Anti-filarial efficacy of Centratherum anthelminticum: unravelling the underlying mechanisms through biochemical, HRAMS proteomics and MD simulation approaches

Traditionally, Centratherum anthelminticum (CA) has been reported to be a potent anti-filarial, however no reports are available detailing its mechanism of action against filarial parasites. In this study, we have evaluated the anti-filarial activity of CA against lymphatic filarial parasites Setaria cervi using ex vivo biochemical, proteomics and in silico approaches. The motility and viability of the parasites decreased significantly after treatment with CA concentrations of ≥125 μg mL-1. An increase in lipid peroxidation (51.92%), protein carbonylation (48.99%), NADPH oxidase (88.88%) activity and decrease in the glutathione (GSH) (-39.23%), glutathione reductase (GR) (-60.17%), and glutathione S-transferase (GST) (-50.48%) activity was also observed after CA treatment. The proteomics analysis was performed by two-dimensional gel electrophoresis and high-resolution accurate mass spectrometry (HRAMS). In total, 185 proteins were differentially expressed (DEPs) following CA treatment. The major DEPs were mostly involved in tRNA processing, biosynthetic processes, metabolic activities, protein transport, the tricarboxylic acid cycle, protein translation, and stress response. The UPLC-ESI-MS/MS analysis of CA extract revealed the presence of 40 bioactive compounds. Further the docking analysis showed 10 CA bioactive compounds to have high binding affinity towards antioxidant proteins of filarial parasites. Additionally, MD simulation studies showed stable interactions (RMSF ≤ 10 Å) of 3-O-methylquercitin, quinic acid, gentisic acid, and vanillin with filarial antioxidant enzymes/proteins. To our knowledge, this is the first report detailing the molecular mechanism of anti-filarial activity of CA, which can be further evaluated for the development of new anti-filarial formulations.

Exploring the antifilarial potential of an important medicinal plant Typhonium trilobatum (L. Schoot): Isolation, characterization, and structural elucidation of bioactive compounds against Brugia malayi

ETHNOPHARMACOLOGY RELEVANCE

The plant Typhonium trilobatum has been utilized in traditional medicine for the treatment of many ailments, including parasitic infections. Recent examinations indicate that the bioactive substances from this plant may have antiparasitic activities against Brugia malayi, which have not been determined.

PURPOSE

The parasitic nematodes Brugia malayi, Brugia timori, and Wuchereria bancrofti causing lymphatic filariasis, remain a significant challenge to global public health. Given the ongoing nature of this enduring menace, the current research endeavours to examine the efficacy of an important medicinal plant, Typhonium trilobatum.

METHODS

Different extracts of the T. trilobatum tubers were evaluated for their antiparasitic activity. The most prominent extract was subjected to Gas Chromatography Mass Spectrometry (GC-MS) and High Performance Liquid Chromatography (HPLC) followed by Column Chromatography for isolating bioactive molecules. The major compounds were isolated and characterized based on different spectroscopic techniques (FTIR, NMR and HRMS). Further, the antiparasitic activity of the isolated compounds was evaluated against B. malayi and compared with clinically used antifilarial drugs like Diethylcarbamazine and Ivermectin.

RESULTS

The methanolic extract of the tuber exhibited significant antiparasitic activity compared to the other extracts. The bioactive molecules isolated from the crude extract were identified as Linoleic acid and Palmitic acid. Antiparasitic activity of both the compounds has been performed against B. malayi and compared with clinically used antifilarial drugs, Ivermectin and DEC. The IC50 value of Linoleic acid was found to be 6.09 ± 0.78 μg/ml after 24 h and 4.27 ± 0.63 μg/ml after 48 h, whereas for Palmitic acid the value was 12.35 ± 1.09 μg/ml after 24 h and 8.79 ± 0.94 μg/ml after 48 h. The IC50 values of both the molecules were found to be similar to the standard drug Ivermectin (IC50 value of 11.88 ± 1.07 μg/ml in 24 h and 2.74 ± 0.43 μg/ml in 48 h), and much better compared to the DEC (IC50 values of 194.2 ± 2.28 μg/ml in 24 h and 101.8 ± 2.06 μg/ml in 48 h). Furthermore, it has been observed that both the crude extracts and the isolated compounds do not exhibit any detrimental effects on the J774.A.1 macrophage cell line.

CONCLUSION

The isolation and characterization of bioactive compounds present in the methanolic tuber extract of Typhonium trilobatum were explored. Moreover, the antimicrofilarial activity of the crude extracts and its two major compounds were determined using Brugia malayi microfilarial parasites without any significant side effects.

Biosynthesis and characterization of Ocimum sanctum green silver nanoparticles and unravelling their enhanced anti-filarial activity through a HRAMS proteomics approach

The available anti-filarial medications are largely ineffective against adult filarial worms. Also, these drugs have several drawbacks such as toxicity and development of resistance owing to long-term usage. Green nanomedicine may offer better solutions for Lymphatic Filariasis treatment due to its tiny size, biocompatibility, and better penetration at considerably lower costs with higher therapeutic efficacy. In the present study, Ocimum sanctum silver nanoparticles (OSAgNPs) were bio-synthesized and their anti-filarial efficacy was evaluated against adult filarial parasites. The green nanoparticles were characterized by UV-VIS spectroscopy, XRD, FTIR, SEM, and TEM analysis. The OSAgNPs significantly affected the motility and viability of adult Setaria cervi parasites after 4 h of incubation at concentrations higher than 0.5 μg ml-1. Proteomics analysis by high resolution accurate mass spectrometry revealed that 213 proteins were differentially expressed following OSAgNP treatment. Mostly these DEPs belonged to the many biochemical and molecular pathways of parasites such as muscle proteins, antioxidant proteins, heat shock proteins, signal recognition proteins, and energy metabolism-related proteins. Undoubtedly, this study will open new avenues for the development of novel anti-filarial drugs based on green nanoparticles.

A Landscape on Lymphatic Filariasis with its Effects and Recent Advanced Treatments

Lymphatic filariasis is an infection caused by parasites that poses a significant health, social, and economic burden, affecting a vast population that exceeds 120 million individuals globally. The Etiology of the infection is attributed to three nematode parasites, namely Wuchereria bancrofti, B. timori, and Brugia malayi, as well as which are phylogenetically related. These parasites are transmitted to humans via mosquitoes belonging to the Anopheles, Aedes genera, and Culex. As per the estimation provided by the WHO, the current number of individuals infected with filariasis stands at approximately 120 million across 81 countries. Furthermore, it is estimated that around 1.34 billion individuals reside in regions that are endemic to filariasis, thereby putting them at risk of contracting the disease. Different synthetic drugs such as Ivermectin, Doxycycline, Albendazole, and Suramin are used in the treatment. Some natural plants are Azadirachta indica, Tinospora cordifolia, Zingiber officinal, as well as, some marine sources are also included for better treatment. We also touch briefly on a few additional filarial diseases. Although there are only a few medications available to treat filariasis, their frequent usage may result in drug resistance. Furthermore, there is no effective vaccination for the treatment of filariasis. Due to these restrictions, it has been crucial to create new anti-filarial medications, which motivates researchers to find novel pharmaceuticals with anti-filarial action. In this article, we examine the latest achievements in the anti-filarial area, including the many forms of filariasis and their historical contexts, elimination programmes, various therapeutic classes (both synthetic and natural), investigated product-derived targets as well as clinical investigations.

In silico exploration and in vitro validation of the filarial thioredoxin reductase inhibitory activity of Scytonemin and its derivatives

Lymphatic filariasis (LF) caused by the vector borne parasitic nematode Wuchereria bancrofti is of major concern of the World Health Organization (WHO). Lack of potential drug candidates worsens the situation. Presently available drugs are promising in killing the microfilaria (mf) but are not effective as adulticidal therapeutics. Previous studies have revealed that routine administration of the available drugs (albendazole, ivermectin and albendazole) sometime is associated with severe adverse effects (SAEs) in co-infection state. Therefore, potential and safe therapeutics are still required. Earlier studies on filarial thioredoxin reductase (TrxR) have shown that successful inhibition of it can lead to apoptotic death of the parasites. TrxR in filarial parasites plays a significant role in disease progression and pathogenesis, hence efficient non-reversible inhibition of TrxR can be a good strategy to treat LF. In this research, inhibitory potential of Scytonemin, a cyanobacterial metabolite on filarial TrxR was evaluated via different in silico methods and validated through in vitro experiments. Parasite death upon exposure to Scytonemin can be correlated with the TrxR inhibiting capacity of the compound. Therefore, this cyanobacterial-derived compound may possibly be used further as novel and safe therapeutic candidate against filarial infection.Communicated by Ramaswamy H. Sarma.

Pharmacotherapeutics Applications and Chemistry of Chalcone Derivatives

Chalcones have been well examined in the extant literature and demonstrated antibacterial, antifungal, anti-inflammatory, and anticancer properties. A detailed evaluation of the purported health benefits of chalcone and its derivatives, including molecular mechanisms of pharmacological activities, can be further explored. Therefore, this review aimed to describe the main characteristics of chalcone and its derivatives, including their method synthesis and pharmacotherapeutics applications with molecular mechanisms. The presence of the reactive α,β-unsaturated system in the chalcone's rings showed different potential pharmacological properties, including inhibitory activity on enzymes, anticancer, anti-inflammatory, antibacterial, antifungal, antimalarial, antiprotozoal, and anti-filarial activity. Changing the structure by adding substituent groups to the aromatic ring can increase potency, reduce toxicity, and broaden pharmacological action. This report also summarized the potential health benefits of chalcone derivatives, particularly antimicrobial activity. We found that several chalcone compounds can inhibit diverse targets of antibiotic-resistance development pathways; therefore, they overcome resistance, and bacteria become susceptible to antibacterial compounds. A few chalcone compounds were more active than conventional antibiotics, like vancomycin and tetracycline. On another note, a series of pyran-fused chalcones and trichalcones can block the NF-B signaling complement system implicated in inflammation, and several compounds demonstrated more potent lipoxygenase inhibition than NSAIDs, such as indomethacin. This report integrated discussion from the domains of medicinal chemistry, organic synthesis, and diverse pharmacological applications, particularly for the development of new anti-infective agents that could be a useful reference for pharmaceutical scientists.

Evaluation of macrofilaricidal and microfilaricidal activities against Onchocerca ochengi and cytotoxicity of some synthesized azo compounds containing thiophene backbone

Control and treatment of onchocerciasis, a devastating tropical filarial disease caused by Onchocerca volvulus, rely solely on the community directed treatment with ivermectin. However, ivermectin is only microfilaricidal with evidence of resistance of the parasite among other limitations, which necessitate the search for new efficacious and safe filaricides. Ten synthetic thienylazoryl dyes were screened in vitro against adult and microfilariae worm stages of Onchocerca ochengi based on worm motility and MTT formazan assay. Cytotoxicity of active compounds was assessed on monkey kidney epithelial cells (LLC-MK2) using the MTT formazan assay. Seven (7) compounds showed both macrofilaricidal activity against adult male worms and microfilaricidal activity among which three 4a, 4c and 4e recorded the highest activity (IC₅₀ = 4.2 to 8.8μM) against adult male worms, comparable to some standard anthelmintics. Five compounds showed rapid activity against microfilariae with 100% inhibition after 24-h incubation. The active compounds were nontoxic on monkey kidney cells (CC₅₀> 4μg/mL), but their selectivity index values were relatively low (≤ 3). The thienylazoaryls with both macrofilaricidal and microfilaricidal activities may yield molecules which could be used for eradication of onchocerciasis following further medicinal chemistry modification of their structures to enhance their selectivity.

Inhibition of thioredoxin reductase (TrxR) triggers oxidative stress-induced apoptosis in filarial nematode Setaria cervi channelized through ASK-1-p38 mediated caspase activation

Inhibition of an imperative antioxidant enzyme with subsequent death is a victorious and widely accepted strategy to combat various infectious diseases. Among different antioxidant enzymes, thioredoxin reductase (TrxR) is an exclusive one. Studies have revealed that direct inhibition of TrxR by different classes of chemical moieties promptly results in the death of an organism. Especially the structural as well as biochemical modifications of the enzyme upon inhibition project serious threat towards the subject organism. Herein, an attempt was made to inhibit TrxR of filarial species by administering Auranofin, 1 chloro 2,4 dinitrobenzene (CDNB), Curcumin, and a novel carbamo dithioperoxo(thioate) derivative (4a). Our study has revealed that inhibition of TrxR resulted in the induction of the classical CED pathway of apoptosis along with the intrinsic and extrinsic pathways of apoptosis (Caspase mediated) routed through the ASK-1/p38 axis. Druggability analysis of filarial TrxR for the selected compounds was performed in silico through molecular docking studies. Therefore, this study attempts to decipher the mechanism of apoptosis induction following TrxR inhibition. The safety of those four compounds in terms of dose and toxicity was taken under consideration. Thitherto, the mechanism of TrxR mediated initiation of cell death in filarial parasite has remained undercover, and therefore, it is a maiden report on the characterization of apoptosis induction upon TrxR inhibition which will eventually help in generating effective antifilarial drugs in the future.

Fecundity of adult female worms were affected when Brugia malayi infected Mongolian gerbils were immunized with a multivalent vaccine (rBmHAXT) against human lymphatic filarial parasite

A multivalent recombinant fusion protein prophylactic vaccine, rBmHAXT developed against lymphatic filariasis (LF) demonstrated over 57% protection against challenge infection in rhesus macaque model. Currently, we do not know if the rBmHAXT vaccination has any effect on adult worms and/or on the fecundity of adult female worms. Thus, the major focus of this study was to determine the effect of rBmHAXT vaccination on Brugia malayi infected mongolian gerbils. We performed two sets of experiments. In the first set of experiment, gerbils were infected with 100 B. malayi L3. After confirming the establishment of infection, four rounds of DEC treatment and rBmHAXT vaccination was given. Results showed that following vaccination with rBmHAXT, the microfilaria (Mf) count was significantly decreased in all vaccinated animals compared to controls. At the end of these experiments, we collected and counted the established adult worms. There was a 36% reduction in the recovery of adult female worms, which might account for the low Mf load in vaccinated animals. In the second set of experiments, animals were vaccinated first with rBmHAXT followed by surgically implanting adult male or female B. malayi parasites into the peritoneal cavity to determine the effect of vaccination on each sex of the parasite. Our results show that the rBmHAXT vaccination has no effect on male adult worms compared to controls. However, there was 40% reduction in the Mf load in vaccinated animals that were transplanted with adult female worms. These findings suggested that the rBmHAXT vaccination has potential damaging effect on the fecundity of adult female worms. Scanning electron microscopy studies showed cuticular damage on the surface of adult female worms. These studies thus show that the rBmHAXT vaccination in infected gerbils has partial microfilaricidal effect and potentially affect the fecundity of adult female worms.

Mosquitoes and the Lymphatic Filarial Parasites: Research Trends and Budding Roadmaps to Future Disease Eradication

The mosquito-borne lymphatic filariasis (LF) is a parasitic, neglected tropical disease that imposes an unbearable human scourge. Despite the unprecedented efforts in mass drug administration (MDA) and morbidity management, achieving the global LF elimination slated for the year 2020 has been thwarted by limited MDA coverage and ineffectiveness in the chemotherapeutic intervention. Moreover, successful and sustainable elimination of mosquito-vectored diseases is often encumbered by reintroduction and resurgence emanating from human residual or new infections being widely disseminated by the vectors even when chemotherapy proves effective, but especially in the absence of effective vaccines. This created impetus for strengthening the current defective mosquito control approach, and profound research in vector⁻pathogen systems and vector biology has been pushing the boundaries of ideas towards developing refined vector-harnessed control strategies. Eventual implementation of these emerging concepts will offer a synergistic approach that will not only accelerate LF elimination, but also augurs well for its future eradication. This brief review focuses on advances in mosquito⁻filaria research and considers the emerging prospects for future eradication of LF.