Current Topics in Medicinal Chemistry - Volume 18, Issue 29, 2018

Gram-positive bacteria signify a surface organelle that decorates the cell surfaces using Sortase enzymes. The mechanism of SrtC links to the formation of amide or peptide bonds between cell surface proteins that sorting signal to strategically positioned amino groups. Sorting signals linked to peptidoglycan function as the principal architects of the cell wall and facilitate each microbe to effectively interact with its host environment. These enzymes play a fundamental role in microbial physiology and interestingly, sequence analysis on Gram-positive bacteria implies that approximately 60% of sortases are categorized into six families, and from that SrtA and SrtC are widely investigated in various literature. Sortase felicitates several functions that include adhesins, internalin's, blood clotting, immune evasion factors and transporters for nutrients across the microbial cell wall envelope. Recent evidence has proved that removal of Sortase genes tends to loss of host cell adhesion mechanism and inhibition of Biofilms. So that, blocking the Sortase enzyme is a powerful target and due to the receptor availability in all Gram-positive types, it is so called as a universal drug target for gram-positive pathogens. Sortase enzymes have been intensely studied for anti-infective studies and this review focus the mechanisms of surface protein anchoring to the cell wall envelope by sortases and highlight how it plays a strong role as a drug target.

Aims: The objective of this study was to investigate the effectiveness of (+)-β-pinene inhibition on Candida spp. growth, aiming at elucidation of the mechanism of action; to determine fungal cell enzyme binding activity (through molecular docking simulations) and its effects on biofilm reduction. Methods: Candida strains (n=25) from referenced and clinical origins, either susceptible or resistant to standard clinical antifungals, were tested for determination of Minimum Inhibitory Concentration (MIC); Minimum Fungicidal Concentration (MFC); and microbial death curves upon treatment with (+)-β-pinene; the effects of (+)-β-pinene on the cell wall (sorbitol assay), membrane ergosterol binding, and effects on biofilm were evaluated by microdilution techniques. We also evaluated the interactions between (+)-β-pinene and cell wall and membrane enzymes of interest. Results: The MIC values of (+)-β-pinene ranged from <56.25 to 1800 μmol/L. The MIC of (+)-β-pinene did not increase when ergosterol was added to the medium, however it did increase in the presence of sorbitol, leading to a doubled MIC for C. tropicalis and C. krusei. The results of the molecular docking simulations indicated better interaction with delta-14-sterol reductase (−51 kcal/mol). (+)-β-pinene presents anti-biofilm activity against multiples species of Candida. Conclusion: (+)-β-pinene has antifungal activity and most likely acts through interference with the cell wall; through molecular interaction with Delta-14-sterol reductase and, to a lesser extent, with the 1,3-β- glucan synthase. This molecule was also found to effectively reduce Candida biofilm adhesion.

Background: Plant protease Inhibitors (PIs) play key roles in regulation of many biological activities and being less toxic, more potent and specific in comparision to chemical inhibitors. Methods: A new proteinaceous trypsin inhibitor was isolated and purified from Macrotyloma uniflorum seeds with a molecular mass of 25 KDa was purified to homogeneity via three sequential purification steps i.e., ammonium sulphate precipitation to CNBr activativated Sepharose 4B coupled trypsin affinity chromatography. Purified protease inhibitor (PI) showed optical specific activities of 665 μmols of tyrosine released/ml/min. Results: Overall, there was a remarkable increase in the fold of purification. MUTI is stable to denaturation by heat (upto 80°C), pH (4-10).The inhibitory activity increased to two fold in the presence of mercuric chloride and got reduced by half in the presence of ferric chloride. SDS, Dithiothreitol, β-mercaptoethanol, Hydrogen peroxide, Triton X 100 enhanced its inhibitory activity whereas activity was reduced in the presence of DMSO. Chemical modification of the inhibitor by DEPC decreased its activity but the activity was increased considerably when modified with NE and PMSF. Presence of protease inhibitor activity was confirmed by reverse zymography and Dot- blot. Also MUPI has antifungal and antimicrobial properties. MUPI inhibited Phytophthora capsici by 16.6% and Rhizoctonia solani by 27.7%. Conclusion: Antibacterial activity was shown against Staphylococcus aureus and Pseudomonas aeruginosa. MUPI retained 90% inhibition upon storage at 4°C for over a period of six months. Thus PI can be effectively exploited to increase the shelf life of seafood.

Introduction: Fabaceae are a rich source of protease inhibitors. Methods: A proteinaceous protease inhibitor of 25 KDa designated as Macrotyloma uniflorum protease inhibitor (MUPI) was isolated from seeds of Macrotyloma uniflorum and purified to homogeneity by ammonium sulphate precipitation, DEAE Sepharose column and CNBr activated Sepharose 4B Trypsin affinity chromatography. The purity was checked by reverse phase HPLC. Long-term type 2 diabetes can lead to various biological complications, such as hypertension and heart-related diseases. The glucose uptake studies were carried out with the purified MUPI and it reveals its potential to be explored as a potent anti-hyperglycemic agent. MUPI was rendered safer on HepG2 cells after MTT cytotoxicity assay. Results: The results of glucose uptake studies suggest MUPI to be equally efficient to that of the positive control drug Metformin against diabetes mellitus. Conclusion: The significance of plant-based inhibitors for modulating carbohydrate breakdown and control of glycemic index is explored to reduce the risk factors and side effects of the available drugs.

Background: According to DCEG investigation, the compared results of the osteosarcoma incidences in different continents, reported it to be the most diagnosed in adolescents and adults above 60 yrs. old. Less than 15% of patients get cured with surgery alone but the addition of chemotherapy to the treatment increases the survival rate of patient by 58%-76%. Surgical resection and aggressive chemotherapy protocols are effective to an extent but have failed to improve the 5-year overall survival rate. Indubitably, new drugs and new therapeutic targets are required to improve the outcome as well as to diminish the long-term toxicities associated with the current benchmark of treatment. STAT3 appears to be an important mediator of chemoresistance in osteosarcoma. Results: Experimental evidence clearly demonstrate the disruption of STAT3 signaling which inhibits the survival and proliferation of osteosarcoma and decreases the growth of disease. This prevailing study approach is by molecular docking, virtual screening to elucidate inhibitor with superior affinity against STAT3 to have a cautious pharma profile. To rectify the best-established drug with high affinity, Mol dock algorithm is executed. The compound Sorafenib (Pub CID 216239) having high-affinity scores is subjected to another similarity search to retrieve the drugs with similar properties. The virtual screened compound with PubChem CID-44815014 as per BOILED-Egg plot reveals its high affinity. Conclusion: Comparative study and ADMET study both showed the compounds to have equivalent properties, whereas interestingly the virtual screened compound having PubChem CID-44815014 is seen to have the lowest rerank score. These drugs are identified to have high potential to act as STAT3 inhibitors and probably can be considered for further studies in wet lab analysis.

Background: Chronic lymphocytic leukemia (CLL) is a B-lineage lymphoid malignancy of self-reactive cells that are focused to produce polyreactive natural autoantibodies. Its surface protein marker CD20 plays an important role in the humoral immune response targeting which has emerged as an attractive therapeutic option for the treatment of CLL. The present study explains the interaction of the CD20 with its established inhibitors and to discover the compound having high binding affinity against the target protein receptor. Technically, during the development of new compound through docking studies, best drug among all pre-exist drugs got filtered, hence in reference to docked best drug study moved ahead. Methods: The 3D structure of CD20 was built using homology base fold recognition method using Smith waterman’s Local alignment and standalone Delta Blast algorithms. 23 established inhibitors towards CD20 were selected in this present investigation. Among these inhibitors, etoposide (RMSD value -96.6481) showed high binding capacity with the receptor CD20 which was further subjected to virtual screening. The said screening presented 380 possible drugs having structural similarity to etoposide. Results: The docking studies of the screened drugs separated the compound having PubChem CID: 11753896 (RMSD value -98.5416). Toxicity and interaction profile validated this compound for having a better affinity with the target protein. Conclusively, this research study says that according to ADMET profile and BOILED-Egg plot, the compound (PubChem CID: 11753896) obtained from Virtual Screen could be the best drug in future during the prevention of Chronic Lymphocytic Leukemia. Conclusion: The compound identified in the present investigation can be subjected further for in vitro and in vivo studies for ADMET properties and it could optimize a good profile in the field of pharmacy and bioavailable for suppressing cancer. The pharmacophore study revealed that the drug CID11753896 is a non-inhibitor of CYP450 microsomal enzymes and was found to be non-toxic, similar to the established compound CID36462. It has a lower LD50 value of 2.5423mol/kg as compared to the established compound whose LD50 value is 2.9588mol/kg. Also, the compound was found to be non-carcinogenic.