Isolation,Structures and Biological Activities of Colletotrichins,Phytotoxic Substances from Colletotrichum nicotianae

From the phytopathogenic fungus, Colletotrichum nicotianae, three phytotoxic substances have been isolated and named colletotrichin, colletotrichins B and C (1, 2 and 3). The structures of these compounds have been elucidated from the physical and chemical evidence. When applied on the tobacco leaves, colletotrichins induced the symptom similar to that of the tobacco anthracnose caused by C. nicotianae. The compounds were also toxic to the lettuce and rice seedlings.     

Isolation and Chemical Characterization of the Peptidyl Factor Inducing Sexual Agglutination in Saccharomyces cereviciae

Ten diether-type monoglycosyl and glycobiosyl glycerolipids, including 3-O-(4-O-β-D-galactopyranosyl-β-D-glucopyranosyl)-l,2,-di-O-n-tetradecyl-sn-glycerol, a synthetic analogue of lactosyl ceramide, were synthesized and their stereochemistry was assigned unambiguously by ¹³C NMR using the values of C-H one bond couplings. Their ¹³C NMR were further analysed to show the diagnostic α-effect of glycosylation in these compounds depending on the anomeric configuration of the glycosyl residue linked to C-3′-O atom.     

Neurodegenerative Evidence in Mice Brains with Cecal Ligation and Puncture-Induced Sepsis: Preventive Effect of the Free Radical Scavenger Edaravone

Sepsis is a major clinical challenge and septic encephalopathy is its nasty complication. The pathogenesis and underlying mechanisms of septic encephalopathy are not well understood. This study sought to fully characterize sepsis-associated biochemical and histopathological changes in brains of mice after cecal ligation and puncture, regarded as a highly clinically relevant animal model of polymicrobial sepsis. Real-time PCR analysis showed that gene expression levels of proinflammatory cytokines, including tumor necrosis factor-α and interleukin-1β, were significantly up-regulated in brain tissues from septic mice, but to a much lesser extent when compared with those in peripheral tissues such as lungs. Blood-brain barrier (BBB) permeability was significantly increased in septic mice, as determined by the measurement of sodium fluorescein and Evans blue content. Sepsis resulted in increases in NADPH oxidase activity and expression of p47^phox and p67^phox and up-regulation of inducible nitric oxide (NO) synthase in brains, indicating that superoxide, produced by NADPH oxidase, reacts with NO to form peroxynitrite, that maybe lead to the loss of BBB integrity. Light and electron microscopic examination of septic mouse brain showed serious neuronal degeneration, as indicated by hyperchromatic, shrunken, pyknotic, and electron-dense neurons. These histopathogical changes were prevented by treatment with the free radical scavenger edaravone. Together, these results suggest that sepsis can lead to rapid neurodegenerative changes in brains via free radical species production and possibly subsequent injury to the BBB. We may also provide a potentially useful therapeutic tool for treating septic encephalopathy.     

Syntheses of Several Compounds Related to Helminthosporol and their Plant Growth-regulating Activities

Several compounds related to helminthosporol (I), a natural plant-growth promoter, were prepared from I and their plant-growth regulating activities were examined together with those of the derivatives reported in the previous paper, using rice and lettuce seedlings. Among the compounds tested, helminthosporic acid (III) exhibited marked elongation effect to the shoot growth of rice and lettuce seedlings, whereas the effect of I was specific to the former. Results of the biological test are reported in details.     

Isolation of o-(Malonylamino)benzoic Acid from Peanut Plant

A new compound was isolated from leaves of peanut. Its structure was determined as o-(malonylamino)benzoic acid on the basis of physicochemical evidences.     

Peptide Thioester Synthesis via an Auxiliary-Mediated N–S Acyl Shift Reaction in Solution

The 4,5-dimethoxy-2-mercaptobenzyl (Dmmb) group attached to a main chain amide in a peptide is easily transformed into an S-peptide via an intramolecular N–S acyl shift reaction under acidic conditions, and the S-peptide produces a peptide thioester through an intermolecular thiol–thioester exchange reaction. In order to develop a method for efficiently preparing peptide thioesters based on the N–S acyl shift reaction, the factors involved in this process were analyzed in detail. The general features of the transformation at the Dmmb group attached amide bond in a trifluoroacetic acid (TFA) solution and the generation of a peptide thioester were examined by ¹³C-NMR spectral measurements, reversed-phase (RP) HPLC analyses, mass measurements, and amino acid analyses. The methoxy group of the Dmmb group was not essential for the N–S acyl shift reaction, but played a role in stabilizing the thioester form. The addition of water to the TFA solution accelerated the N–S acyl shift reaction mediated by the Dmmb group and also suppressed the acid-catalyzed cleavage of the Dmmb group. A peptide thioester was produced from the S-peptide via an intermolecular thiol–thioester exchange reaction with minimal epimerization of the amino acid residue that constituted the thioester bond. Undesirable side reactions, such as the hydrolysis of the thioester bond and an S–N acyl shift reaction occurred during the synthetic process, which is a subject of further investigation.