Synthesis and anticonvulsant activity of a new series of 1,4-dihydropyridine derivatives

Adverse health risk from prolonged consumption of formaldehyde-preserved carps in eastern region of Indian population

Presence of formaldehyde as a preservative in commonly available fishes (Labeo rohita, Catla catla, Anabas testudineus and Clarias gariepinus) has become a serious health concern in the public health of eastern region of India. Formaldehyde content was determined using high-performance liquid chromatography (HPLC). Results showed high formaldehyde content in frozen carp (19.66 and 23.3 mg/kg in Labeo rohita and Catla catla, respectively); however, the amount of formaldehyde was significantly reduced in boiled and fried fish (80 °C and 100 °C for 5 min) in mustard, coconut, and sesame oils. However, formaldehyde contents in non-carp fishes (Anabas testudineus and Clarias gariepinus) were almost negligible, compared to those in L. rohita and C. catla. In vivo toxicity studies showed a time-dependent increase in blood formaldehyde levels in rats after they were fed formaldehyde-contaminated fish (23.3 mg/kg) for 7 days. Histopathological analysis of the stomach of rats fed contaminated fish showed destruction and granulation of the protective mucus layer and detachment from the secretory layer. Taken together, our results indicated that continuous consumption of formaldehyde-contaminated carps commonly available in the eastern region of India may be associated with adverse health effects.

Antimicrobial, anticoagulant, and cytotoxic evaluation of multidrug resistance of new 1,4-dihydropyridine derivatives

A new series of 1,4-dihydropyridine derivatives (2a–h, 3a–e, and 4a–e) were systematically designed and synthesized via ultrasound irradiation methods with easy work-up and good yields. Compounds structures were confirmed by IR, ¹H NMR, ¹³C NMR, and mass spectra. The synthesized compounds were screened for both antimicrobial and anticoagulant activities. Compound 2e (MIC: 0.25 μg/mL) was highly active against Escherichia coli and compound 2c (MIC: 0.5 μg/mL) was also highly active against Pseudomonas aeruginosa compared with ciprofloxacin. (MIC: 1 μg/mL) The antifungal activity of 2c (MIC: 0.5 μg/mL) against Candida albicans was high relative to that of clotrimazole (MIC: 1 μg/mL). Anticoagulant activity was determined by activated partial thromboplastin time (APTT) and prothrombin time (PT) coagulation assays. Compound 4-(4-hydroxyphenyl)-2,6-dimethyl-N³,N⁵-bis(5-phenyl-1,3,4-thiadiazol-2-yl)-1,4-dihydropyridine-3,5-dicarboxamide 3d (>1000 s in APTT assays) was highly active in anticoagulant screening compared with the reference of heparin.

Cytotoxicity was evaluated using HepG2 (liver), HeLa (cervical), and MCF-7 (breast) cancer cell lines, with high toxicities observed for 2c (GI₅₀ = 0.02 μm) against HeLa cell line and 2e (GI₅₀ = 0.03 μm) equipotant against MCF-7 cell line. Therefore, the compounds 2e, 2c and 3d can serve as lead molecules for the development of new classes of antimicrobial and anticoagulant agent.

Divergent synthesis of dual 1,4-dihydropyridines with different substituted patterns from enaminones and aldehydes through domino reactions

A concise and efficient protocol for the regioselective synthesis of dual 1,4-dihydropyridines with several substituted patterns has been developed from a cascade cyclization of enaminones and aldehydes in different media (EtOH/CH₃CN). The one-pot cascade reaction involves at least five reactive sites and generates multiple C–C and C–N bonds. The established protocol explores the chemistry of enaminones by employing their three reactive sites. The method has several advantages including mild conditions, operational simplicity, and high bond-forming efficiency. It may offer promise in a variety of biochemical applications.

A concise and efficient protocol for the regioselective synthesis of dual 1,4-dihydropyridines with several substituted patterns has been developed from a cascade cyclization of enaminones and aldehydes in different media (EtOH/CH₃CN).