Capsicum baccatum Red Pepper Prevents Cardiometabolic Risk in Rats Fed with an Ultra-Processed Diet.

Metabolic syndrome is a serious health condition reaching epidemic proportions worldwide and is closely linked to an increased risk of cardiovascular problems. The lack of appropriate treatment paves the way for developing new therapeutic agents as a high priority in the current research. In this study, we evaluated the protective effects of Capsicum baccatum red pepper on metabolic syndrome scenarios induced by an ultra-processed diet in rats. After four months, the ultra-processed diet increased central obesity, triglycerides, total cholesterol, LDL-cholesterol plasma levels, and impaired glucose tolerance. The oral administration of C. baccatum concomitantly with the ultra-processed diet avoided the accumulation of adipose tissue in the visceral region, reduced the total cholesterol and LDL fraction, and improved glucose homeostasis, factors commonly associated with metabolic syndrome. The data presented herein reveal an important preventive action of C. baccatum in developing metabolic disorders among animals fed a hypercaloric diet, significantly reducing their cardiometabolic risk. Allied with the absence of toxic effects after chronic use, our study suggests C. baccatum red pepper as a secure and enriched source of bioactive compounds promising to protect against pathological processes associated with metabolic syndrome.

Novel Antimicrobial 8-Hydroxyquinoline-Based Agents: Current Development, Structure-Activity Relationships, and Perspectives.

The search for new antimicrobials is imperative due to the emergent resistance of new microorganism strains. In this context, revisiting known classes like 8-hydroxyquinolines could be an interesting strategy to discover new agents. The 8-hydroxyquinoline derivatives nitroxoline and clioquinol are used to treat microbial infections; however, these drugs are underused, being available in few countries or limited to topical use. After years of few advances, in the last two decades, the potent activity of clioquinol and nitroxoline against several targets and the privileged structure of 8-hydroxyquinoline nucleus have prompted an increased interest in the design of novel antimicrobial, anticancer, and anti-Alzheimer agents based on this class. Herein, we discuss the current development and antimicrobial structure-activity relationships of this class in the perspective of using the 8-hydroxyquinoline nucleus for the search for novel antimicrobial agents. Furthermore, the most investigated molecular targets concerning 8-hydroxyquinoline derivatives are explored in the final section.

Rapid size-exclusion high performance liquid chromatography method for the quality control of amyloid-ß oligomers.

Amyloid-ß (Aß) dysmetabolism is thought to be the main trigger for neurodegenerative events in Alzheimer's disease (AD). In particular, soluble Aß oligomers (AßOs) are proposed as key mediators of synaptic and cognitive dysfunction in AD. Over the past few decades, AßOs prepared from synthetic Aß have been widely applied in vitro and in vivo, the so-called chemical models of AD, uncovering their multiple neurotoxic mechanisms. However, the lack of a reliable quality control (QC) for synthetic AßOs may reflect poor experimental reproducibility. In keeping with this, we optimized and validated a rapid and reproducible SECHPLC method using fluorescence detection for the QC of synthetic AßOs. Our analytical method offers an unprecedent alternative to improve the reproducibility of AD chemical models.

Limonene and Perillyl Alcohol Derivatives: Synthesis and Anticancer Activity.

Limonene and perillyl alcohol are natural monoterpenes that have attracted the attention of medicinal chemists due to their promising anticancer activities. Considering this, both compounds were explored as scaffolds to obtain various derivatives with anticancer activity. In this review, the data are organized for the first time, with a focus on the synthetic methods and strategies to obtain the derivatives throughout the period from 2000 to 2020. A brief discussion regarding the structure and activity relationships of the most active derivatives, stereoisomers, and their mechanisms of action is presented. Among the active compounds, a series of limonenes with thiosemicarbazone groups and perillyl alcohol hybrids with glycosides or drugs are illustrated. Taking all of this into account, this review may help researchers develop new promising anticancer candidates based on the structures of limonene and perillyl alcohol.

Modeling Diet-Induced Metabolic Syndrome in Rodents.

Standardized animal models represent one of the most valuable tools available to understand the mechanism underlying the metabolic syndrome (MetS) and to seek for new therapeutic strategies. However, there is considerable variability in the studies conducted with this essential purpose. This review presents an updated discussion of the most recent studies using diverse experimental conditions to induce MetS in rodents with unbalanced diets, discusses the key findings in metabolic outcomes, and critically evaluates what we have been learned from them and how to advance in the field. The study includes scientific reports sourced from the Web of Science and PubMed databases, published between January 2013 and June 2020, which used hypercaloric diets to induce metabolic disorders, and address the impact of the diet on metabolic parameters. The collected data are used as support to discuss variables such as sex, species, and age of the animals, the most favorable type of diet, and the ideal diet length to generate metabolic changes. The experimental characteristics propose herein improve the performance of a preclinical model that resembles the human MetS and will guide researchers to investigate new therapeutic alternatives with confidence and higher translational validity.

Amyloid-ß oligomers in cellular models of Alzheimer's disease.

Amyloid-ß (Aß) dysmetabolism is tightly associated with pathological processes in Alzheimer's disease (AD). Currently, it is thought that, in addition to Aß fibrils that give rise to plaque formation, Aß aggregates into non-fibrillar soluble oligomers (AßOs). Soluble AßOs have been extensively studied for their synaptotoxic and neurotoxic properties. In this review, we discuss physicochemical properties of AßOs and their impact on different brain cell types in AD. Additionally, we summarize three decades of studies with AßOs, providing a compelling bulk of evidence regarding cell-specific mechanisms of toxicity. Cellular models may lead us to a deeper understanding of the detrimental effects of AßOs in neurons and glial cells, putatively shedding light on the development of innovative therapies for AD.

Foamy matters: an update on Quillaja saponins and their use as immunoadjuvants.

Immunoadjuvant Quillaja spp. tree saponins stimulate both cellular and humoral responses, significantly widening vaccine target pathogen spectra. Host toxicity of specific saponins, fractions and extracts may be rather low and further reduced using lipid-based delivery systems. Saponins contain a hydrophobic central aglycone decorated with several sugar residues, posing a challenge for viable chemical synthesis. These, however, may provide simpler analogs. Saponin chemistry affords characteristic interactions with cell membranes, which are essential for its mechanism of action. Natural sources include Quillaja saponaria barks and, more recently, Quillaja brasiliensis leaves. Sustainable large-scale supply can use young plants grown in clonal gardens and elicitation treatments. Quillaja genomic studies will most likely buttress future synthetic biology-based saponin production efforts.

Extracts of the unripe fruit of Ilex paraguariensis as a potential chemical control against the golden apple snail Pomacea canaliculata (Gastropoda, Ampullariidae).

Plant extracts can provide a viable alternative to controlling many crop pests. This study sought to assess the efficacy of vegetable extracts of the unripe fruits of Ilex paraguariensis (yerba maté) for chemical control of the channeled apple snail (Pomacea canaliculata) and of non-target species as the South American catfish (Rhamdia quelen) under laboratory conditions. In P. canaliculata, the LC50 of the decoction extract was 31.39 mg.L-1 and the LT50 was over 26 h. The LC50 of the butanol extract was 24.75 mg.L-1 and the LT50 was in the range of 28 to 32 h. In juvenile R. quelen, the LC50 of the decoction was 17.98 mg.L-1 and the LT50 was in the range of 10-12 h. These extracts are particularly attractive considering the source of compounds and their effectiveness as molluscicides.

SERCA plays a crucial role in the toxicity of a betulinic acid derivative with potential antimalarial activity.

Malaria is one of the most significant infectious diseases that affect poor populations in tropical areas throughout the world. Plants have been shown to be a good source for the development of new antimalarial chemotherapeutic agents, as shown for the discovery of quinine and artemisinin derivatives. Our research group has been working with semisynthetic triterpene derivatives that show potential antimalarial activity toward different strains of Plasmodium falciparum by specifically modulating calcium pathways in the parasite. Promising results were obtained for nanomolar concentrations of the semisynthetic betulinic acid derivative LAFIS13 against the P. falciparum 3D7 strain in vitro, with a selectivity index of 18 compared to a mammalian cell line. Continuing these studies, we present here in vitro and in vivo toxicological evaluations of this compound, followed by docking studies with PfATP6, a sarco/endoplasmic reticulum Ca+2-ATPase (SERCA) protein. LAFIS13 showed an LD50 between 300 and 50 mg/kg, and the acute administration of 50 mg/kg (i.p.) had no negative effects on hematological, biochemical and histopathological parameters. Based on the results of the in vitro assays, LAFIS13 not exerted significant effects on coagulation parameters of human peripheral blood, but a hemolytic activity was verified at higher concentrations. According to the molecular docking study, the PfATP6 protein may be a target for LAFIS13, which corroborates its previously reported modulatory effects on calcium homeostasis in the parasite. Notably, LAFIS13 showed a higher selectivity for the mammalian SERCA protein than for PfATP6, thus impairing the selectivity between parasite and host. In summary, the direct interaction with calcium pumps and the hemolytic potential of the compound proved to be plausible mechanism of LAFIS13 toxicity.

Semisynthesis, cytotoxicity, antimalarial evaluation and structure-activity relationship of two series of triterpene derivatives.

In this report, we describe the semisynthesis of two series of ursolic and betulinic acid derivatives through designed by modifications at the C-3 and C-28 positions and demonstrate their antimalarial activity against chloroquine-resistant P. falciparum (W2 strain). Structural modifications at C-3 were more advantageous to antimalarial activity than simultaneous modifications at C-3 and C-28 positions. The ester derivative, 3ß-butanoyl betulinic acid (7b), was the most active compound (IC50 = 3.4 µM) and it did not exhibit cytotoxicity against VERO nor HepG2 cells (CC50 > 400 µM), showing selectivity towards parasites (selectivity index > 117.47). In combination with artemisinin, compound 7b showed an additive effect (CI = 1.14). While docking analysis showed a possible interaction of 7b with the Plasmodium protease PfSUB1, with an optimum binding affinity of -7.02 kcal/mol, the rather low inhibition displayed on a Bacillus licheniformis subtilisin A protease activity assay (IC50 = 93 µM) and the observed accumulation of ring forms together with a delay of appearance of trophozoites in vitro suggests that the main target of 3ß-butanoyl betulinic acid on Plasmodium may be related to other molecules and processes pertaining to the ring stage. Therefore, compound 7b is the most promising compound for further studies on antimalarial chemotherapy. The results obtained in this study provide suitable information about scaffolds to develop novel antimalarials from natural sources.

Leaf saponins of Quillaja brasiliensis enhance long-term specific immune responses and promote dose-sparing effect in BVDV experimental vaccines.

Saponin-based adjuvants are promising adjuvants that enhance both humoral and T-cell-mediated immunity. One of the most used natural products as vaccine adjuvants are Quillaja saponaria bark saponins and its fraction named Quil A®. Despite that, its use has been restricted for human use due to safety issues. As an alternative, our group has been studying the congener species Quillaja brasiliensis saponins and its performance as vaccine adjuvants, which have shown to trigger humoral and cellular immune responses comparable to Quil A® but with milder side effects. Here, we studied a semi purified aqueous extract (AE) and a previously little characterized saponin-enriched fraction (QB-80) from Q. brasiliensis as vaccine adjuvants and an inactivated virus (bovine viral diarrhea virus, BVDV) antigen co-formulated in experimental vaccines in mice model. For the first time, we show the spectra pattern of the Q. brasiliensis saponins by MALDI-TOF, a novel and cost-effective method that could be used to characterize different batches during saponins production. Both AE and QB-80 exhibited noteworthy chemical similarities to Quil A®. In addition, the haemolytic activity and toxicity were assessed, showing that both AE and QB-80 were less toxic than Quil A®. When subcutaneously inoculated in mice, both fractions promoted long-term strong antibody responses encompassing specific IgG1 and IgG2a, enhanced the avidity of IgG antibodies, induced a robust DTH reaction and significantly increased IFN-É£ production in T CD4+ and T CD8+ cells. Furthermore, we have proven herein that AE has the potential to promote dose-sparing, substantially reducing the dose of antigen required for the BVDV vaccines and still eliciting a mixed Th1/Th2 strong immune response. Based on these results, and considering that AE is a raw extract, easier and cheaper to produce than commercially available saponins, this product can be considered as candidate to be escalated from experimental to industrial uses.

Chemical analysis and antiviral activity evaluation of Baccharis anomala.

The chemical composition and antiviral activity of aqueous extract from Baccharis anomala was studied by bioactivity-guided fractionation. Ethanol precipitation and fractionation by molecular permeation allowed the separation of the anti-herpes simplex virus 1 (HSV-1) active fraction from aqueous extract (Fraction B). Natural Product Reagent A, FeCl3 and thin-layer chromatography indicated the presence of phenolic compounds in the aqueous extract. Fraction B showed pronounced antiviral activity when tested with HSV-1 strains VR733/ATCC and Acyclovir-resistant 29-R, displaying virucidal but not virustatic activity.

Purification of an Immunoadjuvant Saponin Fraction from Quillaja brasiliensis Leaves by Reversed-Phase Silica Gel Chromatography.

Saponins include a large variety of molecules that find several applications in pharmacology. The use of Quillaja saponaria saponins as immunological adjuvants in vaccines is of interest due to their capacity to stimulate both humoral and cellular responses. The congener species Q. brasiliensis has saponins with chemical similarities and adjuvant activity comparable to that of Q. saponaria fraction Quil-A®, with additional advantages of showing lower toxicity and reduced hemolytic activity. Here we describe in detail the methods for preparing the aqueous extract from Q. brasiliensis leaves, as well as the purification of the bioactive saponin fraction QB-90 using silica reversed-phase chromatography.

Red Pepper (Capsicum baccatum) Extracts Present Anti-Inflammatory Effects In Vivo and Inhibit the Production of TNF-α and NO In Vitro.

Capsicum baccatum is the most consumed red pepper species in Brazil. Our previous studies demonstrated the anti-inflammatory properties of its crude extract, whose activity is yet to be fully characterized. Herein, we examined the anti-inflammatory in vivo effects of enriched extracts obtained through bioguided fractionation as dichloromethane (DCM), butanol (BUT), and residual aqueous (RAq) extracts and its influence on inflammatory mediators produced by macrophages in vitro. We demonstrated that all C. baccatum extracts presented anti-inflammatory activity in vivo. In addition, we showed that BUT and RAq were more effective in inhibiting the neutrophil migration induced by carrageenan (Cg) to peritoneal cavity and both extracts inhibited paw edema induced by Cg, prostaglandin E2, and histamine in mice. Furthermore, the pretreatment with C. baccatum extracts significantly reduced the levels of myeloperoxidase (MPO) in the paw tissues of mice compared with the carrageenan group. Once again, RAq and BUT caused the greatest reduction in MPO levels. Moreover, it was demonstrated for the first time that C. baccatum inhibited the nitric oxide and tumor necrosis factor-alpha production by lipopolysaccharide/interferon gamma (IFN-γ)-stimulated macrophages. These anti-inflammatory effects seem to be at least, in part, independent of capsaicin. Hence, red pepper has bioactive compounds and might be used to develop food-derived extracts to treat related inflammatory diseases.

Larvicidal activity of natural and modified triterpenoids against Aedes aegypti (Diptera: Culicidae).

BACKGROUND: Insecticide resistance to commonly used substances demands new molecules for the chemical control of the dengue vector Aedes aegypti. Because natural product sources have been an alternative to obtain larvicidal compounds, the aim of this study was to evaluate the triterpenoids betulinic (BA) and ursolic (UA) acids and their semi-synthetic derivatives against larval Ae. aegypti. BA, UA, ten derivatives modified at the C-3 position and a positive control (diflubenzuron) were evaluated. Larvicidal assays were carried out with early fourth-instar larvae, and mortality was observed between 48 and 96 h. Doses from 200 to 10 ppm were used to calculate lethal concentrations (LCs). RESULTS: Natural compounds, i.e. UA and BA, had the lowest LCs (LC50 of 112 and 142 ppm respectively), except for the modified compound 2b (LC50 of 130 ppm). Larvicidal activity increased significantly from 48 to 96 h for all the compounds evaluated, ranging from 20 to 50% after 48 h and from 48 to 76% after 96 h. Some derivatives, e.g. 2a and 2d, had up to a three-fold larvicidal activity increase from 48 to 96 h. CONCLUSION: BA, UA and their derivatives showed larvicidal activity against Ae. aegypti larvae, increasing significantly from 48 to 96 h. The presence of a hydroxyl group is essential for larvicidal potential in these triterpenoids. © 2016 Society of Chemical Industry.

A rabies vaccine adjuvanted with saponins from leaves of the soap tree (Quillaja brasiliensis) induces specific immune responses and protects against lethal challenge.

Quillaja brasiliensis (Quillajaceae) is a saponin producing species native from southern Brazil and Uruguay. Its saponins are remarkably similar to those of Q. saponaria, which provides most of the saponins used as immunoadjuvants in vaccines. The immunostimulating capacities of aqueous extract (AE) and purified saponin fraction (QB-90) obtained from leaves of Q. brasiliensis were favorably comparable to those of a commercial saponin-based adjuvant preparation (Quil-A) in experimental vaccines against bovine herpesvirus type 1 and 5, poliovirus and bovine viral diarrhea virus in mice model. Herein, the immunogenicity and protection efficacy of rabies vaccines adjuvanted with Q. brasiliensis AE and its saponin fractions were compared with vaccines adjuvanted with either commercial Quil-A or Alum. Mice were vaccinated with one or two doses (on days 0 and 14) of one of the different vaccines and serum levels of total IgG, IgG1 and IgG2a were quantified over time. A challenge experiment with a lethal dose of rabies virus was carried out with the formulations. Viral RNA detection in the brain of mice was performed by qPCR, and RNA copy-numbers were quantified using a standard curve of in vitro transcribed RNA. All Q. brasiliensis saponin-adjuvanted vaccines significantly enhanced levels of specific IgG isotypes when compared with the no adjuvant group (P ≤ 0.05). Overall, one or two doses of saponin-based vaccine were efficient to protect against the lethal rabies exposure. Both AE and saponin fractions from Q. brasiliensis leaves proved potent immunological adjuvants in vaccines against a lethal challenge with a major livestock pathogen, hence confirming their value as competitive or complementary sustainable alternatives to saponins of Q. saponaria.

Quillaja brasiliensis saponins induce robust humoral and cellular responses in a bovine viral diarrhea virus vaccine in mice.

A saponin fraction extracted from Quillaja brasiliensis leaves (QB-90) and a semi-purified aqueous extract (AE) were evaluated as adjuvants in a bovine viral diarrhea virus (BVDV) vaccine in mice. Animals were immunized on days 0 and 14 with antigen plus either QB-90 or AE or an oil-adjuvanted vaccine. Two-weeks after boosting, antibodies were measured by ELISA; cellular immunity was evaluated by DTH, lymphoproliferation, cytokine release and single cell IFN-γ production. Serum anti-BVDV IgG, IgG1 and IgG2b were significantly increased in QB-90- and AE-adjuvanted vaccines. A robust DTH response, increased splenocyte proliferation, Th1-type cytokines and enhanced production of IFN-γ by CD4(+) and CD8(+) T lymphocytes were detected in mice that received QB-90-adjuvanted vaccine. The AE-adjuvanted preparation stimulated humoral responses but not cellular immune responses. These findings reveal that QB-90 is capable of stimulating both cellular and humoral immune responses when used as adjuvant.

Quercetin derivative induces cell death in glioma cells by modulating NF-κB nuclear translocation and caspase-3 activation.

Treated glioblastoma multiforme (GBM) patients only survive 6 to 14months after diagnosis; therefore, the development of novel therapeutic strategies to treat gliomas remains critically necessary. Considering that phenolic compounds, like quercetin, have the potential to be used in the chemotreatment of gliomas and that some flavonoids exhibit the ability to cross the BBB, in the present study, we investigated the antitumor effect of flavonoids (including chalcones, flavones, flavanones and flavonols). Initially their activities were tested in C6 glioma cells screened using the MTT method, resulting in the selection of chalcone 2 whose feasibility was confirmed by a Trypan Blue exclusion assay in the low µM range on C6 glioma cells. Cell cycle and apoptotic death analyses on C6 glioma cells were also performed, and chalcone 2 increased the apoptosis of the cells but did not alter the cell cycle progression. In addition, treatments with these two compounds were not cytotoxic to hippocampal organotypic cultures, a model of healthy neural cells. Furthermore, the results indicated that 2 induced apoptosis by inhibition of NF-κB and activation of active caspase-3 in glioma cells, suggesting that it is a potential prototype to develop new treatments for GBM in the future.

Synthesis and biological evaluation of hydrazone derivatives as antifungal agents.

Emerging yeasts are among the most prevalent causes of systemic infections with high mortality rates and there is an urgent need to develop specific, effective and non-toxic antifungal agents to respond to this issue. In this study 35 aldehydes, hydrazones and hydrazines were obtained and their antifungal activity was evaluated against Candida species (C. parapsilosis, C. tropicalis, C. krusei, C. albicans, C. glabrata and C. lusitaneae) and Trichosporon asahii, in an in vitro screening. The minimum inhibitory concentrations (MICs) of the active compounds in the screening was determined against 10 clinical isolates of C. parapsilosis and 10 of T. asahii. The compounds 4-pyridin-2-ylbenzaldehyde] (13a) and tert-butyl-(2Z)-2-(3,4,5-trihydroxybenzylidine)hydrazine carboxylate (7b) showed the most promising MIC values in the range of 16-32 µg/mL and 8-16 µg/mL, respectively. The compounds' action on the stability of the cell membrane and cell wall was evaluated, which suggested the action of the compounds on the fungal cell membrane. Cell viability of leukocytes and an alkaline comet assay were performed to evaluate the cytotoxicity. Compound 13a was not cytotoxic at the active concentrations. These results support the discovery of promising candidates for the development of new antifungal agents.

Investigation of antimalarial activity, cytotoxicity and action mechanism of piperazine derivatives of betulinic acid.

OBJECTIVES: To semisynthesise piperazine derivatives of betulinic acid to evaluate antimalarial activity, cytotoxicity and action mechanism. METHODS: The new derivatives were evaluated against the CQ-sensitive Plasmodium falciparum 3D7 strain by flow cytometry (FC) using YOYO-1 as stain. Cytotoxicity of 4a and 4b was performed with HEK293T cells for 24 and 48 h by MTT assay. The capability of compound 4a to modulate Ca(2+) in the trophozoite stage was investigated. The trophozoites were stained with Fluo4-AM and analysed by spectrofluorimetry. Effect on mitochondrial membrane potential (ΔΨm) was tested for 4a by FC with DiOC6 (3) as stain. For ß-haematin assay, 4a was incubated for 24 h with reagents such as haemin, and the fluorescence was measured by FlexStation at an absorbance of 405 nm. RESULTS: Antimalarial activity of 4a and 4b was IC50 = 1 and 4 µm, respectively. Compound 4a displayed cytotoxicity with IC50 = 69 and 29 µm for 24 and 48 h, respectively, and 4b was not cytotoxic at the tested concentrations. Addition of 4a leads to an increase in cytosolic Ca(2+) . We have measured ΔΨm after treating parasites with the compound. Data on Figure 4a show that mitochondria were not affected. The action mechanism for 4a, inhibition of ß-haematin formation (17%), was lower than CQ treatment (83%; IC50 = 3 mm). CONCLUSION: Compound 4a showed excellent antimalarial activity, and its action mechanism is involved in Ca(2+) pathway(s).