Search

Propolis is a natural product widely used in folk medicine. Among its various applications, its antiparasitic properties stand out. Due to its great biodiversity, Brazil is a major producer of several types of propolis. This study proposes to evaluate the leishmanicidal properties of the hydroalcoholic extract of propolis collected in the southern region of Brazil (Brown propolis – HEBP) and its main isolated compounds: abietic acid (1), 13-epi-cupressic acid (2), 13-epi-torulosol (3), dehydroabietic acid (4), cis-communic acid (5) and ent-agatic acid (6). In general, the diterpenes did not show activity against the promastigotes of Leishmania (Leishmania) amazonensis at the evaluated concentrations. However, the HEBP was very active with an inhibition concentration of 50% at 8.32 µg/mL. Moreover, transmission electron microscopy (TEM) and scanning electron microscopy (SEM) assays showed morphological and structural alterations in promastigote forms of L. (L.) amazonensis when incubated with HEBP. [ABSTRACT FROM AUTHOR]

Grazing management through pasture rotation has been mentioned as a viable alternative for the control of Rhipicephalus microplus; however, there is limited information on rotational grazing at field level. The objectives of this research were (1) to evaluate the effect of rotational grazing with 30 and 45 days of pasture rest and continuous grazing (without rest) on R. microplus tick loads in Brahman heifers and its most common crosses with Holstein; (2) to know the parasite dynamics of R. microplus under the three grazing systems in the humid tropics of Mexico; and (3) to determine the effect of the treatments on the characteristics of the pastures (availability of forage biomass, plant height, and soil cover). The experiment was carried out for 1 year from April 2022 to March 2023, with three grazing treatments: Treatments 1 and 2 considered rotational grazing with 30 (RT30) and 45 days of rest (RT45), respectively, and Treatment 3 as continuous grazing (CT00). Thirty calves from 8 to 12 months of initial age were distributed in each treatment (n = 10). Every 14 days, the number of engorged and semiengorged female ticks in cattle was determined. Concomitantly, the region's temperature, relative humidity, and rainfall were recorded, as well as the agronomic characteristics of the pasture. Rotational grazing animals with 30 days of rest had the highest number of ticks, while grazing animals with 45 days of rest had the least. Tick load dynamics among groups did not correlate with climatic variables (p > 0.05). The height and grass cover presented significant changes due to grazing (p < 0.05), which could influence the tick cycle by the exposure of the soil, modifying the microclimatic conditions and consequently harming the survival and development of R. microplus in the evaluated systems. The negative effect of rotational grazing on the nonparasitic phase of R. microplus deserves further studies. [ABSTRACT FROM AUTHOR]

Background/Objectives: Leishmaniasis, a neglected disease caused by Leishmania spp. including L. amazonensis, urgently requires new treatments. Polyalthic acid (PA), a natural diterpene from Copaifera spp., has previously demonstrated significant antiparasitic potential. This study evaluated the leishmanicidal effects of polyalthic acid (PA), alone and with amphotericin B (AmpB), on L. amazonensis promastigote and amastigote forms. Results: PA showed significant activity against promastigotes, with 50% effective concentration (EC50) values of 2.01 μM at 24 h and an EC50 of 3.22 μM against amastigotes after 48 h. The PA and AmpB combination exhibited a synergistic effect on both forms without inducing cytotoxicity or hemolysis. Morphological changes in promastigotes, including vacuole formation and cell rounding, were more pronounced with the combination. Conclusions: These findings suggest that PA and AmpB together could form a promising new treatment strategy against Leishmania infections, offering enhanced efficacy without added toxicity. [ABSTRACT FROM AUTHOR]

Background. Bovine trypanosomosis produces significant economic losses due to anemia, loss of body condition, and emaciation. The disease is transmitted biologically by tsetse flies and mechanically by biting flies such as Tabanus and Stomoxys. Therefore, this research is aimed at estimating the prevalence of bovine trypanosomosis and the apparent density of its vectors in the Etang Special District. Methods. A cross‐sectional study was employed from November 2016 to April 2017 for the prevalence and entomological survey. Trypanosoma species were identified using buffy coat and Giemsa staining techniques. Besides, the entomological surveys were conducted using NGU, pyramidal, biconical, and monoconical traps. The vectors were identified to their genus level based on their morphological features like size, color, wing venation, and proboscis. Result. A total of 457 bovine blood samples were collected and tested, of these 16 (3.50%) animals were positive for trypanosomosis. Similarly, 13 T. vivax (81.25%) and 3 T. congolense (18.75%) were the trypanosome species detected. The prevalence in the young (2.56%) and adult (3.99%) age groups was not statistically significant (P > 0.05). However, there were significant (P < 0.05) differences in prevalence between body condition scores, where poor is 6.31%, medium is 1.30%, and good is 0%. Moreover, the difference in mean PCV values between the parasitemic (20.97) and aparasitemic (28.58) groups was statistically significant (P < 0.05). Glossina flies were not found, although 1756 Tabanus and 52 Stomoxys biting flies were gathered. Accordingly, the overall apparent density of Glossina flies was zero (0), with biting flies (20.54) recorded per trap per day. Moreover, the apparent density of Tabanus and 52 Stomoxys was 39.01 and 1.18, respectively. Conclusion. This study confirmed that trypanosomosis and abundant mechanical vectors continue to be problems in the study area, resulting in cattle productivity losses. As a result, strategic management and prevention methods for trypanosomosis and associated vectors should be prioritized. Further investigation of vector needs to be conducted to clear out tsetse presence. [ABSTRACT FROM AUTHOR]

Neglected tropical diseases are significant causes of death and temporary or permanent disability for millions living in developing countries. Unfortunately, there is no effective treatment for these diseases. Thus, this work aimed to conduct a chemical analysis using HPLC/UV and GC/MS to identify the major constituents of the hydroalcoholic extracts of Capsicum frutescens and Capsicum baccatum fruits, evaluating these extracts and their constituents' schistosomicidal, leishmanicidal and trypanocidal activities. The results obtained for the extracts of C. frutescens are better when compared to those obtained for C. baccatum, which can be related to the different concentrations of capsaicin (1) present in the extracts. The lysis of trypomastigote forms results for capsaicin (1) led to a significant value of IC50 = 6.23 µM. Thus, the results point to capsaicin (1) as a possible active constituent in these extracts. [ABSTRACT FROM AUTHOR]

We report the chemical composition of the crude leaf extracts obtained from Stizophyllum perforatum (Cham.) Miers (Bignoniaceae), a simple high-performance liquid chromatography–diode array detection (HPLC-DAD) method based on mangiferin as an internal standard to quantify verbascoside, and the verbascoside acute oral toxicity and antileishmanial activity. HPLC–high-resolution mass spectrometry–DAD (HPLC–HRMS–DAD) analyses of the crude ethanol S. perforatum leaf extracts (CE-1 and CE-2) revealed that verbascoside was the major constituent in both extracts. CE-1 was purified, and verbascoside and casticin, among other compounds, were isolated. The developed HPLC-DAD method was validated and met the required standards. Investigation of the CE-2 acute toxicity indicated a lethal dose (LD50) greater than 2,000 mg/kg of body weight. Both CE-1 and CE-2 exhibited antileishmanial activity. The isolated compounds, verbascoside and casticin, also displayed antileishmanial activity with effective concentrations (IC50) of 6.23 and 24.20 µM against promastigote forms and 3.71 and 18.97 µM against amastigote forms of Leishmania amazonensis, respectively, but they were not cytotoxic to J774A.1 macrophages. Scanning electron microscopy of the L. amazonensis promastigotes showed that the parasites became more rounded and that their plasma membrane was altered in the presence of verbascoside. Additionally, transmission electron microscopy demonstrated that vacuoles emerged, lipids accumulated, kinetoplast size increased, and interstitial extravasation occurred in L. amazonensis promastigotes exposed to verbascoside. These findings suggest that S. perforatum is a promising candidate for further in vivo investigations against L. amazonensis. [ABSTRACT FROM AUTHOR]

Propolis is a natural product of great economic and pharmacological importance. The flora surrounding the bee communities is a determining factor in the composition of propolis and therefore in its biological and medicinal properties. Brown propolis is one of the most important types of propolis in Brazil, produced in the southeastern region. The ethanolic extract of a brown propolis sample from Minas Gerais state was chemically characterized for the subsequent development of a RP‐HPLC method, validated according to the standards of regulatory agencies. The leishmanicidal activity of this extract was assessed. The brown propolis was characterized by the presence of chemical markers reported on green propolis such as ferulic acid, coumaric acid, caffeic acid, cinnamic acid, baccharin, artepillin and drupanin, indicating a probable origin on Baccharis dracunculifolia. The developed method agreed with the parameters established by the validation guidelines, then proved to be reliable for the analysis of this type of propolis. The brown propolis displayed significant activity against Leishmania amazonensis with IC50 values of 1.8 and 2.4 μg/ml against the promastigote and amastigote forms, respectively. The studied propolis exhibited promising evidence for use as a natural source against L. amazonensis. [ABSTRACT FROM AUTHOR]