Percorrer por autor "Garcia, Juliana"
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- Alkaloids from fungiPublication . Silva, Jani; Garcia, Juliana; Guimarães, Rafaela; Palito, Cátia; Lemos, André; Barros, Lillian; Alves, Maria JoséThe prospection of unusual sources and undiscovered habitats is valuable in natural product research. Indeed, the fungi kingdom has received special attention since its ability to produce novel and intriguing secondary metabolites with various biological uses. Among secondary metabolites, alkaloid-derived structures present a wide range of bioactivities, including antineurodegenerative, antidepressive, anxiolytic, anti-inflammatory, cytotoxic, and insecticidal properties. Furthermore, various studies showed particular properties of those alkaloids in reducing nicotine addiction and alcohol dependence. Alkaloids are categorized into several groups based on their heterocyclic ring system and biosynthetic precursor, such as indole, isoxazoles, and muscarine. Therefore, this chapter focuses on those fungi’s bioactive alkaloids with emphasis on pharmacokinetics as well as the current analytical approaches for extraction and compound identification. Furthermore, the main biological activities and action mechanisms of these fungus alkaloids will also be discussed.
- Amanita phalloides poisoning: Mechanisms of toxicity and treatmentPublication . Garcia, Juliana; Costa, Vera M.; Carvalho, Alexandra T.P.; Baptista, Paula; Pinho, P. Guedes de; Bastos, Maria de Lourdes; Carvalho, FélixAmanita phalloides, also known as 'death cap', is one of the most poisonous mushrooms, being involved in the majority of human fatal cases of mushroom poisoning worldwide. This species contains three main groups of toxins: amatoxins, phallotoxins, and virotoxins. From these, amatoxins, especially α-amanitin, are the main responsible for the toxic effects in humans. It is recognized that α-amanitin inhibits RNA polymerase II, causing protein deficit and ultimately cell death, although other mechanisms are thought to be involved. The liver is the main target organ of toxicity, but other organs are also affected, especially the kidneys. Intoxication symptoms usually appear after a latent period and may include gastrointestinal disorders followed by jaundice, seizures, and coma, culminating in death. Therapy consists in supportive measures, gastric decontamination, drug therapy and, ultimately, liver transplantation if clinical condition worsens. The discovery of an effective antidote is still a major unsolved issue. The present paper examines the clinical toxicology of A. phalloides, providing the currently available information on the mechanisms of toxicityinvolved and on the current knowledge on the treatment prescribed against this type of mushrooms. Antidotal perspectives will be raised as to set the pace to new and improved therapy against these mushrooms.
- Antimicrobial and antioxidant activities of aqueous extracts of Lentinula edodes var Donko and KoshinPublication . Afonso, Ana Cristina; Fernandes, Conceição; Garcia, Juliana; Marques, Guilhermina; Nunes, Fernando M.; Saavedra, Maria JoséAntimicrobial resistance is recognizes by the WHO as a serious Public Health problem, representing a global challenge for medicine.
- Assessing the nutritional and functional properties of mushrooms from North-Eastern PortugalPublication . Martins, Joana; Garcia, Juliana; Gouvinhas, Irene; Pinto, Diana; Rodrigues, Francisca; Saavedra, Maria José; Alves, Maria JoséMushrooms are recognized as functional foods with noteworthy nutritional, culinary, and pharmacological properties, leading to their growing consumption. The present study aimed to compare the chemical composition and biological properties of six wild species harvested in north-eastern Portugal and two cultivated species (Lentinula edodes and Pleurotus citrinopileatus, purchased in Portuguese retail markets) to evaluate their potential as sources of nutrients and bioactive compounds. The results showed diverse macronutrient proximate profiles, characterized by high carbohydrate, dietary fibre, and protein, along with low-fat content and with moderate antioxidant activity. Notably, glucans were present in high amounts, with beta-glucans representing the major fraction. Despite species-specific variations, potassium and phosphorus were the predominant mineral elements. Additionally, lysine and arginine were the most abundant free amino acids in the samples. Overall, this manuscript provides a comprehensive insight into the chemical composition, bioactive properties, and nutritional potential of commercially available and wild mushrooms, supplying the first detailed glucan, mineral and antioxidant profile for five under-studied wild species from north-eastern Portugal.
- A breakthrough on Amanita phalloides poisoning: an effective antidotal effect by polymyxin BPublication . Garcia, Juliana; Costa, Vera M.; Carvalho, Alexandra T.P.; Silvestre, Ricardo; Duarte, José A.; Dourado, Daniel F.A.R.; Arbo, Marcelo D.; Baltazar, Teresa; Dinis-Oliveira, Ricardo Jorge; Baptista, Paula; Bastos, Maria de Lourdes; Carvalho, FélixAmanita phalloides is responsible for more than 90 % of mushroom-related fatalities, and no effective antidote is available. α-Amanitin, the main toxin of A. phalloides, inhibits RNA polymerase II (RNAP II), causing hepatic and kidney failure. In silico studies included docking and molecular dynamics simulation coupled to molecular mechanics with generalized Born and surface area method energy decomposition on RNAP II. They were performed with a clinical drug that shares chemical similarities to α-amanitin, polymyxin B. The results show that polymyxin B potentially binds to RNAP II in the same interface of α-amanitin, preventing the toxin from binding to RNAP II. In vivo, the inhibition of the mRNA transcripts elicited by α-amanitin was efficiently reverted by polymyxin B in the kidneys. Moreover, polymyxin B significantly decreased the hepatic and renal α-amanitin-induced injury as seen by the histology and hepatic aminotransferases plasma data. In the survival assay, all animals exposed to α-amanitin died within 5 days, whereas 50 % survived up to 30 days when polymyxin B was administered 4, 8, and 12 h post-α-amanitin. Moreover, a single dose of polymyxin B administered concomitantly with α-amanitin was able to guarantee 100 % survival. Polymyxin B protects RNAP II from inactivation leading to an effective prevention of organ damage and increasing survival in α-amanitin-treated animals. The present use of clinically relevant concentrations of an already human-use-approved drug prompts the use of polymyxin B as an antidote for A. phalloides poisoning in humans.
- Caracterização da resistência a antibióticos de isolados de Klebsiella pneumoniae em infeções associadas aos cuidados de saúde (IACS)Publication . Afonso, Ana Cristina; Fernandes, Conceição; Garcia, Juliana; Duarte, Aida; Saavedra, Maria JoséA emergência e disseminação global de Enterobacteriaceae resistentes aos carbapenemos constitui um grave problema de Saúde Pública, uma vez que estão associadas a altas taxas de morbilidade e mortalidade. Estirpes produtoras de carbapenemases são caracteri -lactâmicos, fluoroquinolonas e aminoglicosídeos. Num estudo longitudinal, num total de 198 isolados clínicos, analisaram-se 102 isolados de Klebsiella pneumoniae resistentes a carbapenemos provenientes do Centro Hospitalar de Trás-os-Montes e Alto Douro (CHTMAD), no âmbito de protocolo aprovado pela Comissão de Ética. Os perfis de suscetibilidade dos isolados de Klebsiella pneumoniae foram estudados. Adicionalmente fez-se a caracterização da origem dos isolados: serviço hospitalar, amostra biológica, idade e género. A maioria dos isolados apresentou fenótipo de multirresistência. Observou-se que nos isolados em que foram testados, todos apresentaram resistência ao Ertapenemo, Doripenemo e Aztreonamo. Dos aminoglicosídeos testados (Amicacina, Gentamicina e Tobramicina) observou-se uma percentagem de suscetibilidade para a Gentamicina. De salientar que o antibiótico com atividade mais eficaz foi a colistina, havendo no entanto estirpes resistentes a este fármaco de último recurso, uma das últimas alternativas terapêuticas para tratar infeções causadas por bacilos Gram-negativo extremamente resistentes (XDR).A multirresistência encontrada nos isolados de Klebsiella pneumoniae em Infeções Associadas aos Cuidados de Saúde (IACs) constitui um sério problema de Saúde Pública a nível Mundial, demonstrando a necessidade de uma vigilância contínua.
- Caracterização da resistência a antibióticos de isolados de Klebsiella pneumoniae em Infeções Associadas aos Cuidados de Saúde (IACS)Publication . Afonso, Ana Cristina; Fernandes, Conceição; Garcia, Juliana; Duarte, Aida; Saavedra, Maria JoséA emergência e disseminação global de Enterobacteriaceae resistentes aos carbapenemos constitui um grave problema de Saúde Pública, uma vez que estão associadas a altas taxas de morbilidade e mortalidade. Estirpes produtoras de carbapenemases são caracteri -lactâmicos, fluoroquinolonas e aminoglicosídeos. Num estudo longitudinal, num total de 198 isolados clínicos, analisaram-se 102 isolados de Klebsiella pneumoniae resistentes a carbapenemos provenientes do Centro Hospitalar de Trás-os-Montes e Alto Douro (CHTMAD), no âmbito de protocolo aprovado pela Comissão de Ética. Os perfis de suscetibilidade dos isolados de Klebsiella pneumoniae foram estudados. Adicionalmente fez-se a caracterização da origem dos isolados: serviço hospitalar, amostra biológica, idade e género. A maioria dos isolados apresentou fenótipo de multirresistência. Observou-se que nos isolados em que foram testados, todos apresentaram resistência ao Ertapenemo, Doripenemo e Aztreonamo. Dos aminoglicosídeos testados (Amicacina, Gentamicina e Tobramicina) observou-se uma percentagem de suscetibilidade para a Gentamicina. De salientar que o antibiótico com atividade mais eficaz foi a colistina, havendo no entanto estirpes resistentes a este fármaco de último recurso, uma das últimas alternativas terapêuticas para tratar infeções causadas por bacilos Gram-negativo extremamente resistentes (XDR).A multirresistência encontrada nos isolados de Klebsiella pneumoniae em Infeções Associadas aos Cuidados de Saúde (IACs) constitui um sério problema de Saúde Pública a nível Mundial, demonstrando a necessidade de uma vigilância contínua.
- Co-ingestion of amatoxins and isoxazoles-containing mushrooms and successful treatment: A case reportPublication . Garcia, Juliana; Costa, Vera M.; Costa, Ana Elisa; Andrade, Sérgio; Carneiro, Ana Cristina; Conceição, Filipe; Paiva, José Artur; Pinho, P. Guedes de; Baptista, Paula; Bastos, Maria de Lourdes; Carvalho, FélixMushroom poisonings occur when ingestion of wild mushrooms containing toxins takes place, placing the consumers at life-threatening risk. In the present case report, an unusual multiple poisoning with isoxazoles- and amatoxins-containing mushrooms in a context of altered mental state and poorly controlled hypertension is presented. A 68-year-old female was presented to São João hospital (Portugal) with complaints of extreme dizziness, hallucinations, vertigo and imbalance, 3 h after consuming a stew of wild mushrooms. The first observations revealed altered mental state and elevated blood pressure. The examination of cooked mushroom fragments allowed a preliminary identification of Amanita pantherina. Gas chromatography-mass spectrometry (GC-MS) showed the presence of muscimol in urine. Moreover, through high-performance liquid chromatography-ultraviolet detection (HPLC-UV) analysis of the gastric juice, the presence of α-amanitin was found, showing that amatoxins-containing mushrooms were also included in the stew. After 4 days of supportive treatment, activated charcoal, silybin and N-acetylcysteine, the patient recovered being discharged 10 days post-ingestion with no organ complications. The prompt and appropriate therapy protocol for life-threatening amatoxins toxicity probably saved the patient's life as oral absorption was decreased and also supportive care was immediately started.
- Comparative antioxidant and antimicrobial properties of Lentinula edodes Donko and Koshin varieties against priority multidrug-resistant pathogensPublication . Garcia, Juliana; Afonso, Ana Cristina; Fernandes, Conceição; Nunes, Fernando M.; Marques, Guilhermina; Saavedra, Maria JoséThe problematic increase in multidrug-resistant bacteria translates into the urgent need to discover novel and effective antimicrobial substances. Herein, mushrooms could be a promising alternative of natural source of new antimicrobials. The present work aimed to compare the phytochemical composition and antimicrobial activity of methanol and aqueous crude extracts of Lentinula edodes var. Koshin and Donko. Disk diffusion method was used to screen the antimicrobial activity and to assess the synergistic effect of the mushroom extracts. Microdilution method was used to determine the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC). Phytochemical characterization of mushrooms extracts was achieved by analysis of total phenols, ortho-diphenols content and its antioxidant activity. The results noticed a positive relation between phenolic compounds content, antioxidant activity, and antimicrobial capacity of the mushroom's extracts. The L. edodes var. Koshin aqueous extracts, which contained the highest amount of total phenolic compounds, exhibited the highest scavenging capacity of ABTS which, in turns, exhibited the highest antimicrobial efficacy in inhibiting the growth of methicillin-resistant Staphylococcus aureus. Moreover, the combination between mushrooms extracts and commercial antibiotics showed favorable synergistic effects against tested bacteria. These results suggest that L. edodes var. Koshin may represent an important and valuable therapeutic source of compounds to be used against multidrug-resistant bacteria.
- A Critical Review of Emerging Solutions for Food Packaging: Opportunities and ChallengesPublication . Martins, Joana; Garcia, Juliana; Guimarães, Rafaela; Gouvinhas, Irene; Alves, Maria José; Saavedra, Maria JoséThe environmental impact of conventional plastics has driven a shift toward biobased food packaging, shaped by consumer expectations, market trends, and regulatory policies within the European Union (EU). Despite extensive research on biopolymers such as starch, cellulose, chitosan, and polylactic acid (PLA), their use in commercial food packaging remains limited. A major challenge identified in the literature is the evaluation of biopolymer performance, in which environmental benefits are often considered independently of mechanical, barrier, and economic factors. This review addresses this gap by critically exploring the functional performance of biopolymers regarding their chemical structure and processing methods, with particular emphasis on the role of bioactive compounds in enhancing these materials’ properties. Although several biopolymers can achieve tensile strength values comparable to conventional petroleum-based plastics, their higher water vapor transmission rates remain an unsolved barrier to scalability. These limitations, together with challenges related to mechanical performance and production costs, are discussed to clarify their impact on industrial feasibility and to identify priorities for future research supporting scalable, cost-effective, and regulatory-compliant food packaging solutions.