Discovery of molluscicidal and cercaricidal activities of 3-substituted quinazolinone derivatives by a scaffold hopping approach using a pseudo-ring based on the intramolecular hydrogen bond formation

Design, synthesis and preliminary structure-activity relationship of 2-iminothiazolidine-4-one derivatives against Schistosoma japonicum in vitro and in vivo

Schistosomiasis, ranking second only to malaria in prevalence, is considered as a significant infectious parasitic disease in tropical and subtropical regions. Current therapeutic and control paradigms remain predominantly dependent on praziquantel monotherapy, highlighting the urgent need for alternative chemotherapeutic agents. Herein, we demonstrate the discovery and preliminary structure-activity relationship of 2-iminothiazolidine-4-one derivatives targeting Schistosoma japonicum in vitro and in vivo. The screening identified several hit compounds in this series exhibiting micromolar-level activity against the adult stage of the parasite in vitro, with a distinct mechanism involving tegumental disintegration of the worms. Notably, compound 17 exhibited potent in vitro activity against adult S. japonicum, with an LC50 (72 h) value of 25.31 ± 1.40 μM. In murine models of schistosomiasis, intraperitoneal administration of compound 17 (25 mg/kg/day × 7) achieved significant worm burden reduction of 52 % and 26 % in adult and juvenile stages, respectively. Furthermore, in vivo therapeutic assessments revealed that the hit compounds not only alleviated liver lesions but also demonstrated safety profiles with low hepatotoxicity. Acute oral toxicity experiments showed that compound 17 also possesses low oral toxicity and maintains an acceptable hepatotoxicological profile. These findings establish the ethyl 4-oxo-2-iminothiazolidin-5-ylidene acetate pharmacophore as a privileged scaffold for schistosomicidal development, providing a robust foundation for subsequent lead optimization toward next-generation antischistosomal therapeutics.

Copper-Catalyzed Domino-Double Annulation of o-Aminobenzamides with 2-Iodoisothiocyanates for the Synthesis of 12H-Benzo[4,5]thiazolo[2,3-b]quinazolin-12-ones

A facile and efficient copper-catalyzed domino-double annulation strategy was developed from easily accessible o-aminobenzamides and 2-iodoisothiocyanates, which affords a direct pathway for the synthesis of tetracyclic fused 12H-benzo[4,5]thiazolo[2,3-b]quinazolin-12-ones in moderate to good yields without the addition of ligands, bases, and external oxidants. The reaction involves a C-N bond cleavage and the formation of a C-N/C-S bond in one step with the advantages of using an inexpensive copper catalyst and easy operation. Mechanistic studies suggest that this transformation proceeds via intermolecular condensation of o-aminobenzamides with 2-iodoisothiocyanates, followed by an intramolecular Ullmann-type cross-coupling cyclization reaction.

Molluscicides against the snail-intermediate host of Schistosoma: a review

Schistosomiasis, a neglected tropical disease (NTD), is one of the most prevalent parasitoses in the World. Certain freshwater snail species are the intermediate host in the life cycle of schistosome species. Controlling snails employing molluscicides is an effective, quick, and convenient intervention strategy to prevent the spread of Schistosoma species in endemic regions. Advances have been made in developing both synthetic molluscicides and molluscicides derived from plants. However, at present, the development of molluscicides is not adapted to the actual demand for snails and schistosoma controlling. We undertake a systematic review of exploitation and application of synthetic molluscicides and molluscicides derived from plants to combat intermediate host snails. The detailed molluscicidal activity, structure–activity relationship, structural feature, and possible mechanism of some molluscicides are also highlighted, which may afford an important reference for the design of new, more effective molluscicides with low environmental impact and realize the aim of controlling schistosome at transmission stages.

Toxicity of a molluscicide candidate PPU07 against Oncomelania hupensis (Gredler, 1881) and local fish in field evaluation

Schistosomiasis japonica caused by Schistosoma japonicum infection is recognized as a considerable economic and public health concern in Asia. Oncomelania hupensis is the sole intermediate host of S. japonicum. The only molluscicide recommended by World Health Organization (WHO) since 1960s is relative toxic to other aquatic species. In this article, we evaluated the novel molluscicide PPU07 in field trials on their efficiency against O. hupensis and toxicity for local fish. 25% PPU07 sulfate WP exhibited similar molluscicidal effect at 2.0 g/m² and 2.0 g/m³ in the spraying and immersion trials with the WHO recommended molluscicide niclosamide (1 g/m² and 1 g/m³). The mortality rates reached 95% and 96%, respectively. Moreover, little toxicity was observed for local fish and other aquatic organisms at the effective molluscicidal concentrations. In all, 25% PPU07 sulfate WP is a promising molluscicide for snail control, particularly in semi-commercial or commercial aquaculture ponds.

Pharmacological characterization of a highly selective Rho kinase (ROCK) inhibitor and its therapeutic effects in experimental pulmonary hypertension

Studies on the role of Rho-associated protein kinase (ROCK) in experimental pulmonary artery hypertension (PAH) relies mainly on the use of pharmacological inhibitors. However, interpreting these data is hampered by the lack of specificity of commonly utilized inhibitors. To fill this gap, we have selected and characterized a novel ROCK inhibitor, Compound 3, previously described in a patent. Inhibitory potency of Compound 3 against enzymatic activity of ROCK-1 and 2 (IC₅₀ = 10 ± 3.1 and 7.8 ± 0.5 nM, respectively) was accompanied by a strong vasodilating effect in phenylephrine pre-contracted isolated rat pulmonary artery rings (IC₅₀ = 51.7 ± 9.1 nM) as well as in aortic rings (IC₅₀ = 45.5 ± 1.1 nM). Compound 3 showed a remarkable selectivity towards ROCK 1 and 2 when tested against a large panel (>400) of human kinases. A partial explanation for its selectivity is provided from docking simulations within ROCK-1. Pharmacokinetic studies showed that Compound 3 is suitable for a twice daily administration without significant accumulation upon repeated dosing. In rats with monocrotaline (MCT)-induced pulmonary hypertension, therapy with Compound 3, (1 and 3 mg/kg, s.c., b.i.d.), started 14 days after induction of the disease, attenuated right ventricle systolic pressure (RVSP) increase. Morphometric histological analysis showed that Compound 3, at both doses, counteracted MCT-induced medial thickening of lung distal arterioles with an effect comparable to macitentan (10 mg/kg, p.o., q.d.). Compound 3 is a potent and highly selective ROCK inhibitor that ameliorates hemodynamic parameters and counteracts pulmonary vascular remodeling in experimental PAH.

Triethylene glycol-modified iridium(iii) complexes for fluorescence imaging of Schistosoma japonicum

Schistosomiasis, an infectious disease caused by the Schistosoma parasitic worm, presents a serious public health issue. To date, investigation of anti-Schistosomiasis drug mechanisms through fluorescence imaging remains challenging due to the lack of appropriate dyes as fluorescent probes. Phosphorescent Ir(iii) complexes have been attracting substantial attention among various classes of fluorophores given their excellent photophysical properties. Herein, four phosphorescent Ir(iii) complexes were synthesized, two of which contained a triethylene glycol (TEG) hydrophilic group. The phosphorescent emission range of the four complexes lay between 500 and 750 nm, and their quantum yields ranged from 0.031 to 0.146. Furthermore, under the experimental concentration conditions, the TEG-modified complexes had low cytotoxicity. Cell fluorescence labeling experiments indicated that the TEG-modified complexes had good membrane permeability. Finally, the TEG-modified complexes showed remarkable labeling effects in adult Schistosoma fluorescence imaging. Thus, TEG-modified Ir(iii) complexes could be used as a new class of bilharzial fluorescent probes.