Molecular evidence of curcumin-induced apoptosis in the filarial worm Setaria cervi

Anthelmintic effects of some medicinal plants on different life stages of Fasciola hepatica: Evidence on oxidative stress biomarkers, and DNA damage

Fasciolosis caused by Fasciola hepatica is a major public health and economic problem worldwide. Due to the lack of a successful vaccine and emerging resistance to the drug triclabendazole, alternative phytotherapeutic approaches are being investigated. This study investigated the in vitro anthelmintic activity of Lavender (Lavandula angustifolia) and carob (Ceratonia siliqua L.) essential oils (EOs) against F. hepatica. The in vitro study was based on an egg hatch assay (EHA), adult motility inhibition assays, DNA damage, reactive oxygen species (ROS) level along with several oxidative stress biomarkers including glutathione peroxidase (GSH), and glutathione-S-transferase (GST), superoxide dismutase (SOD) and malondialdehyde (MDA). To this end, different concentrations of L. angustifolia and C. siliqua EOs (1, 5, 10, 25 and 50 mg/mL) were used to assess anthelmintic effects on different life stages including egg, and adults of F. hepatica for 24 hrs. The results indicated that these EOs play a significant role as anthelminthics, and the effect was dependent on time and concentration. The in vitro treatment of F. hepatica worms with both L. angustifolia and C. siliqua EOs increased DNA damage, ROS production and induction of oxidative stress (decreased SOD, GST and GSH, and increased MDA), significantly compared to control. Therefore, it can be concluded that L. angustifolia and C. siliqua EOs have the potential to be used as novel agents for the control and treatment of F. hepatica infections. Further studies are required to investigate their pharmacological potential and effectiveness in vivo for the treatment of parasitic infections.

In vitro assessment of the anthelmintic activity of copper oxide and zinc oxide nanoparticles on egg and adult stages of Fasciola hepatica: evidence on oxidative stress biomarkers, and DNA damage

OBJECTIVES

Fasciolosis is of significant economic and public health importance worldwide. The lack of a successful vaccine and emerging resistance in flukes to the drug of choice, triclabendazole, has initiated the search for alternative approaches. In recent years, metallic nanoparticles have been extensively investigated for their anthelmintic effects. This study investigates the in vitro anthelmintic activity of copper oxide and zinc oxide nanoparticles against Fasciola hepatica.

METHODS

The in vitro study was based on egg hatchability test (EHA), adult motility inhibition tests, DNA damage, ROS levels, as well as several biomarkers of oxidative stress, including glutathione peroxidase (GSH) and glutathione S-transferase (GST), superoxide dismutase (SOD) and malondialdehyde (MDA). For this purpose, different concentrations of copper oxide nanoparticles (CuO-NPs) and Zinc oxide nanoparticles (ZnO-NPs) (1, 4, 8, 12, and 16 ppm) were used to evaluate the anthelmintic effect on different life stages, including egg and adults of Fasciola hepatica, over 24 h.

RESULTS

In vitro treatment of F. hepatica worms with both CuO-NPs and ZnO-NPs could significantly increase ROS production and oxidative stress induction (decreased SOD, GST and GSH and increased MDA) compared to control group.

CONCLUSIONS

Based on the results, it seems that CuO-NPs and ZnO-NPs may be effective in the control and treatment of F. hepatica infection. Further research is needed to investigate their potential for in vivo use in the treatment of parasitic infections.

Trichinella spiralis: A new parasitic target for curcumin nanoformulas in mice models

Trichinosis spiralis is a global disease with significant economic impact. Albendazole is the current-treatment. Yet, the world-widely emerging antimicrobial resistance necessitates search for therapeutic substitutes. Curcumin is a natural compound with abundant therapeutic benefits. This study aimed to evaluate the potential of crude-curcumin, chitosan and for the first time curcumin-nano-emulsion and curcumin-loaded-chitosan-nanoparticles against Trichinella spiralis adults and larvae in acute and chronic trichinosis models. Trichinosis spiralis was induced in 96 Swiss-albino mice. Infected mice were divided into 2 groups. Group I constituted the acute model, where treatment started 2 h after infection for 5 successive days. Group II constituted the chronic model, where treatment started at the 30th day-post-infection and continued for 10 successive days (Refer to graphical abstract). Each group contained 8 subgroups that were designated Ia-Ih and IIa-IIh and included; a; Untreated-control, b; Albendazole-treated (Alb-treated), c; Crude-curcumin-treated (Cur-treated), d; Curcumin-nanoemulsion-treated (Cur-NE-treated), e; Albendazole and crude-curcumin-treated (Alb-Cur-treated), f; Albendazole and curcumin-nanoemulsion-treated (Alb-Cur-NE-treated), g; Chitosan-nanoparticles-treated (CS-NPs-treated) and h; Curcumin-loaded-chitosan-nanoparticles-treated (Cur-CS-NPs-treated). Additionally, six mice constituted control-uninfected group III. The effects of the used compounds on the parasite tegument, in-vivo parasitic load-worm burden, local pathology and MDA concentration in small intestines of acutely-infected and skeletal muscle of chronically-infected mice were studied. Results showed that albendazole was effective, yet, its combination with Cur-NE showed significant potentiation against adult worms and muscle larvae and alleviated the pathology in both models. Cur-CS-NPs exhibited promising results in both models. Crude-curcumin showed encouraging results especially against muscle larvae on long-term use. Treatments effectively reduced parasite load, local MDA level and CD31 expression with anti-inflammatory effect in intestine and muscle sections.

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.

Programmed cell death pathways as targets for developing antifilarial drugs: Lessons from the recent findings

More than half a century has passed since the introduction of the National Filariasis Control Program; however, as of 2023, lymphatic filariasis (LF) still prevails globally, particularly in the tropical and subtropical regions, posing a substantial challenge to the objective of worldwide elimination. LF is affecting human beings and its economically important livestock leading to a crucial contributor to morbidities and disabilities. The current scenario has been blowing up alarms of attention to develop potent therapeutics and strategies having efficiency against the adult stage of filarial nematodes. In this context, the exploration of a suitable drug target that ensures lethality to macro and microfilariae is now our first goal to achieve. Apoptosis has been the potential target across all three stages of filarial nematodes viz. oocytes, microfilariae (mf) and adults resulting in filarial death after receiving the signal from the reactive oxygen species (ROS) and executed through intrinsic and extrinsic pathways. Hence, it is considered a leading target for developing antifilarial drugs. Herein, we have shown the efficacy of several natural and synthetic compounds/nanoformulations in triggering the apoptotic death of filarial parasites with little or no toxicity to the host body system.

Clinostomum complanatum: Anthelmintic potential of curcumin on the infective progenetic metacercarial stage

The emerging resistance against commonly used antiparasitic drugs has driven investigators to explore alternative approaches using plant-derived active ingredients. These compounds have been tested for antiviral, antibacterial, and anthelmintic properties, particularly against adult worms. However, their effects on larval forms have been neglected. Curcumin is a polyphenol that is a significant constituent of the rhizome of Curcuma longa and possesses various biological activities, including antioxidant, anti-inflammatory, anti-infectious, and anti-carcinogenic. In the present study, the anthelmintic potential of curcumin was tested in vitro for its efficacy against the zoonotically important larval form, the progenetic metacercariae of Clinostomum complanatum, which were procured from the forage fish, Trichogaster fasciatus. Curcumin produced time and concentration-dependent inhibition in the motility of treated metacercarial worms, with the maximum inhibition of motility reported at 60 μM along with a significant increase of (36-92%) in ROS and (57-112%) in GSH levels at the end of a period of 6 h. In contrast, curcumin at the highest concentration significantly inhibited the activities of the antioxidant and detoxification enzymes SOD (36%) and GST (16%), respectively, in addition to altering the polypeptide profile and inhibiting cysteine proteases. The tegumental surface appeared to be highly disrupted in curcumin-treated worms, exhibiting severe blebbing, shearing of the tegument, and spine erosion. Such changes would affect the tegumental functions and survival of worms in the hostile microenvironment. This would render worms more susceptible to host-mediated rejection responses. Based on the results of the present study, it is inferred that C. complanatum could serve as an excellent model for screening novel anthelmintic drugs against larval trematodes of great economic significance. Furthermore, we conclude that curcumin could be exploited as an excellent phytotherapeutic agent against the virulent larval form under investigation.

Evaluating the effect of curcumin on the metacestode of Taenia crassiceps

Curcumin, a curcuminoid present in the rhizome of the plant Curcuma longa has multiple pharmacological effects including anticarcinogenic and anti-inflammatory properties. This work evaluates the anthelmintic effect of the curcumin molecule (98% pure) on Taenia crassiceps cysticerci viability in vitro. Cysticerci incubated in the presence of increasing concentrations of curcumin showed a dose-dependent mortality correlated with a significant increase in the production of reactive oxygen species and a partial inhibition of thioredoxin-glutathione reductase, the only disulfide reductase present in these parasites. At 500 μM curcumin, a 100% of cysticerci lethality was obtained after 2 h of treatment. These results suggest the curcumin-induced oxidative stress could be in the origin of the anthelminthic effect of curcumin. Mice with cysticerci were injected intraperitoneally with 20, 40, or 60 mM curcumin daily for 30 days. A decrease in the burden of cysticerci (46%) was observed with a 60 mM dose of curcumin, supporting this compound as a potential anthelmintic drug.

Thymoquinone Induced Leishmanicidal Effect via Programmed Cell Death in Leishmania donovani

Visceral leishmaniasis (VL) or kala-azar is a vector-borne dreaded protozoal infection that is caused by the parasite Leishmania donovani. With increases in the dramatic infection rates, present drug toxicity, resistance, and the absence of an approved vaccine, the development of new antileishmanial compounds from plant sources remains the keystone for the control of visceral leishmaniasis. In this study, we evaluated the leishmanicidal effect of thymoquinone against L. donovani with an in vitro and ex vivo model. Thymoquinone exhibited potent antipromastigote activity with IC₅₀ and IC₉₀ concentrations achieved at 6.33 ± 1.21 and 20.71 ± 2.15 μM, respectively, whereas the IC₅₀ and IC₉₀ concentrations were found to be 7.83 ± 1.65 and 27.25 ± 2.20 μM against the intramacrophagic form of amastigotes, respectively. Morphological changes in promastigotes and growth reversibility study following treatment confirmed the leishmanicidal effect of thymoquinone. Further, thymoquinone exhibited leishmanicidal activities against L. donovani promastigote through cytoplasmic shrinkage, membrane blebbing, chromatin condensation, cellular and nuclear shrinkage, and DNA fragmentation, as observed under scanning and transmission electron microscopy analyses. The antileishmanial activity was exerted via programmed cell death as proved by exposure of phosphatidylserine, DNA nicking by TUNEL assay, and loss of mitochondrial membrane potential. Thymoquinone at a concentration of 200 μM was devoid of any cytotoxic effects against mammalian macrophage cells. Thymoquinone showed strong leishmanicidal activity against L. donovani, which is mediated via an apoptosis mode of parasitic cell death, and accordingly, thymoquinone may be the source of a new lead molecule for the cure of VL.

Crude protein fraction with high thioredoxin reductase (TrxR) enzyme activity from filarial parasite Setaria cervi counters lipopolysaccharide (LPS)-induced inflammation in macrophages

Host-parasite interaction has always been an area of interest to the parasite biologists. The complex immune interactions between the parasite and/or the parasite-derived products with the host immune cells determine the fate of the disease biology. Parasitic organisms are widely equipped with a vast array of protective machineries including antioxidant enzymes to withstand the hostile condition inside the host body. The reactive oxygen species (ROS) generated inside the host as a result of parasitic intervention can be endured by the parasite by their own tools to ensure their survival. One such antioxidant enzyme in the filarial parasite that plays a significant role in redox homeostasis, survivability and disease progression is the thioredoxin reductase (TrxR). Herein, we have projected a crude lysate of the bovine filarial parasite Setaria cervi enriched with high TrxR enzyme activity has the capacity to downregulate lipopolysaccharide (LPS)-induced inflammatory macrophages. TrxR-mediated inhibition of the TLR4-NF-κB axis resulting into downregulation of the pro-inflammatory cytokines with concomitant upregulation of the anti-inflammatory cytokines supports the filarial parasite to produce an anti-inflammatory milieu which ultimately promotes worm survivability inside the host and pathogenesis.

Identification of promising nutraceuticals against filarial immune-modulatory proteins: insights from in silico and ex vivo studies

Lymphatic filariasis is a neglected tropical disease affecting over 863 million people in 47 countries of the world. The anti-filarial drugs, diethylcarbamazine, albendazole, and ivermectin, are effective only at the larval stages and have proven completely ineffective as adulticides. Besides this, a long-term use of these drugs is associated with several side effects including drug toxicity. Nutraceuticals have emerged as better alternatives for long term treatments due to their safety and lesser side effects. In the present work, we have used drug docking analysis and molecular dynamics simulation approaches to explore the effect of anti-inflammatory nutraceuticals against the immune-modulatory proteins of filarial worms. The filarial proteins enolase, ES-62 precursor, serpin, and cystatin, which are highly efficient in host immune modulation were targeted with more than 50 nutraceuticals. In the in silico study nutraceuticals such as naringin, β-carotene, and emodin showed higher binding efficacy and lower dissociation constant as compared to anti-filarial drugs. Molecular dynamics simulation results showed that immune-modulatory proteins formed highly stable complexes with naringin, β-carotene, and emodin over the entire MD simulation run. The nutraceutical emodin formed the most stable system in silico and hence its effect was investigated on adult filarial parasites under ex vivo conditions too. Emodin significantly affected the motility, viability, ROS production, and genomic DNA fragmentation of filarial parasites. Further in vivo and in vitro studies will help in understanding the mechanism of action of emodin at the molecular level and would help in the development of more effective anti-filarial drugs.

Here in drug docking analysis, molecular dynamics simulations and ex vivo approaches were used to demonstrate the anti-filarial effects of nutraceuticals against immune modulatory proteins of lymphatic filarial parasites.

Filarial thioredoxin reductase exerts anti-inflammatory effects upon lipopolysaccharide induced inflammation in macrophages

Lymphatic filariasis and its associated health hazards have taken enormous tolls especially in the tropical and sub-tropical countries round the globe. Our present work contemplates the immunomodulatory role of filarial Thioredoxin reductase (TrxR) for the survival of the parasite inside the human host. For this, the protein TrxR was purified from the filarial parasite Setaria cervi and further substantiated through specific anti-TrxR antibody raised in mice. Both commercially available anti-TrxR antibody and laboratory raised antibody produced a single band with a molecular mass of ~80 kDa on western blot. The protein is optimally active at pH 7.0 and at temperature 37 °C. This protein contains both alpha helix and beta pleated sheet with selenocysteine at its active site. The Km was found to be 2.75 ± 0.49 mM. TrxR was found to downregulate lipopolysaccharide (LPS)-induced inflammation in macrophages due to inhibition of TLR4-NF-κB pathway. The result was further supported by the downregulation of inflammasome pathway and activation of alternatively activated macrophages upon TrxR treatment. Hence this study projects insights into the importance of filarial TrxR in host-parasite interface as well as it illustrates novel therapeutic strategy towards anti-filarial drug development.

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.

The Genome of Setaria digitata: A Cattle Nematode Closely Related to Human Filarial Parasites

Here we present the draft genome sequence of Setaria digitata, a parasitic nematode affecting cattle. Due to its similarity to Wuchereria bancrofti, the parasitic nematode that causes lymphatic filariasis in humans, S. digitata has been used as a model organism at the genomic level to find drug targets which can be used for the development of novel drugs and/or vaccines for human filariasis. Setaria digitata causes cerebrospinal nematodiasis in goats, sheep, and horses posing a serious threat to livestock in developing countries. The genome sequence of S. digitata will assist in finding candidate genes to use as drug targets in both S. digitata and W. bancrofti. The assembled draft genome is ∼90 Mb long and contains 8,974 genomic scaffolds with a G+C content of 31.73%.

Influence of autophagy, apoptosis and their interplay in filaricidal activity of C-cinnamoyl glycosides

The present work aims to explore the mechanism of action of C-cinnamoyl glycoside as an antifilarial agent against the bovine filarial nematode Setaria cervi. Both apoptosis and autophagy programmed cell death pathways play a significant role in parasitic death. The generation of reactive oxygen species, alteration of the level of antioxidant components and disruption of mitochondrial membrane potential may be the causative factors that drive the parasitic death. Monitoring of autophagic flux via the formation of autophagosome and autophagolysosome was detected via CYTO ID dye. The expression profiling of both apoptotic and autophagic marker proteins strongly support the initial findings of these two cell death processes. The increased interaction of pro-autophagic protein Beclin1 with BCL-2 may promote apoptotic pathway by suppressing anti-apoptotic protein BCL-2 from its function. This in turn partially restrains the autophagic pathway by engaging Beclin1 in the complex. But overall positive increment in autophagic flux was observed. Dynamic interaction and regulative balance of these two critical cellular pathways play a decisive role in controlling disease pathogenesis. Therefore, the present experimental work may prosper the chance for C-cinnamoyl glycosides to become a potential antifilarial therapeutic in the upcoming day after detail in vivo study and proper clinical trial.

Upregulation of Cathepsin B-like Protease Activity During Apoptosis inGiardia duodenalis

Background:

In eukaryotic cells, apoptosis signaling pathways are controlled mainly by aspartic acid cysteine proteases (caspases). However, certain unicellular microorganisms, such as Giardia duodenalis, lack these proteins. Thus, other cysteine proteases may play an important role in the parasite apoptosis signaling pathway.

Objective:

To understand the effect of cathepsin B-like inhibition on the cell viability of Giardia duodenalis and its cell death process.

Methods:

Bioinformatics analysis was performed to identify apoptotic proteases. Analysis showed that cathepsin B-like protease genes from G. duodenalis were the best candidate. A homology modeling technique was used to explore in silico the inhibitory effect of E-64 against cathepsin B-like proteases from G. duodenalis genome and to examine the effect of curcumin on cathepsin B-like activity regulation. In addition, the effect of E-64 on parasite survival and DNA fragmentation was tested.

Results:

Eight cathepsin B-like protease coding genes were identified in silico. Interestingly, while these sequences lacked the cathepsin B characteristic occluding loop, they maintained the catalytic active- site responsible for cathepsin B activity, which was evidenced by the increase in the degradation of the Z-RR-AMC substrate, suggesting the upregulation of the activity of these proteins. Additionally, inhibition of E-64 against G. duodenalis trophozoites caused a decrease in DNA fragmentation compared to control cells and had a positive effect on parasite survival after exposure to curcumin.

Conclusion:

Overall, these results suggested that Giardia duodenalis might have a cell death mechanism in which cathepsin B-like proteases play an important role.

Polyphenol enriched ethanolic extract of Cajanus scarabaeoides (L.) Thouars exerts potential antifilarial activity by inducing oxidative stress and programmed cell death

Development of antifilarial drug from the natural sources is considered as one of the most efficacious, safe, and affordable approaches. In this study, we report the antifilarial activity of a leguminous plant Cajanus scarabaeoides (L.) Thouars. The polyphenol-rich ethanolic extract obtained from the stem part of the plant C. scarabaeoides (EECs) was found to be efficient in killing the filarial nematode Setaria cervi in all the three developmental stages viz. oocytes, microfilariae (Mf) and adults with LD₅₀ values of 2.5, 10 and 35 μg/ml, respectively. While studying the molecular mechanism of action, we found that induction of oxidative stress plays the key role in inducing the mortality in S. cervi. The redox imbalance finally results in activation of the nematode CED pathway that executes the death of the parasite. Intriguingly, EECs was found to be selectively active against the worm and absolutely non-toxic to the mammalian cells and tissues. Taken together, our experimental data demonstrate that C. scarabaeoides can be chosen as an affordable natural therapeutic for treating filarial infection in the future with high efficacy and less toxicity.

Antifilarial activity of azadirachtin fuelled through reactive oxygen species induced apoptosis: a thorough molecular study on Setaria cervi

Efficacious therapeutic strategies against lymphatic filariasis are always sought after. However, natural products are a promising resource for developing effective antifilarial agents. Azadirachtin, a significant tetranortriterpenoid phytocompound found in Azadirachta indica, was evaluated in vitro for antifilarial potential against the filarial parasite Setaria cervi. Dye exclusion and MTT assay confirmed the antifilarial potential of azadirachtin against S. cervi with a median lethal dose (LC50) of 6.28 μg/ml for microfilariae (mf), and 9.55 μg/ml for adult parasites. Morphological aberrations were prominent in the histological sections of the azadirachtin-exposed parasites. Moreover, alterations in the reactive oxygen species (ROS) parameters in treated parasites were evident. Induction of apoptosis in treated parasites was confirmed by DNA laddering, acridine orange (AO)/ethidium bromide (EtBr) double staining and in situ DNA fragmentation. The downregulation of anti-apoptotic CED-9 and upregulation of proapoptotic EGL-1, CED-4 and CED-3 at both the transcription and translation levels confirmed apoptosis execution at the molecular level. Changes in the gene expressions of nuc-1, cps-6 and crn-1 further clarified the molecular cause of DNA degradation. Furthermore, azadirachtin was found to be non-toxic in both in vitro and in vivo toxicity analyses. Therefore, the experimental evidence detailed the pharmacological effectiveness of azadirachtin as a possible therapeutic agent against filariasis.

Oleanolic acid from antifilarial triterpene saponins of Dipterocarpus zeylanicus induces oxidative stress and apoptosis in filarial parasite Setaria digitata in vitro

Absence of a drug that kills adult filarial parasites remains the major challenge in eliminating human lymphatic filariasis (LF); the second leading cause of long-term and permanent disability. Thus, the discovery of novel antifilarial natural products with potent adulticidal activity is an urgent need. In the present study, methanol extracts of leaves, bark and winged seeds of Dipterocarpus zeylanicus (Dipterocarpaceae) were investigated for macro and microfilaricidal activity. Two antifilarial triterpene saponins were isolated from winged seed extracts by bioactivity guided chromatographic separation and identified using Nuclear Magnetic Resonance and mass spectroscopic analysis as oleanolic acid 3-O-β-D- glucopyranoside (1) (IC50 = 20.54 μM for adult worms, 19.71 μM for microfilariae ) and oleanolic acid 3-O-α-L-arabinopyranoside (2) (IC50 = 29.02 μM for adult worms, 25.99 μM for microfilariae). Acid hydrolysis of both compounds yielded oleanolic acid (3) which was non or least toxic to human peripheral blood mono nuclear cells (Selectivity index = >10) while retaining similar macrofilaricidal (IC50 = 38.4 μM) and microfilaricidal (IC50 = 35.6 μM) activities. In adult female worms treated with 50 and 100 μM doses of oleanolic acid, condensation of nuclear DNA, apoptotic body formation and tissue damage was observed by using Hoechst 33342 staining, TUNEL assay and Hematoxylin and Eosin staining respectively. A dose dependent increase in caspase 3/CED3 activity and decrease in total protein content were also observed in these parasites. A dose dependant DNA fragmentation was observed in adult parasites and microfilariae. Decreased levels of reduced glutathione (GSH) and elevated levels of glutathione S transferase (GST), superoxide dismutase (SOD) and reactive oxygen species (ROS) were also observed in parasites treated with oleanolic acid indicating an oxidative stress mediated apoptotic event. Compound 3/oleanolic acid was thus identified as a potent and safe antifilarial compound in vitro.

Anthelmintic Potential of Thymoquinone and Curcumin on Fasciola gigantica

Fasciolosis an economically important global disease of ruminants in the temperate and tropical regions, caused by Fasciola hepatica and F. gigantica, respectively, also poses a potential zoonotic threat. In India alone it causes huge losses to stakeholders. Anthelmintics including triclabendazole have been used to control this menace but the emerging resistance against the available compounds necessitates identification of novel and alternative therapeutic measures involving plant derived natural compounds for their anthelmintic potential. Thymoquinone (T) and curcumin (C), the active ingredients of Nigella sativa and Curcuma longa respectively have been used as antiparasitic agents but the information on their flukicidal effect is very limited. Adult flukes of F. gigantica were in vitro exposed to different concentrations of thymoquinone and curcumin separately for 3h at 37+ 1°C. A significant (p<0.05) reduction in the worm motility at 60 μM concentration of both T and C was observed though all the worms remained alive after 3h exposure, whereas the effect on egg shedding was statistically insignificant. Pronounced tegumental disruptions and erosion of spines in the posterior region and around the acetabulum was evident. A significant (p<0.05) decrease in glutathione-S-transferase and superoxide dismutase activity and reduced glutathione (GSH) level was observed, while protein carbonylation increased differentially. A significant inhibition of CathepsinL (CatL) gene expression in thymoquinone treated worms was also evident. Further, in silico molecular docking of T and C with CatL revealed a stronger interaction of curcumin with the involvement of higher number of amino acids as compared to thymoquinone that could be more effective in inhibiting the antioxidant enzymes of F. gigantica. It is concluded that both the compounds understudy will decrease the detoxification ability of F. gigantica, while inhibition of CatL will significantly affect their virulence potential. Thus, both thymoquinone and curcumin appeared to be promising anthelmintic compounds for further investigations.

Curcumin Generates Oxidative Stress and Induces Apoptosis in Adult Schistosoma mansoni Worms

Inducing apoptosis is an interesting therapeutic approach to develop drugs that act against helminthic parasites. Researchers have investigated how curcumin (CUR), a biologically active compound extracted from rhizomes of Curcuma longa, affects Schistosoma mansoni and several cancer cell lines. This study evaluates how CUR influences the induction of apoptosis and oxidative stress in couples of adult S. mansoni worms. CUR decreased the viability of adult worms and killed them. The tegument of the parasite suffered morphological changes, the mitochondria underwent alterations, and chromatin condensed. Different apoptotic parameters were determined in an attempt to understand how CUR affected adult S. mansoni worms. CUR induced DNA damage and fragmentation and increased the expression of SmCASP3/7 transcripts and the activity of Caspase 3 in female and male worms. However, CUR did not intensify the activity of Caspase 8 in female or male worms. Evaluation of the superoxide anion and different antioxidant enzymes helped to explore the mechanism of parasite death further. The level of superoxide anion and the activity of Superoxide Dismutase (SOD) increased, whereas the activity of Glutathione-S-Transferase (GST), Glutathione reductase (GR), and Glutathione peroxidase (GPX) decreased, which culminated in the oxidation of proteins in adult female and male worms incubated with CUR. In conclusion, CUR generated oxidative stress followed by apoptotic-like-events in both adult female and male S. mansoni worms, ultimately killing them.

Rhizome extracts of Curcuma zedoaria Rosc induce caspase dependant apoptosis via generation of reactive oxygen species in filarial parasite Setaria digitata in vitro

Human lymphatic filariasis (LF) is mainly caused by filarial parasite Wuchereria bancrofti and is the second leading cause of long term and permanent disability in tropical countries. To date, incapability to eliminate long lived adult parasites by current drugs remains the major challenge in the elimination of LF. Hence, in the current study, the efficacy of rhizome extracts of Curcuma zedoaria (a plant traditionally used in Sri Lanka in the management of LF) was evaluated as an effective filaricide in vitro. Sequential solvent extracts of C. zedoaria rhizomes were screened for in vitro antifilarial activity at 0.01-1 mg/mL concentrations by motility inhibition assay and 3-(4, 5 dimethylthiazol-2-yl)-2, 5 diphenyl tetrazolium bromide (MTT) reduction assay using cattle parasite Setaria digitata as a model organism. Exposure of parasites to hexane and chloroform extracts of C. zedoaria caused a dose dependant reduction in motility and viability of microfilariae (IC50 = 72.42 μg/mL for hexane extract, 191.14 μg/mL for chloroform extract) and adult parasites (IC50 = 77.07 μg/mL for hexane extract, 259.87 μg/mL for chloroform extract). Both extracts were less toxic to human peripheral blood mononuclear cells when compared to filariae. A dose dependant increase in caspase 3/CED 3 and a decrease in total protein content, cyclooxygenase (COX) and protein tyrosine phosphatase (PTP) activities were observed in adult parasites treated with hexane or chloroform extract. A significant degree of chromatin condensation and apoptotic body formation were also observed in these worms by Hoechst 33342 and terminal deoxynucleotidyl transferase-mediated dUTP biotin nick end labeling (TUNEL) staining respectively. Dose dependant chromosomal DNA laddering was observed in treated adult worms but not in microfilariae in response to both extracts. Oxidative stress parameters such as reduction in reduced glutathione (GSH) levels and increase in glutathione s transferase (GST), superoxide dismutase (SOD) and catalase activities, increased reactive oxygen levels (ROS) and lipid peroxidation were also observed indicating that an apoptotic event is induced by reactive oxygen species.

Oxidative stress plays major role in mediating apoptosis in filarial nematode Setaria cervi in the presence of trans-stilbene derivatives

Lymphatic filariasis, affecting around 120 million people in 80 countries worldwide, is an extremely painful disease and caused permanent and long term disability. Owing to its alarming prevalence there is immediate need for development of new therapeutics. A series of trans-stilbene derivatives were synthesized using aqueous reaction condition showing potential as antifilarial agents demonstrated in vitro. MTT reduction assay and dye exclusion test were performed to evaluate the micro and macrofilaricidal potential of these compounds. Amid 20 trans-stilbene derivatives together with Resveratrol (RSV), a multifunctional natural product was screened; nine compounds (28, 29, 33, 35, 36, 38, 39, 41 and 42) have showed promising micro and macrofilaricidal activities and four of them (28, 39, 41 and 42) showed better effectiveness than RSV. In the treated parasites apoptosis was established by DNA laddering, in situ DNA fragmentation and FACS analysis. The generation of ROS in the treated parasites was indicated by the depletion in the level of GSH, GR and GST activity and elevation of SOD, catalase, GPx activity and superoxide anion and H2O2 level. Along with the ROS generation and oxidative stress, the decreased expression of anti-apoptotic ced-9 gene and increased expression of nematode specific pro-apoptotic genes, egl-1, ced-4 and ced-3 at the level of transcription and translation level; the up-regulation of caspase-3 activity and involvement of caspase-8,9,3, cytochrome-c and PARP were also observed and which denotes the probable existence of both extrinsic and intrinsic pathways apoptosis in parasitic nematodes. This observation is reported first time and thus it confirmed the mode of action and effectiveness of the compounds. Further, the comparative bioavailability-pharmacokinetics studies showed that compound 28 possesses comparable properties with Ivermectin. This study will certainly intensify our understanding of the pharmacological importance of trans-stilbenes as an anti-filarial agent.

Evidence of reactive oxygen species (ROS) mediated apoptosis in Setaria cervi induced by green silver nanoparticles from Acacia auriculiformis at a very low dose

Green synthesis of silver nanomaterial plays a pivotal role in the growing field of nanotechnology. Development of anti-parasitic drugs from plant metabolites has been in regular practice from the ancient period but most of them were discarded due to their inefficiency to control diseases effectively. At present, nanoparticles are used for developing anti-parasitic therapy for their unique properties such as smallest in size, bio-ability, bio-compatibility and penetration capacity into a cell. The present study aims at synthesis of silver nanoparticles (AgNPs) by using funicles extract of Acacia auriculiformis and tests its efficacy as antifilarial. Experimental evidence show that AgNPs are effective at a very low concentration compared to crude plant extracts. Synthesis of these nanoparticles is a single-step, biogenic, cost effective and eco-friendly process. Synthesized nanoparticles were characterized by UV-Vis spectroscopy, TEM, SAED, FTIR, EDX, FESEM and Z-potential. The antifilarial efficacy of AgNPs was tested against different life cycle stages of bovine filarial parasite Setaria cervi by morphological study, motility assessment and viability assay. These nanoparticles are found to have antifilarial activity with LC50 of 5.61 μg/mL and LC90 of 15.54 μg/mL against microfilaria of S. cervi. The microscopic findings and the detailed molecular studies confirmed that green synthesized AgNPs were effective enough to induce apoptosis through up regulation of ROS (reactive oxygen species).

Diospyros perigrena bark extract induced apoptosis in filarial parasite Setaria cervi through generation of reactive oxygen species

CONTEXT

Lymphatic filariasis is a major neglected tropical disease. Diospyros perigrena Gurke (Ebenaceae) was selected for antifilarial chemotherapy because of unavailability of proper medicine. In India, different parts of this plant were used for the treatment of diabetes, diarrhea, dysentery, cholera, mouth ulcers, and wounds.

OBJECTIVE

The present study was undertaken to access antifilarial potential and mechanism of action of n-butanol extract (NBE) of D. perigrena stem bark on Setaria cervi Rudolphi (Onchocercidae).

MATERIALS AND METHODS

In vitro efficacy and apoptotic mechanism were evaluated by Hoechst, TUNEL, DNA fragmentation assay, pro- and anti-apoptotic gene expression in NBE (250, 125, 62.5, 31.25, and 15.6 µg/ml)-treated S. cervi after 24 h of incubation. Reactive oxygen species (ROS) up-regulation was also determined by GSH, GST, SOD assays, and super oxide anion level.

RESULTS

Significant in vitro antifilarial activity of NBE was found 50% inhibitory concentration (IC50): adult = 57.6 μg/ml, microfilariae (mf) = 56.1 μg/ml, and lethal dose (LD100) in mf is 187.17 μg/ml) after 24 h of treatment. NBF-induced apoptosis was proved by Hoechst, TUNEL, RT-PCR, and Western blot method. NBF (250 µg/ml) decreased the level of GSH (17.8%) and GST (65.4%), increased SOD activity (1.42-fold) and super oxide anion production (1.32-fold) in the treated parasite which culminated into ROS up-regulation.

DISCUSSION AND CONCLUSION

NBE induced apoptosis in different life cycle stages of S. cervi. In future, a detailed study of NBF will give us a novel antifilarial compound which will be used for antifilarial chemotherapy.

Antagonistic effects of black tea against gamma radiation-induced oxidative damage to normal lymphocytes in comparison with cancerous K562 cells

The potential of naturally occurring antioxidants to reduce the cellular oxidative damage induced by ionizing radiation has been studied for more than a decade for their pharmacological application during cancer treatment. It is already known that radioprotective efficacy of phytochemicals might influence various end points of radiation damage. Flavonoids are well-known natural radioprotectors, and their biological effects depend upon their chemical structure. In the present study, radioprotective effect of black tea rich in flavonoids was evaluated against gamma radiation-induced oxidative damage on normal lymphocytes and compared with erythroleukemic K562 cells. Pre-treatment with black tea extract (BTE) significantly reduced radiation-induced loss of cell viability, generation of reactive oxygen species, mitochondrial dysfunction, activation of caspase-3 and apoptosis in normal lymphocytes compared to K562 cells. BTE also regulates the activity of endogenous antioxidant enzymes. The changes in the mRNA expression of bax, bcl2, p53 and Nrf2 were also followed to evaluate regulation of radiation-induced apoptosis by BTE. These findings suggest that black tea may have the potential of a natural radioprotective agent which can be used as adjunct with radiation during cancer treatment.

In vitro antifilarial activity of Azadirachta indica aqueous extract through reactive oxygen species enhancement

OBJECTIVE

To evaluate an aqueous preparation from the Azadirachta indica leaves (AEA) against Setaria cervi (S. cervi), a model filarial parasite.

METHOD

In vitro efficacy of AEA was evaluated against S. cervi through estimation of relative motility value, dye exclusion test and MTT assay. Visible morphological alterations were monitored using conventional microscopic techniques in microfilariae and haematoxylin-eosin stained sections of AEA-treated adults.

RESULTS

Enhancement of reactive oxygen species in S. cervi treated with AEA was established through alteration in the activity of glutathione S-transferase, superoxide dismutase, catalase, peroxidase and level of superoxide anion and reduced glutathione.

CONCLUSION

In vitro filaricidal activity of AEA is possibly through disturbing redox homeostasis by down-regulating and altering the level of some key antioxidants and regulatory enzymes like reduced glutathione, glutathione S-transferase, superoxide dismutase, catalase and glutathione peroxidase of S. cervi.

Antifilarial effect of ursolic acid from Nyctanthes arbortristis: molecular and biochemical evidences

A bio-assay guided fractionation and purification approach was used to examine in vitro antifilarial activities of the crude methanolic extract of Nyctanthes arbortristis as well as fractions and isolated compound. From ethyl-acetate fraction we isolated and identified a triterpenoid compound which has been characterized as ursolic acid (UA) by HPLC and NMR data. We are reporting for the first time isolation and identification of UA from the leaves of N. arbortristis. The crude extract and UA showed significant micro- as well as macrofilaricidal activities against the oocyte, microfilaria and adult of Setaria cervi (S. cervi) by dye exclusion test and MTT reduction assay. Significant microfilaricidal activity of UA was further proved against mf of W. bancrofti by viability assay. The findings thus provide a new lead for development of a suitable filaricide from natural products. The molecular mechanism of UA was investigated by performing TUNEL, Hoechst staining, Annexin V-Cy3, flow cytometric analysis and DNA fragmentation assay. Differential expressions of pro- and anti-apoptotic genes were observed at the transcription and translational levels in a dose-dependent manner. Depletion in the worm GSH level and elevation in the parasite GST, SOD and super oxide anion indicated the generation of ROS. In this investigation we are reporting for the first time that UA acts its antifilarial effect through induction of apoptosis and by downregulating and altering the level of some key antioxidants like GSH, GST and SOD of S. cervi.