3 resultados para Natural products

em Instituto Politécnico de Bragança


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The purine ring system is one of the most widely distributed N-heterocycles in Nature [1] and many structurally modified purine nucleosides and nucleotides have activities ranging from antineoplastic and antiviral to antihypertensive, antiasthmatic, antituberculosis, etc [2]. Among the purine derivatives, we have put our attention on natural N-alkylpurines such as the asmarines or agelasimines, a group of secondary metabolites isolated from marine sponges with very interesting biological properties [3]. They have a diterpenoid moiety attached to the N-7 nitrogen atom of an adenine and are usually isolated in very small quantities, which limited their structure-activity relationship studies. Our research group has been involved for years in the design, synthesis and biological evaluation of cytotoxic compounds related to natural products, including the chemoinduction of bioactivity on inactive terpenoids [4]. These diterpenoid include compounds such as communic or cupressic acids that bear decaline moieties very close to those present in the above-mentioned marine natural products. These facts prompted us to design and prepare new terpenylpurine derivatives starting from natural monoterpenoids and diterpenoids, commercially available or isolated from their natural sources and transformed into appropriate alkylated agents. Thus, we have prepared purines alkylated at N-7 and N-9 positions with isoprenoids, monoterpenoids and diterpenoids, using two different synthetic approaches: from 6-chloropurine or from 4,5-diamine-6-chloropyrimidine. The structure of the synthesized purines are shown in the following figure. The purine analogues synthesized have been evaluated for their cytotoxicity against four tumour human cell lines (breast, non-small lung, cervical and hepatocellular carcinoma) and non-tumour cells (porcine liver primary cells). The most cytotoxic derivatives were those with a diterpenoid rest on the purine. The results obtained allowed to draw conclusions on the structure-activity relationship of the compounds in order to evaluate the influence of the terpenyl size on their cytotoxic properties.

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The particular characteristics of growth and development of mushrooms in nature result in the accumulation of a variety of secondary metabolites, several of them with biological activities. The genus Pleurotus is a cosmopolitan group of mushrooms with high nutritional value and therapeutic properties, besides a wide array of biotechnological and environmental applications. Scope and approach: The present report aims to provide a critical review on aspects related to chemical compounds isolated from the genus Pleurotus with possible biotechnological, nutritional and therapeutic uses. Investigations on the genus have immensely accelerated during the last ten years, so that only reports published after 2005 have been considered. Key findings and conclusions: The most important Pleurotus species cultivated in large scale are P. ostreatus and P. pulmonarius. However, more than 200 species have already been investigated to various degrees. Both basidiomata and mycelia of Pleurotus are a great renewable and easily accessible source of functional foods/nutraceuticals and pharmaceuticals with antioxidant, antimicrobial, anti-inflammatory, antitumor and immunomodulatory effects. A series of compounds have already been precisely defined including several polysaccharides, phenolics, terpenes and sterols. However, intensification of structure determination is highly desirable and demands considerable efforts. Further studies including clinical trials need to be carried out to ascertain the safety of these compounds as adequate alternatives to conventional drugs. Not less important is to extend the search for novel bioactives to less explored Pleurotus species.

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Herbal therapy is characterized by the use of aromatic and medicinal plants (AMP) in different pharmaceutical forms for therapeutic purposes. The present study aims to characterize the use of AMP, drugs and herbal products in Bragança city. For this, a cross-sectional study was conducted through application of a questionnaire to 404 subjects of both gender and aged between 18 and 89 years. AMP were therapeutically used by 53.7% mainly due “to be natural” (43.9%) while 33.8% use drugs and/ or herbal products mainly “because it is good for health” (53.5%). The AMP most used were Cidreira (n=149) and Camomila (n=117) and concerning drugs and/ or herbal products Valdispert® (n=48) and Daflon® 500 (n=41) were the most reported. Overall, the reported uses of AMP, drugs and herbal products were correct, according to the reported in literature. The use of AMP is motivated by self-knowledge (55.4%) while drugs and/ or herbal products are used mostly by medical prescription (44.1%). AMP were obtained by own cultivation (44.1%) and drug and/ or herbal products in pharmacies (89.0%). Of all users, about 90% not combined these products with conventional drugs and it was identified just one potential occurrence of drug interactions related with the use of Hipericão. The occurrence of adverse effects was noted after the use of AMP Sene (11.8%), Hipericão (9.1%) and Ginkgo Biloba (8.3%). The use of these products is a common practice among the residents of Bragança city, which use a wide diversity of AMP and plant-based products.