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

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.

Tubulin as a potential molecular target for resveratrol in Giardia lamblia trophozoites, in vitro and in silico approaches

Giardia lamblia is a globally distributed protozoan parasite that causes intestinal disease. Recently, there is an increase in refractory cases of giardiasis to chemotherapeutic agents, and drugs available cause side effects that may limit its use or cause therapeutic non-compliance. Therefore, search for alternative and less harmful drugs to treat giardiasis is an important task. In this sense, resveratrol (RSV) is a polyphenol with a wide range of pharmacological effects such as antimicrobial, anticarcinogenic and antioxidant. The aim of this study was to evaluate the effects of RSV on Giardia lamblia trophozoites in vitro and in silico, focusing on tubulin affectation, a major protein of the Giardia cytoskeleton which participates in relevant processes for cell survival. In vitro determinations showed that RSV inhibits parasite growth and adherence, causes morphological changes, and induces apoptosis-like cell death through tubulin alterations demonstrated by immunolocalization and Western blot assays. Bioinformatic analysis by molecular docking suggested that RSV binds to Giardia tubulin interface heterodimer, sharing binding residues to those reported with depolymerization inhibitors. These findings suggest that RSV affects microtubular dynamics and make it an interesting compound to study for its safety and antigiardiasic potential.

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.

Transcriptome analysis of Tetrahymena thermophila response to exposure with dihydroartemisinin

Dihydroartemisinin (DHA) is a derivative of artemisinin and is toxic to parasites. We used the Tetrahymena thermophila (T. thermophila) as a model to explore DHA toxicity. Results showed that low concentration of DHA (20 μmol/L) promoted cell proliferation, whereas high concentrations of DHA (40-1280 μmol/L) inhibited that. Appearance of nucleus was pycnosis by laser scanning confocal microscope. DHA significantly elevated activities of SOD and GSH-Px (P < 0.01) and MDA was markedly increased at high level but decreased at low level (P < 0.01). Further results of transcriptome in T. thermophila treated with different concentration DHA group (0, 20, 160 μmol/L) showed that differentially expressed genes (DEGs) were involved in oxidation-reduction and metabolism of exogenous substances indicated oxidative stress stimulation. Kyoto Encyclopedia of Genes and Genomes showed that DEGs were involved in the cytochrome P450-mediated metabolism of exogenous substances, glutathione metabolism and ABC transport. Remarkably, DNA replication was significantly enriched in low concentration DHA, energy metabolism related pathways and necrotic process were considerably enriched in high concentration DHA. The results of RT-qPCR of 13 DEGs were the same as that of transcriptome, in which the expression of GST and GPx family genes were significantly altered after exposed to high-DHA group. DHA induced oxidative stress damage through disturbing with energy. However, detoxification pathways in T. thermophila to resist oxidative damage and cell alleviated low concentration DHA stress by regulating antioxidant enzyme. This study provides good practice on pharmacological mechanism of artemisinin-based drugs in antiparasitic.

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.

Persicaria strigosa (R.Br.) Nakai: a natural anthelmintic?

Persicaria strigosa (R.Br.) Nakai. (Family Polygonaceae) is an important plant of Assam, having several ethnobotanical uses. Tribal communities consume leaf extracts to cure helminth infection. The present study investigated the antioxidant, phytochemicals, and anthelmintic activity of P. strigosa. Total phenolic and flavonoid contents were estimated following standard methods. Antioxidant properties were analyzed by TAC, FRAP, DPPH, ABTS, and TBARS assays. Anthelmintic activity of plant was investigated in Paramphistomum sp. treated with 5 mg/mL, and paralysis and death times were recorded. The most potent solvent extract was performed GC-MS analysis to identify the phytocompounds. Plant extract-treated parasites were further analyzed for biochemical changes. Additionally, molecular docking was performed to study the binding affinities between phytocompounds and enzymes. P. strigosa showed rich phenolics, flavonoids, and antioxidant properties. Ethyl acetate and methanolic extracts showed more powerful antioxidant properties than other extracts. In vitro anthelmintic study found ethyl acetate and diethyl ether the most active extracts. Treated parasites showed a significant decrease in enzyme activity. The highest inhibition was observed in AchE, followed by MDH, LDH, ALP, and ACP. GC-MS study identified 12 probable compounds from the ethyl acetate extract of P. strigosa. Molecular docking showed the strongest binding affinity between the phytocompounds and AchE enzyme (- 7.6 kcal/mol). Overall, compounds C6, C7, and C12 showed better binding affinity compared to other compounds. The in vitro helminth bioassays and biochemical analysis suggest Persicaria strigosa a possible anthelmintic agent. However, isolation and characterization of bioactive compound(s) may promise new drug candidates for helminth infections.

Pharmacokinetic and bioavailability studies of α-viniferin after intravenous and oral administration to rats

Alpha-viniferin is a trimer of resveratrol and has various pharmacological activities including anti-Alzheimer's disease, anti-tuberculosis, anti-tumor, anti-inflammatory and anti-diabetic. To investigate the pharmacokinetic characteristics and absolute bioavailability of α-viniferin in rats, using naringenin as an internal standard (IS), a rapid HPLC-MS/MS method of 5 min complete run time was developed. The chromatographic separation of α-viniferin and naringenin were accomplished with Waters XBridge™ C₁₈ column (2.1 mm × 100 mm, 3.5 μm) and the mobile phase were acetonitrile and 0.1 % formic acid at a flow rate of 0.3 mL/min. Plasma samples were pretreated by ethyl acetate. The negative ion mode with electrospray ionization (ESI) source was used for detecting the sample. Oral bioavailability of α-viniferin was 4.2 %. This study will be beneficial in better understanding the pharmacological properties and the further development of α-viniferin.

Improvement of Mitochondrial Activity and Fibrosis by Resveratrol Treatment in Mice with Schistosoma japonicum Infection

Schistosomiasis caused by Schistosoma japonicum is a major parasitic disease in the People's Republic of China. Liver fibrosis is the main pathological mechanism of schistosomiasis, and it is also the major lesion. The common drug used for its treatment, praziquantel (PZQ), does not have a marked effect on liver fibrosis. Resveratrol (RSV), which is an antioxidant, improves mitochondrial function and also attenuates liver fibrosis. The combination of PZQ and RSV has been found to have a synergistic antischistosomal effect on Schistosoma mansoni; additionally, the activity of PZQ is enhanced in the presence of RSV. Here, we examine the therapeutic effects of RSV on the S. japonicum infection in a mouse model, and we investigate RSV as a novel therapeutic agent for mitochondrial function and schistosomiasis-associated liver fibrosis (SSLF). Mitochondrial membrane potential was examined using flow cytometry analysis. The expression of the mitochondrial biogenesis genes PGC-α and fibrosis-associated genes collagen I, collagen III and α-SMA were examined using western blot analysis. Fibrosis-associated histological changes were examined using Masson trichrome staining. Additionally, the effects of RSV on S. japonicum adult worms were examined using scanning electron microscopy and transmission electron microscopy. RSV treatment improved mitochondrial function by increasing membrane potential and increasing PGC-α expression (mitochondrial biogenesis). Further, RSV attenuated liver injury, including liver scarring, by decreasing collagen deposition and the extent of fibrosis, based on the decrease in expression of the fibrosis-related genes. RSV also decreased the adult worm count and caused considerable physical damage to the worm. These results indicate that RSV upregulates mitochondrial biogenesis and inhibits fibrosis. RSV may have potential as a therapeutic target for the treatment of fibrosis in schistosomiasis.

Comparative Transcriptomic Analysis of the Larval and Adult Stages of Taenia pisiformis

Taenia pisiformis is a tapeworm causing economic losses in the rabbit breeding industry worldwide. Due to the absence of genomic data, our knowledge on the developmental process of T. pisiformis is still inadequate. In this study, to better characterize differential and specific genes and pathways associated with the parasite developments, a comparative transcriptomic analysis of the larval stage (TpM) and the adult stage (TpA) of T. pisiformis was performed by Illumina RNA sequencing (RNA-seq) technology and de novo analysis. In total, 68,588 unigenes were assembled with an average length of 789 nucleotides (nt) and N50 of 1485 nt. Further, we identified 4093 differentially expressed genes (DEGs) in TpA versus TpM, of which 3186 DEGs were upregulated and 907 were downregulated. Gene Ontology (GO) and Kyoto Encyclopedia of Genes (KEGG) analyses revealed that most DEGs involved in metabolic processes and Wnt signaling pathway were much more active in the TpA stage. Quantitative real-time PCR (qPCR) validated that the expression levels of the selected 10 DEGs were consistent with those in RNA-seq, indicating that the transcriptomic data are reliable. The present study provides comparative transcriptomic data concerning two developmental stages of T. pisiformis, which will be of great value for future functional studies on the regulatory mechanisms behind adult worm pathogenesis and for developing drugs and vaccines against this important parasite.

Transcriptomics and proteomic studies reveal acaricidal mechanism of octadecanoic acid-3, 4 - tetrahydrofuran diester against Sarcoptes scabiei var. cuniculi

In our previous study, a new compound, octadecanoic acid-3, 4-tetrahydrofuran diester, possessing potent acaricidal activity was obtained from neem oil. This study performed RNA-seq transcriptomics and iTRAQ proteomics to uncover the acaricidal mechanism of the compound against Sarcoptes scabiei var. cuniculi. The results of transcriptomics indicated that after treatment with octadecanoic acid-3, 4-tetrahydrofuran diester, genes related to “Energy metabolism” were significantly up-/down-regulated, including citrate cycle, oxidative phosphorylation pathway and fatty acid metabolism. Proteomics analysis showed accordant changes of proteins related to oxidative phosphorylation pathway. The target proteins of the compound were NADH dehydrogenase, Ubiquinol-cytochrome c reductase, Cytochrome c oxidase, ATP synthase, enolase and superoxide dismutase. In transcriptomics-proteomics correlation analysis, the concordance rate between protein abundances and their corresponding mRNAs was 57%, while others (43%) were discordant changes, suggesting divergent regulating effects of octadecanoic acid-3, 4-tetrahydrofuran diester. These results suggested that the acaricidal mechanism of octadecanoic acid-3, 4-tetrahydrofuran diester attributed to interference with energy metabolism, especially oxidative phosphorylation pathway.