71 research outputs found
Microtermolides A and B from Termite-Associated Streptomyces sp. and Structural Revision of Vinylamycin
Microtermolides A (1) and B (2) were isolated from a Streptomyces sp. strain associated with fungus-growing termites. The structures of 1 and 2 were determined by 1D- and 2D-NMR spectroscopy and high-resolution mass spectrometry. Structural elucidation of 1 led to the re-examination of the structure originally proposed for vinylamycin (3). Based on a comparison of predicted and experimental H and C NMR chemical shifts, we propose that vinylamycin’s structure be revised from 3 to 4
Studies on the Himalayan yew <i>Taxus wallichiana: </i>Part IX — The chemical constituents of the seeds of <i>Taxus wallichiana</i>
225-227The systematic investigation on the seeds
of Taxus wallichialla has resulted in the isolation of three non-taxoid
constituents, ursolic acid 1, the cyanogenic glycoside amygdalin 2
and β-sitosterol glucoside 3. It is a very important finding that
the seeds of the Himalayan yew did not contain any taxoids in contrast to
the presence of taxoids in the seeds of other species of Taxus and
amygdalin is the major constituent of the seeds. The detailed NMR data
of amygdalin are also provided
Indole-Based Fibrates as Potential Hypolipidemic and Antiobesity Agents
Hypolipidemic and antiobesity effects of the newly synthesized
indole-based fibrates were evaluated in Triton WR-1339 and high fat
diet (HFD)-induced hyperlipidemic rats. Preliminary screening of all
the synthesized compounds was done by using an acute model (Triton
model), in which compounds <b>3f</b> and <b>3l</b> showed
significant antidyslipidemic activity. Furthermore, these compounds <b>3f</b> and <b>3l</b> were found to induce significant weight
loss in the visceral fat mass of HFD-fed hyperlipidemic rats without
affecting the normal feeding behavior. Histological examination of
the liver of rats supplemented with <b>3f</b> and <b>3l</b> revealed a significant decrease in steatosis when compared to the
effect of the standard drug fenofibrate. Additional effects such as
an increase in lecithin cholesterol acyl-transferase (LCAT) enzyme
level and increased receptor mediated catabolism of I<sup>131</sup>-low density lipoproteins (LDL) confirm and reinforce the efficacy
of both of these compounds as a new class of dual-acting hypolipidemic
and antiobesity agents
Development of Leishmania donovani stably expressing DsRed for flow cytometry-based drug screening using chalcone thiazolyl-hydrazone as a new antileishmanial target
Green fluorescent protein produces significant fluorescence and is extremely stable, however its excitation maximum is close to the ultraviolet range and thus can damage living cells. Hence, Leishmania donovani stably expressing DsRed were developed and their suitability for flow cytometry-based antileishmanial screening was assessed by evaluating the efficacies of standard drugs as well as newly synthesised chalcone thiazolyl-hydrazone compounds. The DsRed gene was successfully integrated at the 18S rRNA locus of L. donovani and transfectants (LdDsRed) were selected using hygromycin B. Enhanced expression of DsRed and a high level of infectivity to J774A.1 macrophages were achieved, which was confirmed by fluorescence microscopy and flow cytometry. Furthermore, these LdDsRed transfectants were utilised for development of an in vitro screening assay using the standard antileishmanial drugs miltefosine, amphotericin B, pentamidine and paromomycin. The response of transfectants to standard drugs correlated well with previous reports. Subsequently, the suitability of this system was further assessed by screening a series of 18 newly synthesised chalcone thiazolyl-hydrazone compounds in vitro for their antileishmanial activity, wherein 8 compounds showed moderate antileishmanial activity. The most active compound 5g, with ca. 73% splenic parasite reduction, exerted its activity via generating nitric oxide and reactive oxygen species and inducing apoptosis in LdDsRed-infected macrophages. Thus, these observations established the applicability of LdDsRed transfectants for flow cytometry-based antileishmanial screening. Further efforts aimed at establishing a high-throughput screening assay and determining the in vivo screening of potential antileishmanial leads are required
Novel Chalcone–Thiazole Hybrids as Potent Inhibitors of Drug Resistant <i>Staphylococcus aureus</i>
A series
of novel hybrids possessing chalcone and thiazole moieties were synthesized
and evaluated for their antibacterial activities. In general this
class of hybrids exhibited potency against <i>Staphylococcus
aureus</i>, and in particular, compound <b>27</b> exhibited
potent inhibitory activity with respect to other synthesized hybrids.
Furthermore, the hemolytic and toxicity data demonstrated that the
compound <b>27</b> was nonhemolytic and nontoxic to mammalian
cells. The <i>in vivo</i> studies utilizing a <i>S.
aureus</i> septicemia model demonstrated that compound <b>27</b> was as potent as vancomycin. The results of antibacterial
activities underscore the potential of this scaffold that can be utilized
for developing a new class of novel antibiotics
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