Therapeutic Potential of Flavonoid Derivatives for Certain Neglected Tropical Diseases.

BACKGROUND: Neglected tropical diseases (NTDs) are infectious diseases that mostly affect people living in tropical and subtropical regions, especially in impoverished areas. Ubiquitously found in plants, flavonoids are a group of compounds that have been reported to exhibit a wide range of biological activities against parasites (Leishmania sp., Trypanosoma cruzi, Trypanosoma brucei, Brugia malayi, etc.) that cause certain NTDs. AIMS: The present study aims to highlight and discuss our recent reports on the implication of flavonoids in drug development for NTDs, such as leishmaniasis, Chagas disease, African trypanosomiasis, filariasis, among others. RESULTS: Today, studies show that flavonoids exhibit in vitro antileishmanial, anti-trypanosomiasis, antifilarial activities, among others. Furthermore, the molecular hybridization of flavonoids with the triazole groups has led to the development of compounds with improved biological activity. The incorporation of chemical groups, such as NO2, F, and Cl groups, during the process of design and synthesis, leads to the enhancement of pharmacological activity. CONCLUSION: Flavonoids are useful metabolites that can be prospected as potential leads for the development of new agents against certain NTDs. However, research opportunities, including cytotoxicity and in vivo studies, mechanisms of action, bioavailability of these compounds, remain to be investigated in the future.

In Situ Stabilisation of Silver Nanoparticles at Chitosan-Functionalised Graphene Oxide for Reduction of 2,4-Dinitrophenol in Water.

This investigation reports the in situ growth of silver nanoparticles onto covalently bonded graphene oxide-chitosan, which serve as supported nanocatalysts for the NaBH4 reduction of 2,4-dinitrophenol in aqueous systems. Fumaryl chloride reacted with chitosan in an acidic environment to yield a tailored polymeric material. The latter was, in turn, treated with the pre-synthesised graphene oxide sheets under acidic conditions to generate the GO-functionalised membrane (GO-FL-CS). The adsorption of Ag+ from aqueous media by GO-FL-CS yielded a set of membranes that were decorated with silver nanoparticles (Ag NPs@GO-FL-CS) without any reducing agent. Various analytical tools were used to characterise these composites, including Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller surface area analysis, X-ray diffraction, scanning electron microscopy/energy-dispersive X-ray analysis, inductively coupled plasma-mass spectrometry, and transmission electron microscopy. The silver-loaded materials were further used for the remediation of 2,4-dinitrophenol from aqueous solutions under batch operation. The BET analysis revealed that the functionalisation of GO with chitosan and Ag NPs (average size 20-60 nm) resulted in a three-fold increased surface area. The optimised catalyst (Ag mass loading 16.95%) displayed remarkable activity with an apparent pseudo-first-order rate constant of 13.5 × 10-3 min-1. The cyclic voltammetry experiment was conducted to determine the nitro-conversion pathway. The reusability/stability test showed no significant reduction efficiency of this metal-laden composite over six cycles. Findings from the study revealed that Ag NPs@GO-FL-CS could be employed as a low-cost and recyclable catalyst to convert toxic nitroaromatics in wastewater.