In vitro activities of glycoalkaloids from the Solanum lycocarpum against Leishmania infantum

Health Benefits of the Alkaloids from Lobeira (Solanum lycocarpum St. Hill): A Comprehensive Review

Solanum is the largest genus within the Solanaceae family and has garnered considerable attention in chemical and biological investigations over the past 30 years. In this context, lobeira or "fruta-do-lobo" (Solanum lycocarpum St. Hill), a species predominantly found in the Brazilian Cerrado, stands out. Beyond the interesting nutritional composition of the fruits, various parts of the lobeira plant have been used in folk medicine as hypoglycemic, sedative, diuretic, antiepileptic, and antispasmodic agents. These health-beneficial effects have been correlated with various bioactive compounds found in the plant, particularly alkaloids. In this review, we summarize the alkaloid composition of the lobeira plant and its biological activities that have been reported in the scientific literature in the last decades. The compiled data showed that lobeira plants and fruits contain a wide range of alkaloids, with steroidal glycoalkaloid solamargine and solasonine being the major ones. These alkaloids, but not limited to them, contribute to different biological activities verified in alkaloid-rich extracts/fractions from the lobeira, including antioxidant, anti-inflammatory, anticancer, antigenotoxic, antidiabetic, antinociceptive, and antiparasitic effects. Despite the encouraging results, additional research, especially toxicological, pre-clinical, and clinical trials, is essential to validate these human health benefits and ensure consumers' safety and well-being.

New insights into the mechanism of action of the cyclopalladated complex - CP2 in Leishmania: Calcium Dysregulation, Mitochondrial Dysfunction and Cell Death

The current treatment of leishmaniasis is based on few drugs that present several drawbacks such as high toxicity, difficult administration route, and low efficacy. These disadvantages raise the necessity to develop novel antileishmanial compounds allied to a comprehensive understanding of their mechanisms of action. Here, we elucidate the probably mechanism of action of the antileishmanial binuclear cyclopalladated complex [Pd(dmba)(μ-N₃)]₂ (CP2) in Leishmania amazonensis. CP2 causes oxidative stress in the parasite resulting in disruption of mitochondrial Ca²⁺ homeostasis, cell cycle arrest at S-phase, increasing the ROS production and overexpression of stress-related and cell detoxification proteins, collapsing the Leishmania mitochondrial membrane potential and promotes apoptotic-like features in promastigotes leading to necrosis or directs programmed cell death (PCD)-committed cells toward necrotic-like destruction. Moreover, CP2 is able to reduce the parasite load in both liver and spleen in Leishmania infantum-infected hamsters when treated for 15 days with 1.5 mg/Kg/day CP2, expanding its potential application in addition to the already known effectiveness on cutaneous leishmaniasis for the treatment of visceral leishmaniasis, showing the broad spectrum of action of this cyclopalladated complex. The data herein presented bring new insights into the CP2 molecular mechanisms of action, assisting to promote its rational modification to improve both safety and efficacy.

In vitro evaluation of hydroalcoholic extracts of Capparis Spinosa L., Ricinus communis, and Solanum luteum on Leishmania major (MRHO/IR/75/ER) promastigotes

Background: Plant extracts or compounds derived from plants are a valuable source for finding new anti-leishmaniasis drugs. Objective: In this study, Capparis spinosa L., Ricinus communis, and Solanum luteum were used as lethal agents for the promastigotes of Leishmania major parasites in the culture medium. Methods: Diluted extracts of 12.5, 100, and 500 mg/mL were prepared from medicinal plant dried extracts. Glucantime at a concentration of 500 mg/mL was used as a positive control. Results: For all three extracts, concentrations of 100 and 500 mg/mL could kill promastigotes at higher rates and speeds compared to other concentrations. The high concentrations of extracts (500 mg/mL) presented similar effects. According to the findings, hydroalcoholic extract of C. Spinosa L. presented considerably lower antiparasitic effects, and S. luteum and R. communis extracts were could kill most of the parasitic promastigotes at higher doses. The ANOVA test did not show any significant viability percentage difference of Leishmania extracts between different extract types. Conclusions: In this study, the lethal effects of R. communis and S. luteum hydroalcoholic extracts on L. major promastigotes were found to be stronger than the C. Spinosa L. extract.

Impact of ripening on the health-promoting components from fruta-do-lobo (Solanum lycocarpum St. Hill)

Fruta-do-lobo (Solanum lycocarpum St. Hill) is an underutilized native fruit commonly found in the Brazilian Cerrado, very known due to the presence of glycoalkaloids. In this work we evaluated the biochemical changes on carbohydrates, phenolic and alkaloids during ripening of fruta-do-lobo using chromatographic and spectrometric techniques. During ripening, we observed an increase in glucose, fructose and sucrose, while oligosaccharides levels varied. Chlorogenic acid isomers represented 80% of the identified phenolic compounds in unripe stage, but they reduced during ripening, resulting in predominance of p-coumaroylquinic acid (peel and pulp) and 1-O-sinapoyl-glucoside (seeds). Statistical analysis shows that the unripe fractions were richer in alkaloids compounds, which were the most important for antioxidant activity. Molecular network analysis summarizes the compound changes during ripening, especially regarding the alkaloid compounds, with a reduction of around 85% of solamargine abundance. These data show that fruta-do-lobo can presents different chemical compositions due their ripening stage providing support for future research aimed to the application of these compounds in glycemia control or uses of their extracts with higher content of alkaloids compounds.

Yeasts in native fruits from Brazilian neotropical savannah: occurrence, diversity and enzymatic potential

Abstract: Cerrado is the second largest phytogeographic domain in Brazil, with a huge ethnobotany variety, including fruit species that stand out for their economic, industrial, biotechnological and medicinal potential. The objective of this study was to characterize the diversity of culturable yeasts and their potential for the production of hydrolytic enzymes in fruits of 13 species of native plants of the Cerrado in Brazil. Sequencing the 26S rRNA gene identified the isolates. The enzymatic potential was evaluated using specific substrates for the enzymes amylases, cellulases, proteases, and pectinases. Nine of the 13 fruit species analyzed showed yeast growth, totaling 82 isolates, identified in 26 species. The phylum Ascomycota predominated over Basidiomycota. The fruits of Butia capitata presented the highest species richness. Candida and Meyerozyma were the most frequent genera. About 57% of the isolates were able to produce at least one of the enzymes analyzed. The species Papiliotrema flavescens, Hanseniaspora meyeri, Meyerozyma guilliermondii, and Rhodotorula mucilaginosa produced all the enzymes tested. The results were found to expand the knowledge about the yeast communities present in fruits of the Cerrado native plants, evidencing the presence of species shared among the plants, and their potential for biotechnological use in the future.

Antimicrobial activity of RP-1 peptide conjugate with ferrocene group

Parasitic diseases are a neglected and serious problem, especially in underdeveloped countries. Among the major parasitic diseases, Leishmaniasis figures as an urgent challenge due to its high incidence and severity. At the same time, the indiscriminate use of antibiotics by the population is increasing together with resistance to medicines. To address this problem, new antibiotic-like molecules that directly kill or inhibit the growth of microorganisms are necessary, where antimicrobial peptides (AMPs) can be of great help. In this work, the ferrocene molecule, one active compound with low levels of in vivo toxicity, was coupled to the N-terminus of the RP1 peptide (derived from the human chemokine CXCL4), aiming to evaluate how this change modifies the structure, biological activity, and toxicity of the peptide. The peptide and the conjugate were synthesized using the solid phase peptide synthesis (SPPS). Circular dichroism assays in PBS showed that the RP1 peptide and its conjugate had a typical spectrum for disordered structures. The Fc-RP1 presented anti-amastigote activity against Leishmania amazonensis (IC₅₀ = 0.25 μmol L^–1). In comparison with amphotericin B, a second-line drug approved for leishmaniasis treatment, (IC₅₀ = 0.63 μmol L^-1), Fc-RP1 was more active and showed a 2.5-fold higher selectivity index. The RP1 peptide presented a MIC of 4.3 μmol L^-1 against S. agalactiae, whilst Fc-RP1 was four times more active (MIC = 0.96 μmol L^-1), indicating that ferrocene improved the antimicrobial activity against Gram-positive bacteria. The Fc-RP1 peptide also decreased the minimum inhibitory concentration (MIC) in the assays against E. faecalis (MIC = 7.9 μmol L^-1), E. coli (MIC = 3.9 μmol L^-1) and S. aureus (MIC = 3.9 μmol L^-1). The cytotoxicity of the compounds was tested against HaCaT cells, and no significant activity at the highest concentration tested (500 μg. mL^-1) was observed, showing the high potential of this new compound as a possible new drug. The coupling of ferrocene also increased the vesicle permeabilization of the peptide, showing a direct relation between high peptide concentration and high carboxyfluorescein release, which indicates the action mechanism by pore formation on the vesicles. Several studies have shown that ferrocene destabilizes cell membranes through lipid peroxidation, leading to cell lysis. It is noteworthy that the Fc-RP1 peptide synthesized here is a prototype of a bioconjugation strategy, but it still is a compound with great biological activity against neglected and fish diseases.