1H and13C NMR Spectroscopy of mono-, di-, tri- and tetrasubstituted xanthones

Fernandes, Eduarda; Silva, Artur M. S.; Cavaleiro, José A. S.; Silva, Francisco M.; Fernanda, M.; Borges, Markus; Pinto, Madalena

doi:10.1002/(sici)1097-458x(199804)36:4<305::aid-omr193>3.0.co;2-n

Cited by 39 publications

(17 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…3,6-Dihydroxy-9-oxo-9H-xanthene-9-one (4) and 4-hydroxy-3-methoxy-9-oxo-9H-xanthene-1-carbaldehyde (10) were obtained according to described procedures [38,39].…”

Section: Methodsmentioning

confidence: 99%

Xanthone and Flavone Derivatives as Dual Agents with Acetylcholinesterase Inhibition and Antioxidant Activity as Potential Anti-Alzheimer Agents

Cruz

Puthongking

Cravo

et al. 2017

Journal of Chemistry

View full text Add to dashboard Cite

Alzheimer’s disease (AD) is a multifactorial neurodegenerative disorder that is associated with the elderly. The current therapy that is used to treat AD is based mainly on the administration of acetylcholinesterase (AChE) inhibitors. Due to their low efficacy there is a considerable need for other therapeutic strategies. Considering that the malfunctions of different, but interconnected, biochemical complex pathways play an important role in the pathogenesis of this disease, a promising therapy may consist in administration of drugs that act on more than a target on biochemical scenery of AD. In this work, the synthesis and evaluation of xanthone and flavone derivatives as antioxidants with AChE inhibitory activity were accomplished. Among the obtained compounds, Mannich bases3and14showed capacity to inhibit AChE and antioxidant property, exerting dual activity. Moreover, for the most promising AChE inhibitors, docking studies on the target have been performed aiming to predict the binding mechanism. The results presented here may help to identify new xanthone and flavone derivatives as dual anti-Alzheimer agents with AChE inhibitory and antioxidant activities.

show abstract

“…3,6-Dihydroxy-9-oxo-9H-xanthene-9-one (4) and 4-hydroxy-3-methoxy-9-oxo-9H-xanthene-1-carbaldehyde (10) were obtained according to described procedures [38,39].…”

Section: Methodsmentioning

confidence: 99%

Xanthone and Flavone Derivatives as Dual Agents with Acetylcholinesterase Inhibition and Antioxidant Activity as Potential Anti-Alzheimer Agents

Cruz

Puthongking

Cravo

et al. 2017

Journal of Chemistry

View full text Add to dashboard Cite

show abstract

“…Threalose dihydrate was purchased from Fluka (Sintra, Portugal). 3-Methoxyxanthone (3-MeOXAN) was synthesised in our laboratory according to Fernandes et al [22]. Myritol 318 (caprilic/capric acid triglyceride) was kindly supplied by Henkel (Lisboa, Portugal).…”

Section: Methodsmentioning

confidence: 99%

Development and characterization of PLGA nanospheres and nanocapsules containing xanthone and 3-methoxyxanthone

Teixeira

Alonso

Pinto

et al. 2005

European Journal of Pharmaceutics and Biopharmaceutics

161

View full text Add to dashboard Cite

The aim of the present work was to develop and characterize two different nanosystems, nanospheres and nanocapsules, containing either xanthone (XAN) or 3-methoxyxanthone (3-MeOXAN), with the final goal of improving the delivery of these poorly water-soluble compounds. The xanthones-loaded nanospheres (nanomatrix systems) and nanocapsules (nanoreservoir systems), made of poly(DL-lactideco-glycolide) (PLGA), were prepared by the solvent displacement technique. The following characteristics of nanoparticle formulations were determined: particle size and morphology, zeta potential, incorporation efficiency, thermal behaviour, in vitro release profiles and physical stability at 4 8C. The nanospheres had a mean diameter !170 nm, a narrow size distribution (polydispersity index !0.1), and a negative surface charge (zeta potential !K36 mV). Their incorporation efficiencies were 33% for XAN and 42% for 3-MeOXAN. The presence of the xanthones did not affect the nanospheres size and zeta potential. DSC studies indicated that XAN and 3-MeOXAN were dispersed at a molecular level within the polymeric nanomatrix. Nanocapsules were also nanometric (mean size !300 nm) and exhibited a negative charge (zeta potential !K36 mV). Their incorporation efficiency values (O77%) were higher than those corresponding to nanospheres for both xanthones. The release of 3-MeOXAN from nanocapsules was similar to that observed for the correspondent nanoemulsion, indicating that drug release is mainly governed by its partition between the oil core and the external aqueous medium. In contrast, the release of XAN from nanocapsules was significantly slower than from the nanoemulsion, a behaviour that suggests an interaction of the drug with the polymer. Nanocapsule formulations exhibited good physical stability at 4 8C during a 4-month period for XAN and during a 3-month period for 3-MeOXAN. q

show abstract

“…However, protection of the chelated phenol groups proved to be essential to carry out the palladium catalyzed carbonylation. The substituents most frequently inserted in the aromatic rings after the xanthone nucleus formation are acetyl [141], formyl [121], halogens [54,115,[142][143][144][145], and nitro groups [113,138]. Nevertheless, this strategy is limited because the pattern of substitution thus obtained often follows the electrophilic aromatic substitution rules and/or also depends on the presence of bulky groups.…”

Section: Strategies To Introduce Simple Substituents Into the Xanthonmentioning

confidence: 99%

Synthesis of Xanthones: An Overview

Sousa¹,

Pinto

2005

CMC

125

View full text Add to dashboard Cite

Among the known synthetic routes to obtain xanthones, the Grover, Shah, and Shah reaction, the cyclodehydration of 2, 2'-dihydroxybenzophenones and electrophilic cycloacylation of 2-aryloxybenzoic acids are the most popular methods. Due to important biological applications of xanthones, some synthetic strategies leading to more complex derivatives have been widely explored in the past years. Thus, the purpose of this review is to report some recent improvements of the classical synthetic methods as well as of some non-classical methods to obtain simple oxygenated xanthones. The strategies for introduction of substituents into the xanthonic nucleus are also summarized. Furthermore, different approaches used to synthesize complex structures, with an emphasis on the total synthesis of bioactive natural products, accomplished in the last twenty years, are also discussed. Besides the synthesis of xanthones, the reactivity of the xanthonic nucleus and its role as a key intermediate for the synthesis of other important classes of compounds are also highlighted.

show abstract

1H and13C NMR Spectroscopy of mono-, di-, tri- and tetrasubstituted xanthones

Cited by 39 publications

References 2 publications

Xanthone and Flavone Derivatives as Dual Agents with Acetylcholinesterase Inhibition and Antioxidant Activity as Potential Anti-Alzheimer Agents

Xanthone and Flavone Derivatives as Dual Agents with Acetylcholinesterase Inhibition and Antioxidant Activity as Potential Anti-Alzheimer Agents

Development and characterization of PLGA nanospheres and nanocapsules containing xanthone and 3-methoxyxanthone

Synthesis of Xanthones: An Overview

Contact Info

Product

Resources

About