The effect of bisbenzylisoquinoline alkaloids on Trypanosoma cruzi infections in mice

Effects of Verapamil and Two Bisbenzylisoquinolines, Curine and Guattegaumerine Extracted from Isolona hexaloba, on the Inhibition of ABC Transporters from Pseudomonas aeruginosa

The biological effects of alkaloids, curine, guattegaumerine, and verapamil, on Pseudomonas aeruginosa were investigated. These molecules did not inhibit P. aeruginosa growth but increased the sensitivity of this bacterium to carbenicillin, novobiocin, and erythromycin. The results of another study indicate that curine and guattegaumerine were competitors of verapamil and acted as inhibitors of eukaryotic ABCB1 efflux pump. A BLAST-P carried out between a bacterial MDR transporter LmrA from Lactococcus lactis, a human MDR1/P-glycoprotein (ABCB1), and ABC proteins of P.aeruginosa highlighted five potential candidates that have this bacterium. A study on the sensitivity to carbenicillin in the presence of verapamil allowed us to identify the product of gene PA1113 as the ABC transporter involved in the influx of carbenicillin. Similarly, novobiocin transport performed in the presence of verapamil and a docking analysis highlighted protein MsbA (Lipid A flippase, gene PA4997) as a potential candidate in novobiocin efflux. MsbA has previously been identified as a multidrug transporter in E. coli, and as P. aeruginosa MsbA presented 76% identity with E. coli MsbA, it is possible that novobiocin efflux involves this ABC transporter, accounting for about 30% of the bacterium resistance to this antibiotic.

Effects of Two Natural Bisbenzylisoquinolines, Curine and Guattegaumerine, Extracted from Isolona hexaloba on Rhodamine Efflux by Abcb1b from Rat Glycocholic-Acid-Resistant Hepatocarcinoma Cells

To develop new therapeutic molecules, it is essential to understand the biological effects and targets of clinically relevant compounds. In this article, we describe the extraction and characterization of two alkaloids from the roots of Isolona hexaloba—curine and guattegaumerine. The effect of these alkaloids on the multidrug efflux pump ABCB1 (MDR1/P-Glycoprotein) and their antiproliferative properties were studied. Compared to verapamil, a widely used inhibitor of P-gp, curine and guattegaumerine were found to be weak inhibitors of MDR1/P-Glycoprotein. The highest inhibition of efflux produced by verapamil disappeared in the presence of curine or guattegaumerine as competitors, and the most pronounced effect was achieved with curine. Altogether, this work has provided new insights into the biological effects of these alkaloids on the rat Mdr1b P-gp efflux mechanism and would be beneficial in the design of potent P-gp inhibitors.

In vitro antiprotozoal activity and cytotoxicity of extracts and fractions from the leaves, root bark and stem bark of Isolona hexaloba

ETHNOPHARMACOLOGICAL RELEVANCE

Isolona hexaloba (Pierre) Engl. and Diels (Annonaceae) is traditionally used in D.R. Congo against parasitic diseases including malaria.

MATERIALS AND METHODS

Two crude aqueous extracts, 3 crude methanol extracts and 3 crude 80% ethanol extracts from the leaves, root bark and stem bark together with 12 subfractions from the crude 80% ethanol extracts were evaluated in vitro for their antiprotozoal activity against Trypanosoma brucei brucei, T. cruzi, Leishmania infantum and the chloroquine and pyrimethamine resistant K1 strain of Plasmodium falciparum. Their cytotoxic effects against MRC-5 cell lines were also assessed.

RESULTS

Results indicated that the most pronounced activities against T. b. brucei were recorded for the crude methanol extracts of root bark (IC50=1.97 µg/ml; SI>32.49) and leaves (IC50=2.65 µg/ml; SI>24.15). Three samples displayed good activity against T. cruzi: the 80% methanol extract of leaves (IC50=8.33 µg/ml; SI>3.92), its petroleum ether fraction (IC50=8.50 µg/ml; SI=2.52) and the crude aqueous extract of the stem bark (IC50=9.31 µg/ml; SI=3.46). The crude aqueous extract of the leaves exhibited a pronounced and selective activity against L. infantum (IC50=2.00 µg/ml; SI>32). The crude methanol extract of leaves (IC50=6.35 µg/ml; SI>10.10) and the 2 dichloromethane soluble fractions of the 80% ethanol extracts from root bark (IC50=6.96 µg/ml; SI=6.1) and stem bark (IC50=8 µg/ml; SI>8.00) showed good activity and selectivity against L. infantum. The most active samples against Plasmodium falciparum K1 were the leaves crude 80% ethanol extract (0.92 µg/ml) and its fractions: alkaline aqueous (IC50=0.27 µg/ml), 90% methanol (0.90 µg/ml) and dichloromethane (1.04 µg/ml), respectively, with promising selectivity indexes of 35<SI<237. None of all the tested crude extracts and fractions was found to be cytotoxic against MRC-5 cell lines except the petroleum ether soluble fraction from the leaves which displayed a cytotoxic effect (CC50=21.40 µg/ml).

CONCLUSION

Overall, extracts of I. hexaloba tested here, showed good results concerning parasitic infections such as Chagas' disease, leishmaniasis, malaria and/or sleeping sickness without considerable toxicity. The 80% ethanol extracts from leaves and their fractions turned out to be of special interest as they were the most useful in the treatment of malaria.

Ethnobotany, phytochemistry and pharmacology of Stephania rotunda Lour

ETHNOPHARMACOLOGICAL RELEVANCE

Stephania rotunda Lour. (Menispermaceae) is an important traditional medicinal plant that is grown in Southeast Asia. The stems, leaves, and tubers have been used in the Cambodian, Lao, Indian and Vietnamese folk medicine systems for years to treat a wide range of ailments, including asthma, headache, fever, and diarrhoea.

AIM OF THE REVIEW

To provide an up-to-date, comprehensive overview and analysis of the ethnobotany, phytochemistry, and pharmacology of Stephania rotunda for its potential benefits in human health, as well as to assess the scientific evidence of traditional use and provide a basis for future research directions.

MATERIAL AND METHODS

Peer-reviewed articles on Stephania rotunda were acquired via an electronic search of the major scientific databases (Pubmed, Google Scholar, and ScienceDirect). Data were collected from scientific journals, theses, and books.

RESULTS

The traditional uses of Stephania rotunda were recorded in countries throughout Southeast Asia (Cambodia, Vietnam, Laos, and India). Different parts of Stephania rotunda were used in traditional medicine to treat about twenty health disorders. Phytochemical analyses identified forty alkaloids. The roots primarily contain l-tetrahydropalmatine (l-THP), whereas the tubers contain cepharanthine and xylopinine. Furthermore, the chemical composition differs from one region to another and according to the harvest period. The alkaloids exhibited approximately ten different pharmacological activities. The main pharmacological activities of Stephania rotunda alkaloids are antiplasmodial, anticancer, and immunomodulatory effects. Sinomenine, cepharanthine, and l-stepholidine are the most promising components and have been tested in humans. The pharmacokinetic parameters have been studied for seven compounds, including the three most promising compounds. The toxicity has been evaluated for liriodenine, roemerine, cycleanine, l-tetrahydropalmatine, and oxostephanine.

CONCLUSION

Stephania rotunda is traditionally used for the treatment of a wide range of ailments. Pharmacological investigations have validated different uses of Stephania rotunda in folk medicine. The present review highlights the three most promising compounds of Stephania rotunda, which could constitute potential leads in various medicinal fields, including malaria and cancer.

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.

Screening of African medicinal plants for antimicrobial and enzyme inhibitory activity

Seven plant species, belonging to different families, were collected in the eastern part of the Republic of Congo (Kivu) based on ethnopharmacological information. Their dichloromethane and methanolic extracts were tested for biological activity. Five of the seven collected plants exhibited antiplasmodial activity with IC(50) values ranging from 1.1 to 9.8 microg/ml. The methanolic extract of Cissampelos mucronata was the most active one showing activity against chloroquine sensitive (D6) and chloroquine resistant (W2) Plasmodium falciparum strains with IC(50) values of 1.5 and 1.1 microg/ml, respectively. Additionally, this extract significantly inhibited the enzyme tyrosine kinase p56(lck) (TK). The dichloromethane extract of Amorphophallus bequaertii inhibited the growth of Mycobacterium tuberculosis with a MIC of 100 microg/ml and the methanolic extract of Rubus rigidus inhibited the activity of both enzymes HIV1-reverse transcriptase (HIV1-RT) and TK p56(lck).

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.