Antifilarial activity in vitro and in vivo of some flavonoids tested against Brugia malayi

HRAMS Proteomics Insights on the Anti-Filarial Effect of Ocimum sanctum: Implications in Phytochemical-Based Drug-Targeting and Designing

Lymphatic filariasis (LF) continues to impact 657 million individuals worldwide, resulting in lifelong and chronic impairment. The prevalent anti-filarial medications-DEC, albendazole, and ivermectin-exhibit limited adulticidal efficacy. Despite ongoing LF eradication programs, novel therapeutic strategies are essential for effective control. This study examines the mechanism of action of Ocimum sanctum on the filarial parasites Setaria cervi via a synergistic biochemical and proteomics methodology. The ethanolic extract of Ocimum sanctum (EOS) demonstrated potential anti-filarial action in the MTT reduction experiment, with an LC50 value of 197.24 µg/mL. After EOS treatment, an elevation in lipid peroxidation (51.92%), protein carbonylation (48.99%), and NADPH oxidase (88.88%) activity, along with a reduction in glutathione (GSH) (-39.23%), glutathione reductase (GR) (-60.17%), and glutathione S transferase (GST) (-50.48%) activity, was observed. The 2D gel electrophoresis identified 20 decreased and 11 increased protein spots in the EOS-treated parasites relative to the control group. Additionally, in drug docking analysis, the EOS bioactive substances ursolic acid, rutin, and rosmarinic acid show a significant binding affinity with the principal differentially expressed proteins. This paper demonstrates, for the first time, that the anti-filarial efficacy of EOS is primarily facilitated by its impact on energy metabolism, antioxidant mechanisms, and stress response systems of the parasites.

In vitro and in silico study on the seeds of Veitchia merrillii on trematode worms

Background and Aim

The potential of plants as anthelmintics is very large, but there is still very little research conducted in the search for effective, safe, easily obtained, and affordable anthelmintic candidates. Palem putri (Veitchia merrillii) is an ornamental plant that is interesting to study because it is included in the areca nut group which is reported to have strong abilities as anthelmintics. The study aims to evaluate the anthelmintic efficacy of Veitchia merrillii against trematode worms such as Paramphistomum spp. and Fasciola hepatica.

Materials and Methods

This research employs both in vitro and computational techniques. An anthelmintic in vitro test was carried out on Paramphistomum spp. worms at concentrations of 10%, 25%, and 40% (gr/v), assessing mortality index as the observable outcome, followed by a histopathological investigation of the deceased worms for tissue and cellular damage evaluation. Seventeen compounds from V. merrillii seeds were studied in silico for their anthelmintic activity against F. hepatica worms using the quantitative structure-activity relationship technique, molecular docking, and Lipinski's rule analysis for orally administered medication.

Results

About 25% and 40% extracts of V. merrillii damaged the tegument organs in the worms. Seventeen compounds in V. merrillii seed extract, on average, yielded a higher anthelmintic index on F. hepatica than praziquantel. Eleven of the 17 compounds exhibit stronger affinity than praziquantel, with routine and gallic acid being the top two ligands (∆Gbinding values: -11.65 kcal/mol and -11.07 kcal/mol, respectively). According to Lipinski's rule analysis, only routine compounds cannot be orally administered.

Conclusion

The seeds of V. merrilli have potential as an anthelmintic agent for Paramphistomum spp. at concentrations of 25%-40% (gr/v).

In Vitro Filaricidal Properties of Hydro-Methanolic Extracts of Powdery Fractions of Khaya senegalensis (Meliaceae) on Onchocerca ochengi

PURPOSE

Onchocerciasis is a neglected tropical disease that remains endemic in sub-Saharan African countries. Unfortunately, only a few microfilaricidal agents have been approved so far. This study aimed to assess the in vitro macro and microfilaricidal potentialities of the hydro-methanolic extracts of the different powdery fractions of Khaya senegalensis against Onchocerca ochengi.

METHODS

Adult male worms and microfilariae (mf) of O. ochengi were isolated from cowhides in Ngaoundere II, Cameroon. Parasites were incubated for 4 h (mf) or 48 h (adult worms) in RPMI-1640 medium in the presence or absence of ivermectin, flubendazole, or hydro-methanolic extracts of different plant powdery fractions obtained by controlled differential sieving. The filaricidal effect was evaluated using motility (mfs) and mortality tests (worms) and oxidative stress parameters. Cytotoxicity and acute toxicity tests were performed on monkey-derived kidney cell lines (LLC-MK2) and Swiss albino mice, respectively, and selectivity indexes were determined. Phytochemical screening was also carried out using high-performance liquid chromatography/UV (HPLC/UV), molecular networking, and through quantification of phenolic contents.

RESULTS

The hydro-methanolic extracts of 0-63 µm fractions from leaves and barks exhibited the strongest macrofilaricidal activities with lethal concentrations 50 of 162.4 and 208.8 µg/mL respectively versus 22.78 µg/mL for flubendazole. These two fractions also showed the fastest microfilaricidal activities (T1/2 of 1 h), although it was low when compared to ivermectin (T1/2 < 1 h). Their macrofilaricidal effects were accompanied by a significant inhibition of nitric oxide secretion and a significant increase of glutathione and catalase activity compared to the untreated group. However, no effect was found on superoxide dismutase activity, the GABAergic and glutamatergic receptors. Although neither extract was toxic to Swiss mice until a dose of 2000 mg/kg body weight, the 0-63 µm leaf fraction hydro-methanolic extract was selectively more effective on worms than bark extract (SI = 1.28 versus 0.34). Both extracts were found to contain some flavonoids including procyanidin-, rutin-, myricetin-, and naringenin derivatives as well as new unknown compounds. However, the total polyphenol, flavonoid and tannin contents of the leaf extract were significantly greater (P < 0.05) than that of the bark extract.

CONCLUSION

These results support the anti-filarial effect of K. senegalensis leaves and highlight stress oxidative markers as new therapeutic targets in O. ochengi. Further, in vivo experiments are required in understanding their anti-parasitic properties, and testing combinations of fine fractions.

Molecular docking-based virtual screening, molecular dynamic simulation, and 3-D QSAR modeling of some pyrazolopyrimidine analogs as potent anti-filarial agents

Lymphatic filariasis and onchocerciasis are common filarial diseases caused by filarial worms, which co-habit symbiotically with the Wolbachia organism. One good treatment method seeks Wolbachia as a drug target. Here, a computer-aided molecular docking screening and 3-D QSAR modeling were conducted on a series of Fifty-two (52) pyrazolopyrimidine derivatives against four Wolbachia receptors, including a pharmacokinetics study and Molecular Dynamic (MD) investigation, to find a more potent anti-filarial drug. The DFT approach (B3LYP with 6-31G** option) was used for the structural optimization. Five ligand-protein interaction pairs with the highest binding affinities were identified in the order; 23_7ESX (-10.2 kcal/mol) > 14_6EEZ (- 9.0) > 29_3F4R (- 8.0) > 26_6W9O (- 7.7) ≈ doxycycline_7ESX (- 7.7), with good pharmacological interaction profiles. The built 3-D QSAR model satisfied the requirement of a good model with R2 = 0.9425, Q2 LOO = 0.5019, SDEC = 0.1446, and F test = 98.282. The selected molecules (14, 23, 26, and 29) perfectly obeyed Lipinski's RO5 for oral bio-availability, and showed excellent ADMET properties, except 14 with positive AMES toxicity. The result of the MD simulation showed the great stability associated with the binding of 23 onto 7ESX's binding pocket with an estimated binding free energy (MM/GBSA) of - 60.6552 kcal/mol. Therefore, 23 could be recommended as a potential anti-filarial drug molecule, and/or template for the design of more prominent inhibitors.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40203-022-00136-y.

Contemporary exploitation of natural products for arthropod-borne pathogen transmission-blocking interventions

An integrated approach to innovatively counter the transmission of various arthropod-borne diseases to humans would benefit from strategies that sustainably limit onward passage of infective life cycle stages of pathogens and parasites to the insect vectors and vice versa. Aiming to accelerate the impetus towards a disease-free world amid the challenges posed by climate change, discovery, mindful exploitation and integration of active natural products in design of pathogen transmission-blocking interventions is of high priority. Herein, we provide a review of natural compounds endowed with blockade potential against transmissible forms of human pathogens reported in the last 2 decades from 2000 to 2021. Finally, we propose various translational strategies that can exploit these pathogen transmission-blocking natural products into design of novel and sustainable disease control interventions. In summary, tapping these compounds will potentially aid in integrated combat mission to reduce disease transmission trends.

In silico prediction of flavan-3-ol as a bioactive compound of Calophyllum macrophyllum as a potential drug against angiostrongylus eosinophilic meningitis

Background and Aim:

Angiostrongylus eosinophilic meningitis is caused by larvae of the rat lungworm Angiostrongylus cantonensis. It manifests as meningitis, radiculitis, cranial nerve abnormalities, and encephalitis, which can be fatal. A flavan-3-ol compound isolated from the bark of Calophyllum macrophyllum Scheff. has several medicinal properties, including antioxidant, anti-inflammatory, antidiabetic, and antibacterial activities. This compound is stronger than other types of flavan-3-ols such as catechin. This study aimed to identify the hydroxylation pattern of this flavan-3-ol compound and evaluated its potential as an anti-meningitis drug, using an in silico approach through pharmacophore and molecular docking methods.

Materials and Methods:

Pharmacokinetic and toxicological data were analyzed and supported by the server http://www.swissadme.ch/index.php and https://tox-new.charite.de/protox_II/index.php. The hydroxylation pattern of the flavan-3-ol compound was identified using shear reagents (MeOH, NaOH, NaOAc, HCl, and AlCl₃). The CviR receptor (pdb id.3QP5) was used in the in silico approach, and seven ligands were downloaded from PubChem in “SMILES” format.

Results:

The spectroscopic analysis conducted using the shear reagents confirmed that the flavan-3-ol compound has a “p-diOH” pattern on the cinnamoyl ring. Pharmacophore analysis revealed this compound “hit” with pharmacophore features, and molecular docking analysis showed that this compound has a strong affinity with both receptors.

Conclusion:

The flavan-3-ol compound is a potential drug candidate for meningitis caused by pathogenic bacteria and the worm A. cantonensis. This result was supported by the pharmacokinetic profile, which had a very low toxicity level to the host. However, further investigation is required to confirm the data in vitro and in vivo.

Theoretical modeling and design of some pyrazolopyrimidine derivatives as Wolbachia inhibitors, targeting lymphatic filariasis and onchocerciasis

Lymphatic filariasis and onchocerciasis are two common filarial diseases caused by a group of parasitic nematodes called filarial worms, which play host to the bacteria organism Wolbachia. One good treatment approach seeks Wolbachia as drug target. Here, a QSAR study was conducted to investigate the anti-wolbachia activities (pEC₅₀) of 52 pyrazolopyrimidine analogues, while using the built model to predict the pEC₅₀ values of the newly designed analogues. Density Functional Theory was used for the structural optimization, while the model building was based on Genetic Function Algorithm approach. The built QSAR model was validated thus: R² = 0.8104, R² _adj = 0.7629, Q² _cv = 0.6981, R² _test = 0.7501 and cRp² = 0.7476. The predicted pEC₅₀ of all newly designed compounds were higher than that of the template (43). The new compounds were; observed to pass the drug-likeness criteria, uniformly distributed to the brain, and found to be non-mutagenic. Also, the new compounds and the reference drug (doxycycline), were docked onto Ovarian Tumor (OTU) deubiquitinase receptor (PDB ID: 6W9O) using iGEMDOCK tool. This protein is known to help Wolbachia subvert host ubiquitin signaling. The resulting binding scores of the newly designed compounds except A5 were higher than that of doxycycline, while the protein-ligand interactions were majorly characterized by Hydrogen-bonding and hydrophobic interaction types. Therefore, the newly designed molecules could be developed as potential drug candidates for the treatment of lymphatic filariasis and onchocerciasis.

Suppression of colorectal carcinogenesis by naringin

BACKGROUND

Colorectal cancer is the third most malignant cancer worldwide. Despite novel treatment options, the incidence and mortality rates of colon cancer continue to increase in most countries, especially in US, European and Asian countries. Colorectal carcinogenesis is multifactorial, including dietary and genetic factors, as well as lacking physical activity. Vegetables and fruits contain high amounts of secondary metabolites, which might reduce the risk for colorectal carcinogenesis. Flavonoids are important bioactive polyphenolic compounds. There are more than 4,000 different flavonoids, including flavanones, flavonoids, isoflavonoids, flavones, and catechins in a large variety of plant.

HYPOTHESIS

Among various other flavonoids, naringin in Citrus fruits has been a subject of intense scrutiny for its activity against many types of cancer, including colorectal cancer. We hypothesize that naringin is capable to inhibit the growth of transformed colonocytes and to induce programmed cell death in colon cancer cells.

RESULTS

We comprehensively review the inhibitory effects of naringin on colorectal cancers and address the underlying mechanistic pathways such as NF-κB/IL-6/STAT3, PI3K/AKT/mTOR, apoptosis, NF-κB-COX-2-iNOS, and β-catenin pathways.

CONCLUSION

Naringin suppresses colorectal inflammation and carcinogenesis by various signaling pathways. Randomized clinical trials are needed to determine their effectiveness in combating colorectal cancer.

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.

Bilberry (Vaccinium myrtillus L.) Extracts Comparative Analysis Regarding Their Phytonutrient Profiles, Antioxidant Capacity along with the In Vivo Rescue Effects Tested on a Drosophila melanogaster High-Sugar Diet Model

Bilberries (Vaccinium myrtillus L.) have been reported to hold a plentitude of health-promoting properties beyond basic nutrition, mainly attributed to their anthocyanin content and antioxidant activity. In this article, we built the phytochemical profile of three wild bilberry fruit extract formulations (aqueous, methanolic, and hydro-methanolic) using UHPLC-ESI-MS/MS putative analysis, identifying 88 individual phytochemicals, mainly flavonoids (total content 8.41 ± 0.11 mg QE/g dw), free amino acids, polyphenols (total content 21.68 ± 0.19 mg GAE/g dw), carboxylic acids, and vitamins. Furthermore, the antioxidant activity of the extract was assessed, reaching 78.03 ± 0.16% DPPH free radical scavenging activity, comparable to literature values determined for bilberry extracts of other origin. Due to the increased prevalence of metabolic syndrome and based on the reviewed benefits of bilberries, we tested the most potent formulation of our bilberry extracts in this biological context. The in vivo rescue effect of a bilberry extract supplemented diet on Drosophila melanogaster was assessed by monitoring biochemical and genomic markers. Hemolymph trehalose levels were halved upon addition of 3% hydro-methanolic bilberry extract to a high-sugar (1.5 M sucrose) diet, as compared to the non-supplemented high-sugar diet. Noteworthy, the rescue seen for flies kept on the bilberry extract supplemented high-sugar diet appeared to parallel the trehalose levels observed in the case of the control diet (50 mM sucrose) flies. Moreover, next to the trehalose-lowering type of in vivo effects, other gene expression related rescues were also detected for genes such as InR, Akh, AstA, AstC, Irk, Npc2g, and CCHa2 upon supplementation of the high-sugar diet with our hydro-methanolic bilberry fruit extract. Our findings suggest that such a bilberry fruit extract could generate physiological and genomic type of compensatory mechanisms so that further translational approaches would advance the understanding of some human specific pathological conditions.

Isorhamnetin: A Nematocidal Flavonoid from Prosopis Laevigata Leaves Against Haemonchus Contortus Eggs and Larvae

Haemonchus contortus affect small ruminants all over the world. Anthelmintics cause resistance, contamination, and a risk of public health. Prosopis laevigata is a plant used as a home remedy against many diseases in Mexico. This study arose from a preliminary study where a P. laevigata hydroalcoholic extract (Pl-hae) showed anthelmintic activity (aa) against H. contortus. Searching for bioactive compounds (bac) with high aa, the Pl-hae was fractioned obtaining an aqueous (Aq-F) and an ethyl acetate fraction (EtAc-F), and a flavonoid with aa identified as isorhamnetin was obtained from EtAc-F. Both fractions were in vitro assessed by the egg hatch test (eht) and larval mortality (lm) assays. The bac obtained from EtAc-F were characterised by NMR analysis. The highest aa were recorded with EtAc-F, resulting in 100% eht and 80.45% lm at 0.75 and 30 mg/mL, respectively. Alterations in eggs and larvae attributed to isorhamnetin were recorded by environmental scanning electron microscopy, confocal laser scanning and by high-resolution digital-coupled camera. This flavonoid caused 100% eht at 0.07 mg/mL after 48 h and 100% lm at 7.5 mg/mL after 72 h exposure. Isorhamnetin has promising potential as an anthelmintic against sheep haemonchosis.

An Insight into the Discovery of Potent Antifilarial Leads Against Lymphatic Filariasis

BACKGROUND AND OBJECTIVES

Lymphatic filariasis is a neglected tropical disease caused by infection with filarial worms that are transmitted through mosquito bites. Globally, 120 million people are infected, with nearly 40 million people disfigured and disabled by complications such as severe swelling of the legs (elephantiasis) or scrotum (hydrocele). Current treatments (ivermectin, diethylcarbamazine) have limited effects on adult parasites and produce side effects; therefore, there is an urgent to search for new antifilarial agents. Numerous studies on the antifilarial activity of pure molecules have been reported accross the recent literature. The present study describes the current standings of potent antifilarial compounds against lymphatic filariasis.

METHODS

A literature search was conducted for naturally occurring and synthetic antifilarial compounds by referencing textbooks and scientific databases (SciFinder, PubMed, Science Direct, Wiley, ACS, SciELO, Google Scholar, and Springer, among others) from their inception until September 2019.

RESULTS

Numerous compounds have been reported to exhibit antifilarial acitivity in adult and microfilariae forms of the parasites responsible for lymphatic filariasis. In silico studies of active antifilarial compounds (ligands) showed molecular interactions over the protein targets (trehalose-6-phosphate phosphatase, thymidylate synthase, among others) of lymphatic filariasis, and supported the in vitro results.

CONCLUSION

With reference to in vitro antifilarial studies, there is evidence that natural and synthetic products can serve as basic scaffolds for the development of antifilarial agents. The optimization of the most potent antifilarial compounds can be further performed, followed by their in vivo studies.

In vitro efficacy of ampelopsin against Echinococcus granulosus and Echinococcus multilocularis

The metacestode stage of Echinococcus granulosus and Echinococcus multilocularis cause cystic echinococcosis and alveolar echinococcosis, respectively, which result in severe medical and veterinary problems. In this study, as an exploration of novel treatment agents against echinococcosis, we demonstrated that ampelopsin (AMP), which is extracted from Ampelopsis grossedentata and has been clinically used for treatments of various types of diseases including cancers for a long time, exhibited profound in vitro effect against E. granulosus protoscoleces and E. multilocularis metacestodes. Furthermore, in vitro cytotoxicity assay also demonstrated that AMP at the effective dose against E. granulosus protoscoleces and E. multilocularis metacestodes did not show significant toxicity to human hepatocytes. These results suggest that AMP has the potential as an alternative agent against echinococcosis.

Pharmacokinetic parameters of ifosfamide in mouse pre-administered with grapefruit juice or naringin

Grapefruit juice (GFJ) and naringin when consumed previously or together with medications may alter their bioavailavility and consequently the clinical effect. Ifosfamide (IF) is an antitumoral agent prescribed against various types of cancer. Nevertheless, there is no information regarding its interaction with the ingestion of GFJ or naringin. The aims of the present report were validating a method for the quantitation of IF in the plasma of mouse, and determine if mice pretreated with GFJ or naringin may modify the IF pharmacokinetics. Our HPLC results to quantify IF showed adequate intra and inter-day precision (RSD < 15%) and accuracy (RE < 15%) indicating reliability. Also, the administration of GFJ or naringin increased C_max of IF 22.9% and 17.8%, respectively, and decreased T_max of IF 19.2 and 53.8%, respectively. The concentration of IF was higher when GFJ (71.35 ± 3.5 µg/mL) was administered with respect to that obtained in the combination naringin with IF (64.12 ± µg/mL); however, the time required to reach such concentration was significantly lower when naringin was administered (p < 0.5). We concluded that pre-administering GFJ and naringin to mice increased the T_max and decreased the C_max of IF.

In Vitro and In Vivo Antifilarial Activity of Standardized Extract of Calotropis procera Flowers against Brugia malayi

BACKGROUND

Lymphatic filariasis (LF) is a parasitic disease that causes permanent disability (elephantiasis). Currently used antifilarial drugs are failing to control LF and there is resurgence in some areas. Looking for new antifilarial leads, we found that Calotropis procera plant parts have been used in traditional medicine for alleviating elephantiasis but the antifilarial activity is not known.

OBJECTIVE

In the present study, the antifilarial activity of ethanolic extract (A001) and its hexane fraction (F001) of C. procera flowers was investigated using the human filarial parasite Brugia malayi.

METHODS

A001 and F001 were tested for antifilarial activity using motility and 3-(4,5-dimethylthiazol-2- yl)-2,5 diphenyltetrazolium bromide (MTT) assays (in vitro) and in the rodent models B. malayi- Meriones unguiculatus and B. malayi-Mastomys coucha. In the rodent models, A001 and F001 were administered orally for 5 consecutive days, and the adult worm burden and course of microfilaraemia were determined.

RESULTS

Both A001 and F001 showed microfilaricidal and macrofilaricidal activity in vitro. In animal models, A001 killed ~49-54% adult worms. In M. coucha model, F001 killed 12-60% adult worms in a dose (125-500 mg/kg) dependent manner; A001 and F001 suppressed microfilaraemia till days 91 and 35 post initiation of treatment, respectively. HPTLC revealed 0.61% lupeol, 0.50% β-sitosterol and 1.50% triacontanol in F001.

CONCLUSION

Flowers of C. procera have definite microfilaricidal and macrofilaricidal activities. Whether this activity is due to lupeol, β-sitosterol and triacontanol found in the hexane fraction remains to be investigated. This is the first report on the antifilarial efficacy of flowers of the plant C. procera.

In Vitro and In Silico Studies of Glycyrrhetinic Acid Derivatives as Anti- Filarial Agents

BACKGROUND

Lymphatic filariasis is one of the chronic diseases in many parts of the tropics and sub-tropics of the world despite the use of standard drugs diethylcarbamazine and ivermectin because they kill microfilaries and not the adult parasites. Therefore, new leads with activity on adult parasites are highly desirable.

OBJECTIVE

Anti-filarial lead optimization by semi-synthetic modification of glycyrrhetinic acid (GA).

METHODS

The GA was first converted into 3-O-acyl derivative, which was further converted into 12 amide derivatives. All these derivatives were assessed for their antifilarial potential by parasite motility assay. The binding affinity of active GA derivatives on trehalose-6-phosphate phosphatase (Bm-TPP) was assessed by molecular docking studies.

RESULTS

Among 15 GA derivatives, GAD-2, GAD-3, and GAD-4 were found more potent than the GA and standard drug DEC. These derivatives reduced the motility of Brugia malayi adult worms by up to 74% while the GA and DEC reduced only up to 49%. Further, GA and most of its derivatives exhibited two times more reduction in MTT assay when compared to the standard drug DEC. These derivatives also showed 100% reduction of microfilariae and good interactions with Bm-TPP protein.

CONCLUSION

The present study suggests that 3-O-acyl and linear chain amide derivatives of glycyrrhetinic acid may be potent leads against B. malayi microfilariae and adult worms. These results might be helpful in developing QSAR model for optimizing a new class of antifilarial lead from a very common, inexpensive, and non toxic natural product.

Immunomodulatory Activity of Sulfonamide Chalcone Compounds in Mice Infected with Filarial Parasite, Brugia malayi

Diethyl carbamazine (DEC) is being used as a sole drug to treat the lymphatic filariasis, although encountered with many limitations. Importantly, DEC works with putative host immunomodulating activities without any direct antifilarial effect. This study aimed to assess the possible modulatory effect on host immune system by sulfonamide chalcone compound, having direct antifilarial activity. The immunomodulatory activity of DEC and/or chalcone compound, 4t on mice peritoneal exudate cells (PECs) was analyzed initially in vitro. This was followed by the study of in vivo effect of these test agents in the parasitaemic BALB/c mice induced by Brugia malayi microfilariae. Cytokine profile and iNOS induction were measured from PECs of mice. 4t compound showed anti-inflammatory activity in vivo in contrast to DEC. Further 4t was found to increase anti-inflammatory and regulatory cytokines, IL-10 and TGF-β gene expression with down regulation of pro-inflammatory cytokines TNF-α and IFN-γ and iNOS in mice PECs in in vitro. In conclusion, chalcones having direct antifilarial effect also upsurges anti-inflammatory host immune response. Therefore, the results might be envisaged as 4t to be a better alternative to DEC in the chronic case of lymphatic filariasis.

In-vitro and in silico efficacy of isolated alkaloid compounds from Rauvolfia tetraphylla L. against bovine filarial parasite Setaria cervi: a drug discovery approach

Bioassay guided isolation from the leaves of Rauvolfia tetraphylla L. resulted in the isolation and characterization of three compounds of alkaloid in nature namely, Curan-17-oic acid (F1); 18, 19-Secoyohimban (F2) and Reserpiline (F3). Macrofilaricidal activity of three compounds was tested against bovine filarial parasite Setaria cervi using in vitro assays and supported by in silico docking analysis on glutathione-S-transferase (GST) enzyme of Wuchereria bancrofti. All the molecules inhibited GST enzyme to some extent 35.78%, 78.22% and 64.21% respectively. Results were supported by molecular docking studies, which showed docking scores for compound F1 (- 5.14), compound F2 (- 7.19) and compound F3 (- 7.2) on GST enzyme. Thus, in conclusion the in vitro and in silico studies indicated that isolated compounds are promising, inexpensive and widely available natural leads, which can be designed and developed into the macrofilaricidal drugs.

Ovicidal and larvicidal activity of extracts from medicinal-plants against Haemonchus contortus

The use of medicinal plants (MP) containing bioactive compounds is an alternative strategy to control of parasitic nematode of small ruminants Haemonchus contortus at various stages of their life cycle. The aims of this study were to determine the in vitro anthelmintic activity of both aqueous and methanolic extracts from 13 medicinal plants typical for Central Europe, and to determine quantity of selected plant secondary metabolites (PSMs) in the methanolic extracts. In vitro egg hatch test and larval development tests were conducted to determine the possible anthelmintic effects of methanolic and aqueous extracts of the roots of Althaea officinalis L., Petasites hybridus L. and Inula helenium L.; flowers of Malva sylvestris L. and Chamomilla recutita L.; leaves of Plantago lanceolata L. and Rosmarinus officinalis L.; seeds of Foeniculum vulgare Mill. and stems of Solidago virgaurea L., Fumaria officinalis L., Hyssopus officinalis L., Melisa officinalis L. and Artemisia absinthium L. on eggs and larvae of H. contortus. Ultra-performance liquid chromatography and tandem mass spectroscopy was used for quantifying six PSMs: gallic acid (GA), rutin (RU), diosmin (DI), hesperidin (HE), quercetin (QU) and kaempferol (KA). RU content of the most effective methanolic extracts was in the order: M. sylvestris (9.33 mg/g DM) > A. absinthium (6.10 mg/g DM) > C. recutita (0.42 mg/g DM). The highest concentration of QU (44.8 mg/g DM) and KA (6.59 mg/g DM) were detected in stems of F. officinalis comparing to the other evaluated plants. The most significant (p < 0.05) anthelmintic effects exhibited methanolic extracts of A. absinthium in both in vitro tests (i.e., egg hatch test and larval development test). Additionally, only two methanolic extracts of C. recutita and M. sylvestris were comparable to activity of A. absinthium using the larval development test. Wider spectrum of aqueous extracts exhibited stronger ovicidal activity in comparison to methanolic extracts. The similar trend was observed in evaluating of larvicidal activity of aqueous and methanolic plant extracts.

Susceptibility Testing of Medically Important Parasites

In the last 2 decades, renewed attention to neglected tropical diseases (NTDs) has spurred the development of antiparasitic agents, especially in light of emerging drug resistance. The need for new drugs has required in vitro screening methods using parasite culture. Furthermore, clinical laboratories sought to correlate in vitro susceptibility methods with treatment outcomes, most notably with malaria. Parasites with their various life cycles present greater complexity than bacteria, for which standardized susceptibility methods exist. This review catalogs the state-of-the-art methodologies used to evaluate the effects of drugs on key human parasites from the point of view of drug discovery as well as the need for laboratory methods that correlate with clinical outcomes.

Antifilarial activity of caffeic acid phenethyl ester on Brugia pahangi in vitro and in vivo

Lymphatic filariasis (LF) is a vector borne disease caused by parasitic worms such as Wuchereria bancrofti, Brugia malayi and B. timori, which are transmitted by mosquitoes. Current therapeutics to treat LF are mainly microfilarcidal, and lack activity against adult worms. This set back, poses a challenge for the control and elimination of filariasis. Thus, in this study the activities of caffeic acid phenethyl ester (CAPE) against the filarial worm B. pahangi and its bacterial endosymbiont, Wolbachia were evaluated. Different concentrations (2, 5, 10, 15, 20 μg/ml) of CAPE were used to assess its effects on motility, viability and microfilarial (mf) production of B. pahangi in vitro. Anti-Wolbachial activity of CAPE was measured in worms by quantification of Wolbachial wsp gene copy number using real-time polymerase chain reaction. Our findings show that CAPE was found to significantly reduce adult worm motility, viability, and mf release both in vitro and in vivo. 20 μg/ml of CAPE halts the release of mf in vitro by day 6 of post treatment. Also, the number of adult worms recovered in vivo were reduced significantly during and after treatment with 50 mg/kg of CAPE relative to control drugs, diethylcarbamazine and doxycycline. Real time PCR based on the Wolbachia ftsZ gene revealed a significant reduction in Wolbachia copy number upon treatment. Anti-Wolbachia and antifilarial properties of CAPE require further investigation as an alternative strategy to treat LF.

Recombinant Calponin of human filariid Brugia malayi: Secondary structure and immunoprophylactic potential

In the search for potential vaccine candidates for the control of human lymphatic filariasis, we recently identified calponin-like protein, that regulates actin/myosin interactions, in a proinflammatory fraction F8 (45.24-48.64kDa) of Brugia malayi adult worms. In the present study, the gene was cloned, expressed, and the recombinant Calponin of B. malayi (r-ClpBm) was prepared and characterized. r-ClpBm bears homology with OV9M of Onchocerca volvulus, a non-lymphatic filariid that causes loss of vision and cutaneous pathology. r-ClpBm was found to be a ∼45kDa protein that folds into a predominantly α-helix conformation. The protective efficacy of r-ClpBm against B. malayi infection in Mastomys coucha was investigated by assessing the course of microfilaraemia and adult worm burden in the host immunized with r-ClpBm and subsequently infected with infective third stage larvae (L3). Expression of the Calponin was detected in all life stages (microfilariae, L3, L4, L5 and adults) of the parasite and immunization with r-ClpBm partially protected M. coucha against establishment of infection as inferred by ∼42% inhibition in parasite burden. Upregulated cellular proliferation, TNF-α, IFN-γ, IL-1β, IL-4, nitric oxide (NO) release, expression of iNOS, and specific IgG, IgG1 and IgG2b in immunized animals correlated with parasitological findings. r-ClpBm immunization caused degranulation in majority of mast cells indicating possible involvement of mast cell products in reducing the parasite survival. It appears that complex mechanisms including Th1, Th2, NO and mast cells are involved in the clearance of infection. To the best of our knowledge this is the first report on cloning, expression of the gene and purification of r-ClpBm, determination of its secondary structure and its ability to partially prevent establishment of B. malayi infection. Thus, r-ClpBm may further be studied and developed in combination with other protective molecules of B. malayi as a component of potential filarial cocktail vaccine candidate.

In vitro and in vivo cysticidal activity of extracts and isolated flavanone from the bark of Prunus serotina: A bio-guided study

Currently, neurocysticercosis treatment involves two drugs: albendazole and praziquantel; however, their efficacy is suboptimal and new cysticidal drugs are needed. The present paper reports the cysticidal activity of extracts of the bark from Prunus serotina against Taenia crassiceps cysts and the isolation and identification of the main components of the most active extract. Results showed that all extracts displayed in vitro cysticidal activity (EC₅₀=17.9-88.5μg/mL), being the methanolic the most active and selective. Also, methanolic extract exhibited in vivo efficacy at 300mg/kg which was similar to that obtained with albendazole. Bio-guided fractionation of methanolic extract led the isolation of 2,3-dihydro-5,7-dihydroxy-2-(4-hydroxyphenyl)-4H-1-benzopyran-4-one (naringenin, NGN), 3,4,5-trimethoxybenzoic acid and 1,3,5-trimethoxybenzene. NGN exhibited in vitro activity, in a time-concentration-dependent manner (EC₅₀=89.3μM]. Furthermore, NGN at a dose of 376.1μmol/kg displayed similar in vivo efficacy than those obtained with albendazole at 188.4μmol/kg. NGN also caused a high level of damage in all parasite tissue in a similar manner than that observed with the methanolic extract. This study represents the first report of the cysticidal properties of the bark of P. serotina. NGN was identified as the main active compound of this specie and other studies are required to explore the potential of this flavanone as cysticidal agent.

Two decades of antifilarial drug discovery: a review

Filariasis is one of the oldest, most debilitating, disabling, and disfiguring neglected tropical diseases with various clinical manifestations and a low rate of mortality, but has a high morbidity rate, which results in social stigma.

Antifilarial activity of diterpenoids from Taxodium distichum

BACKGROUND

Lymphatic filariasis caused by Wuchereria bancrofti, Brugia malayi and B. timori, is a debilitating disease with an adverse social and economic impact. The infection remains unabated in spite of treatment with existing antifilarial drugs diethylcarbamazine (DEC) and ivermectin which are chiefly microfilaricides. There is therefore, need for macrofilaricides, embryostatic agents and better microfilaricides. In the present study we explored the antifilarial potential of crude extract and its molecular fractions of the plant Taxodium distichum using in vitro assay systems and rodent models of B. malayi infection.

METHODS

Ethanolic extract (A001) of aerial parts of T. distichum was solvent fractionated and sub-fractionated. Four molecules, 3-Acetoxylabda-8(20), 13-diene-15-oic acid (K001), Beta-sitosterol (K002), labda-8(20),13-diene-15-oic acid (K003) and Metasequoic acid A (K004) were isolated from the fractions and their structure determined by spectroscopic analysis. The extract, subfractions and molecules were evaluated for antifilarial activity against B. malayi by 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT) reduction and motility assays in vitro and in two animal models, Meriones unguiculatus and Mastomys coucha, harbouring B. malayi infection.

RESULTS

A001 was effective in killing microfilariae (mf) and adult worms in vitro. The diterpenoid K003 produced 100 % reduction in motility of both mf and adult worms and > 80 % inhibition in MTT reduction potential of adult female worms. In B. malayi-M. unguiculatus model, A001 killed all the adult worms in > 80 % of infected animals. K003 was embryostatic (> 95 %) in this model. In the B. malayi-M. coucha model, K003 killed ~54 % of adult worms (macrofilaricidal activity) and rendered > 36 % female worms sterile; it also stopped any further rise in microfilaraemia after day 42 post-initiation of treatment.

CONCLUSION

Ethanolic extract of aerial parts of the plant T. distichum possesses potent antifilarial activity and the active principle was localised to K003 which showed significant macrofilaricidal activity and late suppression of peripheral microfilaraemia and some embryostatic activity. These findings indicate that labdane diterpenoid molecule(s) may provide valuable leads for design and development of new macrofilaricidal agent(s). To the best of our knowledge, this is the first report on antifilarial efficacy of products from the plant T. distichum.

An In Vitro/In Vivo Model to Analyze the Effects of Flubendazole Exposure on Adult Female Brugia malayi

Current control strategies for onchocerciasis and lymphatic filariasis (LF) rely on prolonged yearly or twice-yearly mass administration of microfilaricidal drugs. Prospects for near-term elimination or eradication of these diseases would be improved by availability of a macrofilaricide that is highly effective in a short regimen. Flubendazole (FLBZ), a benzimidazole anthelmintic registered for control of human gastrointestinal nematode infections, is a potential candidate for this role. FLBZ has profound and potent macrofilaricidal effects in many experimental animal models of filariases and in one human trial for onchocerciasis after parental administration. Unfortunately, the marketed formulation of FLBZ provides very limited oral bioavailability and parenteral administration is required for macrofilaricidal efficacy. A new formulation that provided sufficient oral bioavailability could advance FLBZ as an effective treatment for onchocerciasis and LF. Short-term in vitro culture experiments in adult filariae have shown that FLBZ damages tissues required for reproduction and survival at pharmacologically relevant concentrations. The current study characterized the long-term effects of FLBZ on adult Brugia malayi by maintaining parasites in jirds for up to eight weeks following brief drug exposure (6–24 hr) to pharmacologically relevant concentrations (100 nM—10 μM) in culture. Morphological damage following exposure to FLBZ was observed prominently in developing embryos and was accompanied by a decrease in microfilarial output at 4 weeks post-exposure. Although FLBZ exposure clearly damaged the parasites, exposed worms recovered and were viable 8 weeks after treatment.

Onchocerciasis and lymphatic filariasis are debilitating diseases caused by infections with filarial nematodes. The World Health Organization aims to eliminate these infections as public health problems. Despite prolonged control efforts, including chemotherapy through mass drug administration (MDA), transmission and infections persist. Addition of a microfilaricide that is efficacious in a short regimen would enhance prospects for achieving elimination goals. We investigated the long-term effects of the macrofilaricidal drug, flubendazole (FLBZ), on Brugia malayi. Adult parasites were exposed in culture to FLBZ at pharmacologically relevant concentrations (100 nM—10 μM) for up to 24 hr prior to implantation into the abdominal cavity of a jird for long-term maintenance. The greatest drug effect was on embryogenesis; morphological damage was most evident in early developmental stages. There was also a decrease in the release of microfilaria (mf) from the adult. Interestingly, no damage was observed to fully formed mf. Although further studies are required to determine to what extent these findings can be extrapolated to a field setting, an exposure profile which may produce similar effects in vivo has been defined.

Protective effects of flavonoids against microbes and toxins: The cases of hesperidin and hesperetin

Many plants produce flavonoids as secondary metabolites. These organic compounds may be involved in the defense against plant-threatening factors, such as microbes and toxins. Certain flavonoids protect their origin source against plant pathogens, but they also exhibit potential healthy properties in human organisms. Hesperidin (Hsd) and its aglycone, hesperetin (Hst), are two flavonoids from the Citrus species that exhibit various biological properties, including antioxidant, antiinflammatory and anticancer effects. Recent studies indicated that Hst and Hsd possess antimicrobial activity. Although the exact mechanisms behind their antimicrobial properties are not fully understood, several mechanisms such as the activation of the host immune system, bacterial membrane disruption, and interference with microbial enzymes, have been proposed. Hsd and Hst may also have protective effects against toxicity induced by various agents. These natural substances may contribute to the protection of cells and tissues through their antioxidant and radical scavenging activities. This review discusses the protective activities of Hsd and Hst against microbes and several toxicities induced by oxidants, chemicals, toxins, chemotherapy and radiotherapy agents, which were reported in vitro and in vivo. Furthermore, the probable mechanisms behind these activities are discussed.

A Review on Pharmacological and Analytical Aspects of Naringenin

Flavonoids are a widely distributed group of phytochemicals having benzo-pyrone nucleus, and more than 4,000 different flavonoids have been described and categorized into flavonols, flavones, flavanones, isoflavones, catechins and anthocyanidins. Flavonoids occurs naturally in fruits, vegetables, nuts, and beverages such as coffee, tea, and red wine, as well as in medical herbs. Flavonoids are responsible for the different colors of plant parts and are important constituents of the human diet. Flavanoids have different pharmacological activities, such as antioxidant, anti-allergic, antibacterial, anti-inflammatory, antimutagenic and anticancer activity. Naringenin belongs to the flavanones and is mainly found in fruits (grapefruit and oranges) and vegetables. Pharmacologically, it has anticancer, antimutagenic, anti-inflammatory, antioxidant, antiproliferative and antiatherogenic activities. Naringenin is used for the treatments of osteoporosis, cancer and cardiovascular diseases, and showed lipid-lowering and insulin-like properties. In the present review, detailed pharmacological and analytical aspects of naringenin have been presented, which revealed the impressive pharmacological profile and the possible usefulness in the treatment of different types of diseases in the future. The information provided in this communication will act as an important source for development of effective medicines for the treatment of various disorders.

Protection against filarial infection by 45-49 kDa molecules of Brugia malayi via IFN-γ-mediated iNOS induction

Nitric oxide (NO) mediated mechanisms have been implicated in killing of some life-stages of Brugia malayi/Wuchereria bancrofti and protect the host through type 1 responses and IFN-γ stimulated toxic mediators' release. However, the identity of NO stimulating molecules of the parasites is not known. Three predominantly NO-stimulating SDS-PAGE resolved fractions F8 (45.24-48.64 kDa), F11 (33.44-38.44 kDa) and F12 (28.44-33.44 kDa) from B. malayi were identified and their proteins were analyzed by 2-DE and MALDI-TOF/TOF. Tropomyosin, calponin and de novo peptides were identified by 2-DE and MALDI-TOF/TOF in F8 and immunization with F8 conferred most significant protection against L3-initiated infection in Mastomys coucha. Immunized animals showed upregulated F8-induced NO, IFN-γ, TNF-α, IL-1β, IL-10, TGF-β release, cellular proliferative responses and specific IgG and IgG1. Anti-IFN-γ, anti-TNF-α, and anti-IL-1β significantly reduced F8-mediated NO generation and iNOS induction at protein levels. Anti-IFN-γ treated cells showed maximum reduction (>74%) in NO generation suggesting a predominant role of IFN-γ in iNOS induction. In conclusion, the findings suggest that F8 which contains tropomyosin, calponin and de novo peptides protects the host via IFN-γ mediated iNOS induction and may hold promise as vaccine candidate(s). This is also the first report of identification of tropomyosin and calponin in B. malayi.

In vitro, in silico and in vivo studies of ursolic acid as an anti-filarial agent

As part of our drug discovery program for anti-filarial agents from Indian medicinal plants, leaves of Eucalyptus tereticornis were chemically investigated, which resulted in the isolation and characterization of an anti-filarial agent, ursolic acid (UA) as a major constituent. Antifilarial activity of UA against the human lymphatic filarial parasite Brugia malayi using in vitro and in vivo assays, and in silico docking search on glutathione-s-transferase (GST) parasitic enzyme were carried out. The UA was lethal to microfilariae (mf; LC100: 50; IC50: 8.84 µM) and female adult worms (LC100: 100; IC50: 35.36 µM) as observed by motility assay; it exerted 86% inhibition in MTT reduction potential of the adult parasites. The selectivity index (SI) of UA for the parasites was found safe. This was supported by the molecular docking studies, which showed adequate docking (LibDock) scores for UA (-8.6) with respect to the standard antifilarial drugs, ivermectin (IVM -8.4) and diethylcarbamazine (DEC-C -4.6) on glutathione-s-transferase enzyme. Further, in silico pharmacokinetic and drug-likeness studies showed that UA possesses drug-like properties. Furthermore, UA was evaluated in vivo in B. malayi-M. coucha model (natural infection), which showed 54% macrofilaricidal activity, 56% female worm sterility and almost unchanged microfilaraemia maintained throughout observation period with no adverse effect on the host. Thus, in conclusion in vitro, in silico and in vivo results indicate that UA is a promising, inexpensive, widely available natural lead, which can be designed and developed into a macrofilaricidal drug. To the best of our knowledge this is the first ever report on the anti-filarial potential of UA from E. tereticornis, which is in full agreement with the Thomson Reuter's 'Metadrug' tool screening predictions.

An integrated in vitro imaging platform for characterizing filarial parasite behavior within a multicellular microenvironment

Lymphatic Filariasis, a Neglected Tropical Disease, is caused by thread-like parasitic worms, including B. malayi, which migrate to the human lymphatic system following transmission. The parasites reside in collecting lymphatic vessels and lymph nodes for years, often resulting in lymphedema, elephantiasis or hydrocele. The mechanisms driving worm migration and retention within the lymphatics are currently unknown. We have developed an integrated in vitro imaging platform capable of quantifying B. malayi migration and behavior in a multicellular microenvironment relevant to the initial site of worm injection by incorporating the worm in a Polydimethylsiloxane (PDMS) microchannel in the presence of human dermal lymphatic endothelial cells (LECs) and human dermal fibroblasts (HDFs). The platform utilizes a motorized controllable microscope with CO2 and temperature regulation to allow for worm tracking experiments with high resolution over large length and time scales. Using post-acquisition algorithms, we quantified four parameters: 1) speed, 2) thrashing intensity, 3) percentage of time spent in a given cell region and 4) persistence ratio. We demonstrated the utility of our system by quantifying these parameters for L3 B. malayi in the presence of LECs and HDFs. Speed and thrashing increased in the presence of both cell types and were altered within minutes upon exposure to the anthelmintic drug, tetramisole. The worms displayed no targeted migration towards either cell type for the time course of this study (3 hours). When cells were not present in the chamber, worm thrashing correlated directly with worm speed. However, this correlation was lost in the presence of cells. The described platform provides the ability to further study B. malayi migration and behavior.

Synthesis and antifilarial activity of chalcone-thiazole derivatives against a human lymphatic filarial parasite, Brugia malayi

Here we report the synthesis of novel chalcone-thiazole compounds and their antifilarial activity. The antifilarial properties of these hybrids were assessed against microfilariae as well as adult worms of Brugia malayi. Among all the synthesized compounds, only two compounds, namely 4g and 4n were identified to be promising in vitro. These active compounds were tested in B. malayi-jird (Meriones unguiculatus) and B. malayi-Mastomys coucha models. Compound 4n showed 100% embryostatic effect and 49% macrofilaricidal in jirds and M. coucha models, respectively. This study provides a new structural clue for the development of novel antifilarial lead molecules.

Diarylheptanoid compounds from Alnus nepalensis express in vitro and in vivo antifilarial activity

A large number of medicinal plants remain to be explored for antifilarial compounds. In the present study a crude methanolic extract of leaves of Alnus nepalensis, chloroform- and n-butanol-partitioned fractions from the crude extract and 6 bioactivity-guided isolated compounds including two new diarylheptanoid from the fractions were assayed for microfilaricidal, macrofilaricidal and female worm sterilizing activity using the lymphatic filariid Brugia malayi in in vitro and in vivo systems. In vitro, the crude methanolic extract exerted better microfilaricidal (LC100: 15.63μg/ml, IC50: 6.00μg/ml) than macrofilaricidal (LC100: >250; IC50: 88μg/ml) activity whereas chloroform and n-butanol fractions were more macrofilaricidal (LC100: 125 and 31.25μg/ml; IC50: 13.14 and 11.84, respectively) than microfilaricidal (LC100: 250-500μg/ml, IC50: 44.16μg/ml). In addition, n-butanol fraction also caused 74% inhibition in MTT reduction potential of the adult worms. In vivo (doses: crude: 100-200mg/kg; fractions: 100mg/kg, i.p.×5 days) the chloroform fraction exerted >50% macrofilaricidal activity whereas methanolic extract and n-butanol fraction produced 38-40% macrofilaricidal action along with some female sterilizing efficacy. Of the 5 diarylheptanoid compounds isolated, alnus dimer, and (5S)-5-hydroxy-1-(4-hydroxyphenyl)-7-(3,4-dihydroxyphenyl)-3-heptanone were found to show the most potent with both macrofilaricidal (LC100: 15.63μg/ml, IC50: 6.57-10.31μg/ml) and microfilaricidal (LC100: 31.25-62.5μg/ml, IC50: 11.05-22.10μg/ml) activity in vitro. These findings indicate that the active diarylheptanoid compounds may provide valuable lead for design and development of new antifilarial agent(s).

Flavonoid naringenin: a potential immunomodulator for Chlamydia trachomatis inflammation

Chlamydia trachomatis, the agent of bacterial sexually transmitted infections, can manifest itself as either acute cervicitis, pelvic inflammatory disease, or a chronic asymptomatic infection. Inflammation induced by C. trachomatis contributes greatly to the pathogenesis of disease. Here we evaluated the anti-inflammatory capacity of naringenin, a polyphenolic compound, to modulate inflammatory mediators produced by mouse J774 macrophages infected with live C. trachomatis. Infected macrophages produced a broad spectrum of inflammatory cytokines (GM-CSF, TNF, IL-1β, IL-1α, IL-6, IL-12p70, and IL-10) and chemokines (CCL4, CCL5, CXCL1, CXCL5, and CXCL10) which were downregulated by naringenin in a dose-dependent manner. Enhanced protein and mRNA gene transcript expressions of TLR2 and TLR4 in addition to the CD86 costimulatory molecule on infected macrophages were modulated by naringenin. Pathway-specific inhibition studies disclosed that p38 mitogen-activated-protein kinase (MAPK) is involved in the production of inflammatory mediators by infected macrophages. Notably, naringenin inhibited the ability of C. trachomatis to phosphorylate p38 in macrophages, suggesting a potential mechanism of its attenuation of concomitantly produced inflammatory mediators. Our data demonstrates that naringenin is an immunomodulator of inflammation triggered by C. trachomatis, which possibly may be mediated upstream by modulation of TLR2, TLR4, and CD86 receptors on infected macrophages and downstream via the p38 MAPK pathway.

Cytotoxic evaluation of Melia azedarach in comparison with, Azadirachta indica and its phytochemical investigation

BACKGROUND

Melia azedarach L. is an important medicinal plant that is used for variety of ailments in Iranian traditional medicine. Azadirachta indica A. Juss is its allied species and possesses similar properties and effects. The present study was undertaken to investigate anticancer activity of these M. azedarach in comparison with A. indica on cancer cell lines and also to evaluate their safety in humans by testing them on normal cell line. The study also aimed to determine the active components that are responsible for medicinal effects of M. azedarach in traditional usages.

METHODS

In this study, the cytotoxic activity of crude extracts from M. azedarach and A. indica leaves, pulps and seeds as well as three main fractions of their leaf extracts were assayed against HT-29, A-549, MCF-7 and HepG-2 and MDBK cell lines. MTT assay was used to evaluate their cytotoxic activities. Methanol leaf fraction of M. azedarach as the safest leaf fraction in terms of cytotoxicity was subjected for phytochemical study.

RESULTS

Results of the present study indicated that seed kernel extract of M. azedarach had the highest cytotoxic activity and selectivity to cancer cell lines (IC50 range of 8.18- 60.10 μg mL-1). In contrast to crude seed extract of A. indica, crude pulp and crude leaf extracts of this plant showed remarkably stronger anti-prolifrative activity (IC50 ranges of 83.45 - 212.16 μg mL-1 and 34.11- 95.51 μg mL-1 respectively) than those of M. azedarach (all IC50 values of both plants > 650 μg mL-1). The phytochemical analysis led to the isolation of four flavonol 3-O-glycosides including rutin, kaempferol-3-O-robinobioside, kaempferol-3-O-rutinoside and isoquercetin along with a purin nucleoside, β-adenosine.

CONCLUSIONS

The anti-prolifrative potentials of extracts from different parts of M. azedarach and A. indica were determined. By comparison, methanol leaf fraction of M. azedarach seems to be safer in terms of cytotoxicity. Our study shows that flavonols are abundant in the leaves of M. azedarach and these compounds seem to be responsible for many of medicinal effects exploited in the traditional uses.

Antifilarial diarylheptanoids from Alnus nepalensis leaves growing in high altitude areas of Uttarakhand, India

Lymphatic filariasis continues to be a major health problem in tropical and subtropical countries. A macrofilaricidal agent capable of eliminating adult filarial parasites is urgently needed. Platyphyllenone (A), alusenone (B), hirustenone (C) and hirsutanonol (D) are important biologically active diarylheptanoids present in Alnus nepalensis. In the present study, we report the antifilarial activity in diarylheptanoids isolated from the leaves of A. nepalensis. Out of four compounds (A-D) tested in vitro one has shown promising anti-filarial activity both in vitro and in vivo studies. This is the first ever report on antifilarial efficacy of a compound of the plant and warrants further studies around this scaffold. In addition, a sensitive, selective and robust densitometric high-performance thin-layer chromatographic method was developed and validated for the above four biomarker compounds. The separation was performed on silica gel 60F(254) high-performance thin layer chromatography plates using chloroform:methanol (9:1, v/v) as mobile phase. The quantitation of marker compounds was carried out using densitometric reflection/absorption mode at 600 nm after post-chromatographic derivatization using vanillin-sulfuric acid reagent. The method was validated for peak purity, precision, robustness, limit of detection (LOD) and quantitation (LOQ) etc., as per the International Conference on Harmonization (ICH) guidelines.

Anthelmintic effect of plant extracts containing condensed and hydrolyzable tannins on Caenorhabditis elegans, and their antioxidant capacity

Although tannin-rich forages are known to increase protein uptake and to reduce gastrointestinal nematode infections in grazing ruminants, most published research involves forages with condensed tannins (CT), while published literature lacks information on the anthelmintic capacity, nutritional benefits, and antioxidant capacity of alternative forages containing hydrolyzable tannins (HT). We evaluated the anthelmintic activity and the antioxidant capacity of plant extracts containing either mostly CT, mostly HT, or both CT and HT. Extracts were prepared with 70% acetone, lyophilized, redissolved to doses ranging from 1.0mg/mL to 25mg/mL, and tested against adult Caenorhabditis elegans as a test model. The extract concentrations that killed 50% (LC(50)) or 90% (LC(90)) of the nematodes in 24h were determined and compared to the veterinary anthelmintic levamisole (8 mg/mL). Extracts were quantified for CT by the acid butanol assay, for HT (based on gallic acid and ellagic acid) by high-performance liquid chromatography (HPLC) and total phenolics, and for their antioxidant activity by the oxygen radical absorbance capacity (ORAC) assay. Extracts with mostly CT were Lespedeza cuneata, Salix X sepulcralis, and Robinia pseudoacacia. Extracts rich in HT were Acer rubrum, Rosa multiflora, and Quercus alba, while Rhus typhina had both HT and CT. The extracts with the lowest LC(50) and LC(90) concentrations, respectively, in the C. elegans assay were Q. alba (0.75 and 1.06 mg/mL), R. typhina collected in 2007 (0.65 and 2.74 mg/mL), A. rubrum (1.03 and 5.54 mg/mL), and R. multiflora (2.14 and 8.70 mg/mL). At the doses of 20 and 25mg/mL, HT-rich, or both CT- and HT-rich, extracts were significantly more lethal to adult C. elegans than extracts containing only CT. All extracts were high in antioxidant capacity, with ORAC values ranging from 1800 μmoles to 4651 μmoles of trolox equivalents/g, but ORAC did not correlate with anthelmintic activity. The total phenolics test had a positive and highly significant (r=0.826, p ≤ 0.01) correlation with total hydrolyzable tannins. Plants used in this research are naturalized to the Appalachian edaphoclimatic conditions, but occur in temperate climate areas worldwide. They represent a rich, renewable, and unexplored source of tannins and antioxidants for grazing ruminants, whereas conventional CT-rich forages, such as L. cuneata, may be hard to establish and adapt to areas with temperate climate. Due to their high in vitro anthelmintic activity, antioxidant capacity, and their adaptability to non-arable lands, Q. alba, R. typhina, A. rubrum, and R. multiflora have a high potential to improve the health of grazing animals and must have their anthelmintic effects confirmed in vivo in both sheep and goats.

In vitro and in vivo antifilarial activity evaluation of 3,6-epoxy [1,5]dioxocines: a new class of antifilarial agents

A series of 3,6-epoxy [1,5]dioxocines were synthesized and evaluated for their antifilarial activity against adult parasites of human lymphatic filarial parasite Brugia malayi (sub-periodic strain) in vitro. Out of these, six compounds (4a-f) possessed improved in vitro anti-filarial activity and examples 4d and 4f were also found to be active in the in vivo experiments. These results demonstrate that 3,6-epoxy [1,5]dioxocines exhibits potent antifilarial activity and might be developed into a new class of antifilarial drug.

A potential inhibitor of rat aortic vascular smooth muscle cell proliferation from the pollen of Typha angustata

By various chromatographic methods, three flavonoids, (2S)-naringenin (1), isorhamnetin 3-O-(2-O-α-L-rhamnopyranosyl) β-D-glucopyranoside (2), typhaneoside (3), and two sterol glycosides, β-sitosterol-3-O-(6-octadecanoyl) β-D-glucopyranoside (4) and β-sitosterol-3-O-(6-octadeca-9Z,12Z-dienoyl) β-D-glucopyranoside (5), were isolated from the pollen of Typha angustata. Their structures were determined on the basis of spectroscopic analyses. The flavonoids (1-3) were evaluated for their effects on the viability and proliferation of rat aortic smooth muscle cells. (2S)-naringenin (1) significantly inhibited cell proliferation in a dose-dependent manner without cytotoxic at concentrations of 30, and 50 μM; it reduced the number of cells following PDGF-BB treatment to 1.83 ± 0.30 × 10(4) and 2.20 ± 0.60 × 10(4) cells/well, respectively. These findings suggest that (2S)-naringenin has antiproliferative effects on aortic smooth muscle cells.