1,721,084 research outputs found
Hibispeptin A, a novel cyclic peptide from Hibiscus syriacus
No full textA new cyclic peptide, hibispeptin A, has been isolated from the root bark of Hibiscus syriacus and the structure was assigned as cyclo[-Ahabpa(- pyro-Glu)-Pro-Leu-Phe-] on the basis of various spectroscopic analyses.open
Coumarins with monoamine oxidase Inhibitory activity and antioxidative coumarino-lignans from Hibiscus syriacus
No full textA previously undescribed coumarin and a new coumarino-lignan, together with the known compounds scopoletin and cleomiscosins A, C, and D, have been isolated from the root bark of Hibiscus syriacus, and their structures were assigned on the basis of various spectral studies. The coumarin analogue and scopoletin inhibited monoamine oxidase with moderate IC50 values. The new coumarino-lignan and cleomiscosin C showed lipid peroxidation inhibitory activity comparable to vitamin E.open
Hibispeptin B, a novel cyclic peptide from Hibiscus syriacus
No full textA new cyclic peptide, designated as hibispeptin B, has been isolated from the root bark of Hibiscus syriacus. Hibispeptin B has a unique amino acid unit assigned as 2-amino-3-(2-hydroxy-5-aminoacetylbenzyl)pentanoic acid (Ahabpa) in cyclic core. Its structure was established as cyclo[Ahabpa(- pyro-Glu)-Pro-Leu-Leu-] on the basis of various spectroscopic analyses. Configurations of all normal amino acids were determined as L by chiral-TLC analysis.open
Taxonomy, fermentation, isolation and characterization of a herbicidal compound, 3D5
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Application as a cosmeceutical ingredient of Euryale ferox seed extract
No full textIn our search for the natural cosmetic ingredients, we found that Euryale ferox seed extract exhibited the strong antioxidative activity. Five active compounds were isolated from the ethyl acetate extract through various chromatographic methods and their structures were determined by NMR and MS spectral analysis. These compounds were identified as fucosterol (1), 3-(4-hydroxy-3-methoxybenzyl)-4-[(7'R),5'-dihydroxy-3'-methoxybenzyl]tetrahydrofuran (2), resorcinol (3), pyrogallol (4) and 4-O-methylgallic acid (5).We evaluated the antioxidative, antielastase activities and melanogenesis inhibitory effects of these compounds. The values of compounds 2 ~ 5 for free radical scavenging activity were and especially compounds 4 and 5 were 6-fold more effective than ferulic acid as a positive control. And compounds 2 ~ 4 inhibited human neutrophil elastase with values of and compound 3 also inhibited melanin synthesis in B16F10 melanoma cells with an value of . These results suggest that Euryale ferox extract having a lot of various active ingredients may be useful as a natural multi-functioning agent.open
Benzastatins H and I, new benzastatin derivatives with neuronal cell protecting activity from Streptomyces nitrosporeus
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Nitric oxide synthase inhibitor decrease NMDA-induced elevations of extracellular glutamate and intracellular ca(2+) levels via a cGMP-independent mechanism in cerebellar granule neurons
No full textThese studies were designed to examine the differential effect of nitric oxide (NO) and cGMP on glutamate neurotransmission. In primary cultures of rat cerebellar granule cells, the glutamate receptor agonist N-methyl-D-aspartate (NMDA) stimulates the elevation of intracellular calcium concentration ([Ca2+]i), the release of glutamate, the synthesis of NO and an increase of cGMP. Although NO has been shown to stimulate guanylyl cyclase, it is unclear yet whether NO alters the NMDA-induced glutamate release and [Ca2+]i elevation. We showed that the NO synthase inhibitor, NG-monomethyl-L-arginine (NMMA), partially prevented the NMDA-induced release of glutamate and elevation of [Ca2+]i and completely blocked the elevation of cGMP. These effects of NO on glutamate release and [Ca2+]i elevation were unlikely to be secondary to cGMP as the cGMP analogue, dibutyryl cGMP (dBcGMP), did not suppress the effects of NMDA. Rather, dBcGMP slightly augmented the NMDA-induced elevation of [Ca2+]i with no change in the basal level of glutamate or [Ca2+]i. The extracellular NO scavenger hydroxocobalamine prevented the NMDA-induced release of glutamate providing indirect evidence that the effect of NO may act on the NMDA receptor. These results suggest that low concentration of NO has a role in maintaining the NMDA receptor activation in a cGMP-independent manner.open
An antibacterial compound against Pasteurella haemolytica produced by Streptomyces sp.
No full textPasteurella haemolytica is well known to cause severe pneumonia, consolidation and oedema of the lung, and fibrinous pleurisy under the stress and infection of virus in the cattle. In the course of our screening for antimicrobial agents against P. haemolytica, compound 51086 has been isolated from the fermentation broth of Streptomyces sp. 51086. The compound 51086 was purified by SiO2, Sephadex LH-20 and ODS column chromatographies and HPLC, subsequently. The structure of compound 51086 was determined as hygromycin A by combination of 1(H) NMR, 13(C) NMR, HMBC, and ESI-MS. This compound showed significant antibacterial activity against P. haemolytica and P. multocida.open
Free radical scavenging and antielastase activities of flavonoids from the fruits of Thuja orientalis
No full textBioassay-guided fractionation of the MeOH extract of Thuja orientalis fruits using a DPPH (2,2-diphenyl-1-picrylhydrazyl) assay led to the isolation of 9 flavonoids: cupressuflavone (1), amentoflavone (2), robustaflavone (3), afzelin (4), (+)-catechin (5), quercitrin (6), hypolaetin 7-O-β- xylopyranoside (7), isoquercitrin (8) and myricitrin (9). Their chemical structures were determined by spectroscopic analyses. The free radical scavenging and human neutrophil elastase (HNE) inhibitory activities were evaluated for the isolated compounds. By DPPH scavenging assay, compounds 5, 6, 7, 8 and 9 showed anti-oxidant activities with IC50 values of 28.66, 31.19, 18.30, 26.63 and 15.10 μM, respectively. By ABTS [2,2′- azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt] scavenging assay, these compounds also exhibited potent anti-oxidant activities with IC50 values of 6.77, 13.96, 6.97, 22.79 and 9.96 μM, respectively. of note, compounds 1, 2 and 3 showed significant HNE inhibitory activities with IC50 values of 8.09, 1.27 and 1.33 μM, respectively.open
Clitocybins, novel isoindolinone free radical scavengers, from mushroom Clitocybe aurantiaca inhibit apoptotic cell death and cellular senescence
No full textHigh concentration of intracellular reactive oxygen species (ROS) plays a role in damaging biological systems. We isolated clitocybin A from the culture broth of Clitocybe aurantiaca and then clitocybin B and C derivatives were synthesized from clitocybin A. IMR-90 lung fibroblast cells were pre-treated or post-treated with clitocybin A, B and C to the addition of 100 μM H 2O2. These compounds inhibited the level of intracellular reactive oxygen species (ROS) and H2O2-induced cell death as judged by hypodiploid cell formation. The inhibitory effect of clitocybins on H2O2-induced cell death was comparable to that with N-acetylcysteine (NAC), a well-known ROS scavenger. The inhibition of H 2O2-induced cell death by clitocybins was mediated by the reduction of caspase 3 and 9 activation, cytochrome c release from mitochondria and the degradation of IκB- aand IκB-β, which could be resulted in the prevention of cellular senescence. It suggests that clitocybins are novel compounds scavenging ROS and protect cells from apoptosis and cellular senescence.open
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