Synthesis, biological evaluation, and molecular docking study of some new rohitukine analogs as protein tyrosine phosphatase 1B inhibitors.

Rohitukine (RH) was extracted from the stem bark of Dysoxylum binectariferum Hook. It was derivatized to different arylsulphanmides by treating with the corresponding aryl sulphonyl chlorides. These derivatives were tested in-vitro on protein tyrosine phosphatase 1B (PTP1B) inhibition. Among these the active compounds K2, K3, K5, and K8 significantly inhibited the PTP1B by 51.3%, 65.6%, 71.9%, and 55.9% respectively at 10 µg/ml, the results were also supported by in-silico docking experiments. The most potent compound K5 was analyzed for antidiabetic and antidyslipidemic activity in vivo. It showed a marked reduction in blood glucose level (random and fasting) and serum insulin level in db/db mice. It improved glucose intolerance as ascertained by the oral glucose tolerance test (OGTT). These NCEs (New Chemical Entities) also lowered cholesterol and triglyceride profiles while improved high-density lipoprotein cholesterol in db/db mice. The K5 was further evaluated for antiadipogenic activity on MDI (Methylisobutylxanthine, dexamethasone, and insulin)-induced adipogenesis. where it significantly inhibited MDI-induced adipogenesis in 3 T3-L1 preadipocytes, at 10 µM and 20 µM concentration. These results were compared with the parent compound RH which inhibited 35% and 45% lipid accumulation while the RH analog K5 inhibited the lipid accumulation by 41% and 51% at 10 and 20 µM concentration, respectively. These results well corroborated with in-silico studies.

Determinants of natural immunity against tuberculosis in an endemic setting: factors operating at the level of macrophage-Mycobacterium tuberculosis interaction.

We aimed to delineate factors operating at the interface of macrophage-mycobacterium interaction which could determine the fate of a 'subclinical' infection in healthy people of a tuberculosis-endemic region. Ten study subjects (blood donors) were classified as 'high' or 'low' responders based on the ability of their monocyte-derived macrophages to restrict or promote an infection with Mycobacterium tuberculosis. Bacterial multiplication between days 4 and 8 in high responder macrophages was significantly lower (P < 0.02) than low responders. All donor sera were positive for antibodies against cell-membrane antigens of M. tuberculosis and bacilli opsonized with heat-inactivated sera were coated with IgG. In low responder macrophages, multiplication of opsonized bacilli was significantly less (P < 0.04) than that of unopsonized bacilli. The levels of tumour necrosis factor (TNF)-alpha and interleukin (IL)-12 produced by infected high responder macrophages was significantly higher (P < 0.05) than low responders. However, infection with opsonized bacilli enhanced the production of IL-12 in low responders to its level in high responders. The antibody level against membrane antigens was also significantly higher (P < 0.05) in high responders, although the antigens recognized by two categories of sera were not remarkably different. Production of certain other cytokines (IL-1beta, IL-4, IL-6 and IL-10) or reactive oxygen species (H2O2 and NO) by macrophages of high and low responders did not differ significantly. The study highlights the heterogeneity of Indian subjects with respect to their capability in handling subclinical infection with M. tuberculosis and the prominent role that TNF-alpha, opsonizing antibodies and, to a certain extent, IL-12 may play in containing it.

Synthesis and antitubercular screening of imidazole derivatives.

A series of imidazole based compounds were synthesized by reacting simple imidazoles with alkyl halides or alkyl halocarboxylate in presence of tetrabutylammonium bromide (TBAB). The compounds bearing carbethoxy group undergo amidation with different amines in the presence of DBU to give respective carboxamides. The synthesized compounds were screened against Mycobacterium tuberculosis where compound 17 exhibited very good in vitro antitubercular activity and may serve as a lead for further optimization.