| 1. |
- Erosa-Rejón, Gilda J., et al.
(författare)
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Pulcaffeate, a Trimeric Caffeic Acid Derivative from Bourreria pulchra
- 2023
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Ingår i: Journal of the Mexican Chemical Society. - 1870-249X. ; 67:3, s. 182-186
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Tidskriftsartikel (refereegranskat)abstract
- The trimeric caffeic acid derivative pulcaffeate (1) was isolated from the organic crude extract of the roots of Bourreria pulchra (Boraginaceae). The biosynthesis of 1 appears to involve an intramolecular Diels-Alder reaction between a cyclohexa-1,3-diene intermediate, generated by the oxidation of the aromatic ring of a cinnamic acid unit, and the conjugated double bond of a caffeic acid unit. The structure of the new metabolite was elucidated through a detailed analysis of its1H and13C NMR spectroscopic data. This is the first report of a trimeric metabolite occurring in B. pulchra.
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| 2. |
- Escobar, Zilma, et al.
(författare)
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Synthesis of poinsettifolin A
- 2014
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Ingår i: Tetrahedron. - : Elsevier BV. - 0040-4020. ; 70:47, s. 9052-9056
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Tidskriftsartikel (refereegranskat)abstract
- A synthesis of poinsettifolin A (1), a prenylated flavonol isolated from Dorstenia poinsettifolia, is described. Two routes starting from quercetin were explored, and 1 could be prepared if a prenyl group first was incorporated at C-6 of the protected quercetin followed by a condensation with citral at C-8. The key synthetic steps are a Mitsunobu reaction, an europium (III)-catalysed Claisen rearrangement coupled with cross-metathesis, and a benzopyran-forming geranylation. The two geranylated 3,5,3',4'-tetrahydroxyflavonols prepared, 1 and 3, were assayed for antileishmanial activity against Leishmania amazonensis and Leishmania braziliensis, and found to be active. Compound 3 showed cytotoxic activity against leukaemia and lung cancer cells while 1 lacked cytotoxicity. (C) 2014 Elsevier Ltd. All rights reserved.
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| 3. |
- Santangelo, Ellen M., 1973-
(författare)
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Stereoselective syntheses of semichemicals : Applications in ecological chemistry
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis describes the syntheses of semiochemicals and their applications in the development of control methods for pest insects. The compounds synthesized are divided into three groups: 1) Lepidoptera pheromones; 2) methyl substituted chiral pheromones and 3) aphid pheromones. Different purification techniques have been explored in order to provide > 99% pure semiochemicals for field tests. Examples of the techniques are uses of urea inclusion complexes, argentum chromatography, low temperature crystallization and what we call the Baeckström isolation technique. Iridoids have been produced in a synthetic strategy including an intramolecular enal-enamine [4+2] cycloaddition, a dynamic acetylation and an enantioselective transesterification mediated by a lipase from Pseudomonas cepacia. The use of chiral auxiliaries to perform the intramolecular [4+2] cycloaddition has also been investigated. A useful asymmetric route to iridoids has been developed.
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| 4. |
- Abo-elmatty, Dina M., et al.
(författare)
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Antioxidant and anti-inflammatory effects of Urtica pilulifera extracts in type2 diabetic rats
- 2013
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Ingår i: Journal of Ethnopharmacology. - : Elsevier BV. - 1872-7573 .- 0378-8741. ; 145:1, s. 269-277
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Tidskriftsartikel (refereegranskat)abstract
- Ethnopharmacological relevance: "Urtica pilulifera has been traditionally used in Egyptian system as an herbal remedy to be a diuretic, antiasthmatic, anti-inflammatory, hypoglycemic, hemostatic, antidandruff and astringent" Aim of the study: To evaluate the potential effects of ethyl acetate (EA), chloroform (CHLOR) and hexane (HEXA) extracts of Urtica piluliferaas oral anti-diabetic agents as well as to evaluate their possible antioxidant and anti-inflammatory effects in type2 diabetic rat model. Material and methods: Type2 diabetes was induced by a high fat diet and low dose streptozotocin (STZ). Diabetic adult male albino rats were allocated into groups and treated according to the following schedule; Pioglitazone HCL (PIO), EA, CHLOR and HEXA extracts of Urtica piluilifera at two doses of 250 and 500 mg/ kg were used. In addition, a normal control group and a diabetic control one were used for comparison. Blood glucose, insulin resistance, antioxidant enzymes, 8-hydroxy-2-deoxyguanosine (8-OHdG) as well as C-reactive protein and tumor necrosis factor-a levels were evaluated. Results: EA and CHLOR extracts of Urtica pilulifera exhibited a significant hypoglycemia associated with antioxidant and anti-inflammatory effects in diabetic rats; however, HEXA extract showed no beneficial effect. These activities are responsible, at least partly, for improvements that have been seen in hyperglycemia and insulin resistance of diabetic rats. Conclusion: Our results encourage the traditional use of Urtica pilulifera extract as an antioxidant and anti-inflammatory agent as an additional therapy of diabetes. (C) 2012 Elsevier Ireland Ltd. All rights reserved.
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| 5. |
- Almanza, Giovanna R., et al.
(författare)
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Antioxidant and Antimutagenic Polyisoprenylated Benzophenones and Xanthones from Rheedia acuminata
- 2011
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Ingår i: Natural Product Communications. - 1934-578X. ; 6:9, s. 1269-1274
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Tidskriftsartikel (refereegranskat)abstract
- Dichloromethane extract of the stem bark of Rheedia acuminata yielded three benzophenones with antioxidant activity, the new one named acuminophenone A (1), guttiferone K (2) and isoxanthochymol (3), along with the known xanthones formoxanthone C (4) and macluraxanthone (5). The structures were established through interpretation of their spectroscopic data, the stereochemistry of compounds (1) and (2) were resolved by experimental and computational experiments and their antioxidant activities were measured using the DPPH, ABTS and TEAC assays. The antioxidant results showed that metabolites 1, 4 and 5 had a better antioxidant activity than the reference compound quercetin. In addition, we evaluate the mutagenicity and antimutagenicity of the CH2Cl2 extract as well as of the free radical scavenger compounds 1, 4 and 5 by the AMES Salmonella/microsomal test. No mutagenicity was found in the CH2Cl2 extract using Salmonella typhimurium strains TA98, TA100, TA102, TA1537 and TA1538, with or without S9 metabolic activation. The pure compounds neither showed mutagenicity in TA 102 strain and the most important result was the strong reduction of mutagenic effect induced by hydrogen peroxide in S. typhimurium TA 102, with or without S9, showed by the compounds 1 (more than 93%) and 4 (more than 88%) at 0.02 mu g/plate.
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| 6. |
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| 7. |
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| 8. |
- Anke, T, et al.
(författare)
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Laschiatrion, a new antifungal agent from a Favolaschia species (Basidiomycetes) active against human pathogens
- 2004
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Ingår i: Journal of Antibiotics. - 0021-8820. ; 57:8, s. 496-501
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Tidskriftsartikel (refereegranskat)abstract
- Laschiatrion (1), a new antifungal antibiotic, was isolated from fermentations of Favolaschia sp. 87129. (1) exhibits broad in vitro activity against several human pathogens while no antibacterial and cytotoxic activities could be detected. The structure was elucidated by spectroscopic techniques. As to our knowledge laschiatrion possesses a new steroid skeleton.
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| 9. |
- Antelo, Luis, et al.
(författare)
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Siderophores produced by Magnaporthe grisea in the presence and absence of iron
- 2006
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Ingår i: Zeitschrift fuer Naturforschung. Section C: A Journal of Biosciences. - 0939-5075. ; 61:5-6, s. 461-464
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Tidskriftsartikel (refereegranskat)abstract
- An analysis of siderophores produced by Magnaporthe grisea revealed the presence of one intracellular storage siderophore, ferricrocin, and four coprogen derivatives secreted into the medium under iron depletion. Structural analysis showed that the compounds are coprogen, coprogen B, 2-N-methylcoprogen and 2-N-methylcoprogen B. Siderophore production under low and high iron conditions was quantified.
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| 10. |
- Appendino, Giovanni, et al.
(författare)
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A meroterpenoid NF-kappa B inhibitor and drimane sesquiterpenoids from asafetida
- 2006
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Ingår i: Journal of Natural Products. - : American Chemical Society (ACS). - 0163-3864 .- 1520-6025. ; 69:7, s. 1101-1104
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Tidskriftsartikel (refereegranskat)abstract
- Investigation of an acetone extract from asafetida afforded two drimane sesquiterpene dienones (fetidones A and B, 1a,b) and several known sesquiterpene coumarin ethers, one of which (8-acetoxy-5-hydroxyumbelliprenin, 2a) showed potent and specific NF-kappa B-inhibiting properties. This, coupled to a negligible cytotoxicity, qualifies 2a as a new anti-inflammatory chemotype, and its occurrence in asafetida might rationalize the use of this gum resin to alleviate and prevent colon inflammatory disturbances.
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