benzofurans and eupomatenoid-6

Topics: Aedes; Animals; Benzofurans; Fibroblasts; Humans; Insecticides; Larva; Lethal Dose 50; Lignans; Molecular Structure; Mosquito Vectors; Phenols; Phytochemicals; Piper; Plant Extracts; Toxicity Tests

Ethyl acetohydroxamate was efficiently arylated with diaryliodonium salts at room temperature under transition-metal-free conditions. The obtained O-arylated products were reacted in situ with ketones under acidic conditions to yield substituted benzo[b]furans through oxime formation, [3,3]-rearrangement, and cyclization in a fast and operationally simple one-pot fashion without using excess reagents. Alternatively, the O-arylated products could be isolated or transformed in situ to aryloxyamines or O-arylaldoximes. The methodology was applied to the synthesis of Stemofuran A and the formal syntheses of Coumestan, Eupomatenoid 6, and (+)-machaeriol B.

Topics: Benzofurans; Benzopyrans; Combinatorial Chemistry Techniques; Coumarins; Cyclization; Oximes; Phenols

The antifungal activity of extracts obtained from Piper regnellii with supercritical carbon dioxide was tested against yeast and filamentous fungi. The most active extract was obtained from leaves extracts of P. regnellii at 40°C and 25 MPa, featuring a minimal inhibitory concentration of 3.9 μg/mL against Trichophyton mentagrophytes. Neolignans eupomatenoid-3, eupomatenoid-5, eupomatenoid-6 and conocarpan were present in all extracts. The results indicate the possibility of further studies on the use of extracts of P. regnellii obtained by supercritical extraction, as potential sources of bioactive compounds for use in medicine.

Topics: Antifungal Agents; Benzofurans; Chromatography, Supercritical Fluid; Microbial Sensitivity Tests; Phenols; Piper; Plant Extracts; Plant Leaves; Trichophyton

Piperaceae is a family of tropical plants known to have antifungal, antibacterial, tumour-inhibitory, antiviral, antioxidant, molluscicidal and leishmanicidal activities. In this work, extracts and fractions from aerial parts of Piper abutiloides (Piperaceae), a traditional medicinal plant, were evaluated against the fungal species Candida albicans, C. parapsilosis, C. krusei, C. glabrata, C. tropicalis, Cryptococcus neoformans and Sporothrix schenckii. The results have shown that the antifungal activity of this plant can be concentrated in the hexanic fraction after partitioning its hydroalcoholic extract between hexane and 90% aqueous methanol. The chromatographic fractionation of the bioactive part was monitored with a bioautographic assay using C. glabrata, and allowed the isolation of three antifungal compounds: pseudodillapiol, eupomatenoid-6 and conocarpan. These compounds presented different potencies against the fungi tested, with the strongest effect being observed for eupomatenoid-6 against C. glabrata, which presented a minimal inhibitory concentration value of 0.3 microg spot(-1). Conocarpan showed antifungal activity without apparent cytotoxic effect on normal human lymphocytes, as assessed by the proliferation assay with human peripheral blood mononuclear cells stimulated with phytohaemaglutinin. This work reveals for the first time the occurrence of these compounds in P. abutiloides and justifies further studies to clarify their mechanisms of action.

Topics: Adult; Antifungal Agents; Benzofurans; Candida albicans; Chemical Fractionation; Chromatography; Cryptococcus neoformans; Female; Humans; Leukocytes, Mononuclear; Male; Microbial Sensitivity Tests; Phenols; Piper; Plant Extracts; Sporothrix; Young Adult

A new and efficient synthesis of 2-arylbenzofurans has been achieved via a route involving acylation and subsequent [3,3]-sigmatropic rearrangement of oxime ethers. Its synthetic utility is demonstrated by a short synthesis of stemofuran A and eupomatenoid 6 in which no procedure for protection of the phenolic hydroxyl groups is needed. [reaction--see text]

Topics: Acylation; Benzofurans; Cyclization; Ether; Molecular Structure; Oximes; Phenols

The antioxidant/photoprotective potential of a standardized Krameria triandra (KT) root extract (15% neolignans) has been evaluated in different cell models, rat erythrocytes and human keratinocytes cell lines, exposed to chemical (cumene hydroperoxide, CuOOH) and physical (UVB radiation) free radical inducers. The extract was significantly more active (IC50 0.28 +/- 0.04 microg/ml) than the typical chain-breaking antioxidant alpha-tocopherol (IC50 = 6.37 +/- 0.41 microg/ml) in inhibiting the CuOOH-induced hemolysis in rat blood cells. The KT constituent 2-(2,4-dihydroxyphenyl)-5-(E)-propenylbenzofuran, was the most active (IC50 = 0.03 +/- 0.005 microg/ml), followed by eupomatenoid 6 (IC50 = 0.29 +/- 0.06 microg/ml) and conocarpan (IC50 = 0.77 +/- 0.08 microg/ml). The same order of potency was observed in red blood cells exposed to UVB irradiation in continuo, with IC50 values 0.78 +/- 0.08 microg/ml for KT extract, 0.18 +/- 0.02 microg/ml for 2-(2,4-dihydroxyphenyl)-5-(E)-propenylbenzofuran, 0.95 +/- 0.11 microg/ml for eupomatenoid 6, and 3.8 +/- 0.39 microg/ml for conocarpan. In cultured human keratinocytes exposed to UVB radiation (50 mJ/cm2), KT extract (2.5-20 microg/ml) significantly and dose-dependently restrained the loss in cell viability and the intracellular oxidative damage: glutathione (GSH) depletion and the rise in dichlorofluorescein (DCF), marker of peroxide accumulation, were suppressed by 20 microg/ml KT and in parallel cell morphology maintained. The cytoprotective effect of the extract was confirmed in a more severe model of cell damage: exposure of keratinocytes to higher UVB doses (300 mJ/cm2), which induce a 50% cell death. In keratinocyte cultures supplemented with 10 microg/ml, cell viability was almost completely preserved and more efficiently than with (-)-epigallocatechin 3-gallate and green tea. The results of this study indicate the potential use of Rhatany extracts, standardized in neolignans, as topical antioxidants/radical scavengers against skin photodamage.

Topics: Animals; Antioxidants; Benzene Derivatives; Benzofurans; Cell Line; Cell Survival; Dose-Response Relationship, Drug; Erythrocytes; Furans; Humans; Inhibitory Concentration 50; Keratinocytes; Lignans; Magnoliopsida; Male; Phenols; Plant Extracts; Plant Roots; Rats; Rats, Wistar; Sunscreening Agents; Ultraviolet Rays

Activity-guided fractionation of the dichloromethane extract from leaves of Piper fulvescens, using an agar overlay bioautographic method, led to the isolation of three antifungal neolignans identified as conocarpan, eupomatenoid 5 and eupomatenoid 6. The minimal inhibitory concentration of these three neolignans against five fungi strains were determined. Conocarpan showed the widest activity, whereas eupomatenoid 6 was the most active against dermatophytes.

Topics: Antifungal Agents; Benzofurans; Candida albicans; Cryptococcus neoformans; Furans; Medicine, Traditional; Microbial Sensitivity Tests; Microsporum; Paraguay; Phenols; Piperaceae; Plant Extracts; Plant Leaves; Saccharomyces cerevisiae; Trichophyton