Search results for "Spectrophotometry"
showing 10 items of 644 documents
Two new biologically active triterpene saponins from Acanthophyllum squarrosum.
2000
Two novel triterpenoid saponins (1 and 2) have been isolated from the roots of Acanthophyllum squarrosum. The structures were established mainly by a combination of 2D NMR techniques as 3-O-beta-D-galactopyranosyl-(1-->2)-[beta-D-xylopyranosyl-(1-->3)]-be ta-D-glucuronopyranosylgypsogenin-28-O-beta-D-xylopyranosyl-(1-->3 )-b eta-D-xylopyranosyl-(1-->4)-alpha-L-rhamnopyranosyl-(1-->4)-[alpha-L- rhamnopyranosyl-(1-->3)]-beta-D-fucopyranoside (1) and 3-O-beta-D-glucopyranosylgypsogenin-28-O-alpha-L-rhamnopyranosyl-( 1-- >2)-alpha-L-arabinopyranosyl-(1-->2)-[beta-D-glucopyranosyl-(1-->6 )]- beta-D-glucopyranoside (2). Compound 1 showed a moderate concentration-dependent immunomodulatory effect …
Dynamics of the biosynthesis of methylursubin in plant cells employing in vivo 13CNMR without labelling.
1995
Abstract In vivo NMR experiments with a digital 600 MHz instrument, exploiting the natural abundance of 13C, allowed us for the first time to follow the biosynthesis of the newly detected glycoside, methylursubin ( 4- methoxyphenyl -O-β- d -primeveroside ), from 4-methoxyphenol through the intermediate methylarbutin in cell suspensions of the Indian medical plant, Rauwolfia serpentina. The metabolic dynamics indicate that, within 48 hr, 4-methoxyphenol is almost completely converted into the primeveroside, methylursubin. Because of the higher sensitivity at 150.9 MHz compared to that at 100.6 MHz, measuring times could be reduced to 1.5 hr. This allows detailed monitoring of the conversion …
New prenylhydroquinone glycosides from Phagnalon rupestre.
2001
Three new hydroquinone glycosides were isolated from the MeOH extract of the aerial parts of Phagnalon rupestre. Their structures were elucidated as 1-O-beta-glucopyranosyl-1,4-dihydroxy-2-(3',3'-dimethylallyl)benzene (1), 1-O-beta-glucopyranosyl-1,4-dihydroxy-2-(3'-hydroxymethyl-3'-methylallyl)benzene (2), and 1-O-(4' '-O-caffeoyl)-beta-glucopyranosyl-1,4-dihydroxy-2-(3',3'-dimethylallyl)benzene (3) by spectroscopic methods.
Triplet-triplet energy transfer controlled by the donor-acceptor distance in rigidly held palladium-containing cofacial bisporphyrins.
2005
Eleven new complexes, including mono-, heterobi-, and homobimetallic cofacial bisporphyrins, (Pd)H 2 DPS, (M)H 2 DPX, (M)H 2 DPB, (PdZn)DPS, (PdZn)DPX, (Pt) 2 DPX, (M) 2 DPB (M=Pd, Pt), and (Pt)P (DPS 4 - = 4,6-bis[5-(2,8,13,17-tetraethyl-3,7,12,18-tetramethylporphyrinyl)]dibenzothiophene tetraanion, DPX 4 - = 4,5-bis[5-(2,8,13,17-tetraethyl-3,7,12,18-tetramethylporphyrinyl)]-9,9-dimethylxanthene tetraanion, DPB 4 - =1,8-bis[5-(2,8,13,17-tetraethyl-3,7,12,18-tetramethylporphyrinyl)]biphenylene tetraanion, P 2 - = 5-phenyl-2,8,13,17-tetraethyl-3,7,12,18-tetramethylporphyrin dianion) have been synthesized and characterized. The photophysical properties of the donor (M)P (M=Pd or Pt, P= porphy…
Polyalthidin: New Prenylated Benzopyran Inhibitor of the Mammalian Mitochondrial Respiratory Chain
1996
Polyalthidin (3), a new benzopyran derivative, was isolated from the stem bark of Polyalthia cerasoides. Its structure was established on the basis of chemical and spectral evidence. Polyalthidin has showed potent biological activity as an inhibitor of the mammalian mitochondrial respiratory chain.
Two New Glycosides from Astragalus caprinus
2001
A new glycoside of flavonol (1) and a new glycoside of a cycloartane-type triterpene (2) were isolated from the leaves and the roots of Astragalus caprinus, respectively. Their structures were elucidated in turn by spectroscopic data interpretation as 3-O-[[beta-D-xylopyranosyl(1-->3)-alpha-L-rhamnopyranosyl(1-->6)][beta-D-apiofuranosyl(1-->2)]]-beta-D-galactopyranosyl kaempferol (1) and 3-O-(beta-D-xylopyranosyl)-24-O-(beta-D-glucopyranosyl)-20,25-epoxycycloartane-3beta,6alpha,16beta,24alpha-tetrol (2).
Elevated levels of 2-arachidonoylglycerol promote atherogenesis in ApoE-/- mice.
2018
Background The endocannabinoid (eCB) 2-arachidonoylglycerol (2-AG) is a known modulator of inflammation and ligand to both, pro-inflammatory cannabinoid receptor 1 (CB1) and anti-inflammatory CB2. While the role of both receptors in atherogenesis has been studied extensively, the significance of 2-AG for atherogenesis is less well characterized. Methods The impact of 2-AG on atherogenesis was studied in two treatment groups of ApoE-/- mice. One group received the monoacylglycerol lipase (MAGL)-inhibitor JZL184 [5 mg/kg i.p.], which impairs 2-AG degradation and thus causes elevated 2-AG levels, the other group received vehicle for four weeks. Simultaneously, both groups were fed a high-chole…
Potential Antioxidant Activity of Calcium and Selected Oxidative Stress Markers in Lead- and Cadmium-Exposed Workers
2020
Occupational lead (Pb) and cadmium (Cd) exposure occurs during processing and casting of nonferrous metals such as zinc. In contrast to Pb and Cd, Ca is essential for living organisms due to its important role in a multitude of functions, from cell signaling to bone growth. Pb and Cd exposure affects calcium metabolism in various ways. The aim of this study was to investigate the blood levels of Pb, Cd, and Ca and the levels of selected oxidative stress biomarkers in workers exposed to Pb and Cd. Population groups included 264 male employees in a lead-zinc smelter. The study population was divided into two subgroups based on the median of Ca serum level (2.42 mmol/l): the low-Ca-level group…
Elevated advanced oxidation protein products (AOPPs) indicate metabolic risk in severely obese children.
2012
Abstract Background and aims The assessment of oxidative stress may aid in the identification of subsequent metabolic risk in obese children. The objective of this study was to determine whether the plasma level of advanced oxidation protein products, analyzed with a recently proposed modified assay that involves a delipidation step (mAOPPs), was related to metabolic risk factors (MRFs) in severely obese children. Methods and results The plasma levels of mAOPPs were determined by spectrophotometry in 54 severely obese and 44 healthy children. We also measured lipid peroxidation biomarkers (thiobarbituric acid-reactive substances, malondialdehyde, and 8-isoprotane F 2α ) and sulfhydryl group…
Effects of a water-soluble extract of rosemary and its purified component rosmarinic acid on xenobiotic-metabolizing enzymes in rat liver
2001
The effects of a water-soluble extract (WSE) of rosemary and its purified antioxidant rosmarinic acid (RA) on xenobiotic metabolizing enzymes (XME) were studied in rat liver after dietary administration. The modulation of phase I enzymes such as cytochrome P450 (CYP) 1A, 2B, 2E1, 3A, and phase II enzymes such as glutathione S-transferase (GST), quinone reductase (QR) and UDP-glucuronosyltransferase (UGT) was evaluated by measuring enzyme activities with specific substrates. Protein levels of CYPs and rGST A1/A2, A3/A5, M1, M2 and P1 were measured using antibodies in Western blots. Caffeic acid was also studied because it results from RA biotransformation in rat after oral administration. Ma…