Hamilton Mitsugu Ishiki

Hybrid Compounds as Direct Multitarget Ligands: A Review

Molecular Hybridization is an approach in rational drug design where new chemical entities are obtained by combining two or more pharmacophoric units from different bioactive compounds into a single molecule. Through this approach, medicinal chemists hope that the new hybrid derivative presents: better affinity and efficacy when compared to the parent drugs; a modified selectivity profile with improvement over pharmacokinetic and pharmacodynamic restrictions; dual or multiple modes of action; reduction of undesirable side effects; decreases in drug-drug interactions; reduced emergence or spread of drug resistance in microorganisms and protozoans; and lower cost. The approach has been successfully used by many research groups around the world and has had very promising results with diseases having multifactorial profiles, like Alzheimer´s, Parkinson´s disease, cancer, inflammation, and hypertension among others. The purpose of this paper is to conduct an updated review of molecular hybridization and multitarget profiling (a rational drug design approach), and its applications to the design and discovery of novel hybrid compounds with anti-inflammatory, antimicrobial, anticancer and antiprotozoal (leishmaniasis, malaria, and schistosomiasis) activities over the last six years.

Docking and PLS Studies on a Set of Thiophenes RNA Polymerase Inhibitors Against Staphylococcus aureus

Staphylococcus aureus lives in commensalism with the majority of the population, being recognized as an important pathogen in patients with chronic liver diseases and can cause a deadly infection. The use of antibiotics as rifampin for the chemotherapy of infections caused by S. aureus has resulted in the selection of mutants with resistance. In an attempt to combat resistant strains new research is continuously conducted, as example searching new biological targets or new inhibitors such as tiophenes derivatives that can inhibit the RNA polymerase enzyme. This work investigated the set of tiophenes, selected from of literature and with RNA polymerase enzyme inhibitory activity of S. aureus. After seeking further information on existing scientific literature, the compounds under study were applied the methodologies of PLS, docking and calculation of Molecular Interaction Fields (MIFs) using Pentacle and VolSurf programmes. In addition, a comparison was made with two tiophenes synthesized in our laboratory and which have been tested against the bacteria. Docking studies showed that active compounds had more interactions with the amino acids on active site when compared with rifampicin. The best model obtained in PLS, considering two LVs (latent variables), after leave-one-outvalidation, exhibited the statistical parameters qcv(2) = 0.68 and r(2) = 0.85. External prediction model presented a rext(2) = 0.67. The obtained model through PLS analyses was able to predict the behavior of compounds synthesized by us. So we extract structural features important for the activity of these compounds. In this paper, first we discussed the topics: S. aureus, tiophenes, RNA polymerase, docking and QSAR methodologies. Then we have selected a series of 56 tiophenes from literature, which have their biological activity tested against the RNA polymerase enzyme of S. aureus. The compounds were subsequently carried out for Partial Least Squares (PLS) Analysis.

Free energies of solvation for peptides and polypeptides using SCRF methods

Abstract The effects of the aqueous solvent in the conformational preferences of peptides and homopeptides have been investigated using two different and widely used self-consistent reaction-field models. The free energies of solvation were predicted using the polarizable continuum model developed by Tomasi and co-workers and adapted to semi-empirical hamiltonians by Orozco and Luque, and the solvation model developed by Cramer and Truhlar. The set of compounds investigated is constituted by five dipeptides with different chemical nature and structural properties as well as by two homopeptides in which the size of the polypeptidic chain was varied. Results provided by the different methods are compared and discussed.

Natural Products as a Source for Antileishmanial and Antitrypanosomal Agents

Natural products are compounds extracted from plants, marine organisms, fungi or bacteria. Many researches for new drugs are based on these natural molecules, mainly by beneficial effects on health, health, efficacy, and therapeutic safety. Leishmaniosis, Chagas disease and African sleeping sickness are neglected diseases caused by the Leishmania and Trypanosoma ssp. parasites. These infections mainly affect population of developing countries; they have different symptoms, and may often lead to death. The therapeutic drugs available to treat these diseases are either obsolete, toxic, or have questionable efficacy, possibly through encountering resistance. Discovery of new, safe, effective, and affordable molecules is urgently needed. Natural organisms, as marine metabolites, alkaloids, flavonoids, steroids, terpene and coumarins provide innumerable molecules with the potential to treat these diseases. This study examines studies of natural bioactive compounds as antileishmanial and antitrypanosomal agents.

Recent Advancement in Natural Hyaluronidase Inhibitors.

The use of natural products for the treatment of disease is one of the oldest cultures exists. Currently, the research of new drugs using natural products shows a poorly explored biodiversity and a great interest of marketing. The enzymatic inhibition by some natural products is investigated among these is the inhibition of hyaluronidase and the consequent reduction of the degradation of hyaluronic acid. So there is a reduction of inflammation and angiogenesis. This study reports the main natural species studied in inhibiting human hyaluronidase that can be the subject of future research for new drugs.

Multi-Target Antitubercular Drugs

Tuberculosis is an infectious disease caused by Mycobacterium tuberculosis, which has high levels of mortality worldwide and has already gained resistance to first- and second-line drugs. The study by new chemical entities with promising activities becomes paramount to broaden the therapeutic strategies in the cure of the patients affected with this disease. In this context, in this review we report the discovery of 3 classes of compounds that can simultaneously interact with more than one target of Mycobacterium tuberculosis.

In silico and In vivo Toxicological Evaluation of Cissampelos Sympodialis Secondary Metabolites in Rattus Norvegicus

Cissampelos sympodialis is a plant in northeastern Brazil used by the populace for treating respiratory diseases. Several studies have shown that ethanol leaf extracts have immunomodulatory and anti-inflammatory activities. Infusions are widely used, popular, and an ancient technique in traditional medicine, using hot water alone as the means of extraction. This study aimed to investigate acute toxicological potential of leaf infusions of Cissampelos sympodialis, when applied orally at a dose of 2000mg/kg to Rattus norvegicus, combined with an in silico study of 117 alkaloids present in the Cissampelos genus; five (5) of which were determined to have high toxicity (21, 8, 93, 32 and 88), and five (5) having both low toxicity (57, 77, 28, 25 and 67) and low liver metabolism. The in vivo toxicological evaluation showed that male water consumption decreased, and the feed intake decreased in both sexes. Yet, the figures as to change in weight gain of the animals were not statistically sufficient. As for the biochemical parameters, there was an increase in urea, and decreases in uric acid and AST in males. In females, there was a decrease in albumin and globulin which consequently leads to a total protein decrease. Despite biochemical changes suggestive of kidney damage, the histological sections revealed no kidney or liver changes. The results therefore indicate that despite presenting alkaloids which may be toxic, the genus Cissampelos, or leaf infusions of Cissampelos sympodialis, when applied orally at a dose of 2000mg/kg present low toxicity.