Marisa Freitas

• PhD
• PostDoc Position at University of Porto

Background/Objectives: Recent interest in dietary components and their effects on xenobiotic metabolism has highlighted their role in modulating drug pharmacokinetics. Cytochrome P450 3A4, a key isoform of the cytochrome P450 superfamily, is involved in the metabolism of over 50% of xenobiotics. Flavonoids, present in various foods and supplements,...

In 2022, World Health Organization (WHO) established global objectives for diabetes, aiming for 80% of people with diabetes to achieve good control of glycaemia and blood pressure by 2030. Currently, there are approximately 537 million adults living with diabetes, placing them at a high risk of developing various complications. Discovering new anti...

The intestinal epithelium plays a pivotal role as a vital barrier between the external environment and the human body, regulating nutrient absorption and preventing the entry of harmful substances. The human oral exposure to silver nanoparticles (AgNP) raises concerns about their potential toxicity, especially at the intestinal level. The objective...

Background/Objectives: Obesity has reached pandemic proportions, with predictions suggesting that, by 2030, over 1.5 billion people will be affected. Pancreatic lipase (PL), the enzyme primarily responsible for the absorption of dietary lipids, presents a potential target for obesity management. However, while porcine pancreatic lipase (PPL) is com...

The rapid development of nanotechnology has resulted in the widespread use of nanoparticles (NPs) in various sectors due to their unique properties and diverse applications. However, the increased exposure of humans to NPs raises concerns about their potential negative impact on human health and the environment. The pathways through which NPs exert...

In patients with type 2 diabetes mellitus (DM), excessive gluconeogenesis is considered a major contributor to hyperglycemia. Therefore, targeting fructose 1,6‐bisphosphatase (FBPase), a key regulatory enzyme involved in gluconeogenesis, has gained interest as a potential therapeutic target for managing DM. In this study, a library of 42 structural...

Obesity represents a global health concern, affecting individuals of all age groups across the world. The prevalence of excess weight and obesity has escalated to pandemic proportions, leading to a substantial increase in the incidence of various comorbidities, such as cardiovascular diseases, type 2 diabetes, and cancer. This chapter seeks to prov...

Background: Parabens, also known as a family of alkyl esters of 4-hydroxybenzoic acid (4-HB), are natural or synthetic compounds that have been used as powerful antimicrobial agents across multiple industries such as cosmetic, pharmaceutical and food industries, since the 1920s [1]. Their widespread use stems from their low cost, broad-spectrum ant...

amylase and α-glucosidase are key enzymes implicated in carbohydrate digestion and their inhibition has been suggested as a powerful approach for regulating blood glucose levels. The present work describes for the first time their inhibition by a group of twelve hydroxylated 2-styrylchromones (2-SC). Our findings revealed that 2-SC display strong s...

Type 2 diabetes mellitus (DM) continues to escalate, necessitating innovative therapeutic approaches that target distinct pathways and address DM complications. Flavonoids have been shown to possess several pharmacological activities that are important for DM. This study aimed to evaluate the in vivo effects of the flavonoid melanoxetin using Goto-...

Rheumatoid arthritis (RA) is a progressive, chronic, autoimmune, inflammatory, and systemic condition that primarily affects the synovial joints and adjacent tissues, including bone, muscle, and tendons. The World Health Organization recognizes RA as one of the most prevalent chronic inflammatory diseases. In the last decade, there was an expansion...

Os neutrófilos são componentes fundamentais na resposta imune inata e, em condições normais, representam cerca de 40 a 70% dos leucócitos circulantes no sangue humano. Estas células constituem a primeira linha de reconhecimento e defesa do organismo contra agentes agressores e/ou estímulos inflamatórios. Um dos mecanismos utilizados pelos neutrófil...

Obesity is a disease of epidemic proportions with a concerning increasing trend. Regarded as one of the main sources of energy, lipids can also represent a big part of an unnecessary intake of calories and be, therefore, directly related to the problem of obesity. Pancreatic lipase is an enzyme that is essential in the absorption and digestion of d...

One of the hallmarks of cancer is metastasis, a process that entails the spread of cancer cells to distant regions in the body, culminating in tumor formation in secondary organs. Importantly, the proinflammatory environment surrounding cancer cells further contributes to cancer cell transformation and extracellular matrix destruction. During metas...

Silver nanoparticles (AgNP) are the most widely produced type of nanoparticles due to their antimicrobial and preservative properties. However, their systemic bioavailability may be considered a potential hazard. When AgNP reach the bloodstream, they interact with the immune cells, contributing to the onset and development of an inflammatory respon...

Silver nanoparticles (AgNP) have gained access to our daily life, resulting in exponential and inevitable human exposure, namely by the oral route. Despite this, the adverse effects of AgNP on intestinal cells are still unexplored. Thus, this study aimed to investigate the potentially toxic and pro-inflammatory effects of polyvinylpyrrolidone (PVP)...

Xanthones are oxygen-containing heterocyclic compounds that exhibit a wide range of biological and pharmacological properties. Some natural and synthetic derivatives have been identified for their antidiabetic profile, mainly as α-glucosidase inhibitors. However, studies concerning the inhibition of both carbohydrate-hydrolyzing enzymes α-amylase a...

Nanotechnology is a promising technology of the twenty-first century, being a rapidly evolving field of research and industrial innovation widely applied in our everyday life. Silver nanoparticles (AgNP) are considered the most commercialized nanosystems worldwide, being applied in diverse sectors, from medicine to the food industry. Considering th...

Depigmenting properties of tyrosinase inhibitors (TAi) boosted the search for new compounds applicable in cosmetics. Kojic acid, a 3-hydroxy-4-pyrone, is the most studied tyrosinase inhibitor but undesirable side effects, like dermatitis, and unspecified mechanism led to its exclusion in several countries. To discover safer and more efficient TA, w...

Neutrophils are polymorphonuclear leukocytes recruited to sites of acute inflammation, in response to pathogen invasion and tissue injury. The modulation of their activity, especially oxidative burst, may be important to control the inflammatory process. 2-Styrylchromones (2-SC) are derived from chromones and despite their recognized multiple biolo...

Glycogen phosphorylase (GP) is a key enzyme in the glycogenolysis pathway. GP inhibitors are currently under investigation as a new liver-targeted approach to managing type 2 diabetes mellitus (DM). The aim of the present study was to evaluate the inhibitory activity of a panel of 52 structurally related chromone derivatives; namely, flavonoids, 2-...

Type 2 diabetes (T2D) is the most common form of diabetes, and the number of people with this metabolic disease is steadily increasing worldwide. Among the available antidiabetic agents, α-glucosidase inhibitors are the most effective at reducing postprandial hyperglycaemia (PPHG), one of the main characteristics of T2D. However, most of the studie...

Styrylchromones (SC) are a group of oxygen-containing heterocyclic compounds, which are characterized by the attachment of a styryl group to the chromone core. SC can be found in nature or can be chemically synthesized in the laboratory. As their presence in nature is scarce, the synthetic origin is the most common. Two types of SC are known: 2-sty...

Glycogen phosphorylase (GP) is a key enzyme in the glycogenolysis pathway and a potential therapeutic target in the management of type 2 diabetes. It catalyzes a reversible reaction: the release of the terminal glucosyl residue from glycogen as glucose 1-phosphate; or the transfer of glucose from glucose 1-phosphate to glycogen. A colorimetric meth...

Curcumin is a natural polyphenol isolated from the rhizome of Curcuma longa with recognised therapeutic potential, namely as an anti-inflammatory, antioxidant, anticancer, and antidiabetic agent. Despite its potential biological properties, the low bioavailability of curcumin hinders its systemic effects. Recently, it was reported that the combinat...

2-Styrylchromones (2-SC) are a group of oxygen-containing heterocyclic compounds, which are characterized by the attachment of a styryl group to the C-2 position of their chromone core. Over the years, several biological activities have been attributed to 2-SC, such as antioxidant, anti-inflammatory, antimicrobial, antiviral, and antitumor activiti...

Diabetes mellitus is one of the biggest health emergencies of the 21st century worldwide, characterized by deficiency in insulin secretion and/or action, leading to hyperglycemia. Despite the currently available antidiabetic therapeutic options, 4.2 million people died in 2019 due to diabetes. Thus, new effective interventions are required. Polyphe...

Type 2 diabetes mellitus (DM) is a complex chronic disorder and a major global health problem. Insulin resistance is the primary detectable abnormality and the main characteristic feature in individuals with type 2 DM. Protein tyrosine phosphatase 1B (PTP1B) is a key negative regulator of the insulin signaling pathway, which dephosphorylates insuli...

Type 2 diabetes (T2D) is an expanding global health problem, resulting from defects in insulin secretion and/or insulin resistance. In the past few years, both protein tyrosine phosphatase 1B (PTP1B) and dipeptidyl peptidase-4 (DPP-4), as well as their role in T2D, have attracted the attention of the scientific community. PTP1B plays an important r...

Type 2 diabetes (T2D) is one of the most prevalent metabolic diseases worldwide and is characterized by increased postprandial hyperglycemia (PPHG). α-Amylase and α-glucosidase inhibitors have been shown to slow the release of glucose from starch and oligosaccharides, resulting in a delay of glucose absorption and a reduction in postprandial blood...

Inflammatory bowel disease (IBD) is a physically incapacitating disorder that significantly disturbs patients' quality of life. IBD is classified into two main pathophysiological forms, ulcerative colitis and Crohn's disease. Literature studies indicate that chronic colitis may contribute to the development of up to 25% of all diagnosed colorectal...

Inflammatory bowel disease (IBD) is characterized by sustained inflammatory processes in the gastrointestinal tract. One of the most threatening risks for IBD patients is the development of colorectal cancer, resulting from the chronic inflammatory state. Current IBD treatment presents limitations in safety and efficacy. As such, it is of paramount...

Several epidemiological studies indicate that neutrophils, under hyperglycemic conditions, are involved in the perpetuation of the inflammatory status, a characteristic of diabetes mellitus, leading to the production of prodigious quantities of reactive species and the release of neutrophil extracellular traps (NETs). Accordingly, our aim was to st...

Diabetes mellitus (DM) is characterized by hyperglycemia, resulting from defects in insulin secretion, insulin action or both. There are several factors such as hyperlipidemia and oxidative stress (OS), namely the production of reactive oxygen/nitrogen species (ROS/RNS), that actively contribute to the development and worsening of DM. Chalcones, al...

Carotenoids are ubiquitously distributed in nature, β-carotene being the most frequently found carotenoid in the human diet. In the human body, β-carotene is absorbed, distributed and metabolized by enzymatic and/or non-enzymatic oxidant cleavage into several metabolites. Despite the broadly accepted biological value of β-carotene, it has also been...

The inhibition of carbohydrate-hydrolyzing enzymes, α-amylase and α-glucosidase, is one of the major therapeutic strategies for the treatment of type 2 diabetes mellitus. Chalcones have been recognized for their multiple biological activities, including antidiabetic properties, through unclear mechanisms. In the present work, a panel of chalcones b...

Dipeptidyl peptidase-4 (DPP-4) inhibitors present a unique approach for the management of type 2 diabetes (T2D). In the present study, the inhibition of DPP-4 was evaluated for a large panel of flavonoids, important components of the human diet, using in vitro and ex vivo models. The activity of the isolated enzyme was assayed in vitro. Subsequentl...

Correction for ‘A study towards drug discovery for the management of type 2 diabetes mellitus through inhibition of the carbohydrate-hydrolyzing enzymes α-amylase and α-glucosidase by chalcone derivatives’ by Sónia Rocha, et al. , Food Funct. , 2019, DOI: 10.1039/c9fo01298b.

Persimmon (Diospyros kaki L.) fruits are used in traditional medicine largely due to their claimed beneficial effects on human health. The aim of this work was to evaluate the anti-inflammatory activity of a persimmon extract in rats with collagen-induced arthritis (CIA). CIA was induced in Wistar rats through an intradermal injection of an emulsio...

Amylase has been considered an important therapeutic target for the management of type 2 diabetes mellitus (T2DM), decreasing postprandial hyperglycaemia (PPHG). In the present work, a panel of 40 structurally related flavonoids was tested, concerning their ability to inhibit α-amylase activity, using a microanalysis screening system, an inhibitory...

The purpose of an experimental design is to improve the productivity of experimentation. It is an efficient procedure for planning experiments, so the data obtained can be analyzed to yield a valid and objective conclusion. This approach has been used as an important tool in the optimization of different analytical approaches. A D-optimal experimen...

In neutrophils, intracellular Ca2+ levels are regulated by several transporters and pathways, namely SERCA [sarco(endo)plasmic reticulum Ca2+-ATPase], SOCE (store-operated calcium entry), and ROCE (receptor-operated calcium entry). However, the exact mechanisms involved in the communication among these transporters are still unclear. In the present...

Silver nanoparticles (AgNPs) have a wide spectrum of applications that reach far beyond therapeutics, being easily found in the everyday human life. Due to their tendency to aggregate, AgNPs are typically synthesized with surface coatings for stabilization. Branched polyethylenimine (PEI) is a multifunctional polymer that has been recently used in...

The use of anti-diabetic drugs has been increasing worldwide and the evolution of therapeutics has been enormous. Still, the currently available anti-diabetic drugs do not present the desired efficacy and are generally associated with serious adverse effects. Thus, entirely new interventions, addressing the underlying etiopathogenesis of type 2 dia...

Carotenoids are lipid soluble plant pigments that make part of human daily diet. These compounds are able to react with diverse reactive species and originate a myriad of oxidation products that have similar or even more reactivity than their parent compounds. These products may be short-chain carbonyl compounds and, the commonly designated, apo-ca...

α-Glucosidase plays an important role in carbohydrate metabolism and is therefore an attractive therapeutic target for the treatment of diabetes, obesity and other related complications. In the last two decades, considerable interest has been given to natural and synthetic xanthone derivatives in this field of research. Herein, a comprehensive revi...

β-carotene is the most abundant carotenoid found in the diet and human tissues [1]. High ingestion of carotenoids has been associated with low incidence of degenerative diseases and it has been mainly attributed to their ability to scavenge physiologically relevant reactive species. In humans, β-carotene is metabolized by oxidative cleavage into tr...

The overproduction of hypochlorous acid (HOCl) is currently associated to the development of several human diseases such as arthritis and cancer. Its assessment in human tissues, namely in whole blood, is therefore of the utmost importance. D-optimal experimental design was used to optimize the experimental conditions for the in vitro detection of...

The overproduction of hypochlorous acid (HOCl) is currently associated to the development of several human diseases such as arthritis and cancer. Its assessment in human tissues, namely in whole blood, is therefore of the utmost importance. D-optimal experimental design was used to optimize the experimental conditions for the in vitro detection of...

Silver nanoparticles (AgNPs) have a wide range of applications. Despite the widespread use of AgNPs in several products, such as cosmetics, textiles, certain types of packaging, etc., its safety is still elusive, namely in what concerns the putative effects in the immune system. Neutrophils are believed to be among the first and primary cell types...

Inflammatory bowel diseases (IBD) comprise two disorders of idiopathic chronic intestinal inflammation that affect about three million people worldwide: Crohn's disease and ulcerative colitis. Nowadays, the first-line of treatment for patients with mild to moderate symptoms of IBD comprises corticosteroids, immunosuppressants, antibiotics, and biol...

The classical non-transmembrane protein tyrosine phosphatase 1B (PTP1B) has emerged as a key negative regulator of insulin signaling pathways that leads to insulin resistance, turning this enzyme a promising therapeutic target in the management of type 2 diabetes mellitus (T2DM). In the present work, the in vitro inhibitory activity of a panel of s...

Carotenoids, present in fruit and vegetables, are an important component of our daily diet [1]. Diverse biological properties have been attributed to these compounds, namely their possible antioxidant activity, which may be related to their ability to diminish the incidence of degenerative diseases. β-Carotene is the most frequently found carotenoi...

Glucosidase inhibitors are described as the most effective in reducing post-prandial hyperglycaemia (PPHG) from all available anti-diabetic drugs used in the management of type 2 diabetes mellitus. As flavonoids are promising modulators of this enzyme’s activity, a panel of 44 flavonoids, organised in five groups, was screened for their inhibitory...

β-carotene is the most abundant carotenoid found in the diet and human tissues [1]. High ingestion of carotenoids has been associated with low incidence of degenerative diseases and it has been mainly attributed to their ability to scavenge physiologically relevant reactive species. In humans, β-carotene is metabolized by oxidative cleavage into tr...

Flavonoids are known to react with neutrophil-generated hypochlorous acid (HOCl) at inflammation loci to form stable mono- and dichlorinated products. Some of these products have been shown to retain or even enhance their inflammatory potential, but further information is required in a broader approach to inflammatory mechanisms. In that sense, we...

Understanding in vivo biodistribution of iron oxide nanoparticles (IONs), and the involvement of the phagocyte system in this process, is crucial for the assessment of their potential health risk. In the present study, the histochemical expression of iron in spleen and liver sections of CD-1 mice (aged 8 weeks) was quantified, 24 hours after intrav...

Polysaccharides are abundant components in marine macroalgae with potential applications in different areas such as pharmaceutical, biomedical, cosmetics and nutrition. The current interest in these compounds is due to their known bioactivities, conferred by their antiallergic, neuroprotective, gastroprotective, cardioprotective, cytotoxic, anticoa...

Polysaccharides are abundant components in marine macroalgae, with potential applications in diferent areas such as pharmaceutical, biomedical, cosmetics and nutrition. The current interest in these compounds is due to their known bioactivities, conferred by their anti-allergic, neuroprotective, gastroprotective, cardioprotective, cytotoxic, antico...

Here we investigated the anti-inflammatory effect of a blueberry extract in the carrageenan-induced paw edema model and collagen-induced arthritis model, both in rats. Along with the chemical characterization of the phenolic content of the fruits and extract, the antioxidant potential of the extract, the cellular antioxidant activity and the effect...

Bactris setosa Mart. is a Brazilian tree from the palm family (Arecaceae), whose fruits are scientifically underexploited. Here, we report, for the first time, the identification and quantification of phenolic compounds and carotenoids in the pulp, seed, and peel extracts of B. setosa fruits and their in vitro biological activity. The anthocyanins...

Ochratoxin A (OTA) is a mycotoxin produced by several species of fungi from the Aspergillus and Penicillium genera that frequently grow in improperly stored food products. OTA has carcinogenic, teratogenic and nephrotoxic potential and sustains a high half-life in human blood. Despite the recently efforts to decontaminate OTA through its conversion...

Colon cancer is one of the most incident cancers in the Western World. While both genetic and epigenetic factors may contribute to the development of colon cancer, it is known that chronic inflammation associated to excessive production of reactive oxygen and nitrogen species by phagocytes may ultimately initiate the multistep process of colon canc...

Iron oxide nanoparticles (IONs) have physical and chemical properties that render them useful for several new biomedical applications. Still, so far, in vivo safety studies of IONs with coatings of biomedical interest are still scarce. The aim of this study, therefore, was to clarify the acute biological effects of polyacrylic acid (PAA)-coated ION...

Different groups of substances are present in grape, must, wine, and derived by-products, which includes water, sugars, organic acids, nitrogen compounds, minerals, vitamins, phenolic, and aromatic substances. The beneficial effects of grape and grape-derived products have been associated with the presence of bioactive components, such as the pheno...

Aims: Silver nanoparticles (AgNPs) have emerged as an important class of nanomaterials with a wide range of industrial and medical applications. The assessment of AgNPs' biological effects in the human organism is therefore essential to evaluate the impact of these nanomaterials in public health and reassure the ratio benefit/risk. In the present...

Ligands of the 3-hydroxy-4-pyridinone (3,4-HPO) type, with one (Hmpp) or two methyl groups (Hdmpp), have been reported to possess biomedical, chemical and analytical applications. In this first screening study aiming to uncover new promising agents to mitigate the oxidative damage highly present in several metabolic disorders, such as diabetes mell...

The production of superoxide anion radical (O2•-) is essential for the life of aerobic organisms. This free radical acts as a signaling molecule, regulating numerous biological processes including apoptosis, aging, and senescence. Nevertheless, when overproduction of O2•- occurs and/or antioxidant defences are deficient, oxidative stress may develo...