Preliminary insight into the potential antiplasmodial activity and cytotoxicity of Bufo bufo and Incilius alvarius poison.

The rise and spread of resistant Plasmodium falciparum strains are responsible for an increase in therapeutic failures in many of the regions endemic with malaria. The need for new therapeutic candidates is now more urgent than ever. Animal venoms have long been considered as interesting resources to exploit in terms of potential therapeutic candidates. Among these, the cutaneous secretions of toads constitute a rich and diverse source of bioactive molecules. We focused on two different species: Bufo bufo and Incilius alvarius. The dried secretions underwent a solvent-based extraction and were submitted to a systematic bio-guided fractionation approach using preparative thin-layer chromatography. Initial crude extracts were tested in vitro for their antiplasmodial activity. Based on these results, only crude extracts displaying IC50 < 100 µg/mL were considered for further fractionation. All extracts and fractions, including those that did not display antiplasmodial properties, were characterized by chromatographic (LC-UV/MS) and spectrometric techniques (HRMS). Antiplasmodial activity was evaluated in vitro using a chloroquine-sensitive strain (3D7) and a resistant one (W2). Toxicity was assessed on normal human cells for the samples displaying IC50 < 100 µg/mL. Crude extracts from Bufo bufo secretions exhibited no appreciable antiplasmodial activities. However, the methanol and dichloromethane extracts from Incilius alvarius secretions gave IC50 of (34 ± 4) µg/mL and (50 ± 1) µg/mL respectively when tested on W2 strain. No significant effect was observed on 3D7. This poison would warrant further investigation in terms of its antiplasmodial potential. Following preliminary characterization, it was revealed that the fractions of interest contained mainly bufotoxins, bufagins and alkaloids.

Uncovering the antimalarial potential of toad venoms through a bioassay-guided fractionation process.

Malaria remains to date one of the most devastating parasitic diseases worldwide. The fight against this disease is rendered more difficult by the emergence and spread of drug-resistant strains. The need for new therapeutic candidates is now greater than ever. In this study, we investigated the antiplasmodial potential of toad venoms. The wide array of bioactive compounds present in Bufonidae venoms has allowed researchers to consider many potential therapeutic applications, especially for cancers and infectious diseases. We focused on small molecules, namely bufadienolides, found in the venom of Rhinella marina (L.). The developed bio-guided fractionation process includes a four solvent-system extraction followed by fractionation using flash chromatography. Sub-fractions were obtained through preparative TLC. All samples were characterized using chromatographic and spectrometric techniques and then underwent testing on in vitro Plasmodium falciparum cultures. Two strains were considered: 3D7 (chloroquine-sensitive) and W2 (chloroquine-resistant). This strategy highlighted a promising activity for one compound named resibufogenin. With IC50 values of (29 ± 8) µg/mL and (23 ± 1) µg/mL for 3D7 and W2 respectively, this makes it an interesting candidate for further investigation. A molecular modelling approach proposed a potential binding mode of resibufogenin to Plasmodium falciparum adenine-triphosphate 4 pump as antimalarial drug target.

Social perceptions of malaria and diagnostic-driven malaria treatment in Burkina Faso.

Malaria is a parasitic disease, endemic in many tropical and sub-tropical countries. Malaria is a well-known disease, familiar to almost all people in endemic regions, as they or their family are regularly confronted with it; everyone in these regions has probably experienced the disease, at least once in their life. To investigate the social perceptions of malaria in Burkina Faso, including its diagnosis-driven treatment, we have conducted a survey in both urban (Saint Camille Hospital, Ouagadougou HOSCO) and rural (Boussé Hospital) areas. Fifty-six individuals, mostly representatives of the society variability, were surveyed by questionnaires and 2 focus groups were organized with traditional healers. In general, populations seem to have grasped the causes, symptoms and means of preventing the disease. However, the majority of interviewees make a marked confusion between malaria and dengue; dengue fever is considered like a severe form of malaria. The care modalities (modern and/or traditional medicine) are plural and the choice of therapeutic practice depends on both the socio-economic conditions and education level of the patient. Whereas some patients mark preferences for one type of medicine, others simultaneously recourse to both; for these, a medicine does not outperform the other and their combination multiplies the chances of a quick recovery. Whether for modern or traditional medicine, the diagnosis is considered very important for effective disease management. Modern medicine uses diagnostic tools based on light microscopy and immunochromatography (rapid diagnostic tests; RDT); traditional medicine has its own diagnostic logic but nevertheless recognizes modern medicine diagnosis to guide its therapy. 90 % of those interviewed first use modern medicine to seek an accurate diagnosis of their disease and thus to receive adequate treatment. Presumptive treatments are still widely prescribed and accepted by most patients who trust the judgment of their caregiver, not perceiving any benefit to an objective diagnosis. In front of a negative diagnosis, patient reactions are diverse, some accepting investigations for other diseases (45 %), others opting for self-medication (15 %), others resorting to traditional medicine (20 %). All are unanimous in the importance of diagnosis and are in favor of in-development diagnostic technologies, provided these obviously meet the features of reliability, ease of use, availability and, of course, economical accessibility.

Affinity capillary electrophoresis for identification of active drug candidates in myotonic dystrophy type 1.

Myotonic dystrophy type 1 (DM1) is an autosomal dominantly inherited degenerative disease with a slow progression. At the present, there is no commercially available treatment, but sustained effort is currently undertaken for the development of a promising lead compound. In the present paper we report the development of a fast, versatile, and cost-effective affinity capillary electrophoresis (ACE) method for the screening and identification of potential drug candidates targeting pathological ARN probes relevant for DM1. The affinity studies were conducted in physiologically relevant conditions using 50 mM HEPES buffer (pH 7.4) in a fused silica capillary dynamically coated with poly(ethylene oxide), by testing a library of potential ligands against (CUG)50 RNA as target probe with a total run time of 4-5 h/ligand. For the most promising ligands, their affinity parameters were assessed and some results formerly reported on the affinity of pentamidine (PTMD) and neomycin against CUG repeats were confirmed. To the best of the authors' knowledge, the estimated binding stoichiometry for some of the tested compounds (i.e., ~ 121:1 for PTMD against the tested RNA probe) is reported for the first time. Additionally, the potential of a novel pentamidine like compound, namely 1,2-ethane bis-1-amino-4-benzamidine (EBAB) with much lower in vivo toxicity than its parent compound has also been confirmed studying its effect on a live cell model by fluorescence microscopy. Further tests, such as the evaluation of the rescue in the mis-splicing of the involved genes, can be performed to corroborate the potential therapeutic value of EBAB in DM1 treatment. Graphical abstract ᅟ.