10−6 M, so that G3A2-ZR is one order of magnitude more potent than 1,3-diphenylurea and one order less potent than zeatin riboside. At least 20% of the cytokinin activity of coconut milk could be attributed to G3A2-ZR.

Conversion of 6-protoilludene into illudin-M and -S by omphalotus olearius

Abstract Deuterium labeled dl -6-protoilludene ( 7 ) was synthesized and fed to the illudin-producing fungus Omphalotus olearius (ATCC 11719). The hydrocarbon ( 7 ) was incorporated into illudin-M ( 2 ) and -S ( 3 ).

Synthesis of diacylglycerol analogs of phosphatidylinositol 3,4,5-trisphosphate

Abstract Phosphatidylinositol 3,4,5-trisphosphate analogs with saturated diacylglycerol substructure have been designed, focusing on their feactivity with PIP3 5-phosphatase. Dephosphorylation of native PIP3 was competitively inhibited in the presence of synthetic PIP3 C2 and PIP3 C4 , respectively.

The structural requirement of phosphatidylinositols as substrate of phosphatidylinositol 3-kinase

Abstract Synthetic distearate phosphatidylinositol (PI) was not phosphorylated by PI 3-kinase. The fatty acids at glycerol sn -2 must be as short as octanoic acid or less to act as a substrate of PI 3-kinase.