Synergic effect of metronidazole and pyrantel pamoate on Giardia lamblia

Antiparasitic activity of Colombian Amazon palm extracts against Giardia lamblia trophozoites: insights into cellular death mechanisms

Introduction

Colombian plants have a long history of use in traditional medicine and ethnopharmacology, particularly for treating stomach pain, digestive issues, diarrhea, and other gastrointestinal disorders. Recent studies have renewed interest in their potential therapeutic properties.

Methods

This study evaluated the giardicidal activity of 15 crude plant extracts native to the Colombian Amazon against Giardia lamblia (genotype A, strain WB/1267). The MTT colorimetric assay was used to determine the effectiveness of these extracts at a concentration of 500 μg/mL. Extracts showing significant activity were further analyzed to determine their half-maximal inhibitory concentration (IC50). The cell death mechanisms of Attalea butyracea were studied using flow cytometry, confocal microscopy, and transmission electron microscopy (TEM).

Results

Among the tested extracts, the Attalea butyracea fruit extract (P-2) exhibited the highest activity against WB/1267 (IC50 = 62.10 ± 6.57 μg/mL) and demonstrated giardicidal activity against GS/M (IC50 = 100.90 ± 3.40 μg/mL, genotype B) human infecting strains. These results prompted a detailed investigation into its mechanism of action using the WB/1267 strain as a model. At its IC50 concentration, P-2 primarily exerted its antiproliferative effect by induction of early apoptosis. A notable increase in late apoptosis and necrosis was observed at 2xIC50. Immunofluorescence assay (IFA) and confocal microscopy revealed chromatin condensation in treated trophozoites, while flow cytometry indicated G1/S cell cycle arrest. Furthermore, exposure to P-2 led to oxidative stress, evidenced by a significant increase in reactive oxygen species (ROS). The extract's ability to disrupt various structural components of the parasite was confirmed through IFA and transmission electron microscopy. Interestingly, the P-2 extract effectively synergized with the first-line drug metronidazole against Giardia WB/1267 trophozoites.

Discussion

These findings underscore the therapeutic potential of Colombian plant extracts in treating giardiasis, particularly highlighting the novel giardicidal activity of Attalea butyracea fruit extract and its promise for further therapeutic development.

Multifunctional Silver(I) Complexes with Metronidazole Drug Reveal Antimicrobial Properties and Antitumor Activity against Human Hepatoma and Colorectal Adenocarcinoma Cells

Simple Summary

Our previous studies demonstrated that a silver(I) nitrate complex with metronidazole presented greater photo-stability, antimicrobial, cytotoxic and genotoxic properties than silver(I) nitrate. These advantages make the complex a better candidate for clinical therapy than pure salt. Therefore, in this study, we decided to synthetize and determine the chemical, cytotoxic and antimicrobial properties of [Ag(MTZ)₂]₂SO₄, a novel metronidazole silver(I) complex, in comparison with pure salt Ag₂SO₄ and [Ag(MTZ)₂NO₃]. The photo-stability, cytotoxicity toward cancer cells and antimicrobial activity of [Ag(MTZ)₂]₂SO₄ is higher than Ag₂SO₄. What is more, we found that the novel synthetized complex shows better cytotoxicity against cancer cells than [Ag(MTZ)₂NO₃]. Both complexes have similar biological activity against the majority of tested bacterial strains.

Abstract

Silver salts and azole derivatives are well known for their antimicrobial properties. Recent evidence has demonstrated also their cytotoxic and genotoxic potential toward both normal and cancer cells. Still, little is known about the action of complexes of azoles with silver(I) salts. Thus, the goal of the study was to compare the chemical, cytotoxic and antimicrobial properties of metronidazole complexes with silver(I) nitrate and silver(I) sulfate to metronidazole and pure silver(I) salts. We synthetized a novel complex, [Ag(MTZ)₂]₂SO₄, and confirmed its chemical structure and properties using ¹H and ¹³C NMR spectroscopy and X-Ray, IR and elemental analysis. To establish the stability of complexes [Ag(MTZ)₂NO₃] and [Ag(MTZ)₂]₂SO₄, they were exposed to daylight and UV-A rays and were visually assessed. Their cytotoxicity toward human cancer cells (HepG2, Caco-2) and mice normal fibroblasts (Balb/c 3T3 clone A31) was determined by MTT, NRU, TPC and LDH assays. The micro-dilution broth method was used to evaluate their antimicrobial properties against Gram-positive and Gram-negative bacteria. A biofilm eradication study was also performed using the crystal violet method and confocal laser scanning microscopy. The photo-stability of the complexes was higher than silver(I) salts. In human cancer cells, [Ag(MTZ)₂]₂SO₄ was more cytotoxic than Ag₂SO₄ and, in turn, AgNO₃ was more cytotoxic than [Ag(MTZ)₂NO₃]. For Balb/c 3T3 cells, Ag₂SO₄ was more cytotoxic than [Ag(MTZ)₂]₂SO₄, while the cytotoxicity of AgNO₃ and [Ag(MTZ)₂NO₃] was similar. Metronidazole in the tested concentration range was non-cytotoxic for both normal and cancer cells. The complexes showed increased bioactivity against aerobic and facultative anaerobic bacteria when compared to metronidazole. For the majority of the tested bacterial strains, the silver(I) salts and complexes showed a higher antibacterial activity than MTZ; however, some bacterial strains presented the reverse effect. Our results showed that silver(I) complexes present higher photo-stability, cytotoxicity and antimicrobial activity in comparison to MTZ and, to a certain extent, to silver(I) salts.

Highly efficient degradation of metronidazole drug using CaFe2O4/PNA nanohybrids as metal-organic catalysts under microwave irradiation

Catalytic degradation based on microwave irradiation is an emerging technique which promises prompt and efficient catalytic degradation of organic pollutants. Calcium ferrite (CaFe₂O₄), poly(1-napththylamine) (PNA), and PNA/CaFe₂O₄ nanohybrids were synthesized via microwave-assisted technique. The properties of the as-prepared CaFe₂O₄, PNA, and PNA/CaFe₂O₄ nanohybrids were characterized by the thermogravimetric analysis (TGA), FTIR, XRD, SEM, and ultraviolet-visible spectrophotometry (UV-vis) analyses. The formation of inorganic-organic hybrids was confirmed by the FTIR and XRD studies. Loading of PNA was confirmed to be 8%, 16%, 32%, and 40% in CaFe₂O₄ which was established by TGA studies and the thermal stability was found to follow the order: CaFe₂O₄ > 8-PNA/CaFe₂O₄ > 16-PNA/CaFe₂O₄ > 32-PNA/CaFe₂O₄ > 40-PNA/CaFe₂O₄ > PNA. CaFe₂O₄ and PNA revealed band gap values of 3.42 eV and 2.60 eV respectively while for the PNA/CaFe₂O₄ nanohybrids, the values were found to be ranging between 2.46 and 3.00 eV. The PNA modified CaFe₂O₄ nanohybrids showed higher degradation efficiency towards metronidazole (MTZ) drug as compared with PNA and pure CaFe₂O₄. MTZ drug showed around 94% degradation within 21 min of microwave irradiation using 40-PNA/CaFe₂O₄ as catalyst. The enhanced catalytic activity was attributed to the high surface area of the nanohybrid catalyst as well as improved microwave catalytic activity of PNA. The reactive species responsible for degradation were confirmed by scavenger studies which formation of ^·OH and O₂^·- radicals. Recyclability tests showed that the 40-PNA/CaFe₂O₄ nanohybrid exhibited 86% degradation of MTZ (90 mg/l) even after the third cycle, which reflected higher reusability of the catalyst. The MTZ fragments were identified using liquid chromatography-mass spectrometry (LC-MS).

Silver(I) Complexes of the Pharmaceutical Agents Metronidazole and 4-Hydroxymethylpyridine: Comparison of Cytotoxic Profile for Potential Clinical Application

In previous papers, we have reported on the high antifungal and significant antibacterial activity against Gram-positive and Gram-negative bacteria of the water-soluble silver(I) complexes of metronidazole and derivatives of pyridine compared to silver nitrate. In the present study, the cytotoxic activity of the silver(I) complexes of metronidazole and 4-hydroxymethylpyridine was compared with that of silver nitrate. Metronidazole and 4-hydroxymethylpyridine were investigated using Balb/c 3T3 and HepG2 cell lines in order to evaluate the potential clinical application of silver(I) complexes. The cells were exposed for 72 h to compounds at eight concentrations. The cytotoxic concentrations (IC₅₀) of the study compounds were assessed within four biochemical endpoints: mitochondrial activity, lysosomal activity, cellular membrane integrity, and total protein content. The investigated silver(I) complexes displayed comparable cytotoxicity to that of silver nitrate used in clinics. Mean cytotoxic concentrations calculated for investigated silver(I) complexes from concentration-response curves ranged from 2.13 to 26.5 µM. HepG2 cells were less sensitive to the tested complexes compared to fibroblasts (Balb/c 3T3). However, the most affected endpoint for HepG2 cells was cellular membrane damage. The cytotoxicity of both silver complexes was comparable for Balb/c 3T3 cells. The cytotoxic potential of the new silver(I) compounds compared to that of silver nitrate used in medicine indicates that they are safe and could be used in clinical practice. The presented results are yet more stimulating to further studies that evaluate the therapeutic use of silver complexes.

Infections by human gastrointestinal helminths are associated with changes in faecal microbiota diversity and composition

Investigations of the impact that patent infections by soil-transmitted gastrointestinal nematode parasites exert on the composition of the host gut commensal flora are attracting growing interest by the scientific community. However, information collected to date varies across experiments, and further studies are needed to identify consistent relationships between parasites and commensal microbial species. Here, we explore the qualitative and quantitative differences between the microbial community profiles of cohorts of human volunteers from Sri Lanka with patent infection by one or more parasitic nematode species (H+), as well as that of uninfected subjects (H-) and of volunteers who had been subjected to regular prophylactic anthelmintic treatment (Ht). High-throughput sequencing of the bacterial 16S rRNA gene, followed by bioinformatics and biostatistical analyses of sequence data revealed no significant differences in alpha diversity (Shannon) and richness between groups (P = 0.65, P = 0.13 respectively); however, beta diversity was significantly increased in H+ and Ht when individually compared to H-volunteers (P = 0.04). Among others, bacteria of the families Verrucomicrobiaceae and Enterobacteriaceae showed a trend towards increased abundance in H+, whereas the Leuconostocaceae and Bacteroidaceae showed a relative increase in H- and Ht respectively. Our findings add valuable knowledge to the vast, and yet little explored, research field of parasite—microbiota interactions and will provide a basis for the elucidation of the role such interactions play in pathogenic and immune-modulatory properties of parasitic nematodes in both human and animal hosts.

Combination therapy in the management of giardiasis: What laboratory and clinical studies tell us, so far

Treatment failures in patients suffering from giardiasis are not uncommon feature. The most frequent approach in these cases is to treat these patients with longer repeated courses and/or higher doses of the primary therapy, or using drugs from a different class to avoid potential cross-resistance. However, a higher rate of adverse events may limit this strategy. In this context, combination therapy (CT) is emerging as a valuable option against refractory giardiasis. In the attempt to evaluate the benefits of CT, a number of experimental studies, clinical series, and randomized clinical trials (RCTs), as well as several veterinary studies have been performed, with varying results. Here, we present a critical analysis of the available information regarding CT for the treatment of Giardia infection, as well as the authors' opinion with respect to its use. RCTs of combination therapy are limited and the optimal combinations and administration strategies need yet to be clarified. Analyses of the cost-effectiveness and RCTs of CTs for Giardia infection are required to assess the role of these drugs for the control of giardiasis, mainly in the case of treatment failures linked to suspected drug tolerance are the case.

Management of chronic Giardia infection

Advances in our understanding of chronic giardiasis (CG) may improve our care of patients in this stage of the disease. This review proposes a new concept of CG and highlights the recent advances in our understanding and management of this condition. According to this review, management requires, initially, an accurate diagnosis, which may exclude several conditions that can mimic CG. Optimal treatment requires a tailored approach which includes the recognition of the known modifiable causes of this health condition, assessment of symptoms and potential complications, their treatment utilizing, if necessary, a multidisciplinary team, and an ongoing monitoring for the effect of therapy - weighing the efficacy of individual drugs - all of these together may lead to a successful treatment of CG.