Leismanicidal Activity of Propolis Collected in the Semiarid Region of Brazil

Meliponini Geopropolis Extracts Induce ROS Production and Death in Leishmania amazonensis Promastigotes and Axenic Amastigotes In Vitro

Leishmania amazonensis, a cause of cutaneous leishmaniasis in Brazil, is a neglected disease with toxic and inconsistently effective treatments. The parasite's survival depends on managing oxidative stress, making redox-regulating enzymes potential therapeutic targets. Geopropolis, a resinous product from native stingless bees, shows promising antiparasitic effects. This study aims to evaluate the anti-L. amazonensis activity of geopropolis produced by Melipona bicolor, M. marginara, M. mondury, and M. quadrifasciata (two samples), targeting enzymes responsible for the parasite's redox balance. Ethanol extracts of geopropolis produced by each bee (BCRL, MRGT, MNDY, MNDA(1), and MNDA(2), respectively) were analyzed for total phenolics and flavonoids. Promastigotes and axenic amastigotes were treated with various extract concentrations, and parasite viability was assessed using the resazurin reduction method. Cytotoxicity was tested on peritoneal macrophages, RAW 264.7, VERO cell lines (MTT assay), and erythrocytes (hemolysis assay). Additionally, mitochondrial dehydrogenase activity, reactive oxygen species (ROS) production, the inhibition of recombinant arginase, and autophagic activity were also evaluated in treated parasites. MRGT showed the highest levels of phenolics (762 mg GAE/g) and flavonoids (345 mg QE/g). MDRY was more effective against promastigote and axenic amastigote forms (IC50 = 168 and 19.7 µg/mL, respectively). MRGT showed lower cytotoxicity against RAW 264.7 and VERO (CC50 = 654 µg/mL and 981 µg/mL, respectively). Erythrocytes exhibited reduced sensitivity to MNDA(2) (HC50 = 710 µg/mL). The activity of dehydrogenases and LiARG was reduced by treating the parasites with the extracts following the induction of ROS and autophagic activity. These results highlight geopropolis extracts as a source of substances with anti-L. amazonensis activity capable of inducing oxidative stress on the parasite.

Chemical Characterization and Antimicrobial Activity of Green Propolis from the Brazilian Caatinga Biome

Green propolis, particularly from the unique flora of the Brazilian Caatinga biome, has gained significant interest due to its diverse chemical composition and biological activities. This study focuses on the chemical characterization and antimicrobial evaluation of Caatinga green propolis. Twelve compounds were isolated through different chromatographic techniques, including flavanones (naringenin, 7-O-methyleriodictyol, sakuranetin), flavones (hispidulin, cirsimaritin), flavonols (quercetin, quercetin-3-methyl ether, kaempferol, 6-methoxykaempferol, viscosine, penduletin), and one chalcone (kukulkanin B). Using liquid chromatography-quadrupole time-of-flight tandem mass spectrometry (LC-QToF-MS), a total of 55 compounds excluding reference standards were tentatively identified, which include flavonoids, phenolic acids derivatives, and alkaloids, with flavonols, flavanones, and flavones being predominant. Antimicrobial testing against pathogens revealed that the crude extract exhibited low inhibitory activity, against Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecium (VRE) (IC50: 148.4 and 120.98 µg/mL, respectively). Although the isolated compounds showed limited individual activity, a fraction containing sakuranetin and penduletin (Fraction 8) exhibited moderated activity against Cryptococcus neoformans (IC50: 47.86 µg/mL), while a fraction containing quercetin and hispidulin showed moderated activity against VRE (IC50: 16.99 µg/mL). These findings highlight the potential application of Caatinga green propolis as an antimicrobial agent, particularly against resistant bacterial strains, and underscore the importance of synergistic interactions between compounds in enhancing biological effects.

Hydrogel Containing Propolis: Physical Characterization and Evaluation of Biological Activities for Potential Use in the Treatment of Skin Lesions

BACKGROUND

Skin injury affects the integrity of the skin structure and induces the wound healing process, which is defined by a well-coordinated series of cellular and molecular reactions that aim to recover or replace the injured tissue. Hydrogels are a group of promising biomaterials that are able to incorporate active ingredients for use as dressings. This study aimed to synthesize hydrogels with and without propolis extract and evaluate their physical characteristics and biological activities in vitro for potential use as active dressings in the treatment of skin lesions.

METHODS

The antifungal [Candida albicans (C. albicans) and Candida tropicalis (C. tropicalis)] and antibacterial [Staphylococcus aureus (S. aureus), Pseudomonas aeruginosas (P. aeruginosas) and Escherichia coli (E. coli)] activity was assessed by the microdilution method in plates and antioxidant potential by the reduction of the phosphomolybdate complex.

RESULTS

The hydrogels showed good water absorption capacity, high solubility, and high gel fraction, as well as good porosity, water retention, and vapor transmission rates. They revealed a totally amorphous structure. The extract and the hydrogels containing the propolis extract (1.0% and 2.5%) did not inhibit fungal growth. However, they showed antibacterial activity against strains of S. aureus and P. aeruginosas. Regarding the E. coli strain, only the extract inhibited its growth. It showed good antioxidant activity by the evaluation method used.

CONCLUSIONS

Therefore, the hydrogels containing propolis extract can be a promising alternative with antibacterial and antioxidant action for use as dressings for the treatment of skin lesions.

Phytochemical Profile and Antimicrobial Potential of Propolis Samples from Kazakhstan

In the current paper, we present the results of Kazakh propolis investigations. Due to limited data about propolis from this country, research was focused mainly on phytochemical analysis and evaluation of propolis antimicrobial activity. uHPLC-DAD (ultra-high-pressure-liquid chromatography coupled with diode array detection, UV/VIS) and uHPLC-MS/MS (ultra-high-pressure-liquid chromatography coupled with tandem mass spectrometry) were used to phytochemical characteristics while antimicrobial activity was evaluated in the serial dilution method (MIC, minimal inhibitory concentration, and MBC/MFC, minimal bactericidal/fungicidal concentration measurements). In the study, Kazakh propolis exhibited a strong presence of markers characteristic of poplar-type propolis—flavonoid aglycones (pinocembrin, galangin, pinobanksin and pinobanskin-3-O-acetate) and hydroxycinnamic acid monoesters (mainly caffeic acid phenethyl ester and different isomers of caffeic acid prenyl ester). The second plant precursor of Kazakh propolis was aspen–poplar with 2-acetyl-1,3-di-p-coumaroyl glycerol as the main marker. Regarding antimicrobial activity, Kazakh propolis revealed stronger activity against reference Gram-positive strains (MIC from 31.3 to above 4000 mg/L) and yeasts (MIC from 62.5 to 1000 mg/L) than against reference Gram-negative strains (MIC ≥ 4000 mg/L). Moreover, Kazakh propolis showed good anti-Helicobacter pylori activity (MIC and MBC were from 31.3 to 62.5 mg/L). All propolis samples were also tested for H. pylori urease inhibitory activity (IC50, half-maximal inhibitory concentration, ranged from 440.73 to 11,177.24 µg/mL). In summary Kazakh propolis are potent antimicrobial agents and may be considered as a medicament in the future.

Leishmanicidal and immunomodulatory properties of Brazilian green propolis extract (EPP-AF®) and a gel formulation in a pre-clinical model

Leishmaniasis is a widespread group of neglected vector-borne tropical diseases that possess serious therapeutic limitations. Propolis has been extensively used in traditional medical applications due to its range of biological effects, including activity against infectious agents. Here we evaluated the leishmanicidal and immunomodulatory properties of Brazilian green propolis extract (EPP-AF^®) and a gel formulation incorporating EPP-AF^®, in both in vitro and in vivo models of Leishmania amazonensis infection. Propolis extract, obtained from a standardized blend following hydroalcoholic extraction, showed the characteristic fingerprint of Brazilian green propolis as confirmed by HPLC/DAD. A carbopol 940 gel formulation was obtained containing propolis glycolic extract at 3.6% w/w. The release profile, assessed using the Franz diffusion cell protocol, demonstrated a gradual and prolonged release of p-coumaric acid and artepillin C from the carbomer gel matrix. Quantification of p-coumaric acid and artepillin C in the gel formulation over time revealed that p-coumaric acid followed the Higuchi model, dependent on the disintegration of the pharmaceutical preparation, while artepillin C followed a zero-order profile with sustained release. In vitro analysis revealed the ability of EPP-AF^® to reduce the infection index of infected macrophages (p < 0.05), while also modulating the production of inflammatory biomarkers. Decreases in nitric oxide and prostaglandin E₂ levels were observed (p < 0.01), suggesting low iNOS and COX-2 activity. Furthermore, EPP-AF^® treatment was found to induce heme oxygenase-1 antioxidant enzyme expression in both uninfected and L. amazonensis-infected cells, as well as inhibit IL-1β production in infected cells (p < 0.01). ERK-1/2 phosphorylation was positively correlated with TNF-α production (p < 0.05), yet no impact on parasite load was detected. In vivo analysis indicated the effectiveness of topical treatment with EPP-AF^® gel alone (p < 0.05 and p < 0.01), or in combination with pentavalent antimony (p < 0.05 and p < 0.001), in the reduction of lesion size in the ears of L. amazonensis-infected BALB/c mice after seven or 3 weeks of treatment, respectively. Taken together, the present results reinforce the leishmanicidal and immunomodulatory effects of Brazilian green propolis, and demonstrate promising potential for the EPP-AF^® propolis gel formulation as a candidate for adjuvant therapy in the treatment of Cutaneous Leishmaniasis.

The Activity of Red Nigerian Propolis and Some of Its Components against Trypanosoma brucei and Trypanosoma congolense

Propolis is a resin that is gathered by bees from exudates produced by various plants. Its exact chemical composition depends on the plants available near the hive. Bees use propolis to coat the surfaces of the hive, where it acts as an anti-infective. Regardless of the chemical composition of propolis, it is always anti-protozoal, probably because protozoan parasites, particularly Lotmarium passim, are widespread in bee populations. The protozoa Trypanosoma brucei and T. congolense cause disease in humans and/or animals. The existing drugs for treating these diseases are old and resistance is an increasingly severe problem. The many types of propolis present a rich source of anti-trypanosomal compounds-from a material gathered by bees in an environmentally friendly way. In the current work, red Nigerian propolis from Rivers State, Nigeria was tested against T. brucei and T. congolense and found to be highly active (EC₅₀ 1.66 and 4.00 µg/mL, respectively). Four isoflavonoids, vestitol, neovestitol, 7-methylvestitol and medicarpin, were isolated from the propolis. The isolated compounds were also tested against T. brucei and T. congolense, and vestitol displayed the highest activity at 3.86 and 4.36 µg/mL, respectively. Activities against drug-resistant forms of T. brucei and T. congolense were similar to those against wild type.

Models for cytotoxicity screening of antileishmanial drugs: what has been done so far?

A growing number of studies have demonstrated the in vitro potential of an impressive number of antileishmanial candidates in the past years. However, the lack of uniformity regarding the choice of cell types for cytotoxicity assays may lead to uncomparable and inconclusive data. In vitro assays relying solely on non-phagocytic cell models may not represent a realistic result as the effect of an antileishmanial agent should ideally be presented based on its cytotoxicity profile against reticuloendothelial system cells. In the present review, we have assembled studies published in the scientific literature from 2015 to 2021 that explored leishmanicidal candidates, emphasising the main host cell models used for cytotoxicity assays. The pros and cons of different host cell types as well as primary cells and cell lines are discussed in order to draw attention to the need to establish standardised protocols for preclinical testing when assessing new antileishmanial candidates.

Bis-1,2,4-triazol derivatives: Synthesis, characterization, DFT, antileishmanial activity and molecular docking studyo

In this study, triazol derivatives, 4,4'-(((1E, 1E')-1,2-phenylenebis (methanylyidene)) bis (azanylidene)) bis (5-methyl-2,4-dihydro-3H-1,2,4-triazol-3-one (2), 4,4'-(((1E, 1E')-1,3-phenylenebis (methanylyidene)) bis (azanylidene)) bis (5-methyl-2,4-dihydro-3H-1,2,4-triazol-3-one (3) and 4,4'-(((1E, 1E')-1,4-phenylene bis (methanyl yidene)) bis (azanylidene)) bis (5-methyl-2,4-dihydro-3H-1,2,4-triazol-3-one (4) were synthesized from the reaction of 4-amino-5-methyl-2,4-dihydro-3H-1,2,4-triazol-3-one and phthalaldehyde/isophthalaldehyde/terephthalaldehyde, respectively. Compounds 2-4 were characterized by Fourier transform infrared (FTIR), proton and carbon-13 nuclear magnetic resonance (¹H- and ¹³C- NMR) spectroscopic methods. Theoretical study for compounds 2-4 were carried out by DFT/B3LYP/6-311++G(d,p). Structural and spectroscopic parameters were determined theoreticaly and compared with experimental ones. Also, the molecular electrostatic potential (MEP) maps of compounds were obtained. Leishmanicidal activity of compounds 2-4 against to Leishmania infantum was determined by microdilution broth method containing alamar blue. As a result of the study, compounds 2-4 were found to be effective against the specie of Leishmania. Molecular docking analysis against Trypanothione Reductase (TRe) with compound 2 was carried out to see the necessary interactions responsible for antileishmanial activity. The docking calculations of compound 2 supported the antileishmanial activity exhibiting high inhibition constant.Communicated by Ramaswamy H. Sarma.

The Antiprotozoal Activity of Papua New Guinea Propolis and Its Triterpenes

Profiling a propolis sample from Papua New Guinea (PNG) using high-resolution mass spectrometry indicated that it contained several triterpenoids. Further fractionation by column chromatography and medium-pressure liquid chromatography (MPLC) followed by nuclear magnetic resonance spectroscopy (NMR) identified 12 triterpenoids. Five of these were obtained pure and the others as mixtures of two or three compounds. The compounds identified were: mangiferonic acid, ambonic acid, isomangiferolic acid, ambolic acid, 27-hydroxyisomangiferolic acid, cycloartenol, cycloeucalenol, 24-methylenecycloartenol, 20-hydroxybetulin, betulin, betulinic acid and madecassic acid. The fractions from the propolis and the purified compounds were tested in vitro against Crithidia fasciculata, Trypanosoma congolense, drug-resistant Trypanosoma congolense, Trypanosoma b. brucei and multidrug-resistant Trypanosoma b. brucei (B48). They were also assayed for their toxicity against U947 cells. The compounds and fractions displayed moderate to high activity against parasitic protozoa but only low cytotoxicity against the mammalian cells. The most active isolated compound, 20-hydroxybetulin, was found to be trypanostatic when different concentrations were tested against T. b. brucei growth.