Research

Our research field is the study of the chemistry and biology of the family Asteraceae or Composite although other plant families are being also investigated, such as Anacardiaceae. Asterraceae is one of the largest among the angiosperms with ca. 25,000 species spread in different biomes from several countries, showing taxonomic, ecological, economic as well as medicinal interest. The family comprises several widely known species such as sunflower, arnica, chamomile, artichoke, daisy, marigold, chrysanthemum, thistle and dahlia.

The research in chemistry of Asteraceae is focused on phytochemistry, metabolomics and chemoinformatics, while the biology research is basically concentrated on biological assays using different models, such as animals, tissue and organ preparations, insects, parasites, microorganisms, cells, enzymes, etc. 

An overview of our main research topics is depicted in the picture below.



                                                                                   Main research topics of the AsterBioChem team


Phytochemistry

Our research is focused on the detection/identification, isolation and structure elucidation of secondary metabolites from crude extracts as well as glandular trichomes of Asteraceae species using phytochemical methods as depicted below:
  • chromatographic methods: column, flash, vacuum liquid and radial chromatography, TLC, GC and reversed-phase HPLC/UHPLC
  • spectrometric methods: UV, IR, MS and NMR (one and two-dimensional)
The taxonomic groups of interest are described as follows:
  • subfamily Barnadesioideae
  • tribes Astereae, Eupatorieae, Heliantheae and Vernonieae
  • subtribes Espeletinae and Helianthinae (Heliantheae); 
    Chrestinae, 
    Lychnophorinae and Vernoniinae (
    Vernonieae)
  • genera Aldama (see pictures below), 
    Baccharis, 
    Chresta, 
    Dasyphyllum
    , 
    Dimerostemma, 
    Espeletia    , 
     Icthyothere,  Mikania, 
    Smallanthus    , Tithonia and Vernonia
Specimens from other families are also welcome and currently the genera Spondias (Anacardiaceae), Ananas (Bromeliaceae), Miconia (Melastomataceae), and Passovia and Struthanthus (Loranthaceaeare) are being investigated. In addition, non conventional food plants are also included in our research.

A plant extract library of different species of Asteraceae is available for metabolomic studies and screening against different targets. This library is under constant update and currently comprises more than 300 standardized extracts obtained in EtOH:H2O of powdered and air-dried plant material. 

The selection criteria for the plant species are mainly based on chemosystematics or ethnobotanical information with focus on anti-inflammatory and immunomodulatory properties. Plant extracts against tropical protozoan parasites (see Biological Assays) are also of interest, especially against Trypanosoma cruzi and Leishmania spp. Other aspects such as biogeography and plant physiology are also of interest.

The main classes of secondary metabolites investigated are the terpenoids (mainly sesqui- and diterpenes) and phenolics (flavonoids and trans-cinnamic acid derivatives). Special attention has been paid to sesquiterpene lactones because of their chemotaxonomic, toxic and pharmacological importance.

Species of the genus Aldama from Brazil (photos by FB Da Costa)

Most of the Brazilian Asteraceae are native from the Cerrado (bush savannah) biome in Brazil (see below). The cerrado is located in the central part of Brazil and comprises several habitats, being the second in the country in number of species and area (ca. 2,000,000 km2), accounting for almost 25% of the Brazilian territory. It has an extremely rich biodiversity and is considered a biodiversity hotspot (high biodiversity under human threat). The cerrado has about 12,000 plants species, of which more than 4,000 are exclusive from this biome.  

Brazilian_biomes
The cerrado biome or Brazilian savannah (source: www.brasil.gov.br)

Species from the subtribe Espeletiinae (frailejones) collected in the high Andean páramos of Venezuela and Colombia are being currently investigated. The páramos is an ecosystem in the high elevations of the northern Andes from South America. This research is being carried out in collaboration with Dr. Mauricio Diazgranados (Missouri Botanical Garden, USA). South American species from the subfamily Barnadesioideae are also of interest and were obtained in Peru and Bolivia.

Metabolomics

  • Metabolic fingerprinting, metabolite profiling and dereplication (see the picture on the right) of plant extracts by LC-UV-MS
  • NMR studies of pure compounds as well as crude extracts
  • Generation of a pure compound library composed of typical metabolites from Asteraceae species (e.g. terpenoids and phenolics) - currently with ca. 150 compounds
  • In house database generation (AsterDB) containing taxonomic and experimental (tR, NMR chemical shifts, IC50, etc.) data as well as calculated (empirical methods) properties of compounds that belong to several genera (Aldama, Espeletia, Tithonia, Smallanthus, etc.) and subtribes (Chestinae, Lychnophorinae, etc.)
  • Database (part of AsterDB) with more than 1,000 structures of sesquiterpene lactones 
  • Data analysis by multivariate statistics, data mining and chemoinformatic tools
  • Ongoing projects: metabolomic study of Barnadesioideae and the genera Aldama, Baccharis, Chresta, Espeletia and Mikania from Asteraceae, including the following non-conventional food plants: Bidens subalternans, Galinsoga parviflora, Sonchus oleraceus, Emilia sonchifolia and E. fosbergii  
                 AsterBioChem Metabolomics Workflow

Chemoinformatics

  • Modeling of liquid chromatography separation, 1H-NMR spectroscopy and biological activities by multivariate statistics and machine learning tools
  • Prediction of retention times for reversed-phase liquid chromatography (QSRR) - see an example below:
Prediction of the retention time of a 3D chemical structure from our data base
  • Prediction and classification of 1H-NMR chemical shifts 
  • QSAR/QSPR studies and virtual screening involving 2D and 3D structures and molecular descriptors
  • Ongoing project: development of a data base (AsterDB) using chemoinformatic methods and machine learning tools to help in the dereplication of plant extracts (see below)
In house data base containing information of our plant extract and pure compound libraries

Biological Assays

  • In vitro and in vivo biological assays with crude extracts and pure compounds (natural, biotransformed or semi-synthetic derivatives) to explore their effects on different targets
  • Main focus: inflammation, cell cytotoxicity and human parasites
  • Ongoing project: screening our plant extract and pure compound libraries against the inflammatory enzymes COX and LOX and DHODH from L. major and T. cruzi
The AsterBioChem team is member of the ResNet NPND (Research Network Natural Products against Neglected Diseases), a research network dedicated to the search of natural products against neglected diseases. 
ResNetNPND
The ResNet NPND network was officially established in April 2011 in Münster, Germany, and is composed of natural products and medicinal chemists, molecular/cellular biologists, biochemists, parasitologists and other professionals from different continents dedicated to the study of neglected diseases caused by Trypanosoma (Chagas' disease and human African trypanosomiasis), Leishmania species (various forms of Leishmaniasis) and Plasmodium species (malaria).