The cardiac glycosides of Gomphocarpusf ruticosus R.Br. I. Afroside

1956 ◽  
Vol 9 (4) ◽  
pp. 497 ◽  
Author(s):  
TR Watson ◽  
SE Wright
Keyword(s):  
Simple Structure ◽  
Lactone Ring ◽  
Aldehyde Group ◽  
Hydroxyl Group ◽  
Naturally Occurring ◽  
Ring Junction ◽  
Infra Red ◽  
Free Aldehyde ◽  
Acetyl Group ◽  
Hydrolysis Of

Afroside, C29H42O9, is a new cardiac glycoside which has been obtained from Gomphocarpus fruticosus R.Br. It contains a carbonyl (aldehyde) group at C10, and a secondary hydroxyl group in the nucleus, which has been placed provisionally at position C11. On the basis of the available evidence, afroside appears to consist of a mixture of the isomeric free aldehyde and the 19-11 cyclic hemiacetal forms. Of these substances, the cyclic hemiacetal form is the only one which has been isolated in pure condition (afroside B). Acetylation of afroside produced a triacetate, C35H46O12.H2O, which is identical with that obtained by the acetylation of afroside B. Reduction of afroside with sodium borohydride produces afrosidol, C29H44O9, which shows no evidence for a carbonyl group at C10. Hydrolysis of afroside produces α-anhydroafrogenin, C23H28-30O5.H2O, which forms a monoacetate, C25H32O7.H2O. The infra-red spectra of these compounds show the presence of a saturated γ-lactone ring in the structure of the nucleus, besides the normal Δα-β-γ-lactone ring at C17 (1786, 1755, 1633 cm-1). Acetyl-α-anhydroafrogenin also shows an intense absorption band of simple structure at 1238 cm-1, which indicates an equatorially orientated acetyl group at C3. As all the naturally occurring cardiac aglycones of known structure have a β-orientated hydroxyl group at C3, for the substituent in this position to be equatorial, the A/B ring junction is probably trans. Hydrolysis of afrosidol produces α-anhydroafrogenol, C23H32O5.H2O, which forms a diacetate, C27H36O7.H2O. The infra-red spectrum of α-anhydroafrogenol shows no evidence of the saturated y-lactone ring which is present in the structure of α-anhydroafrogenin.

The proton affinities and deprotonation enthalpies of β-D-fructopyranose and α-L-sorbopyranose

1991 ◽  
Vol 69 (12) ◽  
pp. 1917-1928 ◽  
Author(s):  
Robert J. Woods ◽  
Walter A. Szarek ◽  
Vedene H. Smith Jr.
Keyword(s):  
Hydrogen Bonding ◽  
Oxygen Atom ◽  
Intramolecular Hydrogen Bonding ◽  
Hydroxyl Group ◽  
Proton Affinities ◽  
Naturally Occurring ◽  
Acid Catalyzed ◽  
Acids And Bases ◽  
Intramolecular Hydrogen ◽  
Hydrolysis Of

The proton affinities (PAs) and deprotonation enthalpies (DPEs) were calculated for the pyranoid forms of two naturally occurring sugars, D-fructose and L-sorbose. In both molecules the PAs of the primary hydroxyl group (HO-1), the anomeric hydroxyl group (HO-2), and the ring-oxygen atom (O-6) were calculated, as were the DPEs of HO-1 and HO-2. The stabilities of the conjugate acids and bases of these sugars are enhanced by the presence of intramolecular hydrogen bonding, a feature that is significant in explaining the differences in sweetness and the rates of mutarotation of the title compounds, as well as the differences in the rates of acid-catalyzed hydrolysis of ketopyranosides. Key words: proton affinity, deprotonation enthalpy, ab initio calculations, AM1, hexuloses.

The Cardiac Glycosides of Gomphocarpus fruticosus R.Br. II. Gomphoside

1957 ◽  
Vol 10 (1) ◽  
pp. 79 ◽  
Author(s):  
RR Watson ◽  
SE Wright
Keyword(s):  
Acetic Acid ◽  
Absorption Spectra ◽  
Cardiac Glycosides ◽  
Chromium Trioxide ◽  
Periodic Acid ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Colour Reaction ◽  
Infra Red ◽  
Hydrolysis Of

Gomphoside is the second glycoside which has been isolated from Gomphocarpus fruticosus R.Br. grown in Australia. This compound analyses for the formula C29H44O8 and contains neither methoxyl nor acetyl groups, but forms a diacetate, C33H48O10, which is unstable to chromium trioxide in acetic acid. Although gomphoside gives a negative Keller-Kiliani reaction, a quantitative oxidation by periodic acid indicates the presence of two free adjacent hydroxyl groups in the molecule. Hydrolysis of gomphoside gives gomphogenin, C23H34O5, which does not give a colour reaction with tetranitromethane. The acetylation of gomphogenin yields acetylgomphogenin, C25H36O6, which is unstable to chromium trioxide in acetic acid. Gomphoside and its derivatives have ultraviolet and infra-red absorption spectra typical of those of the normal digitaloid compounds. The reactions which have been carried out on these substances indicate the presence of an hydroxyl group in gomphogenin, besides the normal hydroxyl groups at C3 and C14, which is resistant to acetylation, but which can be oxidized by chromium trioxide in acetic acid. The nature of the carbohydrate is as yet unknown.

2-Deacetylchelocardin: A Degradation Product of Chelocardin

1975 ◽  
Vol 53 (10) ◽  
pp. 1434-1441 ◽  
Author(s):  
Daniel T. W. Chu ◽  
D. L. Garmaise ◽  
E. Bernstein
Keyword(s):  
Chemical Transformation ◽  
Degradation Product ◽  
Hydroxyl Group ◽  
Acetyl Group ◽  
Hydrolysis Of

A novel chemical transformation is described in which chelocardin 1, under normal ketalization conditions, is converted with elimination of the 2-acetyl group, to the bisdioxolane 2. Hydrolysis of 2 yields 2-deacetylchelocardin 4. The properties of the tricarbonylmethane system in 1 and of the 1,3-cyclohexanedione system in 4 are found to be profoundly modified by the presence of the 4-amino and the 12a-hydroxyl group.

Extractives of Australian timbers. VI. Ebelin lactone

1965 ◽  
Vol 18 (9) ◽  
pp. 1451 ◽  
Author(s):  
RA Eade ◽  
LP Rossler ◽  
HV Simes ◽  
JJH Simes
Keyword(s):  
Lactone Ring ◽  
Carbon Skeleton ◽  
Hydroxyl Group ◽  
Side Chain ◽  
Spectroscopic Evidence ◽  
Isolation And Characterization ◽  
Conjugated Triene ◽  
Hydrolysis Of ◽  
Chemical Evidence

Ebelin lactone, formed by hydrolysis of a saponin, is a carbotricyclic triterpene with a novel carbon skeleton. Chemical evidence leading to the structure (I) for ebelin lactone is now presented in detail. Ebelin lactone, C30H46O3, possesses a secondary, equatorial hydroxyl group shown to be the 3β-hydroxyl group located in a typical triterpene ring A (III). Spectroscopic and chemical results show that the remaining two oxygen atoms are present in a γ-lactone ring (XIII). The side- chain has been subjected to oxidative degradations; an examination of the volatile fragments, and the isolation and characterization of the non-volatile C22 octanor compounds indicate that the side-chain has one of four possible structures (XVII). Structure (XVIII) is preferred on biogenetic grounds. The side-chain is attached equatorially; the conjugated triene system is allotted the trans arrangement of the double bonds on spectroscopic evidence. The biogenesis of ebelin lactone is discussed.

Variation in Quantity of Methanol Recovered from Raisins

1963 ◽  
Vol 46 (2) ◽  
pp. 341-343
Author(s):  
M Alice Brown ◽  
James R Woodward ◽  
Floyd DeEds
Keyword(s):  
Methyl Ester ◽  
Esterase Activity ◽  
Enzymic Hydrolysis ◽  
Methanol Content ◽  
Naturally Occurring ◽  
Pectin Esterase ◽  
Hydrolysis Of

Abstract The amount of naturally occurring methanol in fruit must be known so that the quantity left as fumigation residue can be determined. In a study of methanol content of raisins, which had given inconsistent results, the raisins were subjected to different conditions of treatment immediately prior to methanol determination. Conditions that favored pectin esterase activity gave higher values for methanol content than conditions known to inactivate enzymes. Evidence was also obtained that both chemical and enzymic hydrolysis of methyl ester groups of pectic materials occur during analysis.

scholarly journals Crocetin: A Systematic Review

2022 ◽  
Vol 12 ◽  
Author(s):  
Zi-Liang Guo ◽  
Mao-Xing Li ◽  
Xiao-Lin Li ◽  
Peng Wang ◽  
Wei-Gang Wang ◽  
...  
Keyword(s):  
Systematic Review ◽  
Medicinal Plants ◽  
Total Synthesis ◽  
Drug Safety ◽  
Ripe Fruit ◽  
Bioactive Metabolite ◽  
Naturally Occurring ◽  
Hydrolysis Of ◽  
Application Prospects ◽  
Memory Enhancing

Crocetin is an aglycone of crocin naturally occurring in saffron and produced in biological systems by hydrolysis of crocin as a bioactive metabolite. It is known to exist in several medicinal plants, the desiccative ripe fruit of the cape jasmine belonging to the Rubiaceae family, and stigmas of the saffron plant of the Iridaceae family. According to modern pharmacological investigations, crocetin possesses cardioprotective, hepatoprotective, neuroprotective, antidepressant, antiviral, anticancer, atherosclerotic, antidiabetic, and memory-enhancing properties. Although poor bioavailability hinders therapeutic applications, derivatization and formulation preparation technologies have broadened the application prospects for crocetin. To promote the research and development of crocetin, we summarized the distribution, preparation and production, total synthesis and derivatization technology, pharmacological activity, pharmacokinetics, drug safety, drug formulations, and preparation of crocetin.

scholarly journals Synthesis of Acid Polyols As a Feedstock to Produce Flexible Polyurethanes and Their Effect on the Income Level of Furniture Craftsmen

2019 ◽  
Vol 2 (1) ◽  
pp. 39
Author(s):  
Andi Budirohmi
Keyword(s):  
Fourier Transform ◽  
Fatty Acid ◽  
Raw Materials ◽  
Raw Material ◽  
Polymerization Process ◽  
Hydroxyl Group ◽  
Infra Red ◽  
Renewable Raw Material ◽  
Shoe Soles ◽  
Alternative Feedstock

Polyuretanes are widely used as elastomers, coatings, adhesivesand binders,interior and exterior cars, furniture,shoe soles, carpets, rigit and flexible foams, membrane materials as well as constuction materials .The production of polyurethanes is largely derived  from  polyols derived from petroleum . Howover, petroleum  is a non- renewable raw material . Thus it is necessary to look alternative feedstock  for the manufacture of polyol  as a polyurethane raw material. Synnthesis polyurethane by polymerization process  using  polyol volume based on polyol  oleat acid  polypropylenglycol ( PPG ) in order to know  whether fatty acid can be used  as raw materials  of polyurethane manufacture.From the result of the study. Based on Fourier Transform Infra  Red ( FTIR), showed,that the product  produced is polyol with obtained hydroxyl  group ( OH group )with hydroxylnumber is 129,81 mg KOH / g and 157,60 mg KOH / g sample of 70 

scholarly journals Processing of RNA Containing 8-Oxo-7,8-Dihydroguanosine (8-oxoG) by the Exoribonuclease Xrn-1

2021 ◽  
Vol 8 ◽  
Author(s):  
Cheyenne N. Phillips ◽  
Shawn Schowe ◽  
Conner J. Langeberg ◽  
Namoos Siddique ◽  
Erich G. Chapman ◽  
...  
Keyword(s):  
Secondary Structure ◽  
Conformational Changes ◽  
Solid Phase Synthesis ◽  
Solid Phase ◽  
Spatial Constraints ◽  
Phase Synthesis ◽  
Naturally Occurring ◽  
Processive Enzyme ◽  
Moving Band ◽  
Hydrolysis Of

Understanding how oxidatively damaged RNA is handled intracellularly is of relevance due to the link between oxidized RNA and the progression/development of some diseases as well as aging. Among the ribonucleases responsible for the decay of modified (chemically or naturally) RNA is the exonuclease Xrn-1, a processive enzyme that catalyzes the hydrolysis of 5′-phosphorylated RNA in a 5′→3′ direction. We set out to explore the reactivity of this exonuclease towards oligonucleotides (ONs, 20-nt to 30-nt long) of RNA containing 8-oxo-7,8-dihydroguanosine (8-oxoG), obtained via solid-phase synthesis. The results show that Xrn-1 stalled at sites containing 8-oxoG, evidenced by the presence of a slower moving band (via electrophoretic analyses) than that observed for the canonical analogue. The observed fragment(s) were characterized via PAGE and MALDI-TOF to confirm that the oligonucleotide fragment(s) contained a 5′-phosphorylated 8-oxoG. Furthermore, the yields for this stalling varied from app. 5–30% with 8-oxoG located at different positions and in different sequences. To gain a better understanding of the decreased nuclease efficiency, we probed: 1) H-bonding and spatial constraints; 2) anti-syn conformational changes; 3) concentration of divalent cation; and 4) secondary structure. This was carried out by introducing methylated or brominated purines (m1G, m6,6A, or 8-BrG), probing varying [Mg2+], and using circular dichroism (CD) to explore the formation of structured RNA. It was determined that spatial constraints imposed by conformational changes around the glycosidic bond may be partially responsible for stalling, however, the results do not fully explain some of the observed higher stalling yields. We hypothesize that altered π-π stacking along with induced H-bonding interactions between 8-oxoG and residues within the binding site may also play a role in the decreased Xrn-1 efficiency. Overall, these observations suggest that other factors, yet to be discovered/established, are likely to contribute to the decay of oxidized RNA. In addition, Xrn-1 degraded RNA containing m1G, and stalled mildly at sites where it encountered m6,6A, or 8-BrG, which is of particular interest given that the former two are naturally occurring modifications.

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