In vivo anthelmintic activity of Carex baccans and its active principle resveratrol against Hymenolepis diminuta

Curcusinol from the fruit of Carex baccans with antibacterial activity against multidrug-resistant strains

ETHNOPHARMACOLOGICAL RELEVANCE

Carex baccans, known as Shan-Bai-Zi or Ye-Gao-Liang in China, is a traditional medicinal herb used by several ethnic groups in Yunnan Province. It is utilized for the treatment of wound infections, ulcers, and dysentery. However, there is currently a dearth of research reports on its antimicrobial potential.

AIM OF THE STUDY

The substance basis of the antimicrobial activity of C. baccans will be unveiled, and the in vitro and in vivo antibacterial activities against multidrug-resistant bacteria of its major active compounds, as well as their preliminary mechanisms of action, will be investigated.

MATERIALS AND METHODS

An antibacterial bioactivity-guided isolation method was used to isolate and identify the active compound curcusinol from C. baccans. UPLC-DAD-MS was employed for the quantitative analysis of curcusinol. The antibacterial activity, resistance profile, synergistic effects, anti-biofilm activity, and potential mechanisms of action of curcusinol against methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE), and other multidrug-resistant bacteria (Escherichia coli, Pseudomonas aeruginosa, Acinetobacter baumannii) were investigated using various methods, including the broth microdilution method, scanning electron microscopy, time kill assay, multi-generational resistance induction assay, checkerboard synergy assay, anti-biofilm assay, and metabolomics. Furthermore, the therapeutic efficacy of curcusinol was assessed in vivo by establishing an animal skin wound infection model of MRSA.

RESULTS

Curcusinol was isolated from the fruit of C. baccans, which accounts for 3.1% of the dry weight of the fruit. Curcusinol exhibited significant bactericidal and anti-biofilm activities against antibiotic-resistant Gram-positive bacteria in vitro. Furthermore, curcusinol acted as an antibiotic adjuvant to enhance the activity of various commonly used antibiotics against both Gram-positive and Gram-negative antibiotic-resistant bacteria without cytotoxicity to mammalian cells (A549 and RAW264.7) at 64 μM. Moreover, curcusinol affected arginine biosynthesis, cysteine and methionine metabolism, and alanine, aspartate, and glutamate metabolism significantly in MRSA cells under stress. Additionally, curcusinol effectively treated MRSA-infected mouse skin wounds and accelerated wound healing in vivo.

CONCLUSIONS

The results of this study not only support the traditional uses of C. baccans but also demonstrate that its major active compound, curcusinol, is an effective plant-derived bactericidal agent and antibacterial adjuvant with potential applications in the treatment of skin infections.

Model nematodes as a practical innovation to promote high throughput screening of natural products for anthelmintics discovery in South Asia: Current challenges, proposed practical and conceptual solutions

With the increasing prevalence of anthelmintic resistance in animals recorded globally, and the threat of resistance in human helminths, the need for novel anthelmintic drugs is greater than ever. Most research aimed at discovering novel anthelmintic leads relies on high throughput screening (HTS) of large libraries of synthetic small molecules in industrial and academic settings in developed countries, even though it is the tropical countries that are most plagued by helminth infections. Tropical countries, however, have the advantage of possessing a rich flora that may yield natural products (NP) with promising anthelmintic activity. Focusing on South Asia, which produces one of the world's highest research outputs in NP and NP-based anthelmintic discovery, we find that limited basic research and funding, a lack of awareness of the utility of model organisms, poor industry-academia partnerships and lack of technological innovations greatly limit anthelmintics research in the region. Here we propose that utilizing model organisms including the free-living nematode Caenorhabditis elegans, that can potentially allow rapid target identification of novel anthelmintics, and Oscheius tipulae, a closely related, free-living nematode which is found abundantly in soil in hotter temperatures, could be a much-needed innovation that can enable cost-effective and efficient HTS of NPs for discovering compounds with anthelmintic/antiparasitic potential in South Asia and other tropical regions that historically have devoted limited funding for such research. Additionally, increased collaborations at the national, regional and international level between parasitologists and pharmacologists/ethnobotanists, setting up government-industry-academia partnerships to fund academic research, creating a centralized, regional collection of plant extracts or purified NPs as a dereplication strategy and HTS library, and holding regional C. elegans/O. tipulae-based anthelmintics workshops and conferences to share knowledge and resources regarding model organisms may collectively promote and foster a NP-based anthelmintics landscape in South Asia and beyond.

Resveratrol against Echinococcus sp.: Discrepancies between In Vitro and In Vivo Responses

In an attempt to find new anti-echinococcal drugs, resveratrol (Rsv) effectiveness against the larval stages of Echinococcus granulosus and E. multilocularis was evaluated. The in vitro effect of Rsv on parasites was assessed via optical and electron microscopy, RT-qPCR and immunohistochemistry. In vivo efficacy was evaluated in murine models of cystic (CE) and alveolar echinococcosis (AE). The impact of infection and drug treatment on the mouse bone marrow hematopoietic stem cell (HSC) population and its differentiation into dendritic cells (BMDCs) was investigated via flow cytometry and RT-qPCR. In vitro treatment with Rsv reduced E. granulosus metacestode and protoscolex viability in a concentration-dependent manner, caused ultrastructural damage, increased autophagy gene transcription, and raised Eg-Atg8 expression while suppressing Eg-TOR. However, the intraperitoneal administration of Rsv was not only ineffective, but also promoted parasite development in mice with CE and AE. In the early infection model of AE treated with Rsv, an expansion of HSCs was observed followed by their differentiation towards BMCDs. The latter showed an anti-inflammatory phenotype and reduced LPS-stimulated activation compared to control BMDCs. We suggest that Rsv ineffectiveness could have been caused by the low intracystic concentration achieved in vivo and the drug's hormetic effect, with opposite anti-parasitic and immunomodulatory responses in different doses.

The Tapeworm Hymenolepis diminuta as an Important Model Organism in the Experimental Parasitology of the 21st Century

The tapeworm Hymenolepis diminuta is a common parasite of the small intestine in rodents but it can also infect humans. Due to its characteristics and ease of maintenance in the laboratory, H. diminuta is also an important model species in studies of cestodiasis, including the search for new drugs, treatments, diagnostics and biochemical processes, as well as its host-parasite interrelationships. A great deal of attention has been devoted to the immune response caused by H. diminuta in the host, and several studies indicate that infection with H. diminuta can reduce the severity of concomitant disease. Here, we present a critical review of the experimental research conducted with the use of H. diminuta as a model organism for over more than two decades (in the 21st century). The present review evaluates the tapeworm H. diminuta as a model organism for studying the molecular biology, biochemistry and immunology aspects of parasitology, as well as certain clinical applications. It also systematizes the latest research on this species. Its findings may contribute to a better understanding of the biology of tapeworms and their adaptation to parasitism, including complex correlations between H. diminuta and invertebrate and vertebrate hosts. It places particular emphasis on its value for the further development of modern experimental parasitology.

Anti-parasitic effects of resveratrol on protoscolices and hydatid cyst layers

The main goal of the current study was to evaluate the effectiveness of resveratrol (RESV) on protoscolices and hydatid cysts of Echinococcus granolosus. Echinococcus granolosus protoscolices and hydatid cyst were exposed to RPMI, DMSO, formalin, mebendazole, and different concentrations of RESV in vitro. Then, viability, GGT, and caspase-3 activity of protoscolices were evaluated using light microscopy, colorimetric, and enzymatic assay, respectively. Tissue changes and expression of caspase-3 apoptosis were analyzed on the hydatid cyst wall by histologic and immunohistochemistry methods. The cell toxicity effect of RESV was evaluated on mouse PBMCs by Annexin V-FITC assay. The RESV-treated protoscolices showed loss of viability, increased gamma-glutamyl transpeptidase, and caspase-3 activity with significant differences compared to all control groups (P < 0.05). Dose and time dependence of mortality, GGT, and caspase-3 enzymatic activity was confirmed in the protoscolices of Echinococcus granulosus treated by RESV. Also, the tissue changes and apoptosis were prominent in RESV-treated hydatid cyst layers; however, tissue changes were only time-dependent, and RESV concentration had no apparent effect on tissue. In cell toxicity evaluation, RESV is safe without any significant apoptosis induction from 31.5 to 250 μg/ml; however, it was significant at 350 and 500 μg/ml in PBMCs.

Anti-leishmanial effects of resveratrol and resveratrol nanoemulsion on Leishmania major

Background

Leishmaniasis is a vector-borne disease that is endemic in the tropical and sub-tropical areas of the world. Low efficacy and high cytotoxicity of the current treatment regimens for leishmaniasis is one of the most important health problems. In this experimental study, anti-leishmanial effects of different concentrations of resveratrol and resveratrol nano-emulsion (RNE) were assessed.

Methods

RNE was prepared using the probe ultra-sonication method. The cytotoxicity was evaluated using the MTT technique on the L929 cell line. The anti-leishmanial activities on promastigotes of leishmania were assessed using vital staining and infected BALB/c mice were used to assess the in vivo anti-leishmanial effects.

Results

In vitro and in vivo assays revealed that all concentrations of resveratrol and RNE had valuable inhibitory effects against Leishmania major in comparison to the control group (P < 0.05). The half maximal inhibitory concentration (IC₅₀) values were calculated as 16.23 and 35.71 µg/mL for resveratrol and RNE, respectively. Resveratrol and RNE showed no cytotoxicity against the L929 cell line.

Conclusions

According to the potent in vitro and in vivo anti-leishmanial activity of RNE at low concentration against L. major, we suggest that it could be a promising anti-leishmanial therapeutic against L. major in the future.

Molecular Docking Simulation Studies Identifies Potential Natural Product Derived-Antiwolbachial Compounds as Filaricides against Onchocerciasis

Onchocerciasis is the leading cause of blindness and severe skin lesions which remain a major public health problem, especially in tropical areas. The widespread use of antibiotics and the long duration required for effective treatment continues to add to the increasing global menace of multi-resistant pathogens. Onchocerca volvulus harbors the endosymbiont bacteria Wolbachia, essential for the normal development of embryos, larvae and long-term survival of the adult worm, O. volvulus. We report here results of using structure-based drug design (SBDD) approach aimed at identifying potential novel Wolbachia inhibitors from natural products against the Wolbachia surface protein (WSP). The protein sequence of the WSP with UniProtKB identifier Q0RAI4 was used to model the three-dimensional (3D) structure via homology modelling techniques using three different structure-building algorithms implemented in Modeller, I-TASSER and Robetta. Out of the 15 generated models of WSP, one was selected as the most reasonable quality model which had 82, 15.5, 1.9 and 0.5% of the amino acid residues in the most favored regions, additionally allowed regions, generously allowed regions and disallowed regions, respectively, based on the Ramachandran plot. High throughput virtual screening was performed via Autodock Vina with a library comprising 42,883 natural products from African and Chinese databases, including 23 identified anti-Onchocerca inhibitors. The top six compounds comprising ZINC000095913861, ZINC000095486235, ZINC000035941652, NANPDB4566, acetylaleuritolic acid and rhemannic acid had binding energies of −12.7, −11.1, −11.0, −11, −10.3 and −9.5 kcal/mol, respectively. Molecular dynamics simulations including molecular mechanics Poisson-Boltzmann (MMPBSA) calculations reinforced the stability of the ligand-WSP complexes and plausible binding mechanisms. The residues Arg45, Tyr135, Tyr148 and Phe195 were predicted as potential novel critical residues required for ligand binding in pocket 1. Acetylaleuritolic acid and rhemannic acid (lantedene A) have previously been shown to possess anti-onchocercal activity. This warrants the need to evaluate the anti-WSP activity of the identified molecules. The study suggests the exploitation of compounds which target both pockets 1 and 2, by investigating their potential for effective depletion of Wolbachia. These compounds were predicted to possess reasonably good pharmacological profiles with insignificant toxicity and as drug-like. The compounds were computed to possess biological activity including antibacterial, antiparasitic, anthelmintic and anti-rickettsials. The six natural products are potential novel antiwolbachial agents with insignificant toxicities which can be explored further as filaricides for onchocerciasis.

Chemistry and Pharmacology of Cyperaceae Stilbenoids: A Review

Cyperaceae is a cosmopolitan plant family with approx. 5000 species distributed worldwide. Several members of this family are used in traditional medicines for the treatment of different diseases. In the last few decades, constituents with great chemical diversity were isolated from sedges, and a wide range of biological activities were detected either for crude extracts or for pure compounds. Among the isolated compounds, phenolic derivatives are the most important, especially stilbenoids, and flavonoids. To date, more than 60 stilbenoids were isolated from 28 Cyperaceae species. Pharmacological investigation of Cyperaceae stilbenoids revealed that several compounds possess promising activities; mainly antiproliferative, antibacterial, antioxidant and anthelmintic effects. Isolation, synthesis and pharmacological investigation of stilbenes are increasing constantly. As Cyperaceae species are very good sources of a wide variety of stilbenes, and several of them occur in large amount worldwide, they are worthy for phytochemical and pharmacological investigations. Moreover, stilbenes are important from chemotaxonomical point of view, and they play a key role in plant defense mechanisms as well. This review summarizes the stilbenoids isolated from sedges, and their biological activities.

Studies on the anthelmintic potentials of the roots of Asparagus racemosus willd. (Asparagaceae)

Background

The Santhal tribe in Assam, India use the roots of Asparagus racemosus (Asparagaceae) as a deworming remedy. The study aimed to investigate the anthelmintic credentials of this plant, using two representative groups of helminth parasites.

Methods

The in vitro testing was conducted against Hymenolepis diminuta (cestode) and Syphacia obvelata (nematode). Parasites were exposed to 10, 20 and 30 mg/ml concentrations of plant extract, and efficacy was adjudged on the basis of parasites paralysis and mortality. In vivo efficacy was examined using H. diminuta-rat and S. obvelata-mice models where animals were administered 125, 250 and 500 mg/kg doses of extract.

Results

In vitro assay, against H. diminuta revealed that at 30 mg/ml concentration the extract showed almost a comparable efficacy with that of reference drug praziquantel (PZQ) (1 mg/ml). The in vitro efficacy of extract against S. obvelata was however lower than H. diminuta. In vivo studies against H. diminuta at 500 mg/kg revealed 53.88 and 24 % reduction in eggs per gram (EPG) and worm counts respectively. Against S. obvelata the extract showed 26.61 and 30.93 % reduction for the same.

Conclusions

The findings of this study present suggest that the roots of A. racemosus are effective against intestinal helminthic infections and justifies its use as an anthelmintic in the traditional medicine of the Santhals.

In vitro anthelmintic activity of grape pomace extract against gastrointestinal nematodes of naturally infected sheep

Grape pomace obtained as a byproduct of industrial processing of grapes retains nutrients and substances with anthelmintic potential such as saponins, tannins, and flavonoids. Therefore, this study evaluated the in vitro ovicidal and larvicidal activity of hydroalcoholic grape pomace extract against gastrointestinal nematodes of sheep. The anthelmintic evaluation was performed by in vitro assays with eggs and larvae of nematodes obtained from naturally infected donor sheep. The grape pomace extract showed high in vitro ovicidal and larvicidal activity with LD50 values of 0.30 mg/mL for egg hatching inhibition, 1.01 mg/mL for larval development inhibition and 100% efficacy in larval migration inhibition assays at all concentrations evaluated. The effect of tannins was evaluated by the addition of 50 mg/mL polyvinyl polypyrrolidone to grape pomace extract at the concentration of 12.5 mg/mL. The in vitro ovicidal activity of grape pomace was reduced by only 15% after polyvinyl polypyrrolidone addition, indicating that other phytochemicals also contribute to the ovicidal activity displayed by the extract. Our results demonstrate that grape pomace exhibits in vitro anthelmintic activity, suggesting that, beyond its nutritional potential, this pomace can also be an ally for gastrointestinal nematode control in sheep.

Genistein: is the multifarious botanical a natural anthelmintic too?

Genistein (4',5,7-trihydroxyisoflavone) is naturally present in plants of the soy family and is known to have various pharmacological activities, such as anti-cancer, anti-diabetic, anti-oxidant, etc. The phytoestrogen is one of the major isoflavones found in some medicinal plants having anthelmintic properties. This review describes the putative role of genistein as an anthelmintic, which has been tested on some helminth parasites in vitro. Genistein has been shown to cause paralysis and alterations in the tegument and tegumental enzymes (acid phosphatase, alkaline phosphatase, adenosine triphosphatase, and 5'-nucleotidase) of helminth parasites. Alterations in the activities of several enzymes associated with the coordination system (specifically non-specific esterases, acetylcholine esterase, and nitric oxide synthase), and changes in the concentration of nitric oxide, cGMP, free amino acid pool, and tissue ammonia are observed in helminth parasites treated with genistein. The phytoestrogen also affects the carbohydrate metabolism by altering the activities of key enzymes involved in glycogen- and glucose-metabolism of a cestode parasite. Considering the significance of phosphoenolpyruvate carboxykinase (PEPCK) in glycolysis of the cestode parasite, Ki of the phytoestrogen for PEPCK in the parasite has been determined, and molecular docking of genistein into the active site of the enzyme has also been described. The potential beneficial role of genistein as a natural alternative in management of helminth parasites needs to be further explored, particularly considering its in vivo efficacy and pharmacokinetics.

Anthelmintic activity of a standardized extract from the rhizomes of Acorus calamus Linn. (Acoraceae) against experimentally induced cestodiasis in rats

Background:

The rhizomes of a herb Acorus calamus Linn. (Acoraceae) have been widely used as a traditional medicine to cure intestinal-helminthic infections in India and South Africa.

Aim:

This study was undertaken to investigate the in vivo anthelmintic activity of a standardized methanolic extract obtained from the rhizomes A. calamus in a rodent model.

Materials and Methods:

A methanolic extract obtained from rhizomes of A. calamus was characterized for active principle using nuclear magnetic resonance ¹H NMR, ¹³C NMR, mass and infrared spectroscopy. The amount of active principle in rhizome isolated active fraction of plant was assayed using high-performance liquid chromatography (HPLC). Later, the standardized rhizome extract of plant and its active principle were tested for in vivo anthelmintic efficacy against experimentally induced Hymenolepis diminuta, a zoonotic cestode, infections in rats.

Results:

The study revealed that b-asarone is the active principle of plant. The HPLC analysis of local variety of A. calamus revealed that active fraction contains 83.54% (w/w) of b-asarone. The in vivo study revealed that treatment of H. diminuta infected rats by a single 800 mg/kg dose of rhizome extract for 5 days results into 62.30% reduction in eggs per gram of feces counts and 83.25% reduction in worm counts of animals. These findings compared well with the efficacy of a reference drug, praziquantel. The active principle b-asarone showed slightly better anthelmintic effects than crude extract. In acute toxicity assay, a single oral 2000 mg/kg dose of extract did not reveal any signs of toxicity or mortality in mice, and the LD50 of the extract was noted to be >2000 mg/kg.

Conclusion:

Taken together, the results of this study indicate that rhizomes of A. calamus bear significant dose-dependent effects against intestinal helminths. Further, the Indian variety of A. calamus contains high b-asarone content. Therefore, there exists a great potential to develop some suitable anthelmintic herbal products from this plant.

α-Viniferin and resveratrol induced alteration in the activities of some energy metabolism related enzymes in the cestode parasite Raillietina echinobothrida

α-Viniferin (AVF) and its monomer resveratrol (RESV) are natural phytostilbenes produced by several plants in response to injury or under the influence of pathogens such as bacteria or fungi. Our earlier studies have revealed that both the compounds exert anthelmintic activity through alterations of cestode tegument and its associated enzymes. The present study investigates the effects of these phytochemicals on some energy metabolism related enzymes in the fowl tapeworm, Raillietina echinobothrida. The phytostilbenes AVF, RESV and the reference drug praziquantel (PZQ) were tested against some selected enzymes i.e., phosphoenolpyruvate carboxykinase (PEPCK), lactate dehydrogenase (LDH) and malate dehydrogenase (MDH) of R. echinobothrida. Exposure of the tapeworm to AVF, RESV and PZQ causes reduction in activity of PEPCK to the extent of 40.57/41.96, 24.58/23.75 and 41.11/13.47%, respectively, and LDH up to 48.95/16.25, 38.31/38.42 and 45.67/41.87%, respectively, at the time of paralysis. Whereas activity of MDH decreased by 34.22/37.7, 39.1/35.24 and 28.83/19.26%, respectively. Decrease in activities of LDH and MDH was also visible through histochemical observations. The results suggest that both the phytochemicals interfere with the energy transducing pathways by inhibiting the studied energy metabolism related enzymes of the parasite.

Anthelmintic effects of Oroxylum indicum stem bark extract on juvenile and adult stages of Hymenolepis diminuta (Cestoda), an in vitro and in vivo study

Worldwide, traditional usage of herbal medicines is a common practice to treat various parasitic infections. In India, bark decoction of Oroxylum indicum (L.) Kurz. (Bignoniaceae) is used as a traditional medicine to cure intestinal-helminthic infections. This study investigated the anthelmintic efficacy of methanolic bark extract of O. indicum on Hymenolepis diminuta (Cestoda), using both in vitro and in vivo methods. Utilizing a mini-questionnaire, first, we collected information about the pattern of anthelmintic use of this plant. Later, in vitro efficacy of extract was tested at 10, 20 and 30 mg/ml on both the artificially excysted juveniles and adult H. diminuta worms. Herein, scanning electron microscopy (SEM) was also utilized to determine the possible effects of extract on tegumental surfaces of juvenile and adult cestode. In vivo, extract was tested at 250, 500 and 1000 mg/kg in H. diminuta albino rat model, against juvenile and adult cestode. Praziquantel (PZQ) served as reference drug in anthelmintic assays. The acute toxicity of extract was determined as per the OECD guidelines. The field questionnaire data revealed that 78 % of people in the area use O. indicum stem bark against intestinal helminths, and of these, 75 % of people also believed it highly efficacious anthelmintic remedy. In vitro testing of extract revealed significant effects on juvenile worms, and 30 mg/ml of extract caused mortality of juveniles at the initial period (0.25 ± 0.00 h). Conversely, PZQ (1 mg/ml) showed paralysis and mortality of juvenile cestodes in 0.44 ± 0.04 and 1.11 ± 0.06 h, respectively. As determined by SEM, in vitro exposure to extract showed substantial effects on both juveniles and adult worms in the form of wrinkled scolex, distorted tegument and eroded microtriches. In vivo study revealed better efficacy of extract against juveniles than adult stages of parasite. Treatment of rats with 1000 mg/kg of extract caused 79.3 % reduction in EPG counts and 70.8 % of reduction in worm counts, which compared well to PZQ efficacy. In acute toxicity study, administration of a single oral dose of 2000 mg/kg of extract to mice did not cause any signs of toxicity or mortality within 2-week observation. Hence, the LD50 of extract was estimated to be greater than 2000 mg/kg. In conclusion, the bark extract of O. indicum possesses concentration-dependent effects against the larval and adult H. diminuta worms, and thus the extract holds promise in the control of intestinal helminthiases. This also supports the common belief of people about the reputation of this plant as anthelmintic in traditional medicine. There is a need to standardize the formulations of this plant for their possible use as standardized herbal anthelmintic agents in the future.