Camille Desgrouas

Differences in anti-malarial activity of 4-aminoalcohol quinoline enantiomers and investigation of the presumed underlying mechanism of action

BackgroundA better anti-malarial efficiency and lower neurotoxicity have been reported for mefloquine (MQ) (+)- enantiomer. However, the importance of stereoselectivity remains poorly understood as the anti-malarial activity of pure enantiomer MQ analogues has never been described. Building on these observations, a series of enantiopure 4-aminoalcohol quinoline derivatives has previously been synthesized to optimize the efficiency and reduce possible adverse effects. Their in vitro activity on Plasmodium falciparum W2 and 3D7 strains is reported here along with their inhibition of β-haematin formation and peroxidative degradation of haemin, two possible mechanisms of action of anti-malarial drugs.ResultsThe (S)-enantiomers of this series of 4-aminoalcohol quinoline derivatives were found to be at least as effective as both chloroquine (CQ) and MQ. The derivative with a 5-carbon side-chain length was the more efficient on both P. falciparum strains. (R )-enantiomers displayed an activity decreased by 2 to 15-fold as compared to their (S) counterparts. The inhibition of β-haematin formation was significantly stronger with all tested compounds than with MQ, irrespective of the stereochemistry. Similarly, the inhibition of haemin peroxidation was significantly higher for both (S) and (R)-enantiomers of derivatives with a side-chain length of five or six carbons than for MQ and CQ.ConclusionsThe prominence of stereochemistry in the anti-malarial activity of 4-aminoalcohol quinoline derivatives is confirmed. The inhibition of β-haematin formation and haemin peroxidation can be put forward as presumed mechanisms of action but do not account for the stereoselectivity of action witnessed in vitro.

Efficacy of Proveblue®, Methylene Blue, in an Experimental Cerebral Malaria Murine Model

ABSTRACT Although 100% of untreated mice infected with Plasmodium berghei died with specific signs of cerebral malaria and 100% of mice treated with 3 mg/kg dihydroartemisinin, the active metabolite of artesunate, which is used as the first-line treatment for severe malaria, also died but showed no specific signs of cerebral malaria, 78% of mice treated with 10 mg/kg Proveblue (methylene blue) and 78% of mice treated with a combination of 3 mg dihydroartemisinin and 10 mg/kg Proveblue survived and showed no specific signs of cerebral malaria or detectable parasites.

A Heterozygous ZMPSTE24 Mutation Associated with Severe Metabolic Syndrome, Ectopic Fat Accumulation, and Dilated Cardiomyopathy

ZMPSTE24 encodes the only metalloprotease, which transforms prelamin into mature lamin A. Up to now, mutations in ZMPSTE24 have been linked to Restrictive Dermopathy (RD), Progeria or Mandibulo-Acral Dysplasia (MAD). We report here the phenotype of a patient referred for severe metabolic syndrome and cardiomyopathy, carrying a mutation in ZMPSTE24. The patient presented with a partial lipodystrophic syndrome associating hypertriglyceridemia, early onset type 2 diabetes, and android obesity with truncal and abdominal fat accumulation but without subcutaneous lipoatrophy. Other clinical features included acanthosis nigricans, liver steatosis, dilated cardiomyopathy, and high myocardial and hepatic triglycerides content. Mutated fibroblasts from the patient showed increased nuclear shape abnormalities and premature senescence as demonstrated by a decreased Population Doubling Level, an increased beta-galactosidase activity and a decreased BrdU incorporation rate. Reduced prelamin A expression by siRNA targeted toward LMNA transcripts resulted in decreased nuclear anomalies. We show here that a central obesity without subcutaneous lipoatrophy is associated with a laminopathy due to a heterozygous missense mutation in ZMPSTE24. Given the high prevalence of metabolic syndrome and android obesity in the general population, and in the absence of familial study, the causative link between mutation and phenotype cannot be formally established. Nevertheless, altered lamina architecture observed in mutated fibroblasts are responsible for premature cellular senescence and could contribute to the phenotype observed in this patient.

In vitro and in vivo combination of cepharanthine with anti-malarial drugs

BackgroundStephania rotunda is used by traditional health practitioners in Southeast Asia to treat a wide range of diseases and particularly symptoms related to malaria. Cepharanthine (CEP) is an alkaloid isolated from this plant with potential innovative antiplasmodial activity. The analysis of interactions between antiplasmodial drugs is necessary to develop new drugs combinations to prevent de novo emergence of resistance. The objective of this study was to evaluate the anti-malarial activity of CEP in combination with usual anti-malarial compounds, both in vitro and in vivo.MethodsA fixed ratio method using the isotopic micro test was performed on the chloroquine-resistant plasmodial strain W2 to build isobolograms from eight CEP-based combinations with standard anti-malarial drugs. The efficacy of two combinations was then evaluated in the BALB/c mouse infected with Plasmodium berghei ANKA strain.ResultsIn vitro, efficiency gains were observed when CEP was combined with chloroquine (CQ), lumefantrine (LUM), atovaquone (ATO), piperaquine (PPQ) and particularly monodesethylamodiaquine (MdAQ), whereas an antagonistic interaction was observed with dihydroartemisinin (DHA) and mefloquine (MQ). In vivo, the combination of CEP with CQ or amodiaquine (AQ) improved significantly the survival of mice and extended the delay for parasitic recrudescence.ConclusionAll these observations suggest that CEP could be an interesting lead compound in the development of a combination therapy against 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.

Biologically active carbazole derivatives: focus on oxazinocarbazoles and related compounds

Abstract Four series of carbazole derivatives, including N-substituted-hydroxycarbazoles, oxazinocarbazoles, isoxazolocarbazolequinones, and pyridocarbazolequinones, were studied using diverse biological test methods such as a CE-based assay for CK2 activity measurement, a cytotoxicity assay with IPC-81 cell line, determination of MIC of carbazole derivatives as antibacterial agents, a Plasmodium falciparum susceptibility assay, and an ABCG2-mediated mitoxantrone assay. Two oxazinocarbazoles Ib and Ig showed CK2 inhibition with IC50 = 8.7 and 14.0 µM, respectively. Further chemical syntheses were realized and the 7-isopropyl oxazinocarbazole derivative 2 displayed a stronger activity against CK2 (IC50 = 1.40 µM). Oxazinocarbazoles Ib, Ig, and 2 were then tested against IPC-81 leukemia cells and showed the ability to induce leukemia cell death with IC50 values between 57 and 62 μM. Further investigations were also reported on antibacterial and antiplasmodial activities. No significant inhibitory activity on ABCG2 efflux pump was detected.

Quantitative Analysis of Cepharanthine in Plasma Based on Semiautomatic Microextraction by Packed Sorbent Combined with Liquid Chromatography

The spread of Plasmodium falciparum resistance toward most of the used drugs requires new antimalarial compounds. Taking advantage of the biodiversity, the ethnopharmacological approach opens the way for the discovery and the characterization of potent original molecules. Previous works led to the selection of a bisbenzylisoquinoline, cepharanthine, extracted from Stephania rotunda, which is mainly present in Cambodia. A sensitive and selective liquid chromatography method has been developed for the determination of cepharanthine in mouse plasma. The method involved a semiautomated microextraction by packed sorbent (MEPS) using 4 mg of solid phase silica-C8 sorbent. LC separation was performed on a Kinetex XB-C18 column (2.6 µm) with a mobile phase of acetonitrile containing formic acid and 10 mM ammonium formate buffer pH 3.5. Data were acquired at 282 nm with a diode array detector. The drug/internal standard peak area ratios were linked via linear relationships to plasma concentrations (75–2,000 ng/mL). Precision was below 5% and accuracy was 99.0–102%. Extraction recovery of cepharanthine was 56–58%. The method was successfully used to determine the pharmacokinetic profile of cepharanthine in healthy and Plasmodium berghei infected mice. The infection did not impact pharmacokinetic parameters of cepharanthine.