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Scope and objectives:
To
develop methodologies, based on HPLC and ECZ, to study the phenolic profiles
of plants with interest for human consumption (medicinal species and vegetal
foodstuffs). These methodologies are intended in a qualitative and
quantitative level, in order to define fingerprints useful to assess
authenticity and quality of such plants or plant derivatives.
Results
and ongoing research:
Medicinal
plants: The definition of the phenolic profiles of medicinal plants is
integrated in an investigation project financed by PRAXIS XXI / Agência Inovação
(PLANTAMEDI). Several species, largely used in our country, are being tested
in order to choose a method based in their phenolic profile, which can be
used, routinely to quality control analysis and certification. We have already
adjusted experimental conditions of the species vervain, sage, peppermint,
lavender, cardoon, small centaury and St. John’s worth. An HPLC/DAD method
for separation and identification of the main phenolics present in in vivo and
in vitro biomass of Hypericum androsaemum and Hypericum perforatum has been
developed. This work clearly evidenced a distinct phenolic production between
in vivo and in vitro biomass. This study was done in collaboration with
University of Minho (A.C.P. Dias and M. Ferreira).
Foodstuffs: The phenolic profiles of
several foodstuffs (coffee, honey, wine, quince puree, jam and jelly) were
used to assess their authenticity.
The studies on coffee revealed that the relative amount of
hydroxycinnamic acids could be related to the botanical origin of coffee. The
phenolic profile in authenticity of coffees is integrated in an investigation
project financed by PRAXIS XXI (PBIC/C/TPR/2569/95).
The research carried with honey showed that in heather
honey ellagic acid and myricretin 3`-methylether were chemical markers for its
botanical origin.
We
have, also, analysed different experimental varietal Port wines in order to
determine differences in the concentrations of phenolic compounds among some
of the most commonly used grape varieties. The analysis of phenolics in Port
wines is integrated in an investigation project financed by ICCTI/CSIC (423/CSIC).
When quince production is scarce, quince jam is easily adulterated by
apple (Malus communis Lamk) and/or
pear (Pirus communis Lin.) due to
their low cost and their similar texture to quince. By employing the phenolic
analysis of genuine purees of quince, apple and pear, we could demonstrate the
usefulness of its phenolic diagrams for the determination of genuineness of
quince puree and jam.
Research
team:
CEQUP/Departamento de Farmacognosia/Faculdade de Farmácia/Universidade
do Porto: Rosa Seabra, Paula Andrade, a PhD student, two Master students.
Collaboration with CEQUP/Laboratorio de Bromatologia of the same Faculty (Margarida
Ferreira, Beatriz Oliveira), Biology Department (UM) and CEBAS (Murcia-Spain).
Key
publications:
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P.B. Andrade, A.R.F. Carvalho, R.M. Seabra, M.A. Ferreira. A
previous study of phenolic profiles of quince, pear and apple purees by
HPLC diode array detection for the evaluation of quince puree genuineness.
J. Agric. Food Chem., 46,
968-972 (1998).
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P.B. Andrade, M.T. Amaral, P.
Isabel, J. C.M.F. Carvalho, R. M. Seabra, A.P. Cunha. Physicochemical
attributes and pollen spectrum of Portuguese heather honeys. Food Chem., 66, 503-510 (1999).
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F. Areias , P. Valentão, P.B. Andrade, F. Ferreres, R.M. Seabra. Flavonoids
and phenolic acids of sage:influence of some agricultural factors. J. Agric. Food Chem., 48, 6081-6084 (2000)
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B.M. Silva, P.B. Andrade, G.C.
Mendes, P. Valentão, R.M. Seabra, M.A.Ferreira. Analysis of phenolic compounds in the evaluation of commercial quince
jam authenticity. J.
Agric. Food Chem., 48, 2853-2857 (2000)
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P.B. Andrade, M. B. Oliveira, R.M. Seabra, M.A. Ferreira , F. Ferreres,
C. Garcia-Viguera. Analysis of
phenolic compounds in Spanish Albariño and Portuguese Albarinho and
Loureiro wines by CZE e HPLC. Electrophoresis
(in press) .
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Centaurium erythraea
Scope and objectives:
The potential of higher plants as sources of new drugs
is still largely unexplored. Among the estimated 250 000-500 000 plant species, only a small
percentage has been submitted to a more or less complete phytochemical
investigation and the fraction that has been object of biological or
pharmacological screening is even smaller. Our team has dedicated a good part
of effort to isolate and identify compounds from plants, especially medicinal
ones. One of the ways to guarantee that an herbal medicine can be used with
safety and efficacy is to know its composition. The first step to guaranty its
quality is to have the knowledge of its composition, as complete as possible.
The research work undertaken involves several classes of compounds namely
alkaloids, terpenoids, quininoids and, more recently, phenolic acids and
flavonoids.
Results
and ongoing research:
The species involved are either endemic in Portugal or
African ones. Among the numerous compounds isolated and identified, several
are new compounds namely a series of homologous benzoquinones (Cyperus capitatus), a new naphtoquinone tetramer (Diospyros
chamaethamnus), sulphated flavonoids (Hypericum
elodes), several methylated aurones (Cyperus
capitatus) and xanthones (Hypericum
androsaemum). Species under study are Lippia
graveolens, a medicinal plant from southern America, Centaurium erythraea and Cydonia
oblonga (quince), from which a jam, of great consumption in
Portugal, is prepared.
Research
team:
CEQUP/Departamento de Farmacognosia/Faculdade de Farmácia/Universidade
do Porto: Rosa M. Seabra, A. Correia Alves, M. Áurea C. Costa, M. Manuela
Moreira, M. Isabel Paúl and Paula B. Andrade, a PhD and two master students.
Collaboration with Biology Department (UM).
Key
publications:
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M.A.C. Costa, A.C. Alves, R.M. Seabra, P.B. Andrade. Naphthoquinones
of Diospyros chamaethamnus. Planta
Medica, 64, 391 (1998).
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R.M. Seabra, A.M.S. Silva, P.B. Andrade, M.M. Moreira. Methylaurones
from Cyperus capitatus. Phytochemistry,
48 (8), 1429-1432 (1998).
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M.A.C. Costa, A.M.S. Silva, A.C. Alves, R.M. Seabra. 6-[2-(7-methyljuglonyl)]isoxylospyrin
from Diospyros chamaethamnus.
Natural Product Letters, 13(4),
269-276 (1999).
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A.C.P. Dias, R.M. Seabra,
P.B. Andrade, F.Ferreres, M. Fernandes-Ferreira. Xanthone
biosynthesis and accumulation in calli and
suspended cells of Hypericum
androsaemum. Plant Science,
150, 93-101 (2000).
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A C.P. Dias, R. M. Seabra, P.B. Andrade, F. Ferreres, M. F. Ferreira.
Xanthone production in vitro
cultures of Hypericum perforatum. Plant Phisiology. (in press). |
Hypericum
androsaemum
Scope
and objectives:
Over the two
last decades, interest in drugs of plant origin has been growing steadily.
Consumption of medicinal plants has almost doubled in Western Europe during
that period. Ecological awareness and an increase demand for non-classical
therapies may be invoked as the main reasons for this renewal. After centuries
of empirical use of herbal preparations, the legal dispositions for the
registration of such preparations are being more and more demanding in what
concerns safety and efficacy.
The objective
of the study undertaken is to contribute to the knowledge of the biological
actions of the medicinal species and to the assessment of efficacy and safety
of herbal drugs. It has been proved that the pharmacological actions of many
drugs, especially herbal drugs, are due to an antioxidant activity and among
the antioxidants from plants, phenolics (phenolic acids and flavonoids) are
the most prominent. Since the plants under study are rich in phenolic
compounds we are analysing their antioxidant activity and the relationship
structure/activity of some flavonoids.
Results
and ongoing research:
Medicinal
plants are used, mainly, as aqueous extracts (“teas”). So, four species
– Lippia citriodora, Centaurium erythraea, Cynara
cardunculus and Hypericum
androsaemum - are now under study for the antioxidant activity of its
infusions. For this purpose we are studying the effect of each infusion on
superoxide anion, generated either by an enzymatic system or non-enzymatically.
The discovery
of the antihepatotoxic action of sylibin, a xantolignan isolated from Silybum
marianum, stimulated the investigation of the hepatoprotective activity in
several herbal species, in order to isolate compounds which could be
commercialised, and also to scientifically validate its therapeutical
utilisation. So, in addition, we will proceed to the study of hepatoprotective
action of the infusions, by evaluating its effects on the tert-butyl-hydroperoxide
induced injury in isolated rat hepatocytes.
Several
flavonoids have proven a marked antioxidant activity under several
experimental conditions. However very little is known about the interaction
flavonoids/cell membrane.
With the
collaboration of Neurosciences Center from University of Coimbra (CNC), a
research was undertaken to analyse the antioxidant effect of some flavonoids
on chick retinal cells. Objectives are the knowledge of the mechanisms
involved in the interaction flavonoid/cell membrane and what molecular
features are important in that interaction.
Research
team:
CEQUP/Departamento
de Farmacognosia/Faculdade de Farmácia/Universidade do Porto: Rosa M. Seabra,
Paula Andrade, one PhD and one Master student. Collaboration with CEQUP/Laboratorio de Toxicologia of the same Faculty
(M. Lurdes Bastos, Felix Carvalho, M. Eduarda Fernandes) and with the CNC (UC).
Key
publications:
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F. M. Areias,
A. C. Rego, C. R. Oliveira, R. M. Seabra. Antioxidant effect of flavonoids
after ascorbate/Fe2+ -
induced oxidative stress in cultured retinal cells. Biochem. Pharm. (in press).
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