In vitro investigation of Brazilian Cerrado plant extract activity against Plasmodium falciparum, Trypanosoma cruzi and T. brucei gambiense

Multitask learning-driven identification of novel antitrypanosomal compounds

Background: Chagas disease and human African trypanosomiasis cause substantial death and morbidity, particularly in low- and middle-income countries, making the need for novel drugs urgent. Methodology & results: Therefore, an explainable multitask pipeline to profile the activity of compounds against three trypanosomes (Trypanosoma brucei brucei, Trypanosoma brucei rhodesiense and Trypanosoma cruzi) were created. These models successfully discovered four new experimental hits (LC-3, LC-4, LC-6 and LC-15). Among them, LC-6 showed promising results, with IC50 values ranging 0.01-0.072 μM and selectivity indices >10,000. Conclusion: These results demonstrate that the multitask protocol offers predictivity and interpretability in the virtual screening of new antitrypanosomal compounds and has the potential to improve hit rates in Chagas and human African trypanosomiasis projects.

Anti-Protozoan Activities of Polar Fish-Derived Polyalanine Synthetic Peptides

Chagas disease, sleeping sickness and malaria are infectious diseases caused by protozoan parasites that kill millions of people worldwide. Here, we performed in vitro assays of Pa-MAP, Pa-MAP1.9, and Pa-MAP2 synthetic polyalanine peptides derived from the polar fish Pleuronectes americanus toward Trypanosoma cruzi, T. brucei gambiense and Plasmodium falciparum activities. We demonstrated that the peptides Pa-MAP1.9 and Pa-MAP2 were effective to inhibit T. brucei growth. In addition, structural analyses using molecular dynamics (MD) studies showed that Pa-MAP2 penetrates deeper into the membrane and interacts more with phospholipids than Pa-MAP1.9, corroborating the previous in vitro results showing that Pa-MAP1.9 acts within the cell, while Pa-MAP2 acts via membrane lysis. In conclusion, polyalanine Pa-MAP1.9 and Pa-MAP2 presented activity against bloodstream forms of T. b. gambiense, thus encouraging further studies on the application of these peptides as a treatment for sleeping sickness.

Therapeutic indications, chemical composition and biological activity of native Brazilian species from Psidium genus (Myrtaceae): A review

ETHNOPHARMACOLOGICAL IMPORTANCE

Brazilian medicinal species of the Psidium genus are rich in secondary metabolites such as terpenes and phenolic compounds and present biological activities for several human diseases. For the native Psidium species, there are no specific research reports for any member of the genus about ethnobotanical research, hindering the joint analysis of its therapeutic indications together with the scientific evidence already investigated.

STUDY OBJECTIVE

Analyze the therapeutic indications, the main chemical constituents, and the biological activities of native species of the Psidium to Brazil.

MATERIALS AND METHODS

Systematic research was carried out in the Scopus, ScienceDirect, PubMed, and Web of Science databases over a period of ten years. Articles in English, Portuguese and Spanish were used. The research was divided into three phases, seeking information on ethnobotany, chemical composition and biological activities. The words were combined to structure the descriptors used in the search.

RESULTS

A total of 13 native species belonging to the Psidium genus were identified in this analysis, Psidium acutangulum DC., Psidium brownianum Mart. ex DC., Psidium cattleyanum Sabine, Psidium densicomum Mart. ex DC., Psidium grandifolium Mart. ex DC., Psidium guineense Sw., Psidium laruotteanum Cambess., Psidium myrsinites DC, Psidium myrtoides O. Berg, Psidium salutare (Kunth) O. Berg, Psidium schenckianum Kiaersk., Psidium sobralianum Proença & Landrum, Psidium striatulum Mart. ex DC. Of these, six were indicated in folk medicine, digestive system disorders being their main therapeutic indication. Most species presented an investigation of chemical composition and biological activity. They are rich in phenolic compounds, flavonoids, and terpenes and have antimicrobial, antioxidant, antiproliferative, and repellent activities.

CONCLUSIONS

Native species of the Psidium genus are important sources of active ingredients in combating adversities that affect the human health, especially regarding the digestive system. They have a rich chemical composition, responsible for the biological activities demonstrated for the species.

Antileishmanial compounds from Connarus suberosus: Metabolomics, isolation and mechanism of action

Leishmaniasis is a disease impacting public health worldwide due to its high incidence, morbidity and mortality. Available treatments are costly, lengthy and toxic, not to mention the problem of parasite resistance. The development of alternative treatments is warranted and natural products demonstrate promising activity. This study investigated the activity of Connarus suberosus extracts and compounds against Leishmania species. Several C. suberosus extracts were tested against L. amazonensis promastigotes. Active and inactive extracts were analyzed by UHPLC-MS and data evaluated using a metabolomics platform, revealing an unknown neoflavonoid (connarin, 3), isolated together with the pterocarpans: hemileiocarpin (1) and leiocarpin (2). The aforementioned compounds (1-3), together with the benzoquinones: rapanone (4), embelin (5) and suberonone (6) previously isolated by our group from the same species, were tested against: (i) L. amazonensis and L. infantum promastigotes, and (ii) L. amazonensis intracellular amastigotes, with the most active compound (3) also tested against L. infantum amastigotes. Cytotoxicity against murine peritoneal macrophages was also investigated. Compounds 2 and 3 presented an IC50 33.8 μM and 11.4 μM for L. amazonensis promastigotes; and 44.3 μM and 13.3 μM for L. infantum promastigotes, respectively. For L. amazonensis amastigotes, the IC50 of 2 was 20.4 μM with a selectivity index (SI) of 5.7, while the IC50 of 3 was 2.9 μM with an SI of 6.3. For L. infantum amastigotes, the IC50 of 3 was 7.7 μM. Compounds 2 and 3 presented activity comparable with the miltefosine positive control, with compound 3 found to be 2-4 times more active than the positive control, depending on the Leishmania species and form. The extracts and isolated compounds showed moderate toxicity against macrophages. Compounds 2 and 3 altered the mitochondrial membrane potential (ΔΨm) and neutral lipid body accumulation, while 2 also impacted plasma membrane permeabilization, culminating in cellular disorder and parasite death. Transmission electron microscopy of L. amazonensis promastigotes treated with compound 3 confirmed the presence of lipid bodies. Leiocarpin (2) and connarin (3) demonstrated antileishmanial activity. This study provides knowledge of natural products with antileishmanial activity, paving the way for prototype development to fight this neglected tropical disease.

Activity of natural and synthetic polygodial derivatives against Trypanosoma cruzi amastigotes, trypomastigotes and epimastigotes

Our laboratories have been investigating biological effects of a sesquiterpenoid polygodial and its natural and synthetic analogues. Herein, we report the evaluation of these compounds against the three forms of Trypanosoma cruzi, amastigotes, trypomastigotes and epimastigotes. Although polygodial was found to be poorly active, its natural congener epipolygodial and synthetic Wittig-derived analogues showed low micromolar potency against all three forms of the parasite. Synthetic α,β-unsaturated phosphonate 9 compared favorably with clinically approved drugs benznidazole and nifurtimox, and was effective against trypomastigotes, toward which benznidazole showed no activity.[Formula: see text].

GC-MS and GC-FID analyses of the volatile constituents of Brachychiton rupestris and Brachychiton discolor, their biological activities and their differentiation using multivariate data analysis

The volatile constituents of the leaves and flowers of Brachychiton rupestris and Brachychiton discolor (Malvaceae) were characterized by GC-FID and GC-MS. A total of 92 compounds were identified. The major component of B. rupestris leaves was α-farnesene (34.57%) while in the flowers it was n-heptacosane (29.5%). (8Z, 11Z, 14Z)-heptadecatrienal (21.2%) in the leaves and palmitic acid (83.49%) in the flowers represent the abundant ingredients of B. discolor. Unsupervised pattern recognition techniques of multivariate data analysis exemplified by hierarchical cluster analysis (HCA) and principle component analysis (PCA) relying upon chromatographic results effectively discriminate the two related species. Also, both investigated species were assessed for their cytotoxic and antimicrobial efficacy. Results revealed that B. discolor flowers showed the highest cytotoxicity against human lung carcinoma (A-549) cell lines with IC₅₀ equals 7.98 μg/mL, whereas B. discolor leaves exhibited the highest antimicrobial potency against all tested microorganisms namely Streptococcus pneumonia, Bacillus subtilis, Escherichia coli as well as Aspergillus fumigatus and Geotrichum candidum (MICs between 0.98 and 15.63 µg/mL) except for Salmonella typhi.

Chemical composition and in vitro antibacterial and antiproliferative activities of the essential oil from the leaves of Psidium myrtoides O. Berg (Myrtaceae)

In this study, the chemical composition and antibacterial and antiproliferative potential of the essential oil obtained from fresh leaves of Psidium myrtoides (PM-EO) against oral pathogens and human tumour cell lines were investigated for the first time. GC-FID and GC-MS analyses showed that trans-β-caryophyllene (30.9%), α-humulene (15.9%), α-copaene (7.8%), caryophyllene oxide (7.3%) and α-bisabolol (5.3%) are the major constituents of PM-EO. The antibacterial activity of PM-EO against a panel of oral pathogens was investigated in terms of their minimal inhibitory concentrations (MIC) using the broth microdilution method. PM-EO displayed moderate activity against Streptococcus mitis (MIC = 100 μg/mL), S. sanguinis (MIC = 100 μg/mL), S. sobrinus (MIC = 250 μg/mL), and S. salivarius (MIC = 250 μg/mL), and strong activity against S. mutans (MIC = 62.5 μg/mL). The antiproliferative activity in normal (GM07492A, lung fibroblasts) and tumour cell lines (MCF-7, HeLa, and M059 J) was performed using the XTT assay. PM-EO showed 50% inhibition of normal cell growth at 359.8 ± 6.3 μg/mL. Antiproliferative activity was observed against human tumour cell lines, with IC₅₀ values significantly lower than that obtained for the normal cell line, demonstrating IC₅₀ values for MCF-7 cells (254.5 ± 1.6 μg/mL), HeLa cells (324.2 ± 41.4 μg/mL) and M059 J cells (289.3 ± 10.9 μg/mL). Therefore, the cytotoxicity of PM-EO had little influence on the antibacterial effect, since it showed antibacterial activity at lower concentrations. Our results suggest that PM-EO is a promising source of new antibacterial and antitumour agents.

Chemical Composition and Bioactivity of Essential Oil from Blepharocalyx salicifolius

Natural products represent a source of biologically active molecules that have an important role in drug discovery. The aromatic plant Blepharocalyx salicifolius has a diverse chemical constitution but the biological activities of its essential oils have not been thoroughly investigated. The aims of this paper were to evaluate in vitro cytotoxic, antifungal and antibacterial activities of an essential oil from leaves of B. salicifolius and to identify its main chemical constituents. The essential oil was extracted by steam distillation, chemical composition was determined by gas chromatography/mass spectrometry, and biological activities were performed by a microdilution broth method. The yield of essential oil was 0.86% (w/w), and the main constituents identified were bicyclogermacrene (17.50%), globulol (14.13%), viridiflorol (8.83%), γ-eudesmol (7.89%) and α-eudesmol (6.88%). The essential oil was cytotoxic against the MDA-MB-231 (46.60 μg·mL⁻¹) breast cancer cell line, being more selective for this cell type compared to the normal breast cell line MCF-10A (314.44 μg·mL⁻¹). Flow cytometry and cytotoxicity results showed that this oil does not act by inducing cell death, but rather by impairment of cellular metabolism specifically of the cancer cells. Furthermore, it presented antifungal activity against Paracoccidioides brasiliensis (156.25 μg·mL⁻¹) but was inactive against other fungi and bacteria. Essential oil from B. salicifolius showed promising biological activities and is therefore a source of molecules to be exploited in medicine or by the pharmaceutical industry.

Brazilian Cerrado Qualea grandiflora Mart. Leaves Exhibit Antiplasmodial and Trypanocidal Activities In vitro

Background

The rapid spread of drug-resistant strains of protozoan parasites required the urgent need for new effective drugs. Natural products offer a variety of chemical structures, which make them a valuable source of lead compounds for the development of such new drugs. Cerrado is the second largest biome in Brazil and has the richest flora of all the world savannahs. We selected Qualea grandiflora, a plant species known for its proprieties in folk medicine and its antibacterial activity.

Objective

However, its antiprotozoal activity was not yet explored.

Materials and Methods

We investigated the activities of fractions from the ethyl acetate extract of Q. grandiflora leaves against human life forms of Plasmodium falciparum, Trypanosoma cruzi, and Trypanosoma brucei gambiense, and for its cytotoxicity upon the rat L6-myoblast cell line. Ten fractions were produced by ethyl acetate:hexane chromatography.

Results and Conclusion

The fractions showed no cytotoxicity against L-6 cells (IC₅₀ > 100 μg/mL) and no hemolysis propriety. Three fractions had a moderate activity against P. falciparum, anyone was active against T. cruzi but four fractions demonstrated a high activity against bloodstream forms of T. brucei gambiense (8.0< IC₅₀ <15 μg/mL). Identification and characterization of the active compounds are currently under investigation.

SUMMARY

Qualea grandiflora is an endemic tree of the Brazilian Cerrado, which presents medicinal propertiesTen fractions of the ethyl acetate extract of Q. grandiflora leaves were assessed against Plasmodium falciparum, Trypanosoma Cruzi, and Trypanosoma brucei gambienseNo fraction showed relevant cytotoxicity and hemolysis activityAll the fractions presented antiplasmodial and trypanocidal activitiesThree fractions with moderate antiplasmodial activity (49< IC₅₀ <56 μg/mL)Four fractions with high activity against bloodstream forms of T. brucei gambiense (8.0< IC₅₀ <15 μg/mL). Abbreviations used: CQ: Chloroquine, DMSO: Dimethyl sulfoxide, HEPES: 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid, HMI: Modified Iscove's medium, IC₅₀: Concentration inhibiting 50% of parasite growth, IC₉₀: Concentration inhibiting 90% of parasite growth, MTT: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, RPMI: Roswell Park Memorial Institute, SD: Standard deviation, SI: Ratio of cytotoxicity to biological activity - TC₅₀/IC₅₀, TC₅₀: Concentration causing 50% of cell growth inhibition, TC₉₀: Concentration causing 90% of cell growth inhibition, TLC: Thin-layer chromatography.

Chemical Characterization and Trypanocidal, Leishmanicidal and Cytotoxicity Potential of Lantana camara L. (Verbenaceae) Essential Oil

Drug resistance in the treatment of neglected parasitic diseases, such as leishmaniasis and trypanosomiasis, has led to the search and development of alternative drugs from plant origins. In this context, the essential oil extracted by hydro-distillation from Lantana camara leaves was tested against Leishmania braziliensis and Trypanosoma cruzi. The results demonstrated that L. camara essential oil inhibited T. cruzi and L. braziliensis with IC₅₀ of 201.94 μg/mL and 72.31 μg/mL, respectively. L. camara essential oil was found to be toxic to NCTC929 fibroblasts at 500 μg/mL (IC₅₀ = 301.42 μg/mL). The composition of L. camara essential oil analyzed by gas chromatography–mass spectrometry (GC/MS) revealed large amounts of (E)-caryophyllene (23.75%), biciclogermacrene (15.80%), germacrene D (11.73%), terpinolene (6.1%), and sabinene (5.92%), which might be, at least in part, responsible for its activity. Taken together, our results suggest that L. camara essential oil may be an important source of therapeutic agents for the development of alternative drugs against parasitic diseases.