Anti-Trypanosomal Bufadienolides from the Oocytes of the Toad Rhinella alata (Anura, Bufonidae).

Amphibians are widely known as a prolific source of bioactive metabolites. In this work, we isolated and characterized compounds with antiparasitic activity from the oocytes of the toad Rhinella alata collected in Panama. Bio-guided isolation and structural elucidation were carried out using chromatographic and spectroscopic techniques, respectively. The organic extract was subjected to solid phase extraction followed by HPLC purification of the fraction with in vitro activity against Trypanosoma cruzi trypomastigotes. Seven steroids (1-7) of the bufadienolide family were isolated, and their structures were determined using NMR and MS analyses; of these 19-formyl-dyscinobufotalin, (3) is reported as a new natural product. Compounds 1 and 3-7 resulted in a good anti-trypanosomal activity profile. Among these, 16ß-hydroxyl-hellebrigenin (1) and bufalin (7) showed significant selectivity values of >5 and 2.69, respectively, while the positive control benznidazole showed a selectivity of 18.81. Furthermore, molecular docking analysis showed compounds 1, 3 and 7 interact through H-bonds with the amino acid residues GLN-19, ASP-158, HIS-159 and TRP-177 from cruzipain at the catalytic site. Given the lack of therapeutic options to treat American trypanosomiasis, this work can serve as the basis for further studies that aim for the development of bufadienolides or their derivatives as drugs against Chagas disease.

Cheminformatic characterization of natural products from Panama.

In this work, we discuss the characterization and diversity analysis of 354 natural products (NPs) from Panama, systematically analyzed for the first time. The in-house database was compared to NPs from Brazil, compounds from Traditional Chinese Medicine, natural and semisynthetic collections used in high-throughput screening, and compounds from ChEMBL. An analysis of the "global diversity" was conducted using molecular properties of pharmaceutical interest, three molecular fingerprints of different design, molecular scaffolds, and molecular complexity. The global diversity was visualized using consensus diversity plots that revealed that the secondary metabolites in the Panamanian flora have a large scaffold diversity as compared to other composite databases and also have several unique scaffolds. The large scaffold diversity is in agreement with the broad range of biological activities that this collection of NPs from Panama has shown. This study also provided further quantitative evidence of the large structural complexity of NPs. The results obtained in this study support that NPs from Panama are promising candidates to identify selective molecules and are suitable sources of compounds for virtual screening campaigns.

Neoflavonoids as Inhibitors of HIV-1 Replication by Targeting the Tat and NF-κB Pathways.

Twenty-eight neoflavonoids have been prepared and evaluated in vitro against HIV-1. Antiviral activity was assessed on MT-2 cells infected with viral clones carrying the luciferase reporter gene. Inhibition of HIV transcription and Tat function were tested on cells stably transfected with the HIV-LTR and Tat protein. Seven 4-phenylchromen-2-one derivatives showed HIV transcriptional inhibitory activity but only the phenylchrome-2-one 10 inhibited NF-κB and displayed anti-Tat activity simultaneously. Compounds 10, 14, and 25, inhibited HIV replication in both targets at concentrations <25 µM. The assays of these synthetic 4-phenylchromen-2-ones may aid in the investigation of some aspects of the anti-HIV activity of such compounds and could serve as a scaffold for designing better anti-HIV compounds, which may lead to a potential anti-HIV therapeutic drug.

Updating and profiling the natural product-likeness of Latin American compound libraries.

Compound databases of natural products play a crucial role in drug discovery and development projects and have implications in other areas, such as food chemical research, ecology and metabolomics. Recently, we put together the first version of the Latin American Natural Product database (LANaPDB) as a collective effort of researchers from six countries to ensemble a public and representative library of natural products in a geographical region with a large biodiversity. The present work aims to conduct a comparative and extensive profiling of the natural product-likeness of an updated version of LANaPDB and the individual ten compound databases that form part of LANaPDB. The natural product-likeness profile of the Latin American compound databases is contrasted with the profile of other major natural product databases in the public domain and a set of small-molecule drugs approved for clinical use. As part of the extensive characterization, we employed several chemoinformatics metrics of natural product likeness. The results of this study will capture the attention of the global community engaged in natural product databases, not only in Latin America but across the world.

Design and Diversity Analysis of Chemical Libraries in Drug Discovery.

Chemical libraries and compound data sets are among the main inputs to start the drug discovery process at universities, research institutes, and the pharmaceutical industry. The approach used in the design of compound libraries, the chemical information they possess, and the representation of structures, play a fundamental role in the development of studies: chemoinformatics, food informatics, in silico pharmacokinetics, computational toxicology, bioinformatics, and molecular modeling to generate computational hits that will continue the optimization process of drug candidates. The prospects for growth in drug discovery and development processes in chemical, biotechnological, and pharmaceutical companies began a few years ago by integrating computational tools with artificial intelligence methodologies. It is anticipated that it will increase the number of drugs approved by regulatory agencies shortly.

Understanding the Artemia Salina (Brine Shrimp) Test: Pharmacological Significance and Global Impact.

BACKGROUND: The microplate benchtop brine shrimp test (BST) has been widely used for screening and bio-guided isolation of many active compounds, including natural products. Although the interpretation given to the results appears dissimilar, our findings suggest a correlation between positive results with a specific mechanism of action. OBJECTIVE: This study aimed to evaluate drugs belonging to fifteen pharmacological categories having diverse mechanisms of action and carry out a bibliometric analysis of over 700 citations related to microwell BST. METHODS: Test compounds were evaluated in a serial dilution on the microwell BST using healthy nauplii of Artemia salina and after 24 hrs of exposition, the number of alive and dead nauplii was determined, and the LC50 was estimated. A metric study regarding the citations of the BST miniaturized method, sorted by type of documents cited, contributing country, and interpretation of results was conducted on 706 selected citations found in Google Scholar. RESULTS: Out of 206 drugs tested belonging to fifteen pharmacological categories, twenty-six showed LC50 values <100 µM, most of them belonging to the category of antineoplastic drugs; compounds with different therapeutical uses were found to be cytotoxic as well. A bibliometric analysis showed 706 documents citing the miniaturized BST; 78% of them belonged to academic laboratories from developing countries located on all continents, 63% interpreted their results as cytotoxic activity and 35% indicated general toxicity assessment. CONCLUSION: BST is a simple, affordable, benchtop assay, capable of detecting cytotoxic drugs with specific mechanisms of action, such as protein synthesis inhibition, antimitotic, DNA binding, topoisomerase I inhibitors, and caspases cascade interfering drugs. The microwell BST is a technique that is used worldwide for the bio-guided isolation of cytotoxic compounds from different sources.

Navigating the Chemical Space and Chemical Multiverse of a Unified Latin American Natural Product Database: LANaPDB.

The number of databases of natural products (NPs) has increased substantially. Latin America is extraordinarily rich in biodiversity, enabling the identification of novel NPs, which has encouraged both the development of databases and the implementation of those that are being created or are under development. In a collective effort from several Latin American countries, herein we introduce the first version of the Latin American Natural Products Database (LANaPDB), a public compound collection that gathers the chemical information of NPs contained in diverse databases from this geographical region. The current version of LANaPDB unifies the information from six countries and contains 12,959 chemical structures. The structural classification showed that the most abundant compounds are the terpenoids (63.2%), phenylpropanoids (18%) and alkaloids (11.8%). From the analysis of the distribution of properties of pharmaceutical interest, it was observed that many LANaPDB compounds satisfy some drug-like rules of thumb for physicochemical properties. The concept of the chemical multiverse was employed to generate multiple chemical spaces from two different fingerprints and two dimensionality reduction techniques. Comparing LANaPDB with FDA-approved drugs and the major open-access repository of NPs, COCONUT, it was concluded that the chemical space covered by LANaPDB completely overlaps with COCONUT and, in some regions, with FDA-approved drugs. LANaPDB will be updated, adding more compounds from each database, plus the addition of databases from other Latin American countries.

Latin American databases of natural products: biodiversity and drug discovery against SARS-CoV-2.

In this study, we evaluated 3444 Latin American natural products using cheminformatic tools. We also characterized 196 compounds for the first time from the flora of El Salvador that were compared with the databases of secondary metabolites from Brazil, Mexico, and Panama, and 42 969 compounds (natural, semi-synthetic, synthetic) from different regions of the world. The overall analysis was performed using drug-likeness properties, molecular fingerprints of different designs, two parameters similarity, molecular scaffolds, and molecular complexity metrics. It was found that, in general, Salvadoran natural products have a large diversity based on fingerprints. Simultaneously, those belonging to Mexico and Panama present the greatest diversity of scaffolds compared to the other databases. This study provided evidence of the high structural complexity that Latin America's natural products have as a benchmark. The COVID-19 pandemic has had a negative effect on a global level. Thus, in the search for substances that may influence the coronavirus life cycle, the secondary metabolites from El Salvador and Panama were evaluated by docking against the endoribonuclease NSP-15, an enzyme involved in the SARS CoV-2 viral replication. We propose in this study three natural products as potential inhibitors of NSP-15.

A new cytotoxic friedelane acid--pluricostatic acid--and other compounds from the leaves of Marila pluricostata.

Bioassay-guided fractionation of the dichloromethane extract of the leaves of Marila pluricostata led to the isolation of 2alpha,3beta-dihydroxy-D:A-friedoolean-28-oic acid (pluricostatic acid), a new friedelane triterpenoid, (1), ten known triterpenoids and three sterols. Their chemical structures were elucidated through spectroscopic analysis. The less polar fractions, on GC/MS analysis and comparison with a MS library, resulted in the identification of twenty four sesquiterpenoids. The new triterpenoid acid 1 showed cytotoxicity against the MCF-7, H-460, and SF-268 human cancer cell lines with GI(50) values from 1.2 to 3.3 microg/mL.

Cytotoxic 4-phenylcoumarins from the leaves of Marila pluricostata.

Bioassay-guided fractionation of the CH(2)Cl(2) extract of the leaves of Marila pluricostata led to the isolation of 17 naturally occurring 4-phenylcoumarins, three of them, 5-hydroxy-8,8-dimethyl-4-phenyl-9,10-dihydro-8H-pyrano-[2,3-f]chromen-2-one (1), 5-hydroxy-8,8-dimethyl-4-phenyl-6-propionyl-9,10-dihydro-8H-pyrano-[2,3-f]chromen-2-one (2), and 5,7-dihydroxy-8-(3-methylbut-2-enyl)-4-phenylchromen-2-one (3), are new natural compounds; the remaining (4-17) are known mammea-type coumarins. Their structures were established by spectroscopic means. All compounds were tested in cytotoxicity assays against the MCF-7, H-460, and SF-268 human cancer cell lines.

4-Phenylcoumarins as HIV transcription inhibitors.

We have evaluated the anti-HIV activity of eleven natural 4-phenylcoumarins isolated from Marila pluricostata and three of their derivatives. Antiviral activity was assessed on MT-2 cells infected with viral clones carrying the luciferase gene as reporter. Inhibitions of HIV transcription and Tat function were tested on cells stably transfected with the HIV-LTR and Tat protein. Most of the coumarins tested displayed NF-kappaB inhibition. Two coumarins were also Tat antagonists and the presence of both activities correlated with a stronger inhibition of HIV replication. Our results show that antiviral effect of 4-phenylcoumarins can be related to the inhibition of NF-kappaB and Tat, and suggest that these types of compounds can be useful in the treatment of HIV infection as viral transcription inhibitors.

Diayangambin exerts immunosuppressive and anti-inflammatory effects in vitro and in vivo.

In this study, the furofuran lignan (+)-diayangambin [tetrahydro-1,4-bis(3,4,5-trimethoxyphenyl)-(1 R)-1alpha,3abeta,4alpha,6abeta-1 H,3 H-furo [3,4- c]furan] was evaluated in vitro and in vivo for its immunomodulatory and anti-inflammatory efficacy. Human mononuclear cell proliferation was inhibited by diayangambin with an IC 50 value of 1.5 (0.5 - 2.8) microM. In addition, the compound reduced for 40.8 % prostaglandin E 2 generation in stimulated RAW 264.7 macrophage cell line at 10 microM. In vivo, a clear reduction of ear swelling was observed when diayangambin (40 mg/kg) was administered orally to 2,4-dinitrofluorobenzene-treated mice. The inhibition of swelling was associated with a reduction of leukocyte infiltration determined as myeloperoxidase activity. In the carrageenan mouse paw edema model, diayangambin significantly suppressed inflamed paw volume and prostaglandin E 2 levels. Our findings indicate the potential interest of diayangambin in the treatment of immune and inflammatory responses.