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

Bisbenzylisoquinoline Alkaloids of Cissampelos Sympodialis With in Vitro Antiviral Activity Against Zika Virus

In search of new antiviral compounds against Zika virus we conducted a bioassay-guided fractionation of bisbenzyilisoquinoline alkaloids isolated from Cissampelos sympodialis (Menispermaceae), a medicinal plant species endemic to Brazil. Six subfractions were obtained from a tertiary alkaloidal fraction of the rhizomes (TAFrz) using preparative high-performance liquid chromatography. All the subfractions were tested against Zika virus-infected Vero cells as the cellular model to evaluate cytotoxicity and antiviral effective concentrations. The results showed that three of the six TAFrz subfractions tested were active. The most active ones were the subfraction 6 (that consisted of the alkaloids methylwarifteine and warifteine present as a mixture at a ratio of 8.8:1.2 respectively) and the subfraction 5, that was later identified as warifteine, the major tertiary alkaloid of this species. Warifteine was able to significantly reduce virus titer in Zika virus-infected Vero cells with an IC₅₀ of 2.2 μg/ml and this effect was selective (selectivity index, SI = 68.3). Subfraction 6 had an IC₅₀ = 3.5 μg/ml and was more cytotoxic than pure warifteine, with SI = 6.14. Fraction 5 and fraction 6 were more potent in decreasing the viral titer of Zika virus-infected Vero cells than 6-methylmercaptopurine riboside (IC₅₀ = 24.5 μg/ml and SI = 11.9), a mercaptopurine riboside with ZIKV antiviral activity used as a positive control. Our data demonstrate that alkaloids of the bisbenzylisoquinoline type may be explored as new antiviral agents or as an useful pharmacophore for investigating ZIKV antiviral activity.

The Search for Putative Hits in Combating Leishmaniasis: The Contributions of Natural Products Over the Last Decade

Despite advancements in the areas of omics and chemoinformatics, potent novel biotherapeutic molecules with new modes of actions are needed for leishmaniasis. The socioeconomic burden of leishmaniasis remains alarming in endemic regions. Currently, reports from existing endemic areas such as Nepal, Iran, Brazil, India, Sudan and Afghanistan, as well as newly affected countries such as Peru, Bolivia and Somalia indicate concerns of chemoresistance to the classical antimonial treatment. As a result, effective antileishmanial agents which are safe and affordable are urgently needed. Natural products from both flora and fauna have contributed immensely to chemotherapeutics and serve as vital sources of new chemical agents. This review focuses on a systematic cross-sectional view of all characterized anti-leishmanial compounds from natural sources over the last decade. Furthermore, IC50/EC50, cytotoxicity and suggested mechanisms of action of some of these natural products are provided. The natural product classification includes alkaloids, terpenes, terpenoids, and phenolics. The plethora of reported mechanisms involve calcium channel inhibition, immunomodulation and apoptosis. Making available enriched data pertaining to bioactivity and mechanisms of natural products complement current efforts geared towards unraveling potent leishmanicides of therapeutic relevance.

Emerging therapeutic targets for treatment of leishmaniasis

INTRODUCTION

Parasitic diseases that pose a threat to human life include leishmaniasis - caused by protozoan parasite Leishmania species. Existing drugs have limitations due to deleterious side effects like teratogenicity, high cost and drug resistance. This calls for the need to have an insight into therapeutic aspects of disease. Areas covered: We have identified different drug targets via. molecular, imuunological, metabolic as well as by system biology approaches. We bring these promising drug targets into light so that they can be explored to their maximum. In an effort to bridge the gaps between existing knowledge and prospects of drug discovery, we have compiled interesting studies on drug targets, thereby paving the way for establishment of better therapeutic aspects. Expert opinion: Advancements in technology shed light on many unexplored pathways. Further probing of well established pathways led to the discovery of new drug targets. This review is a comprehensive report on current and emerging drug targets, with emphasis on several metabolic targets, organellar biochemistry, salvage pathways, epigenetics, kinome and more. Identification of new targets can contribute significantly towards strengthening the pipeline for disease elimination.

Ultrastructural analysis of Leishmania infantum chagasi promastigotes forms treated in vitro with usnic acid

Leishmaniasis is considered by the World Health Organization as one of the infectious parasitic diseases endemic of great relevance and a global public health problem. Pentavalent antimonials used for treatment of this disease are limited and new phytochemicals emerge as an alternative to existing treatments, due to the low toxicity and cost reduction. Usnic acid is uniquely found in lichens and is especially abundant in genera such as Alectoria, Cladonia, Evernia, Lecanora, Ramalina, and Usnea. Usnic acid has been shown to exhibit antiviral, antiprotozoal, antiproliferative, anti-inflammatory, and analgesic activity. The aim of this study was to evaluate the antileishmanial activity of usnic acid on Leishmania infantum chagasi promastigotes and the occurrence of drug-induced ultrastructural damage in the parasite. Usnic acid was effective against the promastigote forms (IC₅₀ = 18.30 ± 2.00 µg/mL). Structural and ultrastructural aspects of parasite were analyzed. Morphological alterations were observed as blebs in cell membrane and shapes given off, increasing the number of cytoplasmic vacuoles, and cellular and mitochondrial swelling, with loss of cell polarity. We concluded that the usnic acid presented antileishmanial activity against promastigote forms of Leishmania infantum chagasi and structural and ultrastructural analysis reinforces its cytotoxicity. Further, in vitro studies are warranted to further evaluate this potential.

From arrow poison to herbal medicine--the ethnobotanical, phytochemical and pharmacological significance of Cissampelos (Menispermaceae)

ETHNOPHARMACOLOGICAL RELEVANCE

Cissampelos species have a rich history of traditional use, being used for both therapeutic and toxic properties. It is traditionally applied therapeutically in a diverse range of conditions and diseases including asthma, cough, fever, arthritis, obesity, dysentery, snakebite, jaundice and heart, blood pressure and skin-related problems. Conversely, it was traditionally included in preparations of curare applied as arrow poison during hunting to cause death of animals by asphyxiation. This review unites the ethnobotanical knowledge on Cissampelos with the phytochemistry and pharmacological activity which has been explored thus far. In addition, it identifies knowledge gaps and suggests further research opportunities.

METHODS

The available electronic literature on the genus Cissampelos was collected using database searches including Scopus, Google Scholar, Pubmed, Web of Science, etc. The searches were limited to peer-reviewed English journals with the exception of books and a few articles in foreign languages which were included.

RESULTS

The literature revealed that pharmacological activity including analgesic and antipyretic, anti-inflammatory, anti-allergic, bronchodilator, immunomodulatory, memory-enhancing, antidepressant, neuroprotective, antimicrobial, antimalarial, antiparasitic, anti-ulcer, anticancer, anti-oxidant, cardiovascular, muscle-relaxant, hepatoprotective, antidiabetic, antidiarrhoeal, antifertility, and antivenom activity have been confirmed in vitro and/or in vivo for various Cissampelos species. Cissampelos pareira L. and Cissampelos sympodialis Eichl. are the most explored species of this genus and the smallest number of studies have been conducted on Cissampelos laxiflora Moldenke and Cissampelos tenuipes Engl. Many alkaloids isolated from Cissampelos such as warifteine, methylwarifteine, berberine, hayatin and hayatidin showed promising anti-allergic, immunosuppressive, antidepressant, anticancer, vasodilatory and muscle-relaxant activities.

CONCLUSION

The plants of this genus are used in traditional medicine for the treatment of various ailments. These plants are a rich source of bioactive bisbenzylisoquinoline and aporphine alkaloids together with other minor constituents. Although these plants are reputable and revered in various traditional medicine systems, many have not yet been screened chemically or pharmacologically and so there is a vast amount of research still to be conducted to validate their traditional use.