Loading...
40 results
Search Results
Now showing 1 - 10 of 40
- Sweet Cherries as Anti-Cancer Agents: From Bioactive Compounds to FunctionPublication . Fonseca, Lara R. S.; Silva, Gonçalo R.; Luís, Ângelo; Cardoso, Henrique J.; Correia, Sara; Vaz, CV; Duarte, Ana Paula; Socorro, SílviaSweet cherries (Prunus avium L.) are among the most appreciated fruits worldwide because of their organoleptic properties and nutritional value. The accurate phytochemical composition and nutritional value of sweet cherries depends on the climatic region, cultivar, and bioaccessibility and bioavailability of specific compounds. Nevertheless, sweet cherry extracts are highly enriched in several phenolic compounds with relevant bioactivity. Over the years, technological advances in chemical analysis and fields as varied as proteomics, genomics and bioinformatics, have allowed the detailed characterization of the sweet cherry bioactive phytonutrients and their biological function. In this context, the effect of sweet cherries on suppressing important events in the carcinogenic process, such as oxidative stress and inflammation, was widely documented. Interestingly, results from our research group and others have widened the action of sweet cherries to many hallmarks of cancer, namely metabolic reprogramming. The present review discusses the anticarcinogenic potential of sweet cherries by addressing their phytochemical composition, the bioaccessibility and bioavailability of specific bioactive compounds, and the existing knowledge concerning the effects against oxidative stress, chronic inflammation, deregulated cell proliferation and apoptosis, invasion and metastization, and metabolic alterations. Globally, this review highlights the prospective use of sweet cherries as a dietary supplement or in cancer treatment.
- Some preliminary data on the enzymatic hydrolysis of Pinus pinaster kraft pulpPublication . Duarte, Ana Paula; Spiridon, IulianaEnzymes' applications in pulp and paper manufacturing processes and products is gaining global attention. In fact, several applications, including pitch deposits, drainage enhancement, deinking of wastepapers, pulp bleaching enhancement and modification of fibers' characteristics are already used at industrial level. Enzymes are being produced on a commercial scale and are available at a relatively low price. Research to establish the effect of enzymatic treatment continues in an effort to increase knowledge about the action of enzymes. The present paper, an additional contribution to this field, studies the potential utilization of hydrolytic enzymes to enhance the fiber characteristics derived from Pinus pinaster kraft pulp.
- Cannabis and Its Secondary Metabolites: Their Use as Therapeutic Drugs, Toxicological Aspects, and Analytical DeterminationPublication . Gonçalves, Joana; Rosado, Tiago; Soares, Sofia; Simão, Ana; Caramelo, Débora Almeida; Luís, Ângelo; Fernández, Nicolás; Barroso, Mário; Gallardo, Eugenia; Duarte, Ana PaulaAlthough the medicinal properties of Cannabis species have been known for centuries, the interest on its main active secondary metabolites as therapeutic alternatives for several pathologies has grown in recent years. This potential use has been a revolution worldwide concerning public health, production, use and sale of cannabis, and has led inclusively to legislation changes in some countries. The scientific advances and concerns of the scientific community have allowed a better understanding of cannabis derivatives as pharmacological options in several conditions, such as appetite stimulation, pain treatment, skin pathologies, anticonvulsant therapy, neurodegenerative diseases, and infectious diseases. However, there is some controversy regarding the legal and ethical implications of their use and routes of administration, also concerning the adverse health consequences and deaths attributed to marijuana consumption, and these represent some of the complexities associated with the use of these compounds as therapeutic drugs. This review comprehends the main secondary metabolites of Cannabis, approaching their therapeutic potential and applications, as well as their potential risks, in order to differentiate the consumption as recreational drugs. There will be also a focus on the analytical methodologies for their analysis, in order to aid health professionals and toxicologists in cases where these compounds are present.
- Bark residues valorization potential regarding antioxidant and antimicrobial extractsPublication . Neiva, Duarte; Luís, Ângelo; Gominho, Jorge; Domingues, Fernanda C.; Duarte, Ana Paula; Pereira, HelenaBark residual side streams from industries (Eucalyptus globulus—Eg and Picea abies—Pa) or from control of invasive species in Mediterranean countries (Acacia melanoxylon—Am and Acacia dealbata—Ad) are burned for energy production, although their high content of extractable compounds points to a possible valorization as sources of phytochemicals with antioxidant and antimicrobial activities. Non-polar and polar extracts were obtained, and their phenolic contents, antioxidant activity, antiquorum sensing and antimicrobial potential against several human pathogenic microbes (nine bacteria and two yeasts) were determined. Extraction yield ranged from 0.5 to 37% of barks dry weight varying with species and solvent used, and both water and ethanol extracts presented strong or very strong scavenging antioxidant ability. Eg and Pa non-polar extracts showed the lowest minimum inhibitory concentration for gram-positive bacteria (0.04–1.25 mg/mL), while Ad presented the best results among polar extracts regarding bacteria (0.16 mg/mL for K. pneumoniae) and yeast strains (0.02–0.04 mg/mL). Non-polar extracts showed great response against both Candida species (MIC=0.04–0.63 mg/mL). Each extract had diferent antimicrobial activity showing that species and solvents can be used to tailor compounds to target specifc pathogens. Information regarding these bioactive extracts from residual forest side streams can provide possible utilization routes for natural compounds recovery prior to combustion.
- In Vitro Study of the Bioavailability and Bioaccessibility of the Main Compounds Present in Ayahuasca BeveragesPublication . Gonçalves, Joana; Castilho, Miguel; Rosado, Tiago; Luís, Ângelo; Restolho, José; Fernández, Nicolás; Gallardo, Eugenia; Duarte, Ana PaulaAyahuasca is a psychoactive beverage that contains the psychoactive compound N,N-dimethyltryptamine and β-carboline alkaloids. This study aims at determining in vitro the bioavailability and bioaccessibility of the main compounds present in decoctions of four individual plants, in a commercial mixture and in four mixtures of two individual plants used in the preparation of Ayahuasca. The samples were subjected to an in vitro digestion process, and the Caco-2 cell line was used as an absorption model. The integrity and permeability of the cell monolayer were evaluated, as well as the cytotoxicity of the extracts. After digestion and cell incubation, the compounds absorbed by the cell monolayer were quantified by high-performance liquid chromatography coupled to a diode array detector. The results showed that compounds such as N,N-dimethyltryptamine, Harmine, Harmaline, Harmol, Harmalol and Tetrahydroharmine were released from the matrix during the in vitro digestion process, becoming bioaccessible. Similarly, some of these compounds, after being incubated with the cell monolayer, were absorbed, becoming bioavailable. The extracts did not show cytotoxicity after cell incubation, and the integrity and permeability of the cell monolayer were not compromised.
- Star anise (Illicium verum Hook. f.) essential oil: Antioxidant properties and antibacterial activity against Acinetobacter baumanniiPublication . Luís, Ângelo; Sousa, Sónia; Wackerlig, Judith; Dobusch, Daniel; Duarte, Ana Paula; Pereira, L.; Domingues, F.C.The increased resistance of pathogenic bacteria to multiple antimicrobial agents is becoming a significant public health threat. For many pathogenic bacteria there are already limited or no effective antimicrobials available to treat the infections caused by them. Acinetobacter baumannii is a Gram‐negative, biofilm‐forming, nonmotile coccobacillus and a major human pathogen causing hospital‐acquired infections, such as ventilator‐associated pneumonia, bacteraemia, meningitis, and urinary tract and wound infections. There is therefore a clear need to discover new compounds and strategies to overcome widespread antimicrobial resistance, with a focus on A. bau-mannii strains. Star anise (Illicium verum Hook. f.) has been widely used as an ingredi‐ent in traditional Chinese cooking, as a flavouring agent, and as a medicine for over 3000 years; however, the essential oil (EO) isolated from star anise has not been fur‐ther characterized in terms of its bioactivities and potential applications. In this work, a screening of the biological properties of star anise EO together with its chemical characterization were performed. Special attention was given to the impact of this EO in the formation of biofilms by A. baumannii. It was demonstrated that star anise EO is able to scavenge free radicals, to inhibit lipid peroxidation, and to inhibit protein denaturation, which is associated with its antioxidant and anti‐inflammatory proper‐ties. Moreover, the effects of the EO on the planktonic and biofilm cells of A. bau-mannii, inhibiting the formation of biofilms, dispersing preformed biofilms, and decreasing the capacity of the bacterial cells to adhere to polystyrene, together with its ability to inhibit quorum sensing, were also demonstrated.
- Natural Products: Therapeutic Properties and Beyond IIPublication . Duarte, Ana Paula; Luís, Ângelo; Gallardo, EugeniaHistorically, natural products have contributed to drug discovery as a source of active molecules due to their great diversity and structural complexity. Thus, they have contributed to the development of drugs for applications in different therapeutic areas. In recent decades, there has been a paradigm shift in drug discovery strategies that has allowed for identifying new natural products that exhibit activities on therapeutic targets. Newman and Cragg studied the origin of 1330 new drugs that had been approved between 1981 and 2010 and found that 64% of them were somewhat related to natural compounds [1]. In a recent review by these same authors, it was noted that, within all of the drugs newly approved by the Food and Drug Administration between January 1981 and September 2019, compounds derived from natural products ranked second [2]. Besides the importance of the discovery of new molecules based on natural compounds, the concern today is focused on the therapeutic potential of secondary metabolites classified as drugs of abuse, such as derivatives of cannabis [3] and psilocybin [4], or even on the use of plants used ancestrally in medicine as well [5,6]. On the other hand, with the development of computational techniques, a decision has been made to study the possibilities of analyzing the pharmacological potential of natural products or their derivatives and converting these molecules into low toxicity active products. However, apart from the use of naturally occurring compounds in the field of health, they have been studied and are increasingly used in solutions, for instance in the agrochemical and food industries. After the success of the Special Issue “Natural Products: Therapeutic Properties and Beyond I”, this second edition aims to categorize the state of the art concerning scientific research on natural products, including their applications as compounds with added value to human health. This issue intends to be used as a text for academia or as a reference tool for researchers, particularly for those working in the fields of medicinal chemistry, toxicology, phytochemistry, and natural product chemistry, and for health and industry professionals.
- The Pros and Cons of Estrogens in Prostate Cancer: An Update with a Focus on PhytoestrogensPublication . Figueira, Marília I; Carvalho, Tiago; Monteiro, Joana; Cardoso, Henrique J.; Correia, Sara; Vaz, CV; Duarte, Ana Paula; Socorro, SílviaThe role of estrogens in prostate cancer (PCa) is shrouded in mystery, with its actions going from angelic to devilish. The findings by Huggins and Hodges establishing PCa as a hormone-sensitive cancer have provided the basis for using estrogens in therapy. However, despite the clinical efficacy in suppressing tumor growth and the panoply of experimental evidence describing its anticarcinogenic effects, estrogens were abolished from PCa treatment because of the adverse secondary effects. Notwithstanding, research work over the years has continued investigating the effects of estrogens, reporting their pros and cons in prostate carcinogenesis. In contrast with the beneficial therapeutic effects, many reports have implicated estrogens in the disruption of prostate cell fate and tissue homeostasis. On the other hand, epidemiological data demonstrating the lower incidence of PCa in Eastern countries associated with a higher consumption of phytoestrogens support the beneficial role of estrogens in counteracting cancer development. Many studies have investigated the effects of phytoestrogens and the underlying mechanisms of action, which may contribute to developing safe estrogen-based anti-PCa therapies. This review compiles the existing data on the anti- and protumorigenic actions of estrogens and summarizes the anticancer effects of several phytoestrogens, highlighting their promising features in PCa treatment.
- Characterization of kraft lignin from Pinus pinasterPublication . Duarte, Ana Paula; Batista, Cecilia; Belgacem, Mohamed NaceurThis paper presents the results about the lignin from Pints pinaster, the only softwood used in Portuguese pulp and paper industries. Six samples of lignin were collected and studied. The first three samples were precipitated from kraft black liquors at different H-factors. using conventional batch pulping. The other three corresponded to the lignin obtained from black liquors of flow-through reactor at the same H-factors. The residual sugars from the lignin obtained were hydrolysed according to the trifluoroacetic acid method and quantified by HPLC. The main residual sugars on the lignin samples from both reactors were found to be xylose, galactose and arabinose, which indicates that the lignin-carbohydrate linkages are similar to other common softwoods. The elemental analyses of these samples showed that, in the initial stage of delignification, the HS' anions are strongly involved in the delignification mechanism. It was also shown that the C/H ratio was relatively constant, which indicated the weak participation of condensation reactions. The infrared spectra of these samples evidenced the presence of the main peaks corresponding to different functional groups of softwood lignin structure. They also showed that the content of conjugated carbonyl groups decreased with the reaction time. Finally, the permanganate potassium oxidation of the lignin samples showed the presence of the principal fragments present in softwood lignin. It was also shown that. when the time of delignification increased, the amount of non-condensed units decreased, whereas that corresponding to condensed ones increased.
- Determination of sugar content in Pinus pinaster and its corresponding hollocellulose, cellulose and kraft pulpsPublication . Duarte, Ana Paula; Gaiolas, Carla Sofia Cardona Jorge; Belgacem, Mohamed Naceur; Simões, RogérioThis paper deals with the study of the polysaccharide complex from Portuguese Pinus pinaster, as well as from its main components, i.e., holocellulose, cellulose and pulps obtained using different cooking conditions. Nordic Pinus sylvestris was also studied in order to compare it with Portuguese pine. Two methods were used: one consisted of the hydrolysis of polysaccharides with trifluoroacetic acid (TFA) and quantification of the amount of each sugar using High Performance Liquid Chromatography (HPLC). The latter approach used here consisted of the hydrolysis of the samples under scrutiny by sulphuric acid and converting it into alditols, which were then esterified before injecting to Gas Chromatography coupled with Mass Spectrometry. Myo-inositol was used as an internal standard. The results obtained by the two methods showed that the TFA procedure prevents monosaccharide degradation, comparatively with the sulphuric acid one. In fact, the overall sugar yield was found systematically higher than 93% for TFA hydrolysis, whereas that corresponding to H2SO4 treatment never exceeded 77%. The sugar composition of both pines was found very similar and the sulfidity level (from 10 to 55%) did not affect the pulp sugar composition. The glucose/mannose and xylose/arabinose ratios were found to be around 3.5 for both Portuguese and Nordic pines. Finally, kraft pulping of Pinus pinaster was found to affect drastically galactose, mannose and arabinose.