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The aims of this study were to screen an array of plant families for novel lectins, to isolate candidate lectins whose reactivity suggested may be functionally useful and to assess the reactivity and modulatory effects of the novel lectins on the cells of the gastrointestinal tract (including the immune regions) and lymphocytes. Few of the seed and bulb samples screened had significant levels of lectin. However, the seeds, roots, stem and bark of <I>Morus nigra</I>, the black mulberry tree from the Moraceae plant family, were found to contain particularly high lectin activity. Two new lectins <I>Morus nigra</I> agglutinin-I (MNAI) and <I>Morus nigra</I> agglutinin-II (MNAII) were isolated. They were found to differ significantly from each other in their sugar specificity, subunit structure, amino acid sequence identity, glycosylation and haemagglutinating activity. MNAI has similarities in sugar inhibition characteristics (GalNAc) and amino acid identity to both MPA and jacalin, which also belong to the Moraceae family. MNAI recognises the similar intestinal glycan structures as jacalin and recognises T/Tn blood group antigen, both with and without sialylation. However, it differs significantly from MPA and jacalin in its lymphocyte stimulatory properties. MNAII appears to be novel and did not show amino acid sequence identity with any known proteins contained in the deltamass database. It is inhibitable by α-D-methyl mannoside. It may have an affinity for structures such as some form of N-linked glycans and appears to have low affinity for α2,6 sialylated structures. It labelled glycan structures present on the villus brush border, dome FAE and most M cells of many of the species tested <I>in vitro</I>.

nÃo hà / Previamente demonstrou-se que o Ãleo essencial de Ocimum micranthum (OEOM) e seu constituinte majoritÃrio, cinamato de metila (CM), tÃm aÃÃes miorrelaxante e antinflamatÃria em tecidos traqueais de ratos, e efeito antinociceptivo em camundongos. O objetivo deste estudo foi avaliar o potencial antiespasmÃdico e anti-inflamatÃrio do CM no trato gastrintestinal de ratos submetidos a modelo de colite induzida por Ãcido acÃtico. OEOM inibiu contraÃÃes induzidas por carbamilcolina (CCh; 1 &#61549;M) e KCl (60 mM) em tiras de fundo de estÃmago com CI50 de 91,9 &#61549;g/mL e 46,8 &#61549;g/mL, respectivamente, e reduziu significativamente o tÃnus basal e amplitudes de contraÃÃes espontÃneas de duodeno. CM, em conformaÃÃes isomÃricas (Z)- ou (E)-, tambÃm inibiu essas respostas induzidas por CCh e KCl em fundo, antro, duodeno e cÃlon, sem diferenÃas nos efeitos dos isÃmeros em cada segmento. CM comeÃa a inibir as contraÃÃes induzidas por CCh em concentraÃÃo mais baixa que KCl, contudo com potÃncia menor se comparado aos efeitos da atropina. (E)-CM inibe contraÃÃes dependentes dos estoques intracelulares de cÃlcio, e seu efeito inibitÃrio parece nÃo depender da aÃÃo da Ãxido nÃtrico sintase ou da abertura de canais de potÃssio. Analisadas em microscÃpio confocal, cÃlulas de cÃlon dissociadas a fresco tiveram nÃvel citossÃlico de cÃlcio reduzido para 60% do basal apÃs exposiÃÃo a (E)-CM (600&#61549;M). Avaliando a pressÃo intragÃstrica in vivo, uma dose de (E)-CM 50 mg/kg nÃo afeta amplitude das contraÃÃes gÃstricas, mas se repetida apÃs 30 minutos, as diminui por atà 10 minutos. A induÃÃo de colite foi atravÃs de instilaÃÃo de Ãcido acÃtico a 5% via retal. O grupo sham recebeu instilaÃÃo apenas de salina, e os grupos tratados, alÃm da instilaÃÃo de Ãcido receberam (E)-CM 50 mg/kg/dia ou prednisolona 1 mg/kg/dia durante trÃs dias. A instilaÃÃo com Ãcido acÃtico induziu colite confirmada por alteraÃÃo macroscÃpica, leucocitose, aumento de interleucina-1&#61538; tecidual e dÃficit funcional de resposta dependente de canais para cÃlcio operados por voltagem. Esses parÃmetros foram revertidos pelos tratamentos com (E)-CM e prednisolona. Portanto, OEOM e CM apresentam aÃÃo antiespasmÃdica em trato gastrintestinal de ratos in vitro. O efeito do CM passa pela reduÃÃo dos nÃveis intracelulares basais de cÃlcio e independe da participaÃÃo da enzima Ãxido nÃtrico sintase e de canais de potÃssio. CM possui aÃÃo anti-inflamatÃria de magnitude comparÃvel à prednisolona. / It was previously shown that the essential oil of Ocimum micranthum (EOOM), and its major constituent, methyl cinnamate (MC), have myorelaxant action on tracheal smooth muscle, airway anti-inflammatory and anti-nociceptive on rodents. The present work aimed to evaluate the antispasmodic and anti-inflammatory potential of MC on gastrointestinal tissues from rats subjected to acetic acid-induced colitis model. EOOM inhibited carbamylcholine- (CCh; 1 &#61549;M) and KCl-induced (60 mM) contractions in stomach fundus strips with IC50 of 91.9 &#61549;g/mL and 46.8 &#61549;g/mL, respectively. It significantly reduced the basal tonus as well as the spontaneous contractions in duodenum. The isomers (Z)- or (E)-MC also inhibited CCh and KCl contractions in fundus, antrum, duodenum and colon strips, without differences between the effects caused by the isomers in each segment. MC significantly inhibited CCh in lower concentration in comparison with KCl, but with decreased potency if compared to atropine. (E)-MC inhibited intracellular calcium stores-dependent contractions, and its effect seems not to involve the activity of the nitric oxide synthase or the opening of potassium channels. Analyzed by confocal microscopy, freshly dissociated colon cells showed reduced basal cytosolic calcium levels (60%) after (E)-MC (600 &#61549;M) exposure. In vivo, a first dose of (E)-MC (50 mg/kg) did not affect gastric contractions, but following a second dosage (50 mg/kg) administered a half an hour later, it reduced gastric contractions for 10 minutes. Colitis was induced by rectal instillation of acetic acid 5%. Sham group received only saline in instillation, while treated groups, beyond acid instillation, received (E)-CM 50 mg/kg/day p.o. or prednisolone 1 mg/kg/day p.o. during three days. Acetic acid instillation induced colitis that was macroscopically confirmed, leukocytosis, increased interleucin-1&#946; and functional response loss due to voltage operated calcium channel disorder. These parameters were recovered by (E)-MC or prednisolone. Therefore, EOOM and CM have in vitro antispasmodic effect on rat gastrointestinal tract. The effect of CM involves reduction of the intracellular levels of calcium being independent of the nitric oxide synthase and potassium channels. CM has anti-inflammatory action comparable to prednisolone in magnitude.

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