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101.
Cultured crown gall cells of Catharanthus roseus Don (Vinca rosea L.) was found to contain brassinosteroids. These were identified as brassinolide and castasterone by GC/MS. This is the first conclusive identification of endogenous brassinosteroids in cultured cells.  相似文献   
102.
Shiromodiol-diacetate, shiromool, and shiromodiol-monoacetate are insect feeding inhibitors isolated from Parabenzoin trilobum Nakai. On the bases of chemical and spectral evidence we deduced that these compounds have the structure shown in I, XVIII, and XI, respectively.  相似文献   
103.
Modified fungal product 4-O-methylascochlorin (MAC) is an experimental agent affecting lipid and carbohydrate metabolism in mammals. The hypocholesterolemic properties of MAC were studied using rats fed on a standard laboratory diet. Because of the insolubility in water, reproducibility of the hypocholesterolemic activity had usually been poor for rats fed ad libitum. The difficulty was overcome by controlled reverse-phase feeding; MAC significantly lowered serum total cholesterol (s-TC) in rats only when given by gastric intubation soon after diet intake.

MAC increased fecal excretion of neutral and acidic sterols and also increased biliary flow accompanying increments in biliary cholesterol, bile acids and phospholipids. A much larger increase in neutral sterols was characteristic for MAC. However, intestinal absorption of cholesterol and cholic acid was unaffected by MAC. Three mechanisms therefore seemed to be working in hypocholesterolemic activity: (a) withdrawal of hepatic cholesterol into bile, (b) a larger fecal loss of sterols following increment of biliary sterols and (c) enhanced bile acid synthesis compensating the larger fecal loss. A negative sterol balance often leads to an increase in hepatic cholesterogenesis. However, cholesterogenesis, as judged from incorporation of the precursors, was unchanged by MAC.  相似文献   
104.
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.  相似文献   
105.
106.
In the screening for inhibitors of cyclic adenosine-3′,5′-monophosphate phosphodiesterase, two compounds, PDE-I (C13H13N3O5) and PDE-II (C14H14N2O5), were isolated from culture filtrates of a Streptomyces. Concentrations for 50% inhibitions of PDE-I and PDE-II against the high Km enzyme were 15 µm and 13 µm, and those against the low Km enzyme were 65 µm and 130 µm, respectively. Production, isolation and characterization of these compounds are described.  相似文献   
107.
108.
The chlorinolysis of l-methionine methyl ester hydrochloride with molecular chlorine was carried out under various conditions, resulting in methyl l-2-amino-4,4,4-trichlorobutanoate and methyl l-2-amino-3,4,4,4-tetrachlorobutanoate which were isolated as N-benzoyl and N-carbobenzoxy derivatives. The chlorinolysis of N-acylmethionine ester and methionine sulfoxide ester proceeded also without cleavage of the N-protecting group to give the same products as above. However, the reaction of methionine sulfone derivative with chlorine did not proceed in the same conditions.

It was proved that the resulting polychloroamino acid derivatives are optically pure. The possible chlorinolysis mechanism was also proposed.  相似文献   
109.
A coupled enzyme system of orotidine-5′-phosphate pyrophosphorylase and orotidine-5′-phosphate decarboxylase has been purified approximately 30-fold from cell-free extract of Micrococcus glutamicus 534 Co–147 by means of acid treatment and fractionations with ammonium sulfate and ethanol addition, and properties of the enzyme system have been studied.

Optima of pH, temperature and substrate concentrations for the activity of the purified enzyme system have been investigated, and compared with those of the same enzyme system from dried brewer’s yeast. Furthermore, effects of various inhibitors on the enzyme activity have been examined and it has become evident that the enzyme system is completely inactivated by addition of chelating agent such as EDTA, and regenerated by further addition of magnesium ion.  相似文献   
110.
Streptomyces sp. No. B-1625, which was identified as a strain of Streptomyces antibioticus, is a typical producer of actinomycin, but also produces minor acidic antibiotic components (FA), besides actinomycins X2, D and X. The FA-components, which were obtained with a high-producing mutant, 11M-21, showed antibacterial and antitumor activities, and also similar visible and UV absorption spectra to those characteristic of actinomycin. The FA-components were separated into five components, FA1 FA, FA, FA and FA, on TLC. Among them, one component, FA, isolated in a purified state as an orange powder, has a composition of C, 52.97: H, 6.34: N, 10.48%, and is active against B. subtilis at a MIC of 5mcg/ml. The FA component showed pKa′ of 5.4 and 12.0 and λmax at 443, 427 and 233 nm. From these properties, FA is considered to be an acidic actinomycin congener.  相似文献   
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