Anti-Biofilm Effect of Biodegradable Coatings Based on Hemibastadin Derivative in Marine Environment.

Dibromohemibastadin-1 (DBHB) is an already known potent inhibitor of blue mussel phenoloxidase (which is a key enzyme involved in bioadhesion). Within this study, the potentiality of DBHB against microfouling has been investigated. The activity of DBHB was evaluated on key strains of bacteria and microalgae involved in marine biofilm formation and bioassays assessing impact on growth, adhesion and biofilm formation were used. To assess the efficiency of DBHB when included in a matrix, DBHB varnish was prepared and the anti-microfouling activity of coatings was assessed. Both in vitro and in situ immersions were carried out. Confocal Laser Scanning Microscopy (CLSM) was principally used to determine the biovolume and average thickness of biofilms developed on the coatings. Results showed an evident efficiency of DBHB as compound and varnish to reduce the biofilm development. The mode of action seems to be based principally on a perturbation of biofilm formation rather than on a biocidal activity in the tested conditions.

Modulation of intracellular expression of IFNγ and IL-2 in culture of splenic T lymphocytes by some flavonoid glycosides of Alchornea floribunda.

Context Alchornea floribunda Müll. Arg. (Euphorbiaceae) leaves are widely used in ethnomedicine for the management of rheumatism, arthritis and toothache. Objective In this study, flavonoid glycosides isolated from Alchornea floribunda were screened for their effect on the intracellular expression of interferon-gamma (IFNγ) and interleukin-2 (IL-2) type-1 cytokines. Materials and methods Chromatographic purification of the ethyl acetate fraction of the methanol leaf extract led to the isolation of seven flavonoid glycosides (1-7). Their structures were elucidated by 1D and 2D nuclear magnetic resonance and mass spectrometry. Splenocytes were treated with graded concentrations of the compounds (6.25-25 µg/mL) and incubated for 24 h. Thereafter, their effect on the expression of IFNγ and IL-2 by CD4(+ )and CD8(+ )T-lymphocytes was evaluated using intracellular cytokine staining and FACS analysis. Results Compounds 1-7 (6.25-25 µg/mL) caused the up-regulation of activated CD8(+ )(57.85-72.45% versus 57.85% for untreated control) and, to a lesser extent, activated CD4(+ )(3.21-7.21% versus 2.75% for the untreated control) T-lymphocytes that were both largely interferon-gamma-releasing in treated mouse T lymphocytes relative to untreated control. FACS data analysis showed that stimulation with all the compounds increased the proportion of CD8(+)/IFNγ(+ )and CD4(+)/IFNγ(+ )T lymphocytes up to two-fold when compared with the cells in untreated control wells. Intracellular IL-2 secretion by treated T cells was not detected. Conclusion This recorded T-lymphocyte-specific immune-modulatory property may contribute to explain in part the dynamics associated with the ethnomedicine of Alchornea floribunda, and may find relevance as a necessary cellular immune response precursor to infection-associated disease management.

Evaluation of the in vitro trypanocidal activity of methylated flavonoid constituents of Vitex simplicifolia leaves.

BACKGROUND: Trypanosomiasis is a neglected tropical disease with complex clinical manifestations, tedious diagnosis, and difficult treatments. The drugs available for the treatment of this endemic disease are old, expensive, and associated with other problems including safety and drug resistant parasites. Therefore, there is an urgent need for the development of new, effective, cheap, and safe drugs for its treatment. Plants are potentially rich sources of leads for new drugs against trypanosomiasis. Vitex simplicifolia (Verbenaceae) is used traditionally for the treatment of tooth ache, edema, skin diseases, gout and trypanosomiasis in Nigeria. In a preliminary study, the methanol extract of Vitex simplicifolia was shown to exhibit a pronounced trypanocidal activity against T. b. rhodesiense. The present study was undertaken to investigate the active component responsible for the acclaimed activity of the leaves of Vitex simplicifolia in the traditional treatment of trypanosomiasis in Nigeria and other African countries. Our investigations aim at assessing the plant as a new source of potential trypanocidal compounds. METHODS: The crude extracts were prepared from the dried leaves using methanol, successive extraction with hexane, dichloromethane, ethylacetate and butanol was also done. The ethylacetate fraction was further fractionated and compounds isolated using preparative chromatographic technique and their structures were elucidated by NMR, mass spectrometry and comparison with literature data. Trypanocidal activities and cytotoxicity, using rat skeletal myoblast (L6) cells were investigated and their selectivity indices were determined. RESULTS: The chromatographic separations of the methanol extracts gave rise to seven compounds. The isolated compounds 2, 3, 6 and 7 exhibited promising trypanocidal activity with IC50 values ranging from 4.7-12.3 µg/ml and cytotoxicity in the range of 1.58- 46.20 µg/ml. Compound 6, however, showed the most selective trypanocidal activity with a selectivity index of 9.8. This is the first report of trypanocidal activity of flavonoids from this plant genus. CONCLUSIONS: The isolated compounds from Vitex simplicifolia exhibited noteworthy trypanocidal activities and hence may provide a source of new antitrypanosomal agents. These results also support the traditional use of Vitex simplicifolia in the treatment of trypanosomiasis. This is the first report of trypanocidal effect of flavonoids from this plant genus.