Trypanostatic activity of geranylacetone: Mitigation of Trypanosoma congolense-associated pathological pertubations and insight into the mechanism of anaemia amelioration using in vitro and in silico models

Mitigation of Trypanosoma congolense-Associated Anemia and Expression of Trans-sialidase (TconTS) Gene Variants by Eugenol

PURPOSE

African Animal Trypanosomosis (AAT) caused by Trypanosoma congolense is a parasitic disease affecting the livestock industry in sub-Saharan Africa and usually results in severe anemia, organ damage, and ultimately the death of the infected host. The present study was designed to investigate the possible chemotherapeutic effect of eugenol on T. congolense infections and its inhibitory effect on the trans-sialidase (TconTS) gene expression.

METHODS

Animals were infected with T. congolense and treated with 15 and 30 mg/kg body weight (BW) of eugenol for ten (10) days.

RESULTS

The eugenol (15 mg/kg BW) significantly (P < 0.05) reduced the T. congolense proliferation, increased animal survival, and reduced serum urea level. However, both dosages of eugenol significantly (P < 0.05) ameliorated T. congolense-induced anemia, renal hypertrophy, splenomegaly, and reduced total damage score in the liver and kidney of infected animals. In addition, the compound significantly (P < 0.05) downregulated the expression levels of TconTS1, TconTS2, TconTS3, and TconTS4 but the effect was more pronounced (sevenfold reduction) on TconTS1.

CONCLUSIONS

The oral administration of eugenol suppressed T. congolense proliferation and prevented some major pathologies associated with trypanosomiasis infection. The reversal of renal hypertrophy and splenomegaly by the compound in addition to the reduction in the expression level of the TconTS gene variants could explain the observed anemia ameliorative potential of the compound.

Therapeutic efficacy of β-sitosterol treatment on Trypanosoma congolense infection, anemia development, and trans-sialidase (TconTS1) gene expression

Background

African animal trypanosomiasis hinders sustainable livestock productivity in sub-Saharan Africa. About 17 million infected cattle are treated with trypanocides annually but most of the drugs are associated with drawbacks, necessitating the search for a promising chemotherapeutic agent.

Objectives

In this study, the effects of β-sitosterol on Trypanosoma congolense infection were investigated along with its effect on the trans-sialidase gene expressions.

Results

Oral treatment with β-sitosterol at 15 and 30 mg/kg body weight (BW) for 14 days significantly (p < 0.05) reduced parasitemia and ameliorated the parasite-induced anemia. Also, the parasite-induced increase in serum urea level and renal histopathological damage scores in addition to renal hypertrophy was significantly (p < 0.05) reverted following treatment with 30 mg/kg BW β-sitosterol. The compound also significantly (p < 0.05) down-regulated the expression of TconTS1 but not TconTS2, TconTS3, and TconTS4. Correlation analysis between free serum sialic acid with the TconTS1 and TconTS2 gene variants revealed negative correlations in the β-sitosterol-treated groups although they were non-significant (p > 0.05) in the group treated with 15 mg/kg BW β-sitosterol. Similarly, a non-significant negative (p > 0.05) correlation between the biomolecule and the TconTS3 and TconTS4 gene variants was observed in the β-sitosterol-treated groups while positive correlations were observed in the infected untreated control group.

Conclusion

The observed effect of β-sitosterol on T. congolense infection could make the compound a possible template for the design of novel trypanocides.

β-Sitosterol could serve as a dual inhibitor of Trypanosoma congolense sialidase and phospholipase A2: in vitro kinetic analyses and molecular dynamic simulations

The involvement of Trypanosoma congolense sialidase alongside phospholipase A2 has been widely accepted as the major contributing factor to anemia during African animal trypanosomiasis. The enzymes aid the parasite in scavenging sialic acid and fatty acids necessary for survival in the infected host, but there are no specific drug candidates against the two enzymes. This study investigated the inhibitory effects of β-sitosterol on the partially purified T. congolense sialidase and phospholipase A2. Purification of the enzymes using DEAE cellulose column led to fractions with highest specific activities of 8016.41 and 39.26 µmol/min/mg for sialidase and phospholipase A2, respectively. Inhibition kinetics studies showed that β-sitosterol is non-competitive and an uncompetitive inhibitor of sialidase and phospholipase A2 with inhibition binding constants of 0.368 and 0.549 µM, respectively. Molecular docking of the compound revealed binding energies of - 8.0 and - 8.6 kcal/mol against the sialidase and phospholipase A2, respectively. Furthermore, 100 ns molecular dynamics simulation using GROMACS revealed stable interaction of β-sitosterol with both enzymes. Hydrogen bond interactions between the ligand and Glu284 and Leu102 residues of the sialidase and phospholipase A2, respectively, were found to be the major stabilizing forces. In conclusion, β-sitosterol could serve as a dual inhibitor of T. congolense sialidase and phospholipase A2; hence, the compound could be exploited further in the search for newer trypanocides.

Phytochemical composition, bioactive properties, and toxicological profile of Tetrapleura tetraptera

The use of medicinal plants has gained renewed wide popularity in Africa, Asia, and most parts of the world because of the decreasing efficacy of synthetic drugs. Thus, natural products serve as a potent source of alternative remedy. Tetrapleura tetraptera is a medicinal plant with cultural and traditional significance in West Africa. In addition to the plant being commonly used as a spice in the preparation of traditional spicy food for postpartum care it is also widely used to constitute herbal concoctions and decoctions for treatment of diseases. This review aimed to provide an up-to-date information on the ethnomedicinal uses, pharmacological activities and phytoconstituents of T. tetraptera. Preclinical studies regarding the plant's toxicity profile were also reviewed. For this updated review, literature search was done on PubMed, Science Direct, Wiley, and Google Scholar databases using the relevant keywords. The review used a total of 106 papers that met the inclusion criteria from January 1989 - February 2022 and summarised the bioactivities that have been reported for the rich phytoconstituents of T. tetraptera studied using various chemical methods. Considering the huge report, the review focused on the antimicrobial and antiinflammatory activities of the plant extracts and isolated compounds. Aridan, aridanin and several bioactive compounds of T. tetraptera have shown pharmacological activities though their mechanisms of action are yet to be fully understood. This study also highlighted the influence of plant parts and extraction solvents on its biological activities. It also presented data on the toxicological profile of the plant extracts using different models. From cultural uses to modern pharmacological research the bioactive compounds of T. tetraptera have proved effective in infectious disease management. We hope that this paper provided a robust summary of the biological activities and toxicological profile of T. tetraptera, thus calling for more research into the pharmacological and pharmacokinetic activities of natural products to help combat the growing threat of drug resistance and provide guidelines for their ethnomedicinal uses.

Active Compounds with Medicinal Potential Found in Maxillariinae Benth. (Orchidaceae Juss.) Representatives-A Review

Orchids are widely used in traditional medicine for the treatment of a whole range of different health conditions, and representatives of the Neotropical subtribe Maxillariinae are not an exception. They are utilized, for instance, for their spasmolytic and anti-inflammatory activities. In this work, we analyze the literature concerning the chemical composition of the plant extracts and secretions of this subtribe's representatives published between 1991 and 2022. Maxillariinae is one of the biggest taxa within the orchid family; however, to date, only 19 species have been investigated in this regard and, as we report, they produce 62 semiochemicals of medical potential. The presented review is the first summary of biologically active compounds found in Maxillariinae.

Chemotherapeutic potentials of β-ionone against Trypanosoma congolense infection: Inhibition of parasite proliferation, anemia development, trans-sialidase (TconTS3 and TconTS4) gene expressions, and phospholipase A2

Trypanosoma congolense is a pathogenic African animal trypanosome species causing devastating conditions leading to death of an infected host. The drawbacks of the existing trypanocidal drugs have led to the search for new drug candidates. In this study, β-ionone at 15 and 30 mg/kg body weight (BW) was orally administered to T. congolense infected rats for 14 days followed by an assessment of anemia, organ damages, and the expression of T. congolense trans-sialidase gene variants. A significant decrease in parasitemia (p < .05) was observed in the animals treated with 15 mg/kg BW β-ionone besides increased animal survival rate. A trypanosome-induced decrease in packed cell volume (PCV) and histopathological changes across tissues was significantly (p < .05) ameliorated following treatment with both doses of β-ionone. This is in addition to reversing the parasite-induced upsurge in free serum sialic acid (FSA) and expression of T. congolense trans-sialidase gene variants (TconTS1, TconTS3, and TconTS4). Correlation analysis revealed a positive correlation (p > .05) between FSA with the TconTS gene expressions. In addition, the compound inhibited partially purified T. congolense sialidase and phospholipase A₂ via mixed inhibition pattern with inhibition binding constants of 25.325 and 4.550 µM, respectively, while molecular docking predicted binding energies of -5.6 kcal/mol for both enzymes. In conclusion, treatment with β-ionone suppressed T. congolense proliferation and protected the animals against some of the parasite-induced pathologies whilst the effect on anemia development might be due to inhibition of sialidase and PLA₂ activities as well as the expression levels of TconTS3 and TconTS4.

Partially Purified Leaf Fractions of Azadirachta indica Inhibit Trypanosome Alternative Oxidase and Exert Antitrypanosomal Effects on Trypanosoma congolense

Introduction

Trypanosomiasis is a neglected disease of humans and livestock caused by single-celled flagellated haemo-protozoan parasites belonging to the genus Trypanosoma.

Purpose

Widespread resistance to trypanocidal drugs creates urgent need for new, more effective drugs with potential to inhibit important trypanosome molecular targets.

Methods

Nine column chromatographic, partially purified leaf fractions of Azadirachta indica (AIF) were subjected to trypanosome alternative oxidase (TAO) inhibition assay using ubiquinol oxidase assay. The potent TAO inhibitors were evaluated for trypanocidal activities against T. congolense in rat model using in vitro, ex vivo, and in vivo assays. Complete cessation or reduction in parasite motility was scored from 0 (no parasite) to 6 (greater than or equal to 6 × 10⁷ trypanosomes/milliliter of blood), and was used to evaluate the efficacy of in vitro treatments.

Results

Only AIF1, AIF2, and AIF5 significantly inhibited TAO. AIF1 and AIF5 produced significant, dose-dependent suppression of parasite motility reaching score zero within 1 h with EC₅₀ of 0.005 and 0.004 µg/µL, respectively, while trypanosome-laden blood was still at score six with an EC₅₀ of 44,086 µg/µL. Mice inoculated with the concentrations at scores 0 and 1 (1–2 moribund parasites) at the end of the experiment did not develop parasitaemia. The two fractions significantly (p < 0.05) lowered parasite burden, with the AIF5 exhibiting highest in vivo trypanocidal effects. Packed cell volume was significantly higher in AIF1 (p < 0.05) and AIF5 (p < 0.001) groups compared to DMSO-treated group. Only AIF5 significantly (p < 0.05) lowered malondialdehyde.

Conclusion

AIF1 and AIF5 offer prospects for the discovery of TAO inhibitor(s).

Phloroglucinol as a Potential Candidate against Trypanosoma congolense Infection: Insights from In Vivo, In Vitro, Molecular Docking and Molecular Dynamic Simulation Analyses

Sub-Saharan Africa is profoundly challenged with African Animal Trypanosomiasis and the available trypanocides are faced with drawbacks, necessitating the search for novel agents. Herein, the chemotherapeutic potential of phloroglucinol on T. congolense infection and its inhibitory effects on the partially purified T. congolense sialidase and phospholipase A2 (PLA2) were investigated. Treatment with phloroglucinol for 14 days significantly (p < 0.05) suppressed T. congolense proliferation, increased animal survival and ameliorated anemia induced by the parasite. Using biochemical and histopathological analyses, phloroglucinol was found to prevent renal damages and splenomegaly, besides its protection against T. congolense-associated increase in free serum sialic acids in infected animals. Moreover, the compound inhibited bloodstream T. congolense sialidase via mixed inhibition pattern with inhibition binding constant (Ki) of 0.181 µM, but a very low uncompetitive inhibitory effects against PLA2 (Ki > 9000 µM) was recorded. Molecular docking studies revealed binding energies of -4.9 and -5.3 kcal/mol between phloroglucinol with modeled sialidase and PLA2 respectively, while a 50 ns molecular dynamics simulation using GROMACS revealed the sialidase-phloroglucinol complex to be more compact and stable with higher free binding energy (-67.84 ± 0.50 kJ/mol) than PLA2-phloroglucinol complex (-77.17 ± 0.52 kJ/mol), based on MM-PBSA analysis. The sialidase-phloroglucinol complex had a single hydrogen bond interaction with Ser453 while none was observed for the PLA2-phloroglucinol complex. In conclusion, phloroglucinol showed moderate trypanostatic activity with great potential in ameliorating some of the parasite-induced pathologies and its anti-anemic effects might be linked to inhibition of sialidase rather than PLA2.

In vitro and in vivo antitrypanosomal efficacy of combination therapy of Anogeissus leiocarpus, Khaya senegalensis and potash

ETHNOPHARMACOLOGICAL RELEVANCE

Pastoralists in Nigeria mix barks of Anogeissus leiocarpus (AL) Khaya senegalensis (KS) and potash (Pt) to treat animal African trypanosomosis.

AIM

To evaluate antitrypanosomal potential of A. leiocarpus, K. senegalensis and potash for insights into the traditional claim of antitrypanosomal combination therapy (ATCT).

MATERIALS AND METHODS

Fifty microliter each of six different concentrations of AL, KS, Pt, AL + KS, AL + KS + Pt and diminazene aceturate (DA, positive control) was incubated with 50 μL of parasite-laden blood containing 10⁸Trypanosoma congolense cells in a 96-well microtitre plate. Negative control wells were devoid of the extracts and drug but supplemented with phosphate-buffered saline (PBS). Efficacy of treatment was observed at 1 h interval for complete immobilisation or reduced motility of the parasites. Each incubated mixture was inoculated into mouse at the point of complete immobilisation of parasite motility or at the end of 6-h observation period for concentrations that did not immobilise the parasites completely. For in vivo assessment, thirty-five parasitaemic rats were randomly allocated into seven groups of 5 rats each. Each rat in groups I-V was treated with 500 mg/kg of AL, KS, Pt, AL + KS and AL + KS + Pt, respectively, for 7 days. Rats in groups VI and VII were treated with diminazene aceturate 3.5 mg/kg once and PBS 2 mL/kg (7 days), which served as positive and negative controls, respectively. Daily monitoring of parasitaemia through the tail vein, packed cell volume and malondialdehyde were used to assess efficacy of the treatments.

RESULTS

The AL + KS + Pt group significantly (p < 0.05) and dose-dependently reduced parasite motility and completely immobilized the parasites at 10, 5 and 2.5 μg/μL with an IC₅₀ of 9.1×10^-4 µg/µL. All the mice with conditions that produced complete cessation of parasite motility did not develop parasitaemia within one month of observation. The AL + KS group significantly (p < 0.05) lowered the level of parasitaemia and MDA, and significantly (p < 0.05) maintained higher PCV than PBS group.

CONCLUSION

The combination of A. leiocarpus and K. senegalensis showed better antitrypanosomal effects than single drug treatment and offers prospects for ATCT. Our findings support ethnopharmacological use of combined barks of A. leiocarpus and K. senegalensis by pastoralist in the treatment of animal African trypanosomosis in Nigeria.