Synthesis, Structural Determination, and Pharmacology of Putative Dinitroaniline Antimalarials

Dinitroaniline herbicides: a comprehensive review of toxicity and side effects on animal non-target organisms

The widespread use of herbicides has increased concern about the hazards and risks to animals living in terrestrial and aquatic ecosystems. A comprehensive understanding of their effective action at different levels of biological organization is critical for establishing guidelines to protect ecosystems and human health. Dinitroanilines are broad-spectrum pre-emergence herbicides currently used for weed control in the conventional agriculture. They are considered extremely safe agrochemicals because they act specifically on tubulin proteins and inhibit shoot and root growth of plants. However, there is a lack of toxicity information regarding the potential risk of exposure to non-target organisms. The aim of the present review is to focus on side effects of the most commonly used active ingredients, e.g. pendimethalin, oryzalin, trifluralin and benfluralin, on animal non-target cells of invertebrates and vertebrates. Acute toxicity varies from slightly to high in terrestrial and aquatic species (i.e. nematodes, earthworms, snails, insects, crustaceans, fish and mammals) depending on the species-specific ability of tested organisms to adsorb and discharge toxicants. Cytotoxicity, genotoxicity and activation of oxidative stress pathways as well as alterations of physiological, metabolic, morphological, developmental and behavioural traits, reviewed here, indicate that exposure to sublethal concentrations of active ingredients poses a clear hazard to animals and humans. Further research is required to evaluate the molecular mechanisms of action of these herbicides in the animal cell and on biological functions at multiple levels, from organisms to communities, including the effects of commercial formulations.

Title: A Comprehensive Review on Classifying Fast-acting and Slow-acting Antimalarial Agents Based on Time of Action and Target Organelle of Plasmodium sp

The clinical resistance towards malarial parasites has rendered many antimalarials ineffective, likely due to a lack of understanding of time of action and stage specificity of all life stages. Therefore, to tackle this problem a more incisive comprehensive analysis of the fast and slow-acting profile of antimalarial agents relating to parasite time-kill kinetics and the target organelle on the progression of blood-stage parasites was carried out. It is evident from numerous findings that drugs targeting food vacuole, nuclear components, and endoplasmic reticulum mainly exhibit a fast-killing phenotype within 24h affecting first-cycle activity. Whereas drugs targeting mitochondria, apicoplast, microtubules, parasite invasion and egress exhibit a largely slow-killing phenotype within 96-120h, affecting second-cycle activity with few exemptions as moderately fast-killing. It is essential to understand the susceptibility of drugs on rings, trophozoites, schizonts, merozoites, and the appearance of organelle at each stage of 48h intraerythrocytic parasite cycle. Therefore, these parameters may facilitate the paradigm for understanding the timing of antimalarials action in deciphering its precise mechanism linked with time. Thus, classifying drugs based on the time of killing may promote designing new combination regimens against varied strains of P. falciparum and evaluating potential clinical resistance.

2-Chloro-3-nitro-5-(tri-fluoro-meth-yl)benzoic acid and -benzamide: structural characterization of two precursors for anti-tubercular benzo-thia-zinones

8-Nitro-1,3-benzo-thia-zin-4-ones are a promising class of new anti-tubercular agents, two candidates of which, namely BTZ043 and PBTZ169 (INN: macozinone), have reached clinical trials. The crystal and mol-ecular structures of two synthetic precursors, 2-chloro-3-nitro-5-(tri-fluoro-meth-yl)benzoic acid, C8H3ClF3NO4 (1), and 2-chloro-3-nitro-5-(tri-fluoro-meth-yl)benzamide, C8H4ClF3N2O3 (2), are reported. In 1 and 2, the respective carb-oxy, carboxamide and the nitro groups are significantly twisted out of the plane of the benzene ring. In 1, the nitro group is oriented almost perpendicular to the benzene ring plane. In the crystal, 1 and 2 form O-H⋯O and N-H⋯O hydrogen-bonded dimers, respectively, which in 2 extend into primary amide tapes along the [101] direction. The tri-fluoro-methyl group in 2 exhibits rotational disorder with an occupancy ratio of 0.876 (3):0.124 (3).

[2-Chloro-3-nitro-5-(tri-fluoro-meth-yl)phen-yl](piperidin-1-yl)methanone: structural characterization of a side product in benzo-thia-zinone synthesis

1,3-Benzo-thia-zin-4-ones (BTZs) are a promising new class of anti-tuberculosis drug candidates, some of which have reached clinical trials. The title compound, the benzamide derivative [2-chloro-3-nitro-5-(tri-fluoro-meth-yl)phen-yl](piper-id-in-1-yl)methanone, C13H12ClF3N2O3, occurs as a side product as a result of competitive reaction pathways in the nucleophilic attack during the synthesis of the BTZ 8-nitro-2-(piperidin-1-yl)-6-(tri-fluoro-meth-yl)-1,3-benzo-thia-zin-4-one, following the original synthetic route, whereby the corresponding benzoyl iso-thio-cyanate is reacted with piperidine as secondary amine. In the title compound, the nitro group and the nearly planar amide group are significantly twisted out of the plane of the benzene ring. The piperidine ring adopts a chair conformation. The tri-fluoro-methyl group exhibits slight rotational disorder with a refined ratio of occupancies of 0.972 (2):0.028 (2). There is structural evidence for inter-molecular weak C-H⋯O hydrogen bonds.