Effect of some bisbenzylisoquinoline alkaloids on AmericanLeishmania sp. in BALB/c mice

Phytochemicals and Potential Therapeutic Targets on Toxoplasma gondii Parasite

Identification of drug target in protozoan T. gondii is an important step in the development of chemotherapeutic agents. Likewise, exploring phytochemical compounds effective against the parasite can lead to the development of new drug agent that can be useful for prophylaxis and treatment of toxoplasmosis. In this review, we searched for the relevant literature on the herbs that were tested against T. gondii either in vitro or in vivo, as well as different phytochemicals and their potential activities on T. gondii. Potential activities of major phytochemicals, such as alkaloid, flavonoid, terpenoids and tannins on various target sites on T. gondii as well as other related parasites was discussed. It is believed that the phytochemicals from natural sources are potential drug candidates for the treatment of toxoplasmosis with little or no toxicity to humans.

Northalrugosidine is a bisbenzyltetrahydroisoquinoline alkaloid from Thalictrum alpinum with in vivo antileishmanial activity

Screening of a plant-derived natural product library led to the observation of in vitro antileishmanial activity by three bisbenzyltetrahydroisoquinoline alkaloids (1-3) that were purified previously from Thalictrum alpinum. A spectroscopic study of the active compounds was conducted to confirm their identities. Of the compounds tested, northalrugosidine (1) showed the most potent in vitro activity against Leishmania donovani promastigotes (0.28 μM) and the highest selectivity (29.3-fold) versus its general cytotoxicity against HT-29 human colon adenocarcinoma cells. Northalrugosidine was tested in vivo using a murine model of visceral leishmaniasis, resulting in the observation of a dose-dependent reduction of the parasitic burden in the liver and spleen without overt toxicity effects at 2.8, 5.6, and 11.1 mg/kg per animal when administered intravenously. This represents the first report of a bisbenzyltetrahydroisoquinoline alkaloid with in vivo efficacy against visceral leishmaniasis.

Natural product based leads to fight against leishmaniasis

The growing incidence of parasitic resistance against generic pentavalent antimonials, specifically for visceral disease in Indian subcontinent, is a serious issue in Leishmania control. Notwithstanding the two treatment alternatives, that is amphotericin B and miltefosine are being effectively used but their high cost and therapeutic complications limit their use in endemic areas. In the absence of a vaccine candidate, identification, and characterization of novel drugs and targets is a major requirement of leishmanial research. This review describes current drug regimens, putative drug targets, numerous natural products that have shown promising antileishmanial activity alongwith some key issues and strategies for future research to control leishmaniasis worldwide.

Interactions of antiparasitic alkaloids with Leishmania protein targets: a molecular docking analysis

Background: Leishmaniasis is a collection of chronic diseases caused by protozoa of the genus Leishmania. Current antileishmanial chemotherapeutics have demonstrated adverse side effects and therefore R&D into new safer alternative treatments are needed. Methods: A molecular docking analysis has been carried out to assess possible Leishmania biochemical targets of antiparasitic alkaloids. A total of 209 antiparasitic alkaloids were docked with 24 Leishmania protein targets. Results: The strongest docking alkaloid ligands were flinderoles A and B and juliflorine with Leishmania major methionyl-tRNA synthetase; juliflorine, juliprosine, prosopilosidine and prosopilosine with Leishmania mexicana glycerol-3-phosphate dehydrogenase; and ancistrogriffithine A with L. major N-myristoyl transferase. Conclusion: This molecular docking study has provided evidence for what classes and structural types of alkaloids may be targeting specific Leishmania protein targets.

Antileishmanial activity of warifteine: a bisbenzylisoquinoline alkaloid isolated from Cissampelos sympodialis Eichl. (Menispermaceae)

Leishmania (L.) chagasi is the etiological agent of visceral leishmaniasis, an important endemic zoonosis in the American continent, as well as in many other countries in Asia, Africa, and Mediterranean Europe. The treatment is difficult due to the high toxicity of the available drugs, high costs, and emergence of resistance in the parasites. Therefore, there is an urgent need for new leishmanicidal agents. The bisbenzylisoquinoline alkaloids have been related to antibacterial, antiprotozoal, and antifungal activities. The aim of this study was to evaluate the growth inhibitory activity of warifteine (bisbenzylisoquinoline alkaloid) against L. chagasi promastigotes in axenic cultures and the occurrence of drug-induced ultrastructural changes in the parasite. This bisbenzylisoquinoline alkaloid was isolated from the leaves and roots of Cissampelos sympodialis Eichl. (Menispermaceae), a plant commonly used for the treatment of various diseases in Brazilian folk medicine. Using the purified warifteine, the 50% inhibitory concentration (IC₅₀) was determined at 0.08 mg/mL after 72 h in culture, inducing significant changes in the parasite morphology, like aberrant multisepted forms and blebs in the plasma membrane. In conclusion, warifteine represents an attractive candidate for future pharmacological studies aiming new leishmanicidal drugs.

In vitro antiprotozoal and cytotoxic activity of 33 ethonopharmacologically selected medicinal plants from Democratic Republic of Congo

ETHNOPHARMACOLOGICAL RELEVANCE

The antiprotozoal and cytotoxic activity of the aqueous extracts from 33 medicinal plants, used by traditional healers for the treatment of various parasitic diseases and collected after an ethnopharmacological inventory conducted in the Bolongo area, Bandundu province in DR Congo, was evaluated.

MATERIALS AND METHODS

Decoctions were prepared, lyophilized and evaluated for in vitro antiprotozoal activity against Trypanosoma b. brucei, Trypanosoma cruzi, Leishmania infantum, and the chloroquine- and pyrimethamine-resistant K1 strain of Plasmodium falciparum. Cytotoxicity against MRC-5 cells was included to assess selectivity of activity.

RESULTS

Most of the tested extracts exhibited pronounced (IC(50)≤5μg/ml) or good (5<IC(50)≤10μg/ml) antiprotozoal activity against one or more of the selected protozoa. A total of 19 plant extracts inhibited Trypanosoma b. brucei, especially the extract from Isolona hexaloba stem bark (IC(50)=1.95μg/ml, SI=16.5); 8 plant extracts were active against Trypanosoma cruzi, the extracts from Enanatia chlorantha stem bark and Quassia africana root bark being the most active with IC(50) values of 1.87 and 1.88μg/ml, respectively (SI=3.0 and 3.3, respectively); 8 plant extracts showed activity against Leishmania infantum, with extracts from Napoleona vogelii stem bark and Quassia africana root bark as the most active with IC(50) values of 5.66 and 5.04μg/ml (SI=11.3 and 1.2). Finally, 9 plant extracts inhibited Plasmodium falciparum K1 with the extracts from Quassia africana (root bark and stem bark) being the most active ones with IC(50) values of 0.46 and 1.27μg/ml (SI=13.7 and 13.6). Extracts from Enantia chlorantha stem bark, Piptadeniastrum africanum stem bark and Quassia africana root bark were cytotoxic for MRC-5 cells (CC(50)<10μg/ml).

CONCLUSIONS

These results can partly support and justify the traditional use of some of these plant species for the treatment of parasitic diseases.

Leishmanicidal effect of Spiranthera odoratíssima (Rutaceae) and its isolated alkaloid skimmianine occurs by a nitric oxide dependent mechanism

Leishmaniasis is one of the neglected diseases. High cost, systemic toxicity, and diminished efficacy due to development of resistance by the parasites has a negative impact on the current treatment options. Thus, the search for a new, effective and safer anti-leishmanial drug becomes of paramount importance. Compounds derived from natural products may be a better and cheaper source in this regard. This study evaluated the in vitro anti-leishmanial activity of Spiranthera odoratíssima (Rutaceae) fractions and isolated compounds, using promastigote and amastigote forms of different Leishmania species. J774 A.1 macrophage was used as the parasite host cell for the in vitro assays. Evaluations of cytoxicity, nitric oxide (NO), interleukin-10 and in silico analysis were carried out. In vitro experiments showed that the fruit hexanic fraction (Fhf) and its alkaloid skimmianine (Skm) have a significant (P<0·001) effect against L. braziliensis. This anti-L. braziliensis activity of Fhf and Skm was due to increased production of NO and attenuation of IL-10 production in the macrophages at concentrations ranging from 1·6 to 40·0 μg/ml. The in silico assay demonstrated significant interaction between Skm and amino acid residues of NOS2. Skm is thus a promising drug candidate for L. braziliensis due to its potent immunomodulatory activity.

Annonaceae: bio-resource for tomorrow's drug discovery

One of the rich sources of lead compounds is the Angiosperms. Many of these lead compounds are useful medicines naturally, whereas others have been used as the basis for synthetic agents. These are potent and effective compounds, which have been obtained from plants, including anti-cancer (cytotoxic) agents, anti-malaria (anti-protozoal) agents, and anti-bacterial agents. Today, the number of plant families that have been extensively studied is relatively very few and the vast majorities have not been studied at all. The Annonaceae is the largest family in the order Magnoliales. It includes tropical trees, bushes, and climbers, which are often used as traditional remedies in Southeast Asia. Members of the Annonaceae have the particularity to elaborate a broad spectrum of natural products that have displayed anti-bacterial, anti-fungal, and anti-protozoal effects and have been used for the treatment of medical conditions, such as skin diseases, intestinal worms, inflammation of the eyes, HIV, and cancer. These special effects and the vast range of variation in potent compounds make the Annonaceae unique from other similar families in the Magnoliales and the Angiosperms in general. This paper attempts to summarize some important information and discusses a series of hypotheses about the effects of Annonaceae compounds.

Drug delivery strategies for therapy of visceral leishmaniasis

IMPORTANCE OF THE FIELD

Visceral leishmaniasis (VL) is the most overwhelming type of leishmaniasis associated with the poverty of developing countries and usually mortal if untreated. Most of the conventionally used dosage forms offer us the shortcomings of toxic side effects and emergence of drug resistance. Several efforts have been made to overcome the barriers involved in the treatment of VL. Colloidal carriers extensively represent the drug delivery systems (DDSs) for intracellular localization of antileishmanial compounds in macrophage-rich organs such as liver, spleen and bone marrow. These DDSs offer superior therapeutic efficacy over the conventional treatment in terms of site-specific drug delivery with reduced side effects. However, after 35 years of research in the field, AmBisome (Amphotericin B liposome for injection, Astellas Pharma US, Inc.) is the only DDS used against the VL.

AREAS COVERED IN THIS REVIEW

A literature search was performed (for drugs and DDSs against VL) on PubMed and through Google.

WHAT THE READER WILL GAIN

This review aims to describe the pathophysiology of VL and its current conventional treatment with special reference to DDSs designed against VL.

TAKE HOME MESSAGE

On reviewing the conventional drugs and DDSs developed against VL, it is concluded that advances in the field of targeted drug delivery can result in more efficient strategies for the therapy of VL.

A review of natural products with antileishmanial activity

Infections caused by protozoa of the genus Leishmania are a major worldwide health problem, with high endemicity in developing countries. The incidence of the disease has increased since the emergence of AIDS. In the absence of a vaccine, there is an urgent need for effective drugs to replace/supplement those in current use. The plant kingdom is undoubtedly valuable as a source of new medicinal agents. The present work constitutes a review of the literature on plant extracts and chemically defined molecules of natural origin showing antileishmanial activity. The review refers to 101 plants, their families, and geographical distribution, the parts utilized, the type of extract and the organism tested. It also includes 288 compounds isolated from higher plants and microorganisms, classified into appropriate chemical groups. Some aspects of recent antileishmanial-activity-directed research on natural products are discussed.

Warifteine and milonine, alkaloids isolated from Cissampelos sympodialis Eichl: cytotoxicity on rat hepatocyte culture and in V79 cells

Two alkaloids were isolated from the leaves of Cissampelos sympodialis; a bisbenzylisoquinoline compound named warifteine and a novel 8,14-dihydromorphinandienone alkaloid named milonine. The cytotoxic effects of these alkaloids were assayed in cultured hepatocytes and V79 fibroblasts. Three independent endpoint assays for cytotoxicity in vitro were used: the nucleic acid content (NAC), tetrazolium reduction (MTT) and neutral red uptake (NRU). Milonine was less toxic than warifteine in both cell cultures. The IC50 values determined in the three different viability assays were around 100 and 400 microM after milonine treatment of V79 cells or hepatocytes. IC50 values ranging from 10 to 35 microM were obtained for warifteine in the viability tests evaluated in V79 cells and hepatocytes. Due to the similar cytotoxic effects detected on V79 cells and hepatocytes, probably warifteine and milonine induced toxic effects independent to the cytochrome P450. This hypothesis was corroborated by the results where Cimetidine (1.0 mM), a traditional cytochrome P450 inhibitor, did not protect the cells from the toxic action of warifteine or milonine. In conclusion, these alkaloids merit further investigations as potential novel pharmacological agents although milonine was less toxic than warifteine in the cells models investigated.

A search for natural bioactive compounds in Bolivia through a multidisciplinary approach. Part V. Evaluation of the antimalarial activity of plants used by the Tacana Indians

One hundred and twenty-five extracts of 122 different plant species traditionally used by the Tacana, a native community living in lowland forest at the base of the last foothills of the Cordillera Oriental of the Bolivian Andes, were screened for antimalarial activity in vitro on Plasmodium falciparum chloroquine resistant (D2) and sensitive strains (F32), and were evaluated in vivo on rodent malaria Plasmodium berghei. Five ethanolic stembark extracts showed marked activity either in vitro or in vivo, and only one of them, Bowdichia virgilioides being traditionally used against malaria, was active in vitro (IC50=1 microg/ml on both strains) and in vivo (51% at 100 mg/kg). Other active extracts were from Caesalpinia pluviosa bark displaying activity in vitro against chloroquine resistant strain (IC50 8.3 microg/ml), traditionally used against dysentery; two Lauraceae bark extracts, Nectandra aff. hihua and Licaria canella respectively used for construction purposes and against stomach ache, both displaying activity in vitro against P. falciparum sensible and resistant strains (IC50 around 4 microg/ml); finally, the bark of a strongly aromatic Burseraceae, Protium glabrescens exuding an anti-inflammatory and analgesic resin, was active in vivo only (61% at 100 mg/kg). Results are discussed in relation with Tacana traditional medicine.

Bisbenzylisoquinoline alkaloids from Guatteria boliviana (Annonaceae)

Together with known alkaloids, five new bisbenzylisoquinoline derivatives were isolated from the stem bark of Guatteria boliviana (Annonaceae), puertogalines-A 1 and -B 2, (+)-guatteboline 3, philogaline 4 and (-)-antioquine 5. Their structures were elucidated by spectrometric methods and their antiparasitic activity was evaluated in vitro on Leishmania sp., Trypanosoma cruzi and Plasmodium falciparum. Their cytotoxic activity was also measured in KB cell line.

Efficacy of the bisbenzylisoquinoline alkaloids in acute and chronic Trypanosoma cruzi murine model

We have shown previously that daphnoline and cepharanthine are active against Trypanosoma cruzi and inhibited trypanothione reductase. The effects of oral treatments with daphnoline, cepharanthine and benznidazole were examined in Balb/c mice infected with T. cruzi acutely and chronically. In acute infections, parasitaemia was significantly reduced in the daphnoline-treated mice compared with controls and benznidazole-treated mice. The parasitological cure rate was increased in mice treated with daphnoline. Fifty days after infection, the negative serological response in both models was significantly different for the three tested drugs. Daphnoline showed the highest negative serological rate (48%). In chronically infected mice treated with daphnoline, we were unable to detect parasites in 70% of mice. The results obtained of oral treatment of daphnoline suggest that this bisbenzylisoquinoline may be useful in the treatment of acute and chronic Chagas' disease. This was not seen with cepharanthine, an excellent trypanothione reductase inhibitor.

Leishmanicidal and trypanocidal activities of Bolivian medicinal plants

Cutaneous and mucocutaneous leishmaniasis are endemic diseases in South America, especially in the subandean areas of the humid lowlands of Bolivia. Fourteen plants used topically in folk medicine to treat cutaneous leishmaniasis were collected in the tropical regions of colonization and in the rain forest occupied by Chimane Indians. Three of four plants used by the Chimane Indians exhibited an in vitro activity against three species of Leishmania. Two of ten plants used by the colonists showed an in vitro activity. We have also included results obtained with extracts from 53 Bolivian medicinal plants used for other diseases and from 43 plants collected with basis of chemotaxonomic criteria from all parts of Bolivia. All extracts were also screened in vitro against three strains of Trypanosoma cruzi (Trypanosomatidae), the causative agent of Chagas' disease.