RESUMEN

An investigation of sesquiterpene lactone content in Arnica tincture (German Pharmacopoeia) after storage for three years at different temperatures (+4, +25 and +30 degrees C) was carried out by GC and GC-MS analysis. A decrease (13, 32 and 37%, respectively) in the content of the main active compounds in this preparation, 11 alpha,13-dihydrohelenalin esters, correlating with storage temperature was found. This change was shown to be caused by addition of ethanol to the cyclopentenone structure of these molecules leading to 2-ethoxy-2,3,11,13-tetrahydrohelenalin derivatives.

Asunto(s)

RESUMEN

A polysaccharide consisting of mainly 1,4-linked glucose units was found associated with prion rods, which are composed mainly of insoluble aggregates of the N-terminally truncated prion protein (PrP 27-30) exhibiting the ultrastructural and tinctorial properties of amyloid. The polysaccharide differs in composition from the Asn-linked oligosaccharides and the GPI-anchor of the prion protein. Prion rods were prepared from scrapie-infected hamster brains using two different purification protocols. Prolonged digestion of rods with proteinase K reduced PrP by a factor of at least 500, leaving about 10% (w/w) of the sample as an insoluble remnant. Only glucose was obtained by acid hydrolysis of the remnant and methylation analysis showed 80% 1,4-, 15% 1,6- and 5% 1,4,6-linked glucose units. The physical and chemical properties as well as the absence of terminal glucose units indicate a very high molecular mass of the polysaccharide. No evidence was found for covalent bonds between PrP and the polysaccharide. The polysaccharide certainly contributes to the unusual chemical and physical stability of prion rods, acting like a scaffold. A potential structural and/or functional relevance of the polysaccharide scaffold is discussed.

Asunto(s)

RESUMEN

The n-hexane extract of Houttuynia cordata was shown to inhibit prostaglandin synthase in vitro. Phytochemical examination led to the identification of five fatty acids (linolenic, linoleic, oleic, palmitic and stearic), cepharanone B, phytol and stigmast-4-ene-3,6-dione. The inhibitory effect of the extract on prostaglandin formation in vitro could be attributed mainly to linoleic and linolenic acid.

RESUMEN

We report on an enzymatic-chemical method for the specific preparation of L-amino acid-derived quinoxalinols suitable for the sensitive estimation of 13C- or 2H-label enrichment by gas chromatography-mass spectrometry: Amino acid fractions are isolated from physiological fluids by ion-exchange chromatography. The compound of interest is converted to the corresponding 2-oxo acid by treatment with an L-amino acid dehydrogenase of the desired specificity. Reaction of the 2-oxo acid with o-phenylenediamine yields the quinoxaline derivative. Isotopic label enrichment is then determined by gas chromatographic-mass spectrometric analysis of the O-trimethylsilyl derivative using an ammonia-chemical ionization mode and selected ion monitoring of the quasi-molecular ions [MH]+ and [MH + n]+ (n = number of labeled positions). Details for application of various generally available L-amino acid dehydrogenases (L-ala DH, L-glu DH, L-leu DH, L-phe DH) are presented. The method was used, e.g., for serum analysis in in vivo studies on the decarboxylation rates of branched-chain L-[1-(13)C]-amino acids.

Asunto(s)

RESUMEN

The structures of novel oligoglycosidic cardenolides, alepposide A (C55H86O23) [1] and alepposide B (C48H74O20) [2], have been deduced mainly by nmr methods. Based on homonuclear (1H and 13C nmr, 1H COSY) and proton-detected heteronuclear shift correlation experiments [HMQC both for 1J(C,H) and for long-range couplings], alepposide A [1] was shown to have the structure strophanthidin-3-O-beta-glucopyranosyl-(1-->4)-O-beta-diginopyranosyl -(1-->4)-O - beta-oleandropyranosyl-(1-->4)-O-beta-digitoxopyranosyl-(1-- >4)-O-beta- digitoxopyranoside. The structure of alepposide B [2] was established as strophanthidin-3-O-beta-glucopyranosyl-(1-->4)-O-beta-oleandropyranos yl- (1-->4)-O-beta-digitoxopyranosyl-(1-->4)-O-beta-digitoxopyranos ide.

Asunto(s)

RESUMEN

Capsules with etryptamine have been commonly available on the market since the middle of 1985. Up to 1962 this CNS-stimulating, monoamine-oxidase-inhibiting drug was sold as an antidepressant (Monase). A case of fatal intoxication is reported. The exact amount of etryptamine taken several hours before death are not known, but it could have been in the range of 700 mg. This drug was detected in tissue by means of common analytical techniques (GLC, GC-MS, HPLC, TLC). Etryptamine cross-reacts with the Emit-st amphetamine assay and can also be detected in urine using these techniques. The level in postmortem blood was 1.1 mg/l. The effects the young man showed were like those known from intoxication with amphetamines, MAO inhibitors, and thymoleptics. Malignant hyperthermia is discussed as a possible cause of death. It is suggested that trade in etryptamine should be controlled.

Asunto(s)

RESUMEN

From the flowers of ARNICA MONTANA L. 13 helenanolides were isolated and identified. They are shown to be 11,13-dihydrohelenalin ( 1), helenalin ( 2) and their ester derivatives 3-13 (see figure). The natural occurence of 6-O-isobutyryl-, 6-O-tigloyl-, 6-O-isovaleryl- and 6-O-(2-methyl)-butyrylhelenalin (compounds 9, 11, 12, 13) is reported for the first time. The qualitative sesquiterpene lactone composition in flowers of A. MONTANA from different regions was found to be variable.

Asunto(s)

Asunto(s)

RESUMEN

In photosynthetically competent chloroplasts from spinach the quantum requirements for oxygen evolution during CO2 reduction were higher, by a factor often close to 1.5, than for oxygen evolution during reduction of phosphoglycerate. Mass spectrometer experiments performed under rate-limiting light indicated that an oxygen-reducing photoreaction was responsible for the consumption of extra quanta during carbon dioxide assimilation. Uptake of 18O2 during reduction of CO2 was considerably higher than could be accounted for by oxygen consumption during glycolate formation and by the Mehler reaction of broken chloroplasts which were present in the preparations of intact chloroplasts. The oxygen reducing reaction occurring during CO2 assimilation resulted in the formation of H2O2. This was indicated by a large stimulation of CO2 reduction by catalase, but not of phosphoglycerate reduction. Catalase could be replaced as a stimulant of photosynthesis by dithiothreitol or ascorbate, compounds known to react with superoxide radicals. There was no effect of dithiothreitol and ascorbate on phosphoglycerate reduction. A main effect of superoxide radicals and/or H2O2 was shown to be at the level of phosphoglycerate formation. Evidence for electron transport of oxygen was also obtained from 14CO2 experiments. The oxidation of dihydroxyacetonephosphate during a dark period or after addition of carbonyl cyanide p-trifluoromethoxyphenyl-hydrazone in the light was studied. The results indicated a link between the chloroplast pyridine nucleotide system and oxygen. Oxygen reduction during photosynthesis under conditions where light is rate limiting is seen as important in supplying the ATP which is needed for CO2 reduction but is not provided during electron transport to NADP. A mechanism is discussed which would permit proper distribution of electrons between CO2 and oxygen during photosynthesis.

Asunto(s)

Asunto(s)

Asunto(s)

Asunto(s)