Various essential oils are rich in carvacrol, a monoterpenic phenol isomeric with thymol. This study was undertaken to assess the vasorelaxant effects of thymol and carvacrol in rat isolated aorta and the putative mechanisms underlying these effects. Thymol and carvacrol produced a concentration-dependent relaxation on the aortic ring preparations pre-contracted using KCl (IC(50) value of 64.40 +/- 4.41 and 78.80 +/- 11.91 microm, respectively) or using phenylephrine (PHE, 0.1 microm) (IC(50) value of 106.40 +/- 11.37 and 145.40 +/- 6.07 microm, respectively) and inhibited the concentration-response curves of aortic rings to PHE or KCl. In Ca(2+)-free medium with ethylene glycol-bis(2-aminoethylether)-N,N,N',N'-tetraacetic acid (2 mm), thymol and carvacrol both at 1000 microm completely abolished the phasic component of PHE-induced endothelium-containing ring contractions. At 400 microm, thymol and carvacrol significantly reduced the CaCl(2)-induced contractions in Ca(2+)-free medium. Furthermore, both thymol and carvacrol (300 and 1000 microm) significantly reduced the contraction evoked by phorbol dibutyrate (1 microm), an activator of protein kinase C. Magnitude of this inhibitory effect was enhanced in the presence of the Ca2+ pump inhibitor, thapsigargin (1 microm). At 1000 microm, neither thymol nor carvacrol altered the resting potential of vascular smooth muscle cells. In conclusion, thymol and carvacrol induced an endothelium-independent relaxation in rat isolated aorta, an effect that seems mediated through some mechanisms probably involving a transduction pathway between Ca(2+) release from sarcoplasmic reticulum and/or regulation of the Ca2+ sensitivity of the contractile system. Moreover, it's conceivable that thymol and carvacrol, at low concentrations, block the Ca(2+) influx through the membrane.

The fibrocytes are thought to serve as a source of newly deposited collagens I and III during reparative processes and in certain fibrotic disorders, but their matrix remodelling properties are incompletely understood. We evaluated their ability to produce several extracellular matrix (ECM) components, in comparison with fibroblasts, and to participate in collagen turnover. The collagen gene expression profile of fibrocytes differed from that of fibroblasts because fibrocytes constitutively expressed relatively high levels of the mRNA encoding collagen VI and significantly lower levels of the mRNA encoding collagens I, III and V. The proteoglycan (PG) gene expression profile was also different in fibrocytes and fibroblasts because fibrocytes constitutively expressed the mRNA encoding perlecan and versican at relatively high levels and the mRNA encoding biglycan and decorin at low and very low levels, respectively. Moreover, fibrocytes expressed the mRNA for hyaluronan synthase 2 at higher level than fibroblasts. Significant differences between the two cell populations were also demonstrated by metabolic labelling and analysis of the secreted collagenous proteins, PGs and hyaluronan. Fibrocytes constitutively expressed the scavenger receptors CD163 and CD204 as well as the mannose receptors CD206 and Endo180, and internalized and degraded collagen fragments through an Endo180-mediated mechanism. The results of this study demonstrate that human fibrocytes exhibit ECM remodelling properties previously unexplored, including the ability to participate in collagen turnover. The observed differences in collagen and PG expression profile between fibrocytes and fibroblasts suggest that fibrocytes may predominantly have a matrix-stabilizing function.

Recebido em 10/3/05; aceito em 4/11/05; publicado na web em 5/5/06 ANTIOXIDANT ACTIVITY OF ESSENTIAL OILS FROM NORTHEASTERN BRAZILIAN CROTON SPECIES. Three Croton species, C. zenhtneri, C. nepetaefolius and C. argyrophylloides, were collected at two different times, 6:00 and 13:00 h, their essential oils were extracted by steam distillation and analyzed by gas Chromatography / Mass Spectrometry. The percentage yield of oil constituents changes along the day. The oils were submitted to the antioxidant test thiobarbituric acid reactive species, using BHT and a-tocoferol as the reference compounds. All oils exhibited good antioxidant activities. In general, C. zenhtneri and C. argyrophylloides essential oils showed higher antioxidant activity than C. nepetaefolius.Keywords: essential oil; antioxidant; TBARS test. INTRODUÇÃOO ecossistema Caatinga cobre quase 1 milhão de km 2 no Nordeste do Brasil. A vegetação xerófila característica é afetada pela longa e irregular seca, altas temperaturas e elevada radiação ultravioleta. Principalmente devido às famílias de baixa renda, o uso de plantas medicinais e auto-medicação é grandemente estendido na região 1 . Nas plantas, a síntese de metabólitos secundários antioxidantes que absorvem em 300-400 nm é significantemente aumentada por radiação UV 2 fornecendo, portanto, um alto nível de proteção contra oxidantes prejudiciais gerados termicamente ou pela luz 3 . Além disso, embora plantas medicinais sejam raramente utilizadas como antioxidantes em medicina tradicional, suas características terapêuticas poderiam ser sustentadas devido, em parte, a sua capacidade varredora de radicais livres que podem estar envolvidos em muitas doenças 4 . Câncer, enfisema, cirrose, arterosclerose e artrites têm sido correlacionados com stress oxidativo. Os organismos em geral são protegidos contra os danos causados pelos radicais livres, por enzimas como superóxido desmutase e catalase, ou compostos como ácido ascórbico, tocoferol e glutationa. Quando os mecanismos da proteção antioxidante se tornam ineficientes por fatores como idade, a deterioração das funções fisiológicas pode ocorrer, resultando em doenças e aceleração do envelhecimento. Entretanto, suplementos alimentares antioxidantes podem ser usados para ajudar o corpo humano a reduzir os danos oxidativos 5 . Os óleos, as gorduras e os alimentos que os contêm estão sujeitos, durante o processamento e a estocagem, a reações químicas que podem alterar, de modo indesejável, as características do produto final. Hidrólises e oxidações podem ser responsáveis por esse processo, sobretudo a oxidação dos lipídeos. Antioxidantes são geralmente utilizados em óleos e comidas gordurosas para retardar sua autooxidação . Desta forma, a pesquisa por antioxidantes naturais tem aumentado bastante nos últimos anos 8,9 . Óleos essenciais são constituintes voláteis orgânicos responsá-veis pela fragrância de muitas plantas. Podem ser obtidos de flores, folhas, frutos, sementes, gramas, raízes, rizomas e caules das plantas 10 . A atividade antioxidante dos ól...

It has been widely observed that Pi decreases maximum calcium-activated force (Fmax) and calcium sensitivity of skinned skeletal and cardiac muscle. However, whether a particular ionic species of Pi (i.e., H2PO4-) is responsible for these effects is controversial. To clarify this issue, we examined the influence of Pi and its structural analogue arsenate (Asi) on contraction of skinned rabbit psoas (fast twitch), soleus (slow twitch), and cardiac papillary muscle. Asi decreased Fmax of all three muscles types to a greater extent than Pi. Both Pi and Asi decreased calcium sensitivity of psoas and cardiac muscles, with Asi having the greater effect. The effect of the protonated form of Pi and Asi on Fmax was evaluated by measuring the response to 30 mM total Pi or Asi at pH 7.4, 7.0, 6.6, and 6.2. In psoas fibers we found that both Pi and Asi were more effective in decreasing Fmax as the pH was lowered (i.e., as the concentration of the diprotonated forms increased). On the contrary, soleus and cardiac fibers did not exhibit this behavior. These differences in the effects of Pi and Asi on Fmax in psoas vs. cardiac and soleus muscles may be related to differences in their myosin heavy chains other than the binding site for the gamma-phosphate of ATP which appears to be conserved for all myosins.

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