Antimicrobial activity of Centaurea diffusa.

The methanol soluble fraction of the aqueous extract obtained from the dry heads of Centaurea diffusa demonstrated antimicrobial activity in twelve evaluated microorganisms.

Actividad antimicrobiana de centaurea solstitialis y centaurea calcitrapa / Antimicrobial activity of centaurea solstitialis and centaurea calcitrapa

Centaurea solstitialis y Centaurea calcitrapa (Asteraceae), son plantas conocidas vulgarmente como Abrepuño amarillo y Abrepuño colorado respectivamente. Son malezas que se desarrollan en la región pampeana, siendo la primera de ellas la más abundante. Investigaciones realizadas en otros países han demostrado que el género Centaurea posee propiedades antimicrobianas. El objetivo de este trabajo fue comprobar si esta actividad biológica se encuentra presente en las malezas que crecen en la provincia de La Pampa (Argentina). Se evaluó la Concentración Inhibitoria Mínima y la Concentración Bactericida Mínima mediante el método de dilución en caldo de extractos metanólicos de capítulos secos de ambas especies. Los resultados obtenidos demuestran que Centaurea calcitrapa, bajo nuestras condiciones de trabajo, presenta actividad antimicrobiana en cuatro de las diez cepas ensayadas (Pseudomonas aeruginosa, Staphylococcus aureus, Streptococcus agalactiae y Salmonella typhimurium), mientras que Centaurea solstitialis muestra menor actividad antibacteriana inhibiendo sólo a dos cepas (Streptococcus agalactiae y Staphylococcus aureus) (AU)

Centaurea solstitialis and Centaurea calcitrapa (Asteraceae), commonly known as Abrepuño amarillo and Abrepuño colorado respectively, are weeds that grow in the Province of Pampea Argentina, the former of which being the most abundantly encountered species. Research carried out in other countries has demonstrated that the genus Centaurea possesses antimicrobial properties. The objective of this work was to ascertain the extent to which such a biological activity may be present in these species, found growing in this particular Argentinian Province. Minimum Inhibitory Concentration and Minimum Bactericide Concentration was evaluated by means of the dilution method, in broth of methanolic extracts of dry heads of both species. The results obtained, under the working conditions of this study, demonstrated that Centaurea calcitrapa, presents antimicrobial activity against four of the ten assayed strains: Pseudomonas aeruginosa, Staphylococcus aureus, Streptococcus agalactiae and Salmonella typhimurium, while Centaurea solstitialis shows antibacterial activity to a lesser extent, with inhibitory activity only being found against two strains: Streptococcus agalactiae and Staphylococcus aureus (AU)

Osteolytic activity and reversal of nephrectomy-induced hypocalcemia by a fraction other than 1,25(OH)2-vitamin D3 from Solanum malacoxylon incubated with ruminal fluid.

Previous studies have shown that two lipid soluble fractions (2 and 3) isolated from Solanum malacoxylon leaf extracts incubated with ruminal fluid by Sephadex LH-20 chromatography increase intestinal P absorption and blood Ca. Fraction 2 contains 1,25(OH)2-vitamin D3, vitamin D3, 25(OH)-vitamin D3 and 1,24,25(OH)3-vitamin D3. The osteolytic activity and ability to revert nephrectomy-induced hypocalcemia of fractions 2 and 3 was compared. The tibias from 19-day-old chick embryos injected with both fractions on day 15 were shorter, lighter and had a lower ash content than those from controls. Fractions 2 and 3 also decreased dry weight and ash content in frontal bones, although only the effects of fraction 3 were statistically significant. In agreement with these observations, fraction 3 was more effective than fraction 2 to increase blood Ca levels in nephrectomized rats. Extracts from rumen samples were devoid of activity. The results support the presence of a polar derivative of 1,25(OH)2D3 in ruminal fluid-treated Solanum malacoxylon.

Isolation and identification of vitamin D3, 25-hydroxyvitamin D3, 1,25-dihydroxyvitamin D3 and 1,24,25-trihydroxyvitamin D3 in Solanum malacoxylon incubated with ruminal fluid.

It has been shown that Solanum malacoxylon contains 1 alpha,25-dihydroxyvitamin D3-glycoside. The presence of vitamin D3 and 25-hydroxyvitamin D3 has also been suggested. In the present study vitamin D3 and three of its metabolites, including 1 alpha,25-dihydroxyvitamin D3, were detected in plant leaf extracts preincubated with ruminal fluid (SMRF). Extraction of SMRF with non-polar organic solvents and purification of the lipid extract by TLC followed by HPLC yielded nine ultraviolet-absorbing (264 nm) peaks. Four of them comigrated on a Zorbax-Sil HPLC column with synthetic standards of vitamin D3, 25-hydroxyvitamin D3, 1 alpha,25-dihydroxyvitamin D3 and 1,24R,25-trihydroxyvitamin D3, respectively. These compounds were unequivocally identified by means of mass spectrometry. The results confirm that Solanum malacoxylon contains, in addition to 1 alpha,25-dihydroxyvitamin D3, vitamin D3, 25-hydroxyvitamin D3 and possibly other as yet unidentified derivatives. As 1,24,25-trihydroxyvitamin D3 is absent in plant extracts not incubated with ruminal fluid, the data also indicate that rumen microbes may convert 1 alpha,25-dihydroxyvitamin D3 into 1,24,25-trihydroxyvitamin D3.

Effect of 1,25-dihydroxycholecalciferol and 1,25-dihydroxycholecalciferol glycoside on 2,3-diphosphoglycerate levels of the rat erythrocyte.

The erythrocytes of rats treated with 1, 25-dihydroxycholecalciferol or 1, 25-dihydroxycholecalciferol glycoside showed decreased levels of 2, 3-diphosphoglycerate. The same result has been obtained in vitro, indicating a direct effect of the sterol on the red cell. The glycoside is less active than the free sterol in vivo and more active in vitro. The decreased levels of diphosphoglycerate induced tissue hypoxia as shown by a higher plasma lactate/pyruvate ratio and a three fold increase in plasma erythropoietin concentration.

Modification by rumen of vitamin D-like activity of Solanum malacoxylon in rats.

The biological activity of aqueous extracts of Solanum malacoxylon (SM) and of extracts preincubated with ruminal fluid (SMRF) on calcium and phosphate metabolism in vitamin D depleted rats was compared. The responses in intestinal 32P and 45Ca absorption, measured in an isolated duodenal loop in situ after a single oral dose, were qualitatively similar to that of 1,25-OH2-vit.D3. However, the effects elicited by SMRF were significantly higher than those caused by SM. Both extracts were equally effective in promoting bone resorption when administered orally or subcutaneously. These results provide a basis to explain the greater effectiveness of SMRF to produce calcinosis in rats. The hypothesis is advanced that biologically active steroidal metabolites with predominant action on intestine, are formed during incubation with rumen.

Modification by rumen of vitamin D-like activity of Solanum malacoxylon in rats

The biological activity of aqueous extracts of Solanum malacoxylon (SM) and of extracts preincubated with ruminal fluid (SMRF) on calcium and phosphate metabolism in vitamin D depleted rats was compared. The responses in intestinal 32P and 45Ca absorption, measured in an isolated duodenal loop in situ after a single oral dose, were qualitatively similar to that of 1,25-OH2-vit.D3. However, the effects elicited by SMRF were significantly higher than those caused by SM. Both extracts were equally effective in promoting bone resorption when administered orally or subcutaneously. These results provide a basis to explain the greater effectiveness of SMRF to produce calcinosis in rats. The hypothesis is advanced that biologically active steroidal metabolites with predominant action on intestine, are formed during incubation with rumen.

Modification by rumen of vitamin D-like activity of Solanum malacoxylon in rats.

The biological activity of aqueous extracts of Solanum malacoxylon (SM) and of extracts preincubated with ruminal fluid (SMRF) on calcium and phosphate metabolism in vitamin D depleted rats was compared. The responses in intestinal 32P and 45Ca absorption, measured in an isolated duodenal loop in situ after a single oral dose, were qualitatively similar to that of 1,25-OH2-vit.D3. However, the effects elicited by SMRF were significantly higher than those caused by SM. Both extracts were equally effective in promoting bone resorption when administered orally or subcutaneously. These results provide a basis to explain the greater effectiveness of SMRF to produce calcinosis in rats. The hypothesis is advanced that biologically active steroidal metabolites with predominant action on intestine, are formed during incubation with rumen.