Strategic Project - UI 62 - 2011-2012

Funder

Organizational Unit

Publications

Synthesis of new 1,8-dihydroxy-9h-xanthen-9-ones

Publication . Leal, Stephanie B.; Seca, Ana M. L.; Pinto, Diana C. G. A.; Silva, Artur M. S.; Cavaleiro, José A. S.

Xanthones have a rather restricted occurrence among higher plants, being found almost exclusively in Guttiferae and Gentianaceae. Xanthones are sometimes found as polyhydroxylated derivatives, exhibiting valuable biological activities [1], but more often bearing a variety of substituents. Xanthones are well known for their interesting phytochemical properties, which make them attractive to the pharmaceutical industry. Natural and synthetic derivatives have been described as exhibiting several important biological properties, such as anti-tumor [2], anti-inflammatory [3], antioxidant [4] and anticoagulant/antiplatelet activities [5]. Owing to our continuing interest in the synthesis of novel oxygen heterocycles we have recently developed an unique synthetic procedure towards the synthesis of new (E)-3-aryl-4-benzylidene-8-hydroxy-3,4-dihydro-1H-xanthene-1,9(2H)-diones (2) [6]. In the sequence of that work and pursuing our objective to synthesize xanthone derivatives with potential biological activities, we set up a program aiming the transformation of xanthenediones (2) into new 1,8-dihydroxy-9H-xanthen-9-one derivatives (3). The experimental procedure and the structural characterization (1D and 2D NMR) of the new compounds will be presented and discussed.

2012-08Conference object

Open access

New syntheses of potential biologically active xanthones and benzoxanthones

Publication . Rocha, Djenisa H. A.; Leal, Stephanie B.; Seca, Ana M. L.; Pinto, Diana C. G. A.; Silva, Artur M. S.

The synthesis of xanthones, adequately functionalized for a specific application, is a challenging task. In this presentation, will be disclosed our recent studies with this unique family of compounds, namely the one-pot photoinduced electrocyclisation of (E)-3-styrylflavones 1 and in situ oxidation of cycloadducts to give 5-phenyl-7H-benzo[c]xanthen-7-one derivatives 2,3a and aromatization studies of (E)-3-aryl-4-benzylidene-8-hydroxy-3,4-dihydro-1H-xanthene-1,9(2H)-diones 33b into 4-benzyl-1,8-dihydroxy-3-phenyl-9H-xanthen-9-one derivatives 4.

2013-09Conference object

Open access

Compounds identified on hexane and dichloromethane extracts of Salicornia ramosissima

Publication . Isca, Vera M. S.; Seca, Ana M. L.; Pinto, Diana C. G. A.; Silva, Artur M. S.; Silva, Helena

Salicornia ramosissima J. Woods (common purple glasswort) is an annual halophyte, widely distributed in the salt marsh of Ria de Aveiro (Portugal), that belongs to the Salicornia L. genus (Chenopodiaceae).[4] Although phytochemical studies genus on this genus report the presence of compounds which are well-recognized for their biological activities, such as flavonoids, chromones and alkaloids,[3] too little is known about secondary metabolites on purple glasswort. In our previous work we were able to isolate and identify ethyl o-hydroxycinnamate, (E)-fatty alcohol ferulic acid and scopoletin from the dichloromethane extract of S. ramosissima aerial parts. The structure and spectroscopic characterization of some secondary metabolites isolated from dichloromethane crude extract also will be presented and discussed.

2012-11Conference object

Open access

Synthesis and antioxidant activity of new xanthone-type compounds

Publication . Leal, Stephanie B.; Pinto, Diana C. G. A.; Seca, Ana M. L.; Silva, Artur M. S.; Cavaleiro, José A. S.

Owing to our continuing interest in the synthesis of novel oxygen heterocycles we have recently developed a unique synthetic procedure towards the synthesis of new xanthenodiones (2)[5] and extend the work to their aromatization into xanthones (3). Our aim was also to obtain new derivatives with potential biological activities, therefore their ability to scavenge the DPPH radical and to reduce iron(III) were also evaluated. In the present communication we will present and discussed our last results on the synthetic and potential application of xanthones (3).

2012-11Conference object

Open access

Some aromatic compounds from dichloromethane extract of Salicornia ramosissima.

Publication . Isca, Vera M. S.; Seca, Ana M. L.; Pinto, Diana C. G. A.; Silva, Artur M. S.; Silva, Helena

Salicornia ramosissima J. Woods, is an annual halophyte, confined to saline habitats, widely distributed in the salt marsh of Ria de Aveiro (Portugal) and also present in many salt marshes of the Iberian Peninsula. Our interest in the phytochemical study of this specie, which belongs to the genus Salicornia and family Chenopodiaceae, is based on previous knowledge that plants of this genus presented compounds such as flavonoids, chromones and alkaloids which are well-recognized for their biological activities. Salicornia ramosissima was subject to some studies of growth conditions and salinity, but its phytochemical composition remains unknown. The analysis of the dichloromethane extract from S. ramosissima aerial parts allowed the isolation of some aromatic compounds, from which we present here their unequivocal structure elucidation.

2012-07Conference object

Open access