21 research outputs found
Synthesis of βâ<i>C</i>âGalactosyl Ceramide and Its New Aza Variant via the HornerâWadsworthâEmmons Reaction
A simple
strategy for the synthesis of β-<i>C</i>-galactosyl
ceramide and its new aza-variant analogue is described using the HornerâWadsworthâEmmons
reaction as the key step in combining the sugar and aglycone portions
Solid-State 2H NMR Spectroscopy Reveals Micromechanics of Raft-Like Ternary Lipid Membranes Containing Sphingomyelin and Cholesterol
Metal-Free Multiple CarbonâCarbon and CarbonâHydrogen Bond Activations via Charge-Switching Mechanism in Unstrained Diindolylmethanes
A transformation of the unstrained
phenol substituted 3,3â˛-diindolylÂmethanes
(DIPMs) to 2,3â˛-diindolylketones (DIKs) by double CâC
single bond cleavage with associated rearrangements, triggered by
phenyliodineÂ(III) diacetate (PIDA), is reported. Density functional
theory studies reveal a mechanism involving multiple âcharge-switchingâ
steps by synergistic involvement of the two indole units with overall
low activation energy. The indole âcharge-switchingâ
mechanism in DIPMs was further extended toward synthesis of a natural
product motif cycloheptaÂ[<i>b</i>]Âindole from biaryl appended
DIBM
Pseudopyronine B: A Potent Antimicrobial and Anticancer Molecule Isolated from a Pseudomonas mosselii
In continuation of our search for new bioactive compounds from soil microbes, a fluorescent Pseudomonas strain isolated from paddy field soil of Kuttanad, Kerala, India was screened for the production of bioactive secondary metabolites. This strain was identified as Pseudomonas mosselii through 16S rDNA gene sequencing followed by BLAST analysis and the bioactive metabolites produced were purified by column chromatography (silica gel) and a pure bioactive secondary metabolite was isolated. This bioactive compound was identified as Pseudopyronine B by NMR and HR-ESI-MS. Pseudopyronine B recorded significant antimicrobial activity especially against Gram-positive bacteria and agriculturally important fungi. MTT assay was used for finding cell proliferation inhibition, and Pseudopyronine B recorded significant antitumor activity against non-small cell lung cancer cell (A549), and mouse melanoma cell (B16F10). The preliminary MTT assay results revealed that Pseudopyronine B recorded both dose- and time-dependent inhibition of the growth of test cancer cell lines. Pseudopyronine B induced apoptotic cell death in cancer cells as evidenced by Acridine orange/ethidium bromide and Hoechst staining, and this was further confirmed by flow cytometry analysis using Annexin V. Cell cycle analysis also supports apoptosis by inducing G2/M accumulation in both A549 and B16F10 cells. Pseudopyronine B treated cells recorded significant up-regulation of caspase 3 activity. Moreover, this compound recorded immunomodulatory activity by enhancing the proliferation of lymphocytes. The production of Pseudopyronine B by P. mosselii and its anticancer activity in A549 and B16F10 cell lines is reported here for the first time. The present study has a substantial influence on the information of Pseudopyronine B from P. mosselii as potential sources of novel drug molecule for the pharmaceutical companies, especially as potent antimicrobial and anticancer agent
Metal-Free Diaryl Etherification of Tertiary Amines by <i>Ortho</i>-C(sp<sup>2</sup>)âH Functionalization for Synthesis of Dibenzoxazepines and -ones
A phenyliodineÂ(III)
diacetate mediated umpolung reactivity of the
tertiary amines with suitably substituted <i>o</i>-hydroxybenzyl
and phenyl groups is exploited to facilitate <i>o</i>-CÂ(sp<sup>2</sup>)âH functionalization to afford diaryl ethers. The
presence of an <i>o</i>-CHO and secondary amine functionalities
in the resulting diaryl ether, generated in situ, were utilized for
synthesis of dibenzoxazepines and dibenzoxazepinones. Mild conditions
and relative broad substrate scope, and potential for further diversification
of the diaryl ethers are highlights of this methodology