RESUMO
The role of the transporter P-glycoprotein (P-gp) in the disposition kinetics of different drugs therapeutically used in veterinary medicine has been demonstrated. Considering the anatomo-physiological features of the ruminant species, the constitutive expression of P-gp (ABCB1) along the sheep gastrointestinal tract was studied. Additionally, the effect of repeated dexamethasone (DEX) administrations on the ABCB1 gene expression in the liver and small intestine was also assessed. The ABCB1 mRNA expression was determined by real-time quantitative PCR. P-gp activity was evaluated in diffusion chambers to determine the efflux of rhodamine 123 (Rho 123) in the ileum from experimental sheep. The constitutive ABCB1 expression was 65-fold higher in the liver than in the intestine (ileum). The highest ABCB1 mRNA expression along the small intestine was observed in the ileum (between 6- and 120-fold higher). The treatment with DEX did not elicit a significant effect on the P-gp gene expression levels in any of the investigated gastrointestinal tissues. Consistently, no significant differences were observed in the intestinal secretion of Rho 123, between untreated control (Peff S-M = 3.99 × 10(-6) ± 2.07 × 10(-6) ) and DEX-treated animals (Peff S-M = 6.00 × 10(-6) ± 2.5 × 10(-6) ). The understanding of the efflux transporters expression and activity along the digestive tract may help to elucidate clinical implications emerging from drug interactions in livestock.
Assuntos
Membro 1 da Subfamília B de Cassetes de Ligação de ATP/metabolismo , Regulação da Expressão Gênica/fisiologia , Intestino Delgado/metabolismo , Fígado/metabolismo , Ovinos/fisiologia , Membro 1 da Subfamília B de Cassetes de Ligação de ATP/genética , Animais , Masculino , RNA Mensageiro/genética , RNA Mensageiro/metabolismoRESUMO
The effects of repeated administrations of dexamethasone (DEX) (3 mg/kg/day by i.m. route for 7 days) on the gene expression profile of a cytochrome P450 (CYP) 3A28-like isoenzyme, on the expression of a CYP3A-immunoreactive protein and on CYP3A-dependent metabolic activities in sheep liver and small intestinal mucosa were evaluated in the current work. CYP 3A-dependent metabolic activities (erythromycin and triacetyl-oleandomycin N-demethylations) were assessed in microsomal fractions. The mRNA expression of CYP3A28-like, glucocorticoid receptor, constitutive androstane receptor, pregnane X receptor and retinoic X receptor alpha (RXRα) was determined by quantitative real-time PCR. The expression of a CYP3A-immunoreactive protein was measured by Western blot analyses. In the liver, DEX treatment increased CYP3A28-like mRNA levels (2.67-fold, P<0.01) and CYP3A apoprotein expression (1.34-fold, P<0.05) and stimulated CYP3A-dependent metabolism. High and significant correlation coefficients between CYP3A-dependent activities and CYP3A28-like gene (r=0.835-0.856, P<0.01) or protein (r=0.728-0.855, P<0.05) expression profiles were observed. Among the transcriptional factors, DEX only stimulated (2.1-fold, P<0.01) the mRNA expression of RXRα. In sheep small intestine, DEX caused a slight increment (34.6%, P<0.05) in erythromycin N-demethylase activity in the jejunal mucosa and a significant enhancement (P<0.05) of CYP3A apoprotein level in the duodenal mucosa.
Assuntos
Citocromo P-450 CYP3A/metabolismo , Dexametasona/farmacologia , Mucosa Intestinal/metabolismo , Fígado/enzimologia , Ovinos/metabolismo , Animais , Biomarcadores , Western Blotting , Citocromo P-450 CYP3A/genética , Eletroforese em Gel de Poliacrilamida/veterinária , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Masculino , RNA/genética , RNA/metabolismo , Reação em Cadeia da Polimerase em Tempo RealRESUMO
The diterpenoid kaurenoic acid is the main component of the resin from the medicinal plant Pseudognaphalium vira vira. As some diterpenoids have antimicrobial properties, the effect of this resin and the kaurenoic acid on soil bacteria was studied. The resin of P. vira vira and purified kaurenoic acid were two to four times more effective as antibacterial agents with Gram-positive than with Gram-negative soil isolates. The chemical stability of kaurenoic acid and the antibacterial activity of both the resin and the diterpenoid were studied in microcosms containing plant-associated soil. After 15 days of incubation, the diterpenoid was stable, as determined by 1H nuclear magnetic resonance and thin-layer chromatography, and soil extracts still exhibited antibacterial activity. However, after 30 days of incubation, loss of antibacterial activity of soil extracts correlated with removal or chemical modification of kaurenoic acid. The effect of the resin or this diterpenoid on the soil bacteria community was analyzed by the terminal restriction fragment length polymorphisms technique. After 15 days of incubation, the resin and the pure compound caused significant changes in the soil bacterial community. The relative abundance of specific bacterial groups was differentially affected by the resin components, being the effects with the resin stronger than with the kaurenoic acid. After 30 days of incubation, these changes mostly reverted. These results indicate that a plant resin containing diterpenoid compounds plays a significant role controlling specific groups of microorganisms in the soil associated with the plant.
Assuntos
Asteraceae/química , Diterpenos/farmacologia , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Positivas/efeitos dos fármacos , Resinas Vegetais/farmacologia , Microbiologia do Solo , Antibacterianos/análise , Antibacterianos/farmacologia , Diterpenos/análise , Bactérias Gram-Negativas/isolamento & purificação , Bactérias Gram-Positivas/isolamento & purificação , Polimorfismo de Fragmento de Restrição , RNA Ribossômico 16S/genética , Solo/análiseRESUMO
The antibacterial activity of Haplopappus uncinatus is attributed to a new clerodane diterpenoid, 18-acetoxy-cis-cleroda-3-en-15-oic acid (10 betaH, 16 xi 19 beta, 17beta, 20 alpha form) (1), isolated as a major component from the resinous exudates of its twigs and leaves, together with the inactive 3,5-dihydroxy-6,7,3',4'-tetramethoxyflavone, n-alkanes and a few sesquiterpenoids.
Assuntos
Anti-Infecciosos/química , Diterpenos/química , Haplopappus , Extratos Vegetais/química , Anti-Infecciosos/isolamento & purificação , Diterpenos/isolamento & purificação , Testes de Sensibilidade Microbiana , Extratos Vegetais/isolamento & purificação , Relação Estrutura-AtividadeRESUMO
The antimicrobial properties of the resinous exudates from twigs and leaves of four Chilean species of Pseudognaphalium: P. viravira, P. robustum, P. heterotrichium and P. cheiranthifolium were tested against six gram negative bacteria and five gram positive bacteria. The extracts share similar antimicrobial activities against the gram positive bacteria. The antimicrobial activity correlated very well with the presence in the resinous exudates of ent-16-kauren-19-oic acid and to a lesser extent with the presence of ent-9(11),16-kauradien-19-oic. Introduction of an hydrophilic 3 beta-OH drastically reduced the antimicrobial activity of these compound. The activity was not correlated with the flavonoid content of those resinous exudates.