Maria G. Campos

Antioxidant, Antiproliferative, and Pro-apoptotic Capacities of Pentacyclic Triterpenes Found in the Skin of Olives on MCF-7 Human Breast Cancer Cells and Their Effects on DNA Damage

This research aimed to investigate erythrodiol, uvaol, oleanolic acid, and maslinic acid scavenging capacities and their effects on cytotoxicity, cell proliferation, cell cycle, apoptosis, reactive oxygen species (ROS) level, and oxidative DNA damage on human MCF-7 breast cancer cell line. The results showed that erythrodiol, uvaol, and oleanolic acid have a significant cytotoxic effect and inhibit proliferation in a dose- and time-dependent manner. At 100 μM, erythrodiol growth inhibition occurred through apoptosis, with the observation of important ROS production and DNA damage, whereas uvaol and oleanolic acid growth inhibition involved cell cycle arrest. Moreover, although all tested triterpenes did not show free radical scavenging activity using ABTS and DPPH assays, they protected against oxidative DNA damage at the concentration 10 μM. Uvaol and oleanolic and maslinic acids, tested at 10 and 100 μM, also reduced intracellular ROS level and prevented H(2)O(2)-induced oxidative injury. Overall, the results suggest that tested triterpenes may have the potential to provide significant natural defense against human breast cancer.

An approach to the characterization of bee pollens via their flavonoid/phenolic profiles

Bee pollen is a mix of bee-collected floral pollens which varies widely in composition. A systematic method for characterising bee pollens in terms of their constituent pollens is needed in view of the growing phytotherapeutic interest in bee pollen products. Studies involving three bee pollen samples collected from Portugal and New Zealand are reported. An approach based on flavonoid/phenolics profiles derived from high pressure liquid chromatography is demonstrated to be more precise and informative than traditional microscopy. This method provides a convenient means for identifying the contributing pollens, and for characterising bee pollens in terms of their predominant constituent pollens. The flavonoid/phenolics profiles obtained in the course of this work also highlight other observations of interest. For example: bees are shown to be highly selective pollen gatherers from the finding that bee pollens comprise pollen from only a few of the available species; pollen from only one floral source is found in each bee pollen pellet; and flavonoids are normally found as glycosides in pollens but are shown to occur naturally as aglycones in Eucalyptus globulus pollen. Two of these aglycones, tricetin and 3-O-methylquercetin, are reported as pollen constituents for the first time.

Plants with neurobiological activity as potential targets for drug discovery

Significant number of studies has been performed to find alternatives or treatments for diseases of the nervous forum by identifying structures with activity at the central nervous system (CNS). However most of the screenings are usually conducted on an ad hoc basis and not systematically. The initial purpose of this review was to screen plants with neurological bioactivity, in particular those that have not been fully studied and that have molecular mechanisms whose active constituents responsible for the activity remain to be identified. The second purpose was to identify potential target plants for future studies of new and alternative therapies for the treatment of neurological disorders and neurodegenerative diseases. All plants considered in this review were selected for three qualities: possible molecular requirements to act at the CNS; representative of the main classes of compounds with the referred bioactivity and the major families containing species with those compounds; and diffuse world distribution. We identified several examples of plants that have potential for further study. We have included the main families of these plants, their known molecular mechanisms involved in neurological bioactivity, and the active constituents responsible for such activity. Also included is a brief discussion about the requirements of the different compounds to reach the CNS. These requirements may be less limited than what researchers have previously thought.

Application of FTIR-ATR spectroscopy to the quantification of sugar in honey.

A Fourier transform infrared spectroscopic method with attenuated total reflectance (FTIR-ATR) and partial least squares (PLS) regression model for the prediction of sugar content in honey samples was calculated. Standards of trehalose, glucose, fructose, sucrose, melezitose, turanose and maltose were used to identify and quantify the individual sugar components in 63 honey samples by HPAEC-IPAD. Fructose and glucose are the highest sugars in honey with an average value of 36% and 26%, respectively. The 1stDer spectra with MSC or SLS in the wave number range from 1500 to 750cm(-1) provide the best calibration model with a r(2) of 86.60 and 86.01 with RPD of 2.6 and 2.55, respectively for fructose and glucose. For turanose and melezitose good models were also found. The FTIR-ATR showed to be a good methodology to quantify the main sugar content in honey and easily adapted to routine analysis.

Bioactive properties of the main triterpenes found in olives, virgin olive oil, and leaves of Olea europaea.

Oleanolic acid, maslinic acid, uvaol, and erythrodiol are the main triterpenes present in olives, olive tree leaves, and virgin olive oil. Their concentration in virgin olive oil depends on the quality of the olive oil and the variety of the olive tree. These triterpenes are described to present different properties, such as antitumoral activity, cardioprotective activity, anti-inflammatory activity, and antioxidant protection. Olive oil triterpenes are a natural source of antioxidants that could be useful compounds for the prevention of multiple diseases related to cell oxidative damage. However, special attention has to be paid to the concentrations used, because higher concentration may lead to cytotoxic or biphasic effects. This work explores all of the bioactive properties so far described for the main triterpenes present in virgin olive oil.

7- and 8-O-methylherbacetin-3-O-sophorosides from bee pollens and some structure/activity observations

Abstract A new flavonol glycoside, 7-O-methylherbacetin-3-O-sophoroside, has been characterized from Ranunculus sardous pollen, 8-O-methylherbacetin-3-O-sophoroside from Ulex europaeus pollen and 8-O-methylherbacetin8-O-glucoside from Raphanus raphanistrum pollen; all pollens were obtained from bee pollen. It is demonstrated that the unusual UV-visible absorption spectra of 7- and 8-O-methylherbacetin 3-O-glycosides can be used conveniently to distinguish these and their aglycones. The distribution of various flavonol glycosides in pollen is discussed in terms of its significance to the previously established role of flavonols in pollen germination. No evidence for taxa specificity of individual flavonol glycosides was found; however, a case is made for elevating the significance of flavonol glycosides, particularly the 2″-O-glucosides of flavonol-3-O-glycosides in stimulating pollen tube growth.

Structure information from HPLC and on-line measured absorption spectra: flavones, flavonols and phenolic acids

Na medida em que todas as obras da UC Digitalis se encontram protegidas pelo Código do Direito de Autor e Direitos Conexos e demais legislação aplicável, toda a cópia, parcial ou total, deste documento, nos casos em que é legalmente admitida, deverá conter ou fazer-se acompanhar por este aviso. Structure information from HPLC and on-line measured absorption spectra: flavones, flavonols and phenolic acids Autor(es): Campos, Maria da Graça; Markham, Kenneth R. Publicado por: Imprensa da Universidade de Coimbra URL persistente: URI:http://hdl.handle.net/10316.2/2664 DOI: DOI:http://dx.doi.org/10.14195/978-989-26-0480-0

The Unique Occurrence of the Flavone Aglycone Tricetin in Myrtaceae Pollen

In pollen, flavonoids are usually found as glycosides and in particular, flavonol 3-O-diglycosides. However, in members of the Myrtaceae, subfamily Leptospermoideae, the rare flavone aglycone tricetin, along with other flavonoid aglycones including 3-O-methyl quercetin and luteolin, have been found to comprise a significant portion of the constituent flavonoids.

Cyanobacteria and microalgae: a renewable source of bioactive compounds and other chemicals.

Microalgae and cyanobacteria are rich sources of many valuable compounds, including important bioactive and biotechnologically relevant chemicals. Their enormous biodiversity, and the consequent variability in the respective biochemical composition, make microalgae cultivations a promising resource for many novel chemically and biologically active molecules and compounds of high commercial value such as lipids and dyes. The nature of the chemicals produced can be manipulated by changing the cultivation media and conditions. Algae are extremely versatile because they can be adapted to a variety of cell culture conditions. They do not require arable land, can be cultivated on saline water and wastewaters, and require much less water than plants. They possess an extremely high growth rate making these microorganisms very attractive for use in biofuel production – some species of algae can achieve around 100 times more oil than oil seeds. In addition, microalgae and cyanobacteria can accumulate various biotoxins and can contribute to mitigate greenhouse gases since they produce biomass through carbon dioxide fixation. In this review, we provide an overview of the application of microalgae in the production of bioactive and other chemicals.

An unusually lipophilic flavonol glycoside from Ranunculus sardous pollen

Abstract A lipophilic flavonoid detected by HPLC in earlier work and assumed to be a flavone aglycone from preliminary screening has been isolated from Ranunculus sardous pollen. It is shown, principally by NMR techniques, to be a new flavonoid glycoside, 7- O -methylherbacetin 3-O-[2-O-E- feruloyl -β- d -glucoside ] .