952 research outputs found

    An in vitro study of the antifungal activity of Trichoderma virens 7b and a profile of its non-polar antifungal components released against Ganoderma boninense

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    Ganoderma boninense is the causal agent of a devastating disease affecting oil palm in Southeast Asian countries. Basal stem rot (BSR) disease slowly rots the base of palms, which radically reduces productive lifespan of this lucrative crop. Previous reports have indicated the successful use of Trichoderma as biological control agent (BCA) against G. boninense and isolate T. virens 7b was selected based on its initial screening. This study attempts to decipher the mechanisms responsible for the inhibition of G. boninense by identifying and characterizing the chemical compounds as well as the physical mechanisms by T. virens 7b. Hexane extract of the isolate gave 62.60% ± 6.41 inhibition against G. boninense and observation under scanning electron microscope (SEM) detected severe mycelial deformation of the pathogen at the region of inhibition. Similar mycelia deformation of G. boninense was observed with a fungicide treatment, Benlate® indicating comparable fungicidal effect by T. virens 7b. Fraction 4 and 5 of hexane active fractions through preparative thin layer chromatography (P-TLC) was identified giving the best inhibition of the pathogen. These fractions comprised of ketones, alcohols, aldehydes, lactones, sesquiterpenes, monoterpenes, sulphides, and free fatty acids profiled through gas chromatography mass spectrometry detector (GC/MSD). A novel antifungal compound discovery of phenylethyl alcohol (PEA) by T. virens 7b is reported through this study. T. virens 7b also proved to be an active siderophore producer through chrome azurol S (CAS) agar assay. The study demonstrated the possible mechanisms involved and responsible in the successful inhibition of G. boninense

    Cytotoxic Aaptamines from Malaysian Aaptos aaptos

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    In a preliminary screen, Aaptos aaptos showed significant cytotoxic activity towards a panel of cell lines and was thus subjected to bioassay-guided isolation of the bioactive constituents. In addition to the known aaptamine, two new derivatives of the alkaloid were isolated from the bioactive chloroform fraction of the crude methanolic extract. Detailed analysis by NMR and mass spectroscopy enabled their identification to be 3-(phenethylamino)demethyl(oxy)aaptamine and 3-(isopentylamino)demethyl(oxy) aaptamine. The cytotoxic activities of the three alkaloids were further evaluated against CEM-SS cells

    Pituitary tumor transforming gene-1 haplotypes and risk of pituitary adenoma: a case-control study

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    <p>Abstract</p> <p>Background</p> <p>It has been suggested that pituitary adenoma results from accumulation of multiple genetic and/or epigenetic aberrations, which may be identified through association studies. As pituitary tumor transforming gene-1 (<it>PTTG1</it>)/securin plays a critical role in promoting genomic instability in pituitary neoplasia, the present study explored the association of <it>PTTG1 </it>haplotypes with the risk of pituitary adenoma.</p> <p>Methods</p> <p>We genotyped five <it>PTTG1 </it>haplotype-tagging SNPs (htSNP) by PCR-RFLP assays in a case-control study, which included 280 Han Chinese patients diagnosed with pituitary adenoma and 280 age-, gender- and geographically matched Han Chinese controls. Haplotypes were reconstructed according to the genotyping data and linkage disequilibrium status of the htSNPs.</p> <p>Results</p> <p>No significant differences in allele and genotype frequencies of the htSNPs were observed between pituitary adenoma patients and controls, indicating that none of the individual <it>PTTG1 </it>SNPs examined in this study is associated with the risk of pituitary adenoma. In addition, no significant association was detected between the reconstructed <it>PTTG1 </it>haplotypes and pituitary adenoma cases or the controls.</p> <p>Conclusions</p> <p>Though no significant association was found between <it>PTTG1 </it>haplotypes and the risk of pituitary adenoma, this is the first report on the association of individual <it>PTTG1 </it>SNPs or <it>PTTG1 </it>haplotypes with the risk of pituitary adenoma based on a solid study; it will provide an important reference for future studies on the association between genetic alterations in <it>PTTG1 </it>and the risk of pituitary adenoma or other tumors.</p

    Enhanced thermoelectric performance of a chalcopyrite compound CuIn3Se5-xTex (x=0~0.5) through crystal structure engineering

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    In this work the chalcopyrite CuIn3Se5−xTex (x = 0~0.5) with space group through isoelectronic substitution of Te for Se have been prepared, and the crystal structure dilation has been observed with increasing Te content. This substitution allows the anion position displacement ∆u = 0.25-u to be zero at x ≈ 0.15. However, the material at x = 0.1 (∆u = 0.15 × 10−3), which is the critical Te content, presents the best thermoelectric (TE) performance with dimensionless figure of merit ZT = 0.4 at 930 K. As x value increases from 0.1, the quality factor B, which informs about how large a ZT can be expected for any given material, decreases, and the TE performance degrades gradually due to the reduction in nH and enhancement in κL. Combining with the ZTs from several chalcopyrite compounds, it is believable that the best thermoelectric performance can be achieved at a certain ∆u value (∆u ≠ 0) for a specific space group if their crystal structures can be engineered
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