In vitro efficacy of the essential oil of Piper cubeba L. (Piperaceae) against Schistosoma mansoni

Anti-inflammatory potential of Piper betleoides C. DC., a promising Piper species of Northeast India: in vitro and in vivo evidence and mechanistic insight

The present study aims to investigate the anti-inflammatory potential of the leaf hydroalcoholic extract of Piper betleoides C. DC., also known as "Jangli Paan" in Northeast India, using lipopolysaccharide (LPS)-treated both cell culture (RAW264.7, macrophage cells) and animal (albino rat) model of inflammation. Treatment with leaf hydroalcoholic extract of Piper betleoides (PBtE) dose-dependently (5, 10, and 20 µg/mL) decreased the secretion of pro-inflammatory (TNF-α, IL-6, and MCP-1) and increased anti-inflammatory (IL-4 and IL-10) cytokines in LPS-treated macrophages. Similarly, treatment with PBtE also prevented the alternation in mRNA expression of inflammatory markers (TNF-α, CCL-2, IL-6, and IL-10) in LPS-treated macrophages. Dose-dependent supplementation with PBtE further reduced the production of intracellular ROS and increased the phagocytosis efficacies in LPS-treated cells. Further in vivo studies demonstrated that treatment with PBtE dose-dependently (50, 100, and 200 mg/kg body weight) prevented the dysregulation of the secretion of inflammatory cytokines (TNF-α, IL-4, IL-6, and IL-10) and reduced the circulatory levels of prostaglandin (PGE2) and nitric oxide products (nitrite) in LPS-treated animals. In addition, alternation of blood cell profiling and the liver as well as kidney dysfunctions were also prevented by the treatment with PBtE in LPS-treated rats. The anti-inflammatory potential of PBtE was comparable to those seen in sodium diclofenac (positive control) treated group. LC-MS analyses showed piperine, piperlongumine, piperolactam-A, and dehydropipernonaline and GC-MS analyses demonstrated phytol, caryophyllene, and falcarinol as the phytochemicals present in Piper betleoides, which might play an important role in preventing inflammation and associated pathophysiology. Different treatments didn't cause any toxicity in cell culture and animal models. This study for the first time demonstrated the promising anti-inflammatory potential of the leaf hydroalcoholic extract of Piper betleoides.

Extraction, identification and antitumor activity in cell cultures of cubebin isolated from dry seeds Piper cubeba (Piperaceae)

The Pipercubeba, it is one spice, widely consumed in Europe, which has several bioactive molecules, between those a lignan named cubebin. Cubebin has several known biological activities, such as analgesic activity and anti-inflammatory, trypanocidal activity, leishmanicidal and antitumor activity. The objective of this study was to evaluate the antiproliferative activity "in vitro" cubebin in eight different human tumor cell lines. It was fully characterized by IR analysis, NMR, mass spectrometry, DSC, TGA, residual solvent and elemental analysis. The antitumor activity of cubebin was evaluated "in vitro" on eight different human tumor cell lineages. Cubebin showed GI50≤30μg/mL for lineage cell U251 (glioma CNS), 786-0 (kidney), PC-3 (prostate), HT-29 (colon rectum). For K562 cells (leukemia), cubebin presented GI50≤to 4.0mg/mL. For the other lineages cells, MCF-7 (breast) and NCI-H460 to cubebin can be considered inactive because of GI50>250mg/mL. Analyzing the selectivity index for cubebin, it can be observed that high selectivity of cubebin to K562 lineage cells (leukemia). Analyzing the cytotoxic potential of cubebin was observed that probably acts cubebin altering metabolism, inhibiting cell growth - a cytostatic effect, showing no cytocidal effect on any lineage cell.

Larvicidal potential of extracts and isolated compounds from Piper cubeba fruits against Aedes aegypti (Diptera: Culicidae) larvae

Aedes aegypti is the primary vector of virus transmission that causes dengue, yellow fever, chikungunya and zika. The primary prevention method has been vector control and synthetic insecticides that can cause environmental side effects. Thus, the work aimed to evaluate the larvicidal potential of extracts and isolated compounds from Piper cubeba against A. aegypti larvae. The larvicidal activity method was executed according to the World Health Organization protocol. The larvae were analyzed by scanning electron microscopy (SEM). Through molecular docking, the action mechanism was investigated. The hydroalcoholic and hexane extracts showed similar larvicidal activity with LC₅₀ of 191.1 μg/mL and 185.84 μg/mL, respectively. Between isolated compounds, hinokinin presented LC₅₀= 97.74 μg/mL. The SEM analysis showed structural damage to the larva's tegument caused by extracts and isolated compounds. Therefore, the results demonstrate the larvicidal action of hinokinin and extracts, which can lead to the development of new natural larvicides.

In Vitro Cercaricidal and Schistosomicidal Activities of the Raffia Wine and Hydroethanolic Extracts of Pedilanthus tithymaloides Linn (Poit). Stem Barks

Schistosomiasis control remains a public health concern, and there is a need to evaluate new strategies for targeting larval and adult stages of the parasite. As Pedilanthus tithymaloides is empirically used to treat schistosomiasis, it becomes essential to know its effective action scientifically. This study assessed the cercaricidal and schistosomicidal activity of P. tithymaloides stem barks raffia wine extract (RwPt) and hydroethanolic extract (HePt). Different concentrations of these extracts were tested against cercariae (31.25–1000 μg/mL) and adult worms (62.5–2000 μg/mL) of Schistosoma mansoni. Niclosamide-olamine 5% (1 μg/mL) and praziquantel (10 μg/mL) were used as pharmacological controls. Cercariae viability was determined every 30 min for 180 min, and adult worms’ motor activity and viability after 24 and 48 h incubation. In addition, cytotoxicity and phytochemical analysis were performed. HePt was lethal to cercariae and adult worms with LC50 of 73.91 μg/mL after 60 min of incubation and 731.17 μg/mL after 48 h of incubation, respectively. Furthermore, a significant reduction of 94.44% in motor activity was observed in surviving worms at the concentration of 2000 μg/mL. RwPt was less effective on S. mansoni cercariae with an LC50 of 617.86 μg/mL after 180 min and on adult worms with a mortality rate of 9.83% at 2000 μg/mL for 48 h incubation. Both extracts showed a weak cytotoxicity profile with an IC50 of 983.50 μg/mL for HePt and more than 1000 μg/mL for RwPt. The LC-MS analysis of HePt allowed the detection of two annotated diterpenoids. Based on the selectivity index, the hydroethanolic extract of P. tithymaloides stem barks disclosed an intense cercaricidal activity and a moderate schistosomicidal effect with low cytotoxicity. These findings may support the potential use of Pedilanthus tithymaloides as a natural product or a source of natural-derived compounds for interrupting schistosomiasis transmission.

Antischistosomal Activity of Essential Oils: An Updated Review

This review article covers literature on the antischistosomal activity of essential oils (EOs)( between 2011 and 2021. Criteria for classifying results from in vitro schistosomicidal assays are proposed for the first time. Parameters to evaluate the in vitro antischistosomal potential of EOs other than their ability to cause the death of Schistosoma mansoni adult worms ( e.g ., couple separation, egg laying, and egg development inhibition) are also addressed and discussed.

Synthetic Aurones: New Features for Schistosoma mansoni Therapy

In this work, two synthetic aurones revealed moderate schistosomicidal potential in in vitro and in vivo assays. Aurones (1) and (2) promoted changes in tegument integrity and motor activity, leading to death of adult Schistosoma mansoni worms in in vitro assays. When administered orally (two doses of 50 mg/kg) in experimentally infected animals, synthetic aurones (1) and (2) promoted reductions of 56.20 % and 57.61 % of the parasite load and stimulated the displacement towards the liver of the remaining adult worms. The oogram analysis revealed that the treatment with both aurones interferes with the egg development kinetics in the intestinal tissue. Seeking an action target for compounds (1) and (2), the connection with NTPDases enzymes, recognized as important therapeutic targets for S. mansoni, was evaluated. Molecular docking studies have shown promising results. The dataset reveals the anthelmintic character of these compounds, which can be used in the development of new therapies for schistosomiasis.

Remedia Sternutatoria over the Centuries: TRP Mediation

Sneezing (sternutatio) is a poorly understood polysynaptic physiologic reflex phenomenon. Sneezing has exerted a strange fascination on humans throughout history, and induced sneezing was widely used by physicians for therapeutic purposes, on the assumption that sneezing eliminates noxious factors from the body, mainly from the head. The present contribution examines the various mixtures used for inducing sneezes (remedia sternutatoria) over the centuries. The majority of the constituents of the sneeze-inducing remedies are modulators of transient receptor potential (TRP) channels. The TRP channel superfamily consists of large heterogeneous groups of channels that play numerous physiological roles such as thermosensation, chemosensation, osmosensation and mechanosensation. Sneezing is associated with the activation of the wasabi receptor, (TRPA1), typical ligand is allyl isothiocyanate and the hot chili pepper receptor, (TRPV1), typical agonist is capsaicin, in the vagal sensory nerve terminals, activated by noxious stimulants.

In vitro anthelmintic activity of the crude hydroalcoholic extract of Piper cubeba fruits and isolated natural products against gastrointestinal nematodes in sheep

This study describes the in vitro anthelmintic activity of a hydroalcoholic extract from the fruit of Piper cubeba and its major isolated components against the eggs and larvae of gastrointestinal nematodes obtained from naturally-infected ovines. In vitro anthelmintic activity was evaluated using the egg hatch test (EHT), larval development test (LDT) and L3 migration inhibition test (LMT). The extract showed ovicidal and larvicidal activity, with an EC₅₀ of 200 μg/mL and 83.00 μg/mL in the EHT and LDT, respectively. The extract inhibited 100% of larval migration at the lowest tested concentration (95 μg/mL). The crude extract was purified using successive silica gel chromatographic columns, which revealed the lignans hinokinin, cubebin and dihydrocubebin as the major compounds that were present, which were then used in in vitro tests. Cubebin, dihydrocubebin and hinokinin showed higher activity than the crude extract, with an EC₅₀ for ovicidal activity of 150.00 μg/mL, 186.70 μg/mL and 68.38 μg/mL, respectively. In the LDT, cubebin presented an EC₅₀ of 14.89 μg/mL and dihydrocubebin of 30.75 μg/mL. Hinokinin inhibited 100% the larval development at all concentrations evaluated. In the LMT, dihydrocubebin inhibited 100% the larval migration in all concentrations evaluated while cubebin and hinokinin showed EC₅₀ values of 0.89 μg/mL and 0.34 μg/mL, respectively. P. cubeba extract is rich in several classes of active compounds, but here we demonstrate that the described anthelmintic activity may be related to the presence of these lignans, which are present in larger concentrations than other components of the extract. Our results demonstrate for first time the anthelmintic activity against gastrointestinal nematodes in sheep for this class of special metabolites that are present in P. cubeba fruit. However, future detailed studies are needed to evaluate the effectiveness of P. cubeba fruits extract and active lignans in in vivo tests.

Antimicrobial Activity and Proposed Action Mechanism of 3-Carene against Brochothrix thermosphacta and Pseudomonas fluorescens

3-Carene is an antimicrobial monoterpene that occurs naturally in a variety of plants and has an ambiguous antibacterial mechanism against food-borne germs. The antibacterial effects and action mechanism of 3-carene against Gram-positive Brochothrix thermosphacta ACCC 03870 and Gram-negative Pseudomonas fluorescens ATCC 13525 were studied. Scanning electron microscopy (SEM) examination and leakage of alkaline phosphatase (AKP) verified that 3-carene caused more obvious damage to the morphology and wall structure of B. thermosphacta than P. fluorescens. The release of potassium ions and proteins, the reduction in membrane potential (MP), and fluorescein diacetate (FDA) staining further confirmed that the loss of the barrier function of the cell membrane and the leakage of cytoplasmic contents were due to the 3-carene treatment. Furthermore, the disorder of succinate dehydrogenase (SDH), malate dehydrogenase (MDH), pyruvate kinase (PK), and ATP content indicated that 3-carene could lead to metabolic dysfunction and inhibit energy synthesis. In addition, the results from the fluorescence analysis revealed that 3-carene could probably bind to bacterial DNA and affect the conformation and structure of genomic DNA. These results revealed that 3-carene had strong antibacterial activity against B. thermosphacta and P. fluorescens via membrane damage, bacterial metabolic perturbations, and genomic DNA structure disruption, interfering in cellular functions and even causing cell death.

Biological Activities and Chemical Constituents of Essential Oils from Piper cubeba Bojer and Piper nigrum L

In this study, we evaluated antioxidant, antihyperuricemic, and herbicidal activities of essential oils (EOs) from Piper cubeba Bojer and Piper nigrum L.; two pepper species widely distributed in tropics, and examined their chemical compositions. Dried berries of P. cubeba and P. nigrum were hydro-distilled to yield essential oil (EO) of 1.23 and 1.11% dry weight, respectively. In the antioxidant assay, the radical scavenging capacities of P. cubeba EO against DPPH and ABTS free radicals were 28.69 and 24.13% greater than P. nigrum, respectively. In the antihyperuricemic activity, P. cubeba EO also exhibited stronger inhibitory effects on xanthine oxidase (IC50 = 54.87 µg/mL) than P. nigrum EO (IC50 = 77.11 µg/mL). In the herbicidal activity, P. cubeba EO showed greater inhibition on germination and growth of Bidens pilosa and Echinochloa crus-galli than P. nigrum EO. Besides, P. cubeba EO decreased 15.98-73.00% of photosynthesis pigments of B. pilosa and E. crus-galli, while electrolyte leakages, lipid peroxidations, prolines, phenolics, and flavonoids contents were increased 10.82-80.82% at 1.93 mg/mL dose. Gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) analyses revealed that P. nigrum and P. cubeba EOs principally possessed complex mixtures of monoterpenes and sesquiterpenes. Terpinen-4-ol (42.41%), α-copaene (20.04%), and γ-elemene (17.68%) were the major components of P. cubeba EO, whereas β-caryophyllene (51.12%) and β-thujene (20.58%) were the dominant components of P. nigrum EO. Findings of this study suggest both P. cubeba and P. nigrum EOs were potential to treat antioxidative stress and antihyperuricemic related diseases. In addition, the EOs of the two plants may be useful to control B. pilosa and E. crus-galli, the two invasive and problematic weeds in agriculture practice.

Piper Species: A Comprehensive Review on Their Phytochemistry, Biological Activities and Applications

Piper species are aromatic plants used as spices in the kitchen, but their secondary metabolites have also shown biological effects on human health. These plants are rich in essential oils, which can be found in their fruits, seeds, leaves, branches, roots and stems. Some Piper species have simple chemical profiles, while others, such as Piper nigrum, Piper betle, and Piper auritum, contain very diverse suites of secondary metabolites. In traditional medicine, Piper species have been used worldwide to treat several diseases such as urological problems, skin, liver and stomach ailments, for wound healing, and as antipyretic and anti-inflammatory agents. In addition, Piper species could be used as natural antioxidants and antimicrobial agents in food preservation. The phytochemicals and essential oils of Piper species have shown strong antioxidant activity, in comparison with synthetic antioxidants, and demonstrated antibacterial and antifungal activities against human pathogens. Moreover, Piper species possess therapeutic and preventive potential against several chronic disorders. Among the functional properties of Piper plants/extracts/active components the antiproliferative, anti-inflammatory, and neuropharmacological activities of the extracts and extract-derived bioactive constituents are thought to be key effects for the protection against chronic conditions, based on preclinical in vitro and in vivo studies, besides clinical studies. Habitats and cultivation of Piper species are also covered in this review. In this current work, available literature of chemical constituents of the essential oils Piper plants, their use in traditional medicine, their applications as a food preservative, their antiparasitic activities and other important biological activities are reviewed.

Screening of a PDE-focused library identifies imidazoles with in vitro and in vivo antischistosomal activity

We report the evaluation of 265 compounds from a PDE-focused library for their antischistosomal activity, assessed in vitro using Schistosoma mansoni. Of the tested compounds, 171 (64%) displayed selective in vitro activity, with 16 causing worm hypermotility/spastic contractions and 41 inducing various degrees of worm killing at 100 μM, with the surviving worms displaying sluggish movement, worm unpairing and complete absence of eggs. The compounds that did not affect worm viability (n = 72) induced a complete cessation of ovipositing. 82% of the compounds had an impact on male worms whereas female worms were barely affected. In vivo evaluation in S. mansoni-infected mice with the in vitro 'hit' NPD-0274 at 20 mg/kg/day orally for 5 days resulted in worm burden reductions of 29% and intestinal tissue egg load reduction of 35% at 10 days post-treatment. Combination of praziquantel (PZQ) at 10 mg/kg/day for 5 days with NPD-0274 or NPD-0298 resulted in significantly higher worm killing than PZQ alone, as well as a reduction in intestinal tissue egg load, disappearance of immature eggs and an increase in the number of dead eggs.

Evaluation of Lignans from Piper cubeba against Schistosoma mansoni Adult Worms: A Combined Experimental and Theoretical Study

Six dibenzylbutyrolactonic lignans ((-)-hinokinin (1), (-)-cubebin (2), (-)-yatein (3), (-)-5-methoxyyatein (4), dihydrocubebin (5) and dihydroclusin (6)) were isolated from Piper cubeba seed extract and evaluated against Schistosoma mansoni. All lignans, except 5, were able to separate the adult worm pairs and reduce the egg numbers during 24 h of incubation. Lignans 1, 3 and 4 (containing a lactone ring) were the most efficient concerning antiparasitary activity. Comparing structures 3 and 4, the presence of the methoxy group at position 5 appears to be important for this activity. Considering 1 and 3, it is possible to see that the substitution pattern change (methylenedioxy or methoxy groups) in positions 3' and 4' alter the biological response, with 1 being the second most active compound. Computational calculations suggest that the activity of compound 4 can be correlated with the largest lipophilicity value.

Extracellular vesicles have variable dose-dependent effects on cultured draining cells in the eye

The role of extracellular vesicles (EVs) as signal mediators has been described in many biological fields. How many EVs are needed to deliver the desired physiological signal is yet unclear. Using a normal trabecular meshwork (NTM) cell culture exposed to non-pigmented ciliary epithelium (NPCE)-derived EVs, a relevant model for studying the human ocular drainage system, we addressed the EVs dose-response effects on the Wnt signaling. The objective of the study was to investigate the dosing effects of NPCE-derived EVs on TM Wnt signaling. EVs were isolated by PEG 8000 method from NPCE and RPE cells (used as controls) conditioned media. Concentrations were determined by Tunable Resistive Pulse Sensing method. Various exosomes concentration were incubated with TM cells, for the determination of mRNA (β-Catenin, Axin2 and LEF1) and protein (β-Catenin, GSK-3β) expression using real-time quantitative PCR and Western blot, respectively. Exposure of NTM cells for 8 hrs to low EVs concentrations was associated with a significant decreased expression of β-Catenin, GSK-3β, as opposed to exposure to high exosomal concentrations. Pro-MMP9 and MMP9 activities were significantly enhanced in NTM cells treated with high EV concentrations of (X10) as compared to low EV concentrations of either NPCE- or RPE-derived EVs and to untreated control. Our data support the concept that EVs biological effects are concentration-dependent at their target site. Specifically in the present study, we described a general dose-response at the gene and MMPs activity and a different dose-response regarding key canonical Wnt proteins expression.

Laboratory assessment of divaricatic acid against Biomphalaria glabrata and Schistosoma mansoni cercariae

In this study, the molluscicidal and antiparasitic activities of divaricatic acid was evaluated, targeting the mollusc Biomphalaria glabrata and cercariae of the helminth Schistosoma mansoni. In addition, the environmental toxicity of divaricatic acid was assessed by bioassay using the microcrustacean Artemia salina. Divaricatic acid showed high toxicity against both adult snails (5μg/mL) and embryos (20μg/mL after 6h of exposure). Similar activity was observed in Schistosoma mansoni cercariae after only a short exposure time (10μg/mL after 30min of exposure). The divaricatic acid did not show toxicity in the acute test using Artemia salina at concentrations equal to or below 200μg/mL. The divaricatic acid proved to be a promising substance for the elimination of the snail Biomphalaria glabrata, an intermediate host of schistosomiasis, as well as the cercariae of the pathogen, while being non-toxic to the Artemia salina at the same concentrations. This is the first experimental observation of the molluscicidal and cercaricide activity of divaricatic acid.

In vitro schistosomicidal activity of the lignan (-)-6,6'-dinitrohinokinin (DNHK) loaded into poly(lactic-co-glycolic acid) nanoparticles against Schistosoma mansoni

CONTEXT

(-)-6,6'-Dinitrohinokinin (DNHK) display remarkable antiparasitic activity and was, therefore, incorporated into a nanoparticle formulation.

OBJECTIVE

Incorporation of DNHK in poly lactic-co-glycolic acid (PLGA) nanoparticles aiming to improve its biological activities.

MATERIALS AND METHODS

Synthesis, characterization and incorporation of DNHK into glycolic acid (PLGA) nanoparticles by nanoprecipitation method. The nanoparticles were characterized by ultraviolet-visible spectroscopy, X-ray diffraction, field emission electron microscopic scanning mansoni (FESEM), and dynamic light scattering (DLS). For the in vitro test with Schistosoma mansoni, the DNHK-loaded PLGA was diluted into the medium, and added at concentrations 10-200 µM to the culture medium containing one adult worm pair. The parasites were kept for 120 h and monitored every 24 h to evaluate their general condition, including: pairing, alterations in motor activity and mortality.

RESULTS

The loaded PLGA nanoparticles gave an encapsulation efficiency of 42.2% and showed spherical characteristics in monodisperse polymeric matrix. The adult worm pairs were separated after 120 h of incubation for concentrations higher than 50 µM of DNHK-loaded PLGA. The groups incubated with 150 and 200 µM of DNHK-loaded PLGA for 24 and 120 h killed 100% of adult worms, afforded LC50 values of 137.0 ± 2.12 µM and 79.01 ± 1.90 µM, respectively, which was similar to the effect displayed by 10 µM of praziquantel.

DISCUSSION AND CONCLUSIONS

The incorporation of DNHK-loaded showed schistosomicidal activity and allowed its sustained release. The loaded PLGA system can be administered intravenously, as well as it may be internalized by endocytosis by the target organisms.

Barbatic Acid Offers a New Possibility for Control of Biomphalaria Glabrata and Schistosomiasis

This study evaluated the biological activity of an ether extract and barbatic acid (BAR) from Cladia aggregata on embryos and adult mollusks of Biomphalaria glabrata, cercariae of Schistosoma mansoni and the microcrustacean Artemia salina. The ether extract and BAR were obtained by successive extractions with diethyl ether. The obtained extracts were analyzed using thin-layer chromatography (TLC), high-performance liquid chromatography (HPLC), proton nuclear magnetic resonance (¹H-NMR) and infrared (IR) spectroscopy. The results demonstrated that the ether extract exerted embryotoxic effects at 50 and 100 µg/mL and molluscicidal effects at 20 and 25 µg/mL. BAR exhibited no embryotoxicity, and its molluscicidal concentration was equal to that of the ether extract. However, after 60 min of exposure, 1 µg/mL BAR presented cercaricidal activity against the parasite S. mansoni at the second larval stage. Neither substance induced toxicity against A. salina. These results indicate the potential molluscicidal activities of the ether extract and BAR against B. glabrata and S. mansoni cercariae. In addition to these effects, there was a lack of toxicity against the aquatic environment and no damage to the biota, indicating the potential of these products for large-scale control and/or eradication of schistosomiasis.

Antischistosomal and Cytotoxic Effects of the Essential Oil of Tetradenia riparia (Lamiaceae)

This paper reports on the antischistosomal and cytotoxic effects of the essential oil obtained from Tetradenia riparia leaves (TR-EO). At concentrations of 50 and 100 μg/mL, TR-EO killed all the worms after 120 and 24 h of incubation, respectively. At a concentration equal to or higher than 50 μg/mL, this oil also separated the coupled pairs and decreased the adult worm motor activity after incubation periods higher than 72 h. In addition, at 120 h of incubation, TR-EO slightly decreased the number of eggs produced by Schistosoma mansoni adult worms and significantly reduced the percentage of developed eggs, in a dose-dependent manner. XTT-colorimetric assays showed that the tested TR-EO concentrations were not considerably cytotoxic to V79 cells (IC50 = 253.5 μg/mL). The effects of TR-EO on egg development were noteworthy; therefore, this essential oil deserves further investigation to identify the chemical constituents that elicit activity against S. mansoni.

In vitro and in vivo anthelmintic activity of (-)-6,6'-dinitrohinokinin against schistosomula and juvenile and adult worms of Schistosoma mansoni

The chemotherapy of schistosomiasis relies on the use of praziquantel. However, concerns over drug resistance have encouraged the search for new drug leads. This paper is the first report on the in vitro and in vivo activity of (-)-6,6'-dinitrohinokinin (DNK) against Schistosoma mansoni. In vitro, the lethal concentrations for 50% of parasites (LC50) of DNK against adult worms were 103.9±3.6 and 102.5±4.8μM at 24 and 72h, respectively. Scanning electron microscopy images showed extensive tegumental alterations such as peeling and smaller numbers of tubercles in the spine of adult worms. DNK also elicited high mortality of schistosomula, with LC50 values of 57.4±2.3, 32.5±0.9, and 20.4±1.2μM at 24, 48, and 72h, respectively. DNK displayed moderate activity against the juvenile liver parasite, with an LC50 value of 179.5±2.3 μM at 72h. This compound reduced the total number of eggs by over 83%, and it affected the development of eggs produced by adult worms. The selectivity index showed that at 24h, DNK was 8.5 and 15.4 times more toxic to the adult worms and schistosomula than to Chinese hamster lung fibroblast cells, respectively. Treatment of infected mice with DNK moderately decreased worm burden (33.8-52.3%), egg production (40.7-60.0%), and spleen and liver weights. Together, our results indicated that DNK presents moderate in vitro and in vivo activities against S. mansoni, and it might therefore be interesting to explore the structure-activity relationship of the antischistosomal activity of this compound.

Furofuran lignans display schistosomicidal and trypanocidal activities

Parasitic diseases continue to be a major worldwide health problem, and there is an urgent need for development of therapeutic drugs. This paper describes synthesis of dehydrodiferulic acid dilactone 1 and dehydrodisinapic acid dilactone 2 furofuran lignans by oxidative coupling of ferulic and sinapic acids, respectively. Their schistosomicidal, trypanocidal, and leishmanicidal activities were evaluated in vitro against Schistosoma mansoni adult worms, trypomastigote and amastigotes forms of Trypanosoma cruzi, and promastigote forms of Leishmania amazonensis. Compound 1 did not display significant schistosomicidal activity, but it presented potent trypanocidal activity, since it induced death of trypomastigotes and amastigotes with IC50/24h of 9.3μM and 7.3μM, respectively. Compound 2 had slight trypanocidal and schistosomicidal activities. None of the compounds were active against L. amazonensis. These results demonstrated that furofuran lignans are potentially useful for anti-parasitic drugs development and should be further investigated.

The lignan (-)-hinokinin displays modulatory effects on human monoamine and GABA transporter activities

The neurotransmitter transporters of the SLC6 family play critical roles in the regulation of neurotransmission and are the primary targets of therapeutic agents used to treat clinical disorders involving compromised neurotransmitter signaling. The dopamine and norepinephrine transporters have been implicated in clinical disorders such as attention deficit hyperactivity disorder (ADHD) and substance abuse. The GABA transporters (GATs) serve as a target for anxiolytic, antidepressant, and antiepileptic therapies. In this work, the interaction with neurotransmitter transporters was characterized for a derivative of the lignan (-)-cubebin (1), namely, (-)-hinokinin (2). Using in vitro pharmacological assays, 2 selectively inhibited the human dopamine and norepinephrine transporters, in a noncompetitive manner possibly mediated by binding to a novel site within the transporters, and displayed low affinity for the serotonin transporter. Compound 2 also specifically inhibited the GAT-1 GABA transporter subtype. Compound 2 is not a substrate of the carriers as it had no effect on the efflux of either of the neurotransmitters investigated. This compound is inactive toward glutamate and glycine transporters. These results suggest that 2 may serve as a tool to develop new therapeutic drugs for ADHD and anxiety that target the DAT, NET, and GAT-1 transporters.

In vitro schistosomicidal effects of aqueous and dichloromethane fractions from leaves and stems of Piper species and the isolation of an active amide from P. amalago L. (Piperaceae)

Dichloromethane and aqueous fractions from leaves and stems of Piper arboreum Aubl., P. aduncum L., P. amalago L., P. crassinervium H.B. & K., P. diospyrifolium Kunth, P. hispidum Sw. and P. xylosteoides (Kunth) Steud. were tested against adult worms of Schistosoma mansoni. The in vitro activity was evaluated in terms of mortality, number of separated worms and number of worms with reduced motor activity. Most dichloromethane fractions from all Piper species showed moderate schistosomicidal activity, but aqueous fractions were not active. The dichloromethane fraction of P. amalago leaves (at 100 μg/ml) showed the highest activity, resulting in worm mortality, the separation of worm pairs and reduced motor activity. Chromatographic fractionation of the dichloromethane fraction of P. amalago leaves led to the isolation of its major compound, which was also tested against adults of S. mansoni. The isolated piperamide N-[7-(3′,4′-methylenedioxyphenyl)-2(Z),4(Z)-heptadienoyl] pyrrolidine, at 100 μm, resulted in the mortality of all adult worms after 24 h of incubation. The findings suggest that species of Piper are potential sources of schistosomicidal compounds.

Comparative in vivo antioxidant levels in Schistosoma mansoni infected mice treated with praziquantel or the essential oil of Melaleuca armillaris leaves

Plant extracts are continuously investigated for their extensive inclusion of biologically active constituents that exert therapeutic activities against many diseases. The aim of this study was to assess the antioxidant/anti-schistosomal activities of the essential oil of the fresh leaves of Melaleuca armillaris (M. armillaris) compared to Praziquantel (PZQ) on normal and Schistosoma mansoni-infected mice. The oil was isolated by hydrodistillation and analyzed by gas chromatography/mass spectrometry (GC/MS). The oil was rich in 1,8-cineole (33.93%), terpinen-4-ol (18.79%), limonene (10.37%) and B-pinene (6.59%). M. armillaris oil (150 mg kg(-1), orally) was administered from the second week post infection twice per week for six weeks. PZQ (500 mg kg(-1), orally) was administered for two successive days 8 weeks post infection and mice sacrificed one week later. Total protein, Malondialdehyde (MDA), Glutathione (GSH), vitamins C and E, the antioxidant enzymes catalase and superoxide dismutase, as well as liver weights and liver/body weight were determined in the liver tissues. Results showed that, both treatments significantly ameliorated the disturbed levels ofGSH and MDA in infected mice. Both vitamins were significantly elevated after treatment with the oil while a significant increase in catalase accompanied by a pronounced decrease in SOD were obtained after treatment with PZQ. Both treatments markedly improved liver and body weights in infected mice compared to the infected-untreated ones. In conclusion, natural plant sources may be used as promising alternative agents to chemical drugs for schistosomiasis treatment, since the latter may result in drug-induced resistance arising from repeated use.

Schistosoma mansoni: in vitro schistosomicidal activity of essential oil of Baccharis trimera (less) DC

Schistosomiasis is a chronic parasitic disease caused by the trematode species Schistosoma mansoni. Chemotherapy is the only immediate recourse to minimize the prevalence and incidence of this disease worldwide. At present, praziquantel (PZQ) is the drug of choice for the treatment of all forms of schistosomiasis. However, dependence on a single drug is concern because some strains can become resistant. In this context, medicinal plants become potential candidates as sources of new drug prototypes. This study provides findings on the schistosomicidal activity of the essential oil of Baccharis trimera in in vitro assays. During the assays parameters such as motility of adult worms, oviposition, morphological changes on the tegument and especially the mortality rate of adult worms of the BH strain were evaluated. The assays, which were carried out with four concentrations - 24, 48, 91 and 130 μg/mL - of the essential oil, have shown a promising activity regarding the parameters under study. It was possible to notice a significant decline in the motility of the worms and a mortality rate of 100% 30 h after they had been exposed to the essential oil in the concentration of 130 μg/mL. Male worms were more susceptible, producing a dose-response effect within a smaller exposition period than female worms. In what refers to morphological changes, the essential oil of B. trimera induced a peeling on the tegument surface, as well as the destruction of tubercles and spines, which resulted in smooth areas on the body surface. The essential oil also caused tegument destruction in female worms, in addition to destruction of the oral and acetabular suckers. It is the first time that the schistosomicidal activity has been reported for essential oil of B. trimera (less) DC.