Antioxidant activity of Spathodea campanulata (Bignoneaceae) extracts / Atividade antioxidante de extratos de Spathodea campanulata (Bignoneaceae)

Spathodea campanulata is used in traditional medicine in Africa as diuretic and anti-inflammatory. Although few studies have reported the mechanism of antioxidant action, this study evidenced the antioxidant activity of S. campanulata bark and flower extracts and their possible mechanism of action. Ethanol extracts of S. campanulata bark and flowers showed antioxidant activity on lipid peroxidation of liver microsome induced by Fe3+-ascorbic acid. Bark extract was 5 times more efficient than flower extract. The antioxidant activity of flower extract, previously complexed with increasing concentrations of Fe3+ (20 - 100 µM) which resulted in antioxidant activity loss, was shown to be related to iron complex formation. In contrast, the antioxidant activity of bark extract was not inhibited by the previous incubation with Fe3+, although complexation was demonstrated by spectral analysis of the solution. These results suggest an antioxidant mechanism other than Fe3+ complex formation. Therefore, the antioxidant mechanisms of S. campanulata flower and bark extracts are distinct from each other, reflecting the extract heterogeneous composition and the mechanism of action.

Spathodea campanulata é usada na medicina popular na África como diurético e antiinflamatório. Embora poucos estudos relatem o mecanismo de ação antioxidante, neste trabalho foi evidenciado a atividade antioxidante dos extratos da casca e da flor da S. campanulata e o possível mecanismo de ação. Os extratos etanólicos da casca e da flor da S. campanulata mostrou possuir atividade antioxidante sobre a lipoperoxidação de microssoma hepático induzida por Fe3+-ácido ascórbico. O extrato da casca foi 5 vezes mais eficiente que da flor. O extrato da flor foi previamente complexado com concentrações crescentes de Fe3+ (20 - 100 µM) o qual resultou na perda da atividade antioxidante, demonstrando que esta está relacionada com a formação de complexo com o ferro. Por outro lado, a atividade antioxidante do extrato da casca não foi inibida pela prévia incubação com o ferro, embora haja a formação do complexo evidenciado pela análise espectral da solução. Estes resultados sugerem que o mecanismo antioxidante seja outro que não a complexação com o Fe3+. Portanto, o mecanismo antioxidante dos extratos da flor e da casca da S. campanulata é distinto entre si o que reflete a composição heterogênica do extrato e o mecanismo de ação.

Dual function of the selenoprotein PHGPx during sperm maturation.

The selenoprotein phospholipid hydroperoxide glutathione peroxidase (PHGPx) changes its physical characteristics and biological functions during sperm maturation. PHGPx exists as a soluble peroxidase in spermatids but persists in mature spermatozoa as an enzymatically inactive, oxidatively cross-linked, insoluble protein. In the midpiece of mature spermatozoa, PHGPx protein represents at least 50 percent of the capsule material that embeds the helix of mitochondria. The role of PHGPx as a structural protein may explain the mechanical instability of the mitochondrial midpiece that is observed in selenium deficiency.

Chromosome painting as a supplement to cytogenetic banding analysis in non-Hodgkin's lymphoma.

Chromosomal in situ suppression (CISS) hybridization with biotin labeled chromosome-specific libraries was performed on short-term cultures from five cases of non-Hodgkin's lymphoma (NHL). The painting analysis proceeded in three stages. First-stage CISS hybridization was done with libraries specific for chromosomes that seemed to be lost or rearranged as judged by banding analysis. Second-stage CISS included hybridization with probes specific for chromosomes that, because of banding pattern similarities, were considered to be likely candidates to have contributed unidentified chromatin blocks in the abnormal karyotype. The third and final stage was a confirmation hybridization with a library specific for the chromosome that, at the stage two analysis, was found to have donated the previously unknown chromosomal segment. The aberrant chromosomes were often more complex than the banding analysis had led us to believe. Among the rearrangements whose nature was determined by CISS hybridization were two add(1)(p36) which, in both cases, were shown to be a der(1)t(1;2)(p36;q31). This study illustrates the potential use of chromosome painting in resolving karyotypic uncertainties in NHL, and it shows that new cytogenetic subgroups may emerge when classical banding analysis is supplemented with fluorescence in situ hybridization techniques.

Chromosome abnormalities in eighty-three head and neck squamous cell carcinomas: influence of culture conditions on karyotypic pattern.

Short-term cultures from 115 squamous cell carcinomas (SCC) of the head and neck were cytogenetically investigated. Thirty-six of the tumors have been reported previously, whereas 79 are new cases. The material was divided into two series based on the medium used. The 80 tumors of series I were cultured in RPMI 1640 supplemented with fetal calf serum, glutamine, antibiotics, insulin, cholera toxin, and epidermal growth factor. The 35 tumors of series II were cultured in a chemically defined, serum-free medium with a low calcium concentration, MCDB 153, which stimulates epithelial growth while inhibiting fibroblasts. A total of 83 tumors with clonal karyotypic abnormalities were detected in the two series. Series II had a higher proportion of tumors with complex karyotypic changes than series I (43% versus 15%), a lower proportion of tumors with pseudo- or neardiploid clones characterized by simple rearrangements (3% versus 34%), and a lower frequency of unrelated clones (3% versus 24%), indicating that the different culture conditions favored growth of different cell populations. Except for rearrangements of 1p22, which were mainly found in series I, the distribution of breakpoints in structural aberrations was similar in the two series and clustered to several chromosomal bands or regions, in particular 11q13, 1p22, 1p11-12, 3p11-q11, 5q13, 1q25, 15q10, and 8q10. Unbalanced structural aberrations were more common in series II, frequently leading to loss of segments from chromosome arms 3p, 7q, 8p, 11q, 13p, 14p, and 15p, whereas gain of genetic material often involved chromosome arms 1q, 3q, 8q, and 15q.