Hydroxylated analogues of the orally active broad spectrum antifungal, Sch 51048 (1), and the discovery of posaconazole [Sch 56592; 2 or (S,S)-5

As part of a detailed study, the syntheses, biological activities, and pharmacokinetic properties of hydroxylated analogues of the previously described broad spectrum antifungal agents, Sch 51048 (1), Sch 50001 (3), and Sch 50002 (4), are described. Based on an overall superior profile, one of the alcohols, Sch 56592 (2), was selected for clinical studies.     

The latch modulates nucleotide and DNA binding to the helicase-like domain of Thermotoga maritima reverse gyrase and is required for positive DNA supercoiling

Reverse gyrase is the only topoisomerase that can introduce positive supercoils into DNA in an ATP-dependent process. It has a modular structure and harnesses a helicase-like domain to support a topoisomerase activity, thereby creating the unique function of positive DNA supercoiling. The isolated topoisomerase domain can relax negatively supercoiled DNA, an activity that is suppressed in reverse gyrase. The isolated helicase-like domain is a nucleotide-dependent switch that is attenuated by the topoisomerase domain. Inter-domain communication thus appears central for the functional cooperation of the two domains. The latch, an insertion into the helicase-like domain, has been suggested as an important element in coordinating their activities. Here, we have dissected the influence of the latch on nucleotide and DNA binding to the helicase-like domain, and on DNA supercoiling by reverse gyrase. We find that the latch is required for positive DNA supercoiling. It is crucial for the cooperativity of DNA and nucleotide binding to the helicase-like domain. The latch contributes to DNA binding, and affects the preference of reverse gyrase for ssDNA. Thus, the latch coordinates the individual domain activities by modulating the helicase-like domain, and by communicating changes in the nucleotide state to the topoisomerase domain.     

18-oxocortisol: effect of dexamethasone, ACTH and sodium restriction

The urinary excretion of 18-oxocortisol in 37 normal subjects consuming a normal sodium diet was 1.2 +/- 0.9(SD) microgram/24 h. Dexamethasone administration to 5 normal individuals suppressed the excretion of 18-oxocortisol from 1.16 +/- 0.5 micrograms/24 h to 0.6 +/- 0.2 micrograms/24 h. While they still received dexamethasone, ACTH administration raised the 18-oxo-cortisol excretion to 3.82 +/- 1.2 micrograms/24 h. Seven normal subjects were placed on a sodium restricted diet, and the urinary excretion of 18-oxocortisol rose from 1.5 +/- 1.21 micrograms/24 h to 8.54 +/- 5.08 micrograms/24 h and aldosterone from 6.6 +/- 2.0 micrograms/24 h to 39.7 +/- 14.6 micrograms/24 h. Two of the seven individuals showed minimal increases in the excretion of 18-oxocortisol, but in all cases aldosterone increased with sodium restriction. The urinary excretion of 18-oxocortisol correlated significantly with the excretion of aldosterone, 18-hydroxycortisol, cortisol, and 19-nordeoxycorticosterone. These studies indicate that 18-oxocortisol secretion is under ACTH regulation, but since sodium restriction also increases the excretion of 18-oxocortisol, the renin-angiotensin system must also participate in its regulation. However, some individuals do not increase their excretion of 18-oxocortisol with sodium restriction, although aldosterone excretion increases as expected, suggesting that additional factors participate in the regulation of 18-oxocortisol production.     

Evaluation of Salmonella Porins as a Broad Spectrum Vaccine Candidate

Porins were prepared from smooth strain of Salmonella typhi 0–901 and chemotype of rough mutant of S. typhimurium Ra-30. Mice were immunized with both the porin preparations in different groups and challenged with S. typhimurium LT2–71 and S. enteritidis SH-1269. Porin immunized mice showed significant protection (P <0.01) against challenge with homologous as well as heterologous strains. Hence, the use of porins may be attempted in future to protect against salmonellosis.     

Spectroscopic investigations to reveal the nature of interactions between the haem protein myoglobin and the dye rhodamine 6G

In the present investigation, steady‐state and time‐resolved fluorescence with the combination of circular dichroism (CD) spectroscopic techniques were applied to study the interactions of the well‐known dye rhodamine 6 G (R6G) with the haem protein human myoglobin (Mb). From the analysis of the results it appears that the static type of fluorescence quenching mechanism is primarily involved, due to ground‐state interactions. Although considerable overlapping of fluorescence emission of the dye R6G with the absorption of Mb in the Q‐band region exists, the possibility of occurrences of the excitational singlet–singlet non‐radiative energy transfer process from R6G to Mb appears to be unlikely, according to time‐resolved fluorescence measurements. From the determinations of the thermodynamic parameters, it was apparent that the combined effect of van der Waals' interactions and hydrogen bonding plays a vital role in Mb–R6G interactions. Induced circular dichroism (ICD) studies demonstrate the possibility of interactions between R6G and Mb. The binding constants, number of binding sites and thermodynamic parameters have been computed. From CD measurements it is apparent that the binding of the dye R6G with the haem protein Mb induces negligible conformational changes in the protein and Mb retains its secondary structure and helicity when it interacts with R6G. The present detailed studies on the interactions with Mb should be helpful in further advancement of medical diagnostics and biotechnology. Copyright © 2011 John Wiley & Sons, Ltd.     

Immunomodulatory effect of Tylophora indica on Con A induced lymphoproliferation.

Our preliminary studies with tylophora alkaloids had shown that they inhibit cellular immune responses like contact sensitivity to dinitro-flurobenzene and delayed hypersensitivity to sheep red blood cells, in vivo. Investigations were hence carried out to determine the cellular targets of tylophora alkaloids in in vitro systems. Con A induced proliferation of splenocytes was used as a model system to study the effect of the alkaloids on cellular immune responses. The alkaloid mixture was found to inhibit proliferation of splenocytes at higher concentrations and augment the same at lower concentrations. Both macrophages and T cells were found to be vulnerable to tylophora alkaloids. The alkaloid mixture suppressed IL-2 production in Con A stimulated splenocytes at the inhibitory or higher concentrations and enhanced production at the lower concentrations. IL-1 production by activated macrophages on the contrary was doubled in the presence of inhibitory concentrations of tylophora. These studies indicate that tylophora alkaloids have a concentration dependent biphasic effect on Con A induced mitogenesis. At lower concentrations they augment Con A induced lymphoproliferation by enhancing IL-2 production. Inhibition of proliferation at higher concentrations of the alkaloid is due to inhibition of IL-2 production and activation of macrophages, which have a cytostatic effect.