Highly efficient catalyst-free domino conjugate addition,decarboxylation and esterification/amidation of coumarin carboxylic acid/esters with pyrazolones: a green chemistry approach

Tandem conjugate addition, decarboxylation and esterification/amidation of coumarin 3-carboxylic acid derivatives with pyrazolones have been developed. The reactions were performed with coumarin 3-carboxylic acid/esters and pyrazolone in alcohol as a solvent to afford the corresponding pyrazolyl 2-hydroxy phenylpropionate derivatives. Amines and green solvents were employed for amidation in the addition reaction. The methodology has advantages such as excellent yields, a broad substrate scope, catalyst-free, easy purification by simple filtration without any workup, mild conditions and does not require any organic solvents, ligands, base or any additives. This is a green and general synthetic protocol, which could be applicable for the synthesis of substituted pyrazolyl phenyl propionate/amide derivatives. This approach demonstrates the importance of the coumarin 3-carboxylic acid/ester core structure for Michael addition.

Tandem conjugate addition, decarboxylation and esterification/amidation of coumarin 3-carboxylic acid derivatives with pyrazolones have been developed.     

Bio-nanoparticle assembly: a potent on-site biolarvicidal agent against mosquito vectors

Background: Vector-borne diseases such as malaria, dengue, yellow fever, encephalitis and filariasis are considered serious human health concerns in the field of medical entomology. Controlling the population of mosquito vectors is one of the best strategies for combating such vector-borne diseases. However, the use of synthetic insecticides for longer periods of time increases mosquito resistance to the insecticides. Recently, the search for new environmentally friendly and efficient insecticides has attracted major attention globally. With the evolution of material sciences, researchers have reported the effective control of such diseases using various sustainable resources. The present investigation demonstrates a potent on-site biolarvicidal agent against different mosquito vectors such as Aedes albopictus, Anopheles stephensi and Culex quinquefasciatus. Methods: Stable and photo-induced colloidal silver nanoparticles were generated via the surface functionalization of the root extract of Cyprus rotundas. Characterizations of the nanoparticles were performed using assorted techniques, such as UV-visible spectroscopy, FTIR spectroscopy, DLS and HRTEM. The bioefficacy of the synthesized nanoparticles was investigated against different species of mosquito larvae through the evaluation of their life history trait studies, fecundity and hatchability rate of the treated larvae. Histopathological and polymerase chain reaction-random amplified polymorphic DNA (RAPD) analyses of the treated larvae were also examined to establish the cellular damage. Results: The synthesized nanoparticles showed remarkable larvicidal activity against mosquito larvae in a very low concentration range (0.001–1.00) mg L⁻¹. The histopathological study confirmed that the present nanoparticles could easily enter the cuticle membrane of mosquito larvae and subsequently obliterate their complete intestinal system. Furthermore, RAPD analysis of the treated larvae could assess the damage of the DNA banding pattern. Conclusion: The present work demonstrates a potent biolarvicidal agent using sustainable bioresources of the aqueous Cyprus rotundas root extract. The results showed that the synthesized nanoparticles were stable under different physiological conditions such as temperature and photo-induced oxidation. The effectiveness of these materials against mosquito larvae was quantified at very low dose concentrations. The present biolarvicidal agent can be considered as an environmentally benign material to control the mosquito vectors with an immense potential for on-site field applications.

The present work demonstrates a potent and stable biolarvicidal agent using sustainable bioresources. The synthesized nanomaterials can control the mosquito vectors at a very low concentration range (0.01–1.00 mg L⁻¹) for on-site field applications.     

Regio- and diastereoselective synthesis of spiropyrroloquinoxaline grafted indole heterocyclic hybrids and evaluation of their anti-Mycobacterium tuberculosis activity

An efficient and eco compatible approach for the regio- and stereoselective synthesis of structurally diverse novel hybrid heterocycles comprising spiropyrrolidine, indenoquinoxaline and indole structural units in excellent yields, has been achieved through a one-pot multicomponent process involving 1,3-dipolar cycloaddition as a key step. The 1,3-dipolar component is the azomethine ylide generated in situ from indenoquinoxaline and l-tryptophan and reacts with various substituted β-nitrostyrenes affording the spiroheterocyclic hybrids. The ring system thus created possesses two C–C and three C–N bonds and four adjacent stereogenic carbons, one of which is quaternary and the reaction proceeded with full diastereomeric control. All the synthesized compounds were assayed for their in vitro activity against Mycobacterium tuberculosis H37Rv using MABA assay. Interestingly, the compound bearing a 2-fluoro substituent on the aryl ring displayed an equipotent activity (MIC 1.56 μg mL⁻¹) to ethambutol against Mycobacterium tuberculosis H37Rv.

An efficient and eco compatible approach for the regio- and stereoselective synthesis of structurally diverse novel spiropyrrolidine tethered indole hybrids in excellent yields employing a one-pot multicomponent 1,3-dipolar cycloaddition strategy.     

Effect of antiasthmatic medication on dental disease: dental caries and periodontal disease

The prevalence of asthma has been increasing since the 1980s. Asthma and tooth decay are the two major causes of school absenteeism. There are few studies present in the literature. The objectives of the present study were to know the severity of dental caries and periodontal problems in children before and after taking antiasthmatic medication. The present study was conducted on 105, six- to fourteen-year-old asthmatic children to determine the condition of their dental caries and their periodontal status before and after taking antiasthmatic medication, for a period of 1 year and these were matched with their controls. The results showed that salbutamol inhaler shows increased caries rate with high significance over other groups, which was followed by salbutamol tablets and beclamethasone inhaler respectively. It has been concluded that antiasthmatic medication has its effects on dental caries and periodontal disease and asthmatic patients are recommended to adopt more precautionary oral hygiene practices and keep their caries activity and periodontal health under constant check.