Frederico F. Ribeiro

Antileishmanial activity of new thiophene-indole hybrids: Design, synthesis, biological and cytotoxic evaluation, and chemometric studies.

In the present work, thirty-two hybrid compounds containing cycloalka[b]thiophene and indole moieties (TN5, TN5 1-7, TN6, TN6 1-7, TN7, TN7 1-7, TN8, TN8 1-7) were designed, synthesized and evaluated for their cytotoxic and antileishmanial activity against Leishmania amazonensis promastigotes. More than half of the compounds (18 compounds) exhibited significant antileishmanial activity (IC50 lower than 10.0μg/L), showing better performance than the reference drugs (tri- and penta-valent antimonials). The most active compounds were TN8-7, TN6-1 and TN7 with respective IC50 values of 2.1, 2.3 and 3.2μg/mL. Demonstrating that all of the compounds were less toxic than the reference drugs, even at the highest evaluated concentration (400μg/mL), no compound tested presented human erythrocyte cytotoxicity. Compound TN8-7s effectiveness against a trivalent antimony-resistant culture was demonstrated. It was observed that TN8-7s antileishmanial activity is associated with DNA fragmentation of L. amazonensis promastigotes. Chemometric studies (CPCA, PCA, and PLS) highlight intrinsic solubility/lipophilicity, and compound size and shape as closely related to activity. Our results suggest that hybrid cycloalka[b]thiophene-indole derivatives may be considered as lead compounds for further development of new drugs for the treatment of leishmaniasis.

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.

Computer-Aided Drug Design Studies in Food Chemistry

In silico methods or computer-aided drug design (CADD) studies, which involve an understanding of molecular interactions from both a qualitative and quantitative point of view, are increasingly being used in both industrial and academic settings. Analysis of the molecular structure of a given system allows relevant information to be extracted, and the potential of bioactive compounds to be predicted. In silico tools used in medicinal chemistry include chemometric methods, structure–activity relationships (SAR), mole cular modeling, and quantitative structure–activity relationships (QSAR), which correlate the structural or property descriptors of compounds to several types of biological activities. This chapter will report some studies to show how computational chemistry can be used to predict important chemical structure information and how these techniques can be applied in food research.

Natural Product Inhibitors of Topoisomerases: Review and Docking Study

Since ancient times, natural products have been used in treating various diseases effectively and safely. Nowadays, these natural compounds are submitted to sophisticated methodologies from isolation, computing, analytical, and even serving as pharmacophore suggestions for synthesis. The substances extracted from marine species, plants, and microorganisms present activities beneficial to our health, including protection against malignant tumors. The topoisomerase enzymes play an important role in DNA metabolism, and searching for enzyme inhibitors is an important target in the search for new anticancer drugs. This review discusses this problem, reporting research involving alkaloids, terpenes, flavonoids, xanthones, coumarins, acetogenins, and in addition, includes a docking study with our Brazilian diterpenes to topoisomerases I and II. The better compound, the trachylobane 1, forms one hydrogen bond when submitted to docking with Topo I (with the ASP533 residue) and two with residues in Topo II (THR213 and TYR188). The difference observed in the energy of formation can be attributed to hydrogen-bond interactions. The difference observed in the energy of formation can be attributed to hydrogen-bond interactions.

Docking of Natural Products against Neurodegenerative Diseases: General Concepts

BACKGROUND Since antiquity, humanity has used medicinal plant preparations to cure its ills, and, as research has progressed, new technologies have enabled more investigations on natural compounds which originate from plants, fungi, and marine species. The health benefits that these natural products provide have become a motive for treatment studies of various diseases. OBJECTIVE Among them, the neurodegenerative diseases like Alzheimers and Parkinsons, a major age-related neurodegenerative disorder. Studies with natural products for neurodegenerative diseases (particularly through molecular docking) search for, and then focus on those ligands which offer effective inhibition of the enzymes monoamine oxidase and acetylcholinesterase. METHOD This review introduces the main concepts involved in docking studies with natural products: and also in our group, which has conducted a docking study of natural products isolated from Tetrapterys mucronata for inhibition of acetylcholinesterase. RESULTS We observed that compounds 4 and 5 formed more interactions than the theoretical ligand, but that ligands with greater activity also interacted with residues HIS 381 and GLN 527. CONCLUSION We have reported on our docking study performed with AChE and alkaloids isolated from the plant Tetrapterys mucronata. Our docking results corroborate the experiments conducted, and emphasize the positive contribution that these theoretical studies involving natural products bring to the fight against neurodegenerative diseases.

Anthocyanins: Multi-Target Agents for Prevention and Therapy of Chronic Diseases

Anthocyanins, a flavonoid class of polyphenols, are water soluble dark colored natural pigments found in fruits and vegetables. Owing to their wide distribution in plant materials, dietary consumption of anthocyanins is high compared to other flavonoids. Anthocyanins, due to their multifaceted medicinal properties are the active components in many herbal folk medicines. As in vitro and in vivo results, animal models, and clinical trials in various cell lines suggest, anthocyanins possess antioxidant, antidiabetic, antihyperlipidemic, anti-inflammatory, anticarcinogenic, antiulcer, and preventive activities against cardiovascular diseases. Additionally, anthocyanins exhibit chemotherapeutic, cardioprotective, hepatoprotective, and neuroprotective activities. In the diet, anthocyanins are absorbed in the stomach and intestinal cells and rapidly detected in the plasma. These promising properties of anthocyanins may well provide health benefits against chronic diseases.

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.