Synthesis and screening of (E)-1-(β-D-galactopyranosyl)-4-(aryl)but-3-ene-2-one against Mycobacterium tuberculosis

A series of galactose-derived aryl enones were synthesised and screened against Mycobacterium tuberculosis H₃₇Rv. Preliminary results were promising with MIC values in the range 1.56-12.5 μg/mL.     

Secretion of streptavidin from Bacillus subtilis.

Streptavidin is an extracellular tetrameric protein produced by Streptomyces avidinii. A series of hybrid gene fusions consisting of Bacillus signal peptide coding regions fused to the mature streptavidin sequence were constructed. B. subtilis strains harboring these plasmids accumulate a tetrameric streptavidin in the growth medium. The properties of the streptavidin produced by B. subtilis are similar to those of the streptavidin produced by S. avidinii. B. subtilis strains carrying the various fusions can be grown to a high cell density in a biotin-free medium. Thus, B. subtilis represents an alternate host system for the production of streptavidin.     

Synthesis and study of anti-inflammatory activity of some novel cyclophane amides

Macrocyclic di- and tetra-amides with thia- and oxylinkages were synthesized and screened for in vitro anti-inflammatory activity. Cyclophane diamide 15 showed a dose-dependent activity, while the other cyclophane amides 16-20 exhibited mild activity.     

Identification of novel angiogenesis inhibitors

Vascular endothelial growth factor (VEGF) is a key stimulant of angiogenesis, which is the process of generating new capillary blood vessels. Inhibition of the vascular endothelial growth factor receptor (VEGFR) kinase is known to result in blockage of angiogenesis. A pharmacophore was developed based on the binding of ATP to the hinge region of the kinase domain of VEGFR and a database search of 18,000 compounds was conducted. Selected hits were assessed for their ability to limit the induction of web-like network of capillary tubes by the human umbilical vascular endothelial cells. Two compounds (1 and 4) showed good inhibitory ability to prevent sprouting and closed polygon formation of the tubular networks, promising them to be lead compounds. Compound 4 showed 60% inhibition at 0.05 microM.     

Synthesis and evaluation of anti-HIV activity of isatin beta-thiosemicarbazone derivatives

On the basis of pharmacophoric modelling studies of existing NNRTIs, a series of isatin beta-thiosemicarbazone derivatives was synthesized and evaluated for their anti-HIV activity in HTLV-III(B) strain in the CEM cell line. Three compounds showed significant anti-HIV activity, whereupon compound 6 was found to be the most active compound with an EC(50) value of 2.62 microM and a selectivity index of 17.41, while not being cytotoxic to the cell line at a CC(50) value of 44.90 microM. Other tested compounds exhibited marked activity below their toxicity threshold.     

Test of the Binding Threshold Hypothesis for olfactory receptors: explanation of the differential binding of ketones to the mouse and human orthologs of olfactory receptor 912-93

We tested the Binding Threshold Hypothesis (BTH) for activation of olfactory receptors (ORs): To activate an OR, the odorant must bind to the OR with binding energy above some threshold value. The olfactory receptor (OR) 912-93 is known experimentally to be activated by ketones in mouse, but is inactive to ketones in human, despite an amino acid sequence identity of approximately 66%. To investigate the origins of this difference, we used the MembStruk first-principles method to predict the tertiary structure of the mouse OR 912-93 (mOR912-93), and the HierDock first-principles method to predict the binding site for ketones to this receptor. We found that the strong binding of ketones to mOR912-93 is dominated by a hydrogen bond of the ketone carbonyl group to Ser105. All ketones predicted to have a binding energy stronger than EBindThresh = 26 kcal/mol were observed experimentally to activate this OR, while the two ketones predicted to bind more weakly do not. In addition, we predict that 2-undecanone and 2-dodecanone both bind sufficiently strongly to activate mOR912-93. A similar binding site for ketones was predicted in hOR912-93, but the binding is much weaker because the human ortholog has a Gly at the position of Ser105. We predict that mutating this Gly to Ser in human should lead to activation of hOR912-93 by these ketones. Experimental substantiations of the above predictions would provide further tests of the validity of the BTH, our predicted 3D structures, and our predicted binding sites for these ORs.     

Augmented efficacy of tamoxifen in rat breast tumorigenesis when gavaged along with riboflavin, niacin, and CoQ10: effects on lipid peroxidation and antioxidants in mitochondria

Reactive oxygen species (ROS) play a major role in causing mitochondrial changes linked to cancer and metastasis. Uptake of antioxidants by tissue to reduce the ROS production could be instrumental in controlling cancer. Tamoxifen (TAM), a nonsteroidal anti-estrogen drug most used in the chemotherapy and chemoprevention of breast cancer. Riboflavin, niacin and coenzyme Q10 (CoQ10) are proved to be potent antioxidants and protective agents against many diseases including cancer. The objective of this research is to determine the therapeutic efficacy of combinatorial therapy on mammary carcinoma bearing rats in terms of the mitochondrial lipid peroxidation and antioxidant status especially MnSOD. Female albino rats of Sprague-Dawley strain were selected for the investigation. Mammary carcinoma was induced with 7,12-dimethyl benz(a)anthracene (DMBA: 25 mg), and the treatment was started by the oral administration of TAM (10 mg/kg body weight/day) along with riboflavin (45 mg/kg body weight/day), niacin (100 mg/kg body weight/day) and CoQ10 (40 mg/kg body weight/day) for 28 days. The levels of lipid peroxides, activities of enzymic and non-enzymic antioxidants were measured in the mitochondria isolated from the mammary gland and liver of control and experimental rats. Rats treated with DMBA showed an increase in mitochondrial lipid peroxidation (mammary gland 52.3%; liver 25.1%) accompanied by high malondialdehyde levels along with lowered activities of mitochondrial enzymic antioxidants [superoxide dismutase (mammary gland 19.9%; liver 24.8%), catalase (mammary gland 50%; liver 19.7%), glutathione peroxidase (mammary gland 47.8%; liver 31.1%)] and non-enzymic antioxidants [reduced glutathione (mammary gland 14.3%; liver 13.3%), Vitamin C (mammary gland 6.49%; liver 21.4%) and E (mammary gland 20.3%; liver 22.2%)]. Administration of combinatorial therapy restored lipid peroxide level and the activities of enzymic and non-enzymic antioxidants to near normalcy. In addition, antitumour activity was also found to be enhanced which is evident from the increased expression of tumour suppressor gene MnSOD thereby preventing cancer cell proliferation. These results suggested that TAM treatment is the most effective during co-administration of riboflavin, niacin and CoQ10 in terms of mitochondrial antioxidant and antitumour activity.