In vitro molluscicidal activity and biochemical impacts of some thiophene derivatives against the glassy clover snail, Monacha obstructa (Pfeiffer)

The glassy clover snail, Monacha obstructa (Pfeiffer), is considered one of the major agricultural pests that ruin many field crops, vegetables, orchards of fruits, plants of ornament as well as many other plantations. Synthesis of the Schiff base ligand, namely bis-[4-benzylidene-thiophene-2′-yl] methane (L), produced from the reaction between thiophene-2-carboxaldehyde and diaminodiphenylmethane (MDA), alongside its copper complex were conducted. The output chemical compounds were evaluated in vitro for their molluscicidal activity against the glassy clover snail, M. obstructa by performing the contact technique. Stock solutions were prepared via using (distilled water + DMF) mixture. Furthermore, the impact of these compounds on some critical biochemical indicators: cholesterol, total protein, and acetylcholinesterase (AChE), was evaluated. The outcome results demonstrated the significantly higher molluscicidal activity of the Cu(II) chelate compared to its free ligand (L), which in turn reveals the importance of metal chelation in enhancing toxicity against the target species. Particularly, the LC25 and LC50 values are (27.25, 34.65) and (17.88, 25.31) ppm for the ligand (L) and its copper construction, respectively. Additionally, the data confirmed the significant effectiveness of the tested compounds on the assessed biochemical indicators of treated snails. Total protein and cholesterol levels were elevated after treatment with both the ligand (L) and its copper complex while AChE activity increased after treatment with the ligand (L) and reduced upon the exposure to the Cu(II) chelate. The findings established that the copper complex exhibited a markedly higher molluscicidal activity compared to the free ligand (L). Also, the results confirmed the significant effects of the investigated compounds on the assessed biochemical indicators of treated M. obstructa snails.