Structures of Ezomycins A1 and A2

The structures of ezomycins A₁. and A₂, antifungal antibiotics produced by a strain of Streptomyces, were determined as 1 and 2, respectively, by degradative and spectrometric studies.     

Isolation,Structure and Physiological Activities of Piericidin B,Natural Insecticide Produced by a Streptomyces

Piericidin B was isolated from mycellia of Streptomyces mobaraensis besides piericidin A. On the basis of IR, NMR and mass spectral studies together with chemical evidences, its structure was assigned as Id. Its physiological activities are also deescribd.     

13C-NMR Spectra and Streochemistry of Isoechinulins A,B and C

¹³C-NMR spectra of isoechinulins A, B and C, metabolites from Aspergillus ruber, were fully assigned on the basis of chemical shifts and multiplicities and comparison with their analogues. Taking advantage of the symmetrical structure of the diketopiperazine ring, the stereochemistry of the trisubstituted carbon-carbon double bond in a dehydrotryptophyl moiety was determined as Z (cis) by measuring the coupling constants, , in the proton nondecoupled spectrum of isoechinulin B.     

Metabolism of Glutamate in Purple Nonsulfur Bacteria Participation of Vitamin B12

Purple nonsulfur bacteria, Rhodospirillum rubrum and Rhodopseudomonas spheroides were found to possess coenzyme B₁₂-dependent glutamate mutase activity. Cell-free extracts of these bacteria grown on Co²⁺-containing media catalyzed the conversion of glutamate to β-methylaspartate and further to mesaconate. The activity of the cell-free extracts of these organisms cultivated on Co²⁺-deficient media was markedly lower than that of the normal cells. Addition of coenzyme B₁₂ to the former reaction mixture enhanced the mesaconate formation via β-methylaspartate. These results indicate the involvement of coenzyme Independent glutamate mutase of these bacteria in the dissimilation of glutamate to acetyl-CoA and pyruvate through the following pathway.

glutamate→β→methylaspartate→mesaconate→citramalate→→acetyl-CoA, pyruvate On the other hand, a greater part of glutamate was converted to α-hydroxyglutarate and succinate with the cell-free extracts of these photosynthetic bacteria. This fact, taking account of the presence of propionyl-CoA carboxylase in these bacteria, implies the participation of coenzyme B₁₂-dependent (R)-methylmalonyl-CoA mutase in the formation of succinate via the following route.

glutamate→α-ketoglutarate→α-hydroxyglutarate→propionate→propionyl-CoA→(S)-methylmalonyl-CoA→(R)-methylmalonyl-CoA→succinyl-CoA     

Isolation and Structure Elucidation of Three New Insecticidal Cyclodepsipeptides,Destruxins C and D and Desmethyldestruxin B,Produced by Metarrhizium anisopliae

A multi-channel continuous-flow analyzer equipped with biosensing devices was developed for multi-component measurement and its use in automating routine analysis was evaluated.

Biosensing was achieved by the aid of an immobilized enzyme reactor installed in the channel, and the channel switching process for the sensing of a different compound was made by using a column-switching rotary valve. Another rotary valve was used for auto-sampling. Both of the two rotary valves were interfaced to a system controller and work conjugatively in a programmed manner. Signal subtraction between different channels was found to be more precise compared with the multi-channel flow-injection analysis method, which is of merit for an analysis utilizing enzyme relay reaction (as for sucrose analysis) or for background signal subtraction. Glucose, lactate, and sucrose content in real samples were measured automatically with high reproducibility, and the results agree well with the kit method.     

Isolation and Identification of a Sexual Hormone in Yeast

5-Fluorotryptophan (5FT), indolmycin (IM), 4-fluorotryptophan and 7-azatryptophan were found on screening to be tryptophan antagonists among various chemically synthesized and naturally occurring tryptophan analogues for the isolation of l-tryptophan (l-Trp) producing mutants of Bacillus subtilis K.

From among 5FT resistant mutants, potent l-Trp producers were obtained using an improved isolation medium. Growth of the isolated 5FT-resistant l-Trp producer, AJ 11709, was inhibited by IM. From among 5FT and IM resistant mutants, the best strain, AJ 11979, which produced 9.0 g/liter of l-Trp from 13% glucose on 120hr cultivation, was selected.     

Gibberellins in Immature Seeds of Pharbitis nil

A new gibberellin, gibberellin A₂₀ (GA₂₀), was isolated from immature seeds of morning-glory (Pharbitis nil). Its structure was established as 4aα, 7α-dihydroxy-1β-methyl-8-methylenegibbane-1α, 10β-dicarboxylic acid-1→4a lactone (I) on the basis of its physicochemical analysis as well as chemical evidences. GA₂₀ shows marked growth promoting activities on dwarf maize d₂ and d₅ but weak activities on d₁, rice seedling and dwarf pea.     

Evaluation of O,O-Dialkyl O-Cyanophenyl Phosphates and Phosphorothioates as Insecticides

Various O,O-dialkyl O-cyanophenyl phosphates and phosphorothioates were prepared and their biological activities were examined. Among them, O,O-dimethyl O- (4-chloro-2-cyanophenyl) phosphorothioate was found to have selective and high toxicity to houseflies. O,O-Dimethyl O- (4-cyanophenyl) phosphorothioate, O,O-diethyl O- (4-cyanophenyl) phosphorothioate and O,O-diethyl O- (2-chloro-4-cyanophenyl) phosphorothioate showed high insecticidal activty to American cockroaches, though the former two were not so effective to houseflies. The dimethyl esters of these series exhibited markedly lowered mammalian toxicity. Among the O-ethyl O-cyanophenyl phenylphosphonothioates, O-ethyl O- (2-chloro-4-cyanophenyl) phenylphosphonothioate was highly effective to mites, while less effective to insects.     

Structure of Carbohydrate Moiety of Asterosaponin A

Partial acid hydrolysis of asterosaponin A, a steroidal saponin, afforded two new disaccharides in addition to O-(6-deoxy-α-d-glucopyranosyl)-(l→4)-6-deoxy-d-glucose which has been characterized in the preceding paper. The formers were demonstrated as O-(6-deoxy-α-d-galactopyranosyl)-(1→4)-6-deoxy-d-glucose and O-(6-deoxy-α-d-galactopyranosyl)-(l→4)-6-deoxy-d-galactose, respectively.

Accordingly, the structure of carbohydrate moiety being composed of two moles each of 6-deoxy-d-galactose and 6-deoxy-d-glucose, was established as O-(6-deoxy-α-d-galactopyranosyl)-(l→4)-O-(6-deoxy-α-d-galactopyranosyl)-(l→4)-O-(6-deoxy-α-d-glucopyranosyl)-(l→4)-6-deoxy-d-glucose, which is attached to the steroidal aglycone through an O-acetal glycosidic linkage.