Bioactive Natural Products as Potential Candidates to Control Aedes aegypti, the Vector of Dengue

Targeting Breast Cancer-Derived Stem Cells by Dietary Phytochemicals: A Strategy for Cancer Prevention and Treatment

Breast cancer is heterogeneous disease with variable prognosis and therapeutic response. Approximately, 70% of diagnosed breast cancer represents the luminal A subtype. This subpopulation has a fair prognosis with a lower rate of relapse than the other clinical subtypes. Acquisition of stemness in luminal A subtype modifies the phenotype plasticity to accomplish increased aggressiveness and therapeutic resistance. Therefore, targeting luminal A-derived breast cancer stem cells (BCSCs) could be a promising strategy for its prevention and treatment. Extensive studies reveal that dietary phytochemicals have the potential to target BCSCs by modulating the molecular and signal transduction pathways. Dietary phytochemicals alone or in combination with standard therapeutic modalities exert higher efficacy in targeting BCSCs through changes in stemness, self-renewal properties and hypoxia-related factors. These combinations offer achieving higher radio- and chemo- sensitization through alteration in the key signaling pathways such as AMPK, STAT3, NF-ĸB, Hedgehog, PI3K/Akt/mTOR, Notch, GSK3β, and Wnt related to cancer stemness and drug resistance. In this review, we highlight the concept of targeting luminal A-derived BCSCs with dietary phytochemicals by summarizing the pathways and underlying mechanism(s) involved during therapeutic resistance.

Advances in the Biotechnological Potential of Brazilian Marine Microalgae and Cyanobacteria

Due the worldwide need to improve care for the environment and people, there is a great demand for the development of new renewable, sustainable, and less polluting technologies for food, health, and environmental industries. The marine environment is one of the main areas investigated in the search for alternatives to the raw materials currently used. Thereby, cyanobacteria and marine microalgae are microorganisms that are capable of producing a diverse range of metabolites useful for their cellular maintenance, but that also represent a great biotechnological potential. Due its great potential, they have an enormous appeal in the scientific research where, the biological activity of metabolites produced by these microorganisms, such as the antioxidant action of sterols are, some examples of biotechnological applications investigated around the world. Thereby, Brazil due to its extensive biodiversity, has high potential as a raw material supplier of marine waters, researching cyanobacteria and microalgae metabolites and their applications. Thus, this rapid review intends to present some important contributions and advances from Brazilian researchers, using the biomass of Brazilian cyanobacteria and marine microalgae, in order to illustrate the value of what has already been discovered and the enormous potential of what remains unexplored so far.

Structural diversity, biosynthetic aspects, and LC-HRMS data compilation for the identification of bioactive compounds of Lepidium meyenii

Lepidium meyenii is widely used as a food supplement because of its medicinal properties and nutritional value. Several studies have described the identification of its metabolites and LC-HRMS analysis is one of the most frequently used analytical tool to assess plant extract metabolome. Nevertheless, proper and reliable metabolite identification is essential for such metabolomics studies. Although HRMS distinguishes even minor changes in the metabolites structures, highly specialized secondary metabolites might not be present on available databases imposing serious obstacles for metabolite identification This review discusses the structural diversity and biosynthetic aspects of 101 compounds previously identified in L. meyenii. More importantly, we have compiled the available information on expected and experimental high-resolution masses of L. meyenii compounds. This will help upcoming metabolomics studies not only of L. meyenii but also other plant species by providing the necessary tools to perform proper and reliable identification of their bioactive compounds.

Hydrophobic Nanoprecipitates of β-Cyclodextrin/Avermectins Inclusion Compounds Reveal Insecticide Activity against Aedes aegypti Larvae and Low Toxicity against Fibroblasts

In the present work, hydrophobic nanoprecipitates (HNPs) of inclusion complexes formed between β-cyclodextrin (βCD) and the avermectins (AVMs) named eprinomectin (EPRI) and ivermectin (IVER) were synthesized and characterized, and their larvicidal activity against Aedes aegypti and human safety against fibroblasts were evaluated. Initially, thermogravimetric analysis/differential thermal analysis data revealed that inclusion increased the thermal stability of AVMs in the presence of βCD. Nuclear magnetic resonance experiments and density functional theory calculations pointed out the inclusion of the benzofuran ring of the two AVMs in the βCD cavity. Isothermal titration calorimetry experiments allowed identification of different binding constants for EPRI/βCD ( K_b = 1060) and βCD/IVER ( K_b = 1700) systems, despite the structural similarity. Dynamic light scattering titrations of AVMs' dimethyl sulfoxide solution in βCD aqueous solution demonstrated that the formed HNPs have lower sizes in the presence of βCD. Finally, the inclusion of EPRI in βCD increased its larval toxicity and reduced its human cytotoxicity, while for IVER/βCD no beneficial effect was observed upon inclusion. These results were rationalized in terms of structural differences between the two molecules. Finally, the EPRI/βCD complex has great potential as an insecticide against A. aegypti larvae with high human safety.

Larvicidal efficacies of plants from Midwestern Brazil: melianodiol from Guarea kunthiana as a potential biopesticide against Aedes aegypti

A total of 36 ethanol extracts from different anatomical parts of 27 plant species (18 families), native to the Pantanal and Cerrado biomes in Midwest Brazil, was assessed for their effect against Aedes aegypti larvae, the vector of dengue, hemorrhagic dengue, Zika and chikungunya fevers. Only the extract obtained from seeds of Guarea kunthiana (Meliaceae) proved active (LC50 = 169.93 μg/mL). A bioassay-guided investigation of this extract led to the isolation and identification of melianodiol, a protolimonoid, as the active constituent (LC50 = 14.44 mg/mL). Meliantriol, which was also obtained from the bioactive fraction, was nevertheless devoid of any larval toxicity, even at the highest concentration tested (LC50 > 100.0 mg/mL). These results indicate that the larvicidal activity of melianodiol stems from the presence of the carbonyl moiety at C-3 in the 21,23-epoxy-21,24,25-trihydroxy-tirucall-7-ene-type skeleton. The structures of both protolimonoids were established on the basis of spectral methods (1H and 13C NMR and MS). This is the first report on the toxicity of melianodiol against Ae. aegypti larvae. Based on the results, melianodiol can be regarded as a potential candidate for use as an ecologically sound biocontrol agent for reducing the larval population of this vector.

Phytochemical screening, antioxidant and antibacterial activities of extracts prepared from different tissues of Schinus terebinthifolius Raddi that occurs in the coast of Bahia, Brazil

BACKGROUND

Schinus terebinthifolius is widely used in traditional medicine by Brazilian quilombola and indigenous communities for treatment of several diseases. Extracts from different tissues are being used to produce creams to treat cervicitis and cervicovaginitis. However, most studies are limited to the assessment of the essential oils and extracts obtained from the leaves.

OBJECTIVE

The aim was to evaluate antioxidant and antibacterial activities, to assess the phytochemical profile and to quantify total phenolic compounds of various extracts prepared from S. terebinthifolius grown in the coast of Bahia, Brazil.

MATERIALS AND METHODS

Extracts were obtained by hot continuous extraction (soxhlet) and by maceration. Quantification of phenolic compounds was performed using the Folin-Ciocalteu method and antioxidant properties were assessed by 2,2-diphenyl-1-picrylhydrazyl radical scavenging assay. Phytochemical screening was performed as described by in the literature and antibacterial activity against Enterococcus faecalis (ATCC 29212) was determined by the microdilution broth assay.

RESULTS

Extraction method greatly affected the metabolite profile of the extracts. Antioxidant activity varied between 21.92% and 85.76%, while total phenols ranged between 5.44 and 309.03 mg EAG/g of extract. Leaf extract obtained with soxhlet showed minimum inhibitory concentration (MIC) of 15.62 μg/mL, while stem extract obtained by maceration was able to inhibit the growth of E. faecalis at 62.5 μg/mL. Stem bark extracts showed a MIC of 500 μg/mL for both extraction methods, while no inhibition was observed for fruit extracts.

CONCLUSION

In general, total phenolic content, antioxidant and antibacterial activities were higher in samples obtained by soxhlet. Our results provide important clues in order to identify alternative sources of bioactive compounds that can be used to develop new drugs.