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- Antihyperglycaemic and protective effects of flavonoids on streptozotocin-induced diabetic ratsPublication . Rauter, A. P.; Martins, A.; Borges, C.; Mota-Filipe, H.; Pinto, R.; Justino, JorgeThe antihyperglycaemic effect of eight standard flavonoids, previously identified in the ethanol extract of the claimed antidiabetic plant Genista tenera, was evaluated on streptozotocin (STZ)-induced diabetic Wistar rats. The aglycones apigenin, chrysoeriol and genistein, the monoglucosides apigenin 7-O-glucoside, luteolin 7-O-glucoside and genistein 7-O-glucoside and the diglycosides rutin and luteolin 7,3′-di-O-glucoside were administered i.p. for 7 days (4 mg/kg b.w./day). The protective effect of these compounds over liver and kidneys of STZ–diabetic models was also evaluated by the determination of seric AST, ALT and urea levels. After 7 days of treatment, apigenin, chrysoeriol and genistein significantly lowered the blood glucose levels of diabetic animals; this effect was more pronounced (P < 0.01) in the oral glucose tolerance test. Glucose tolerance was also significantly improved in the rutin (P < 0.01) and in the genistein 7–O–glucoside (P < 0.05) treated groups. In addition, almost all the tested compounds effectively protected the liver and kidneys against STZ-induced damage in rats
- Bioactivity studies and chemical profile of the antidiabetic plant Genista teneraPublication . Rauter, A. P.; Martins, F.; Lopes, R.; Ferreira, J.; Serralheiro, L. M; Araújo, M. E.; Borges, C; Justino, Jorge; V.M. Silva, Filipa; Goulart, Margarida; Thomas-Oates, J.; Rodriges, J. A. P; Edwards, E; Noronha, J. P.; Pinto, R.; Mota-Filipe, H.Aim of the study: Genista tenera is a plant endemic to the island of Madeira and is used in folk medicine to control diabetes. In the present work we evaluate the antihyperglycaemic activity of its n-butanol extract and determine its chromatographic profile. In addition, this extract, the ethyl acetate and diethyl ether plant extracts were studied in order to assess the plant antioxidant and acetylcholinesterase inhibitory activities, as well as its cyto- and genotoxicities. Materials and methods: HPLC-DAD-ESI-MS was used to analyze the flavonoid profile of the n-butanol extract. The antihyperglycaemic activity of this extract was performed over streptozotocin induced diabetic Wistar rats (200mg/kg, bw/day), for 15 days. Antioxidant activity (DPPH assay) and acetylcholinesterase inhibitory effect (Ellman method) were also performed. Acute cytotoxicity and genotoxicity were assessed by proliferative index quantification and the short-term chromosomal aberration technique, after exposure of lymphocytes to the extracts. Results and conclusions: The n-butanol extract, where 21 monoglycosyl and 12 diglycosyl flavonoids were detected, significantly lowered blood glucose levels, bringing them to normal values after 15 days of treatment. The best radical scavenging activity was observed for the ethyl acetate extract (48.7% at 139.1μg/mL), which was also the most effective one at the minimal concentration tested. The highest acetylcholinesterase inhibitory activity (77.0% at 70. 0μg/mL) was also obtained with the ethyl acetate extract. In vitro toxicity studies showed no evidence for acute cytotoxicity or genotoxicity. This is the first report on antidiabetic activity of genus Genista.
- Phytochemical profile and anticholinesterase and antimicobial activities of supercritical versus conventional extracts of Satureja montanaPublication . Silva, Filipa; Martins, A.; Salta, J.; Neng, N. R.; Nogueira, J.; Mira, Delfina; Gaspar, Natália; Justino, Jorge; Grosso, C.; Urieta, J. S.; Palavra, A. M. S.; Rauter, A. P.Winter savory Satureja montana is a medicinal herb used in traditional gastronomy for seasoning meats and salads. This study reports a comparison between conventional (hydrodistillation, HID, and Soxhlet extraction, SE) and alternative (supercritical fluid extraction, SFE) extraction methods to assess the best option to obtain bioactive compounds. Two different types of extracts were tested, the volatile (SFE-90 bar, second separator vs HID) and the nonvolatile fractions (SFE-250 bar, first and second separator vs SE). The inhibitory activity over acetyl- and butyrylcholinesterase by S. montana extracts was assessed as a potential indicator for the control of Alzheimer's disease. The supercritical nonvolatile fractions, which showed the highest content of (+)-catechin, chlorogenic, vanillic, and protocatechuic acids, also inhibited selectively and significantly butyrylcholinesterase, whereas the nonvolatile conventional extract did not affect this enzyme. Microbial susceptibility tests revealed the great potential of S. montana volatile supercritical fluid extract for the growth control and inactivation of Bacillus subtilis and Bacillus cereus, showing some activity against Botrytis spp. and Pyricularia oryzae. Although some studies were carried out on S. montana, the phytochemical analysis together with the biological properties, namely, the anticholinesterase and antimicrobial activities of the plant nonvolatile and volatile supercritical fluid extracts, are described herein for the first time.
- Synthesis of new pseudo‐C‐nucleosides containing pyrazole rings in their structurePublication . Rauter, A. P.; Figueiredo, J.A.; Ismael, M.I.; Justino, JorgeSynthetic approaches to new 4-(furanos-4-C-yl)-1H-pyrazole and 3-(furanos-4-C-yl)-1H-pyrazole derivatives are described, including its pyrazole-5-carboxylate derivative, which is a pyrazofurin analogue. Preparation of related 5-acetoxy-1-acetyl-1H-pyrazole, 5-acetoxy-1H-pyrazole-1-carboxylate, and 4,5-dihydro-1-phenyl-1H-pyrazol-5-one derivatives is also reported. The formation of the pyrazole rings was accomplished either by reaction of enones and of 1,3-diketones with N-nucleophiles or by ring closure of a diazoketone.
- Synthesis and biological evaluation of sugars containing α,β-Unsaturated γ-LactonesPublication . Xavier, N. M.; Silva, S.; Madeira, P. J. A; Florêncio, M. H.; Silva, Filipa; Justino, Jorge; Thiem, J.; Rauter, A. P.The stereocontrolled synthesis of new sugar derivatives carrying the α,β-unsaturated δ-lactone (butenolide) moiety is described. Sugar-fused or sugar-linked butenolides can be constructed by an efficient reaction sequence involving Wittig olefination of 3- or 5-keto sugars and intramolecular cyclization of the intermediate γ-hydroxy α,β-unsaturated esters. The antimicrobial activities of the products and that of a known sugar-derived pyranoid α,β-unsaturated δ-lactone were investigated against six pathogenic bacteria and six fungi. The pyranoid α,β-unsaturated δ-lactone 29 proved to be the most active compound in this series towards the plant pathogenic fungi Colletotrichum coffeanum (coffee berry disease) and Pyricularia oryzae (rice blast disease).
- Phenolic composition and antioxidant activity of Rocha pear and other pear cultivars: a comparative studyPublication . Salta, J.; Martins, A.; Santos, R. G.; Neng, N. R.; Nogueira, J. M.; Justino, Jorge; Rauter, A. P.The phenolic profile and the antioxidant activity of Rocha pear, a Portuguese pear cultivar, were determined and compared with the commercially available pear varieties Cornice, Abate, General Leclerc and Passe Crassane. Phenolic composition of the methanolic extracts of these pears was determined by high performance liquid chromatography with diode array detection (HPLC-DAD), while antioxidant activities were evaluated using three complementary test systems: DPPH radical scavenging activity, ferric reducing power capacity and beta-carotene/linoleic acid bleaching assay. When compared to the studied varieties, Rocha pear (peel and flesh) presented the highest content of total phenolics. Among them, chlorogenic, syringic, ferulic and coumaric acids, arbutin and (-)-epicatechin were detected as major components. In addition, among the tested varieties, Rocha pear presented the best antioxidant activities in the DPPH and ferric reducing power assays.
- A new dihydroxysterol from the marine phytoplankton Diacronema sp.Publication . Rauter, A. P.; Filipe, M.M.; Prata, C.; Noronha, J.P.; Sampayo, M.A.M.; Justino, Jorge; Bermejo, J.Diacronema sp. was cultured and its sterols were separated by column chromatography on silica gel. The new sterol 24-ethyl-4α-methyl-cholestane-3,20-diol (1) was characterised by NMR and MS spectrometry, as well as (22E)-24-ethyl-4α-methyl-5α-cholest-22-en-3β-ol (2) and β-sitosterol, the major components of the sterol fractions. Neither the biosynthetic origin of the new dihydroxysterol nor its role in the biochemistry of Diacronema is known.
- Estudo da quebra de dormência em sementes de piorno [Genista tenera (Jacq. Ex murr.) O. Kuntze]Publication . D' Avó, Margarida; Grego, José; Lopes, Maria; Rauter, Amélia; Justino, Jorge; Goulart, MargaridaO piorno [Genista tenera (Jacq. ex Murr.) O. Kuntze] é uma planta endémica da ilha da Madeira usada na medicina popular dado o seu efeito antidiabético. O presente estudo pretende avaliar o efeito da digestão ácida das sementes de piorno com ácido sulfúrico na redução da espessura do tegumento, rijo, da semente, para ultrapassar a dormência das sementes e assim maximizar a taxa de germinação. Um grupo de acessos do Instituto Superior de Agronomia foi digerido com ácido durante 0, 10, 20 e 40 minutos. Após a digestão usou-se carbonato de sódio a 5 % como agente neutralizante e em seguida as sementes foram lavadas em água corrente para eliminar resíduos do ácido. Para avaliar os melhores tempos de digestão as sementes foram colocadas a germinar em placas de petri, envolvidas em dupla camada de papel de filtro e a uma temperatura constante de 22 ºC. A digestão ácida das sementes teve um efeito estatisticamente significativo sobre a percentagem de germinação das sementes. No entanto, a percentagem de germinação obtida com a digestão ácida (abaixo dos 30 %) é pouco interessante do ponto de vista produtivo, daí a necessidade de se estudarem outros tratamentos. Genista tenera is a plant endemic to the island of Madeira and is used in folk medicine to control diabetes. In the present work we evaluate the effects of concentrated sulphuric acid as an efficient technique for reducing the thickness of hard seed coats and to overcome dormancy and so to bring the highest proportion of viable seeds to the point of germination. A group formed by accessions from “Instituto Superior de Agronomia” were placed in the concentrated acid for 0, 10, 20 and 40 minutes of treatment. After treatments, a 5% solution of sodium carbonate in water was used as a neutralizing agent and seeds were washed in running water to remove all traces of the acid. To assess the optimum time for acid scarification the seeds were put in Petri dishes and a sandwich paper filter, and the percentage of germinated seeds per treatment at constant 22ºC was determined. Acid digestation significantly improved the germination but at rates lower than 30%. More work should be conducted to determine the optimum conditions to overcome the seed dormancy.
- Synthesis of phenylseleno sugars from epoxides and of α,β-unsaturated carbonyl derivatives for the study of their insecticidal activityPublication . Rauter, A.P.; Canda, T.; Justino, Jorge; Ismael, M.I.; Figueiredo, J.A.This work reports the synthesis of sugar epoxides and their derivatives obtained by reaction with the dianion of phenyl selenoacetic acid. Approaches to the introduction of α,β-unsaturated carbonyl units in pyranoid systems were investigated. Preparation of a protected D-glycero-hex-3-enepyranosid-2-ulose and of a D-erythro-hex-2-enono-1,5-lactone is described. Some of the synthesized compounds possess insecticidal activity against fruit flies, house flies, and white flies.
- A novel pentacyclic triterpene from Leontodon filiiPublication . Tostão, Z.; Noronha, J.P.; Cabrita, E.J.; Medeiros, J.; Justino, Jorge; Bermejo, J.; Rauter, A. P.A novel oleanene triterpenetetrol was isolated from the chloroform extract of the aerial parts of Leontodon filii. Its structure was shown to be 2β,3β,15α,21β-olean-12-ene-2,3,15,21-tetrol by chemical and spectroscopic methods. The fungicidal efficacy of the chloroform and methanol extracts of the plant was also evaluated, a protective effect being found against Plasmopara viticola, Botrytis cinerea, particularly powerful against Pyricularia oryzae.