Manisha Sathe

Synthesis of 4-Aryl Substituted 3,4-Dihydropyrimidinones Using Silica-chloride Under Solvent Free Conditions

This paper describes an improved procedure for the efficient and facile synthesis of 4-aryl substituted 3, 4-dihydropyrimidinones under mild reaction conditions with excellent yields using inexpensive silica chloride under solvent free conditions.

Titania nanomaterials: efficient and recyclable heterogeneous catalysts for the solvent-free synthesis of poly-substituted quinolines via Friedlander hetero-annulation

The present communication describes the use of titania (TiO2) nanomaterials of different sizes (16 nm, 35 nm, 70 nm, 200 nm, and 1000 nm) as heterogeneous catalysts for the preparation of a series of medicinally significant poly-substituted quinoline derivatives via Friedlander hetero-annulation. These TiO2 nanomaterials exhibited remarkable catalytic activity with a high substrate to catalyst molar ratio (20 : 1) to achieve the synthetic targets in excellent yields ranging from 81–94%. The effect of catalyst particle size on the yield of the quinolines was also investigated. Yields of product were found to decrease when the TiO2 particle size increased from 16 nm to 1000 nm. GC-MS data indicated that TiO2 nanoparticles having 16 nm and 35 nm size of anatase phase provided better yields of the target compound, followed by particles of 70 nm in size, whereas 200 nm and 1000 nm size of anatase phase did not show the formation of the product under the same reaction conditions. The use of catalyst in solvent-free reaction conditions and its reusability up to five-cycles with similar catalytic response are the unique features of this heterogeneous catalysis. Furthermore, greater selectivity, cost-efficiency, clean reaction profiles, simple work-up procedure and high yield are the noteworthy features of this eco-friendly green protocol.

In vivo antimalarial evaluation of Gomphostenins.

AIM OF THE STUDY The present study aims to evaluate the in vivo antimalarial potential of the leaf extract of Gomphostemma niveum and two new compounds; named as Gomphostenin (GN-6) and acetyl Gomphostenin (GN-10) isolated and purified from this plant against Plasmodium berghei in mice. MATERIALS AND METHODS The blood schizontocidal activity was performed in early infection of Plasmodium berghei and also in established infection of Plasmodium berghei. The mice were orally administrated with various doses of water and chloroform extracts of leaves of Gomphostemma niveum (GN-W and GN-C, 300, 400 and 500 mg/kg/day), GN-6 and GN-10 (50, 100, 150 and 200mg/kg/day). Chloroquine (8 mg/kg) used as a positive control, while an equal volume of saline plus 0.5% tween-80 was used as a negative control. RESULTS GN-W, GN-C and pure compounds (GN-6 and GN-10) produced a dose dependent chemosuppression effect at various dose levels. GN-10 exhibited highest percent of chemosuppression i.e. 92.65% at a dose level of 200mg/kg/day. In case of curative test, the survival period of the parasitized infected mice was significantly prolonged at 200mg/kg dose of GN-10. CONCLUSIONS The studies have indicated that clerodane class of diterpenes GN-6 and GN-10 certainly holds great promise for malaria control and will be useful in antimalarial chemotherapy.

Synthesis and Antimalarial Evaluation of Cyclic β-Amino Acid-Containing Dipeptides

This paper describes an efficient synthesis and the antiparasitic evaluation of cyclic β-amino acid-containing dipeptides 3.1-3.6 and 4.1-4.5. The antimalarial properties of all these dipeptides have been evaluated in vitro against Plasmodium falciparum and in vivo against Plasmodium berghai. Compounds 4.4 and 4.5 have been found to be very effective in this respect, with IC50 values of 3.87 and 3.64 μg/mL in the in vitro test, while 4.5 has also been found to be active in the in vivo evaluation.

Synthesis of some novel phosphorylated and thiophosphorylated benzimidazoles and benzothiazoles and their evaluation for larvicidal potential to Aedes albopictus and Culex quinquefasciatus.

Series of benzimidazole and benzothiazole linked phosphoramidates and phosphoramidothioates (5a-j) and benzimidazole linked phenylphosphoramidates and phenylphosphoramidothioates (10a-e) were synthesized. The title compounds were preliminary screened for mosquito larvicidal properties against Aedes albopictus and Culex quinquefasciatus at different concentration from 40 to 5 mg/L. Among the screened compounds three compounds revealed potential larvicidal effects with 100% mortality in the order of 10e>5j>5e. Compound 10e was found to be the most toxic compound to Ae. albopictus and Cx. quinquefasciatus. The LC50 of 10e against Ae. albopictus was found to be 6.42 and 5.25 mg/L at 24 and 48 h, respectively, whereas it was 7.01 and 3.88 mg/L, respectively in Cx. quinquefasciatus. Temephos was used as positive control.

Synthesis and exploration of QSAR model of 2-methyl-3-[2-(2-methylprop-1-en-1-yl)-1H-benzimidazol-1-yl]pyrimido[1,2-a]benzimidazol-4(3H)-one as potential antibacterial agents.

Present communication deals with the synthesis of novel 2-methyl-3-[2-(2-methylprop-1-en-1-yl)-1H-benzimidazol-1-yl]pyrimido[1,2-a]benzimidazol-4(3H)-one derivatives under phase transfer catalysis (PTC) conditions using benzyl triethyl ammonium chloride (BTEAC) as PTC. It also elicits the studies on in vitro antimicrobial evaluation of synthesized compounds against a representative genera of gram-negative and gram-positive bacteria i.e., Bacillus subtilis, Staphylococcus aureus, Pseudomonas diminuta and Escherichia coli. All the compounds have been found to manifest profound antimicrobial activity. Moreover, extensive quantitative structure-activity relationship (QSAR) studies have been performed to deduce a correlation between molecular descriptors under consideration and the elicited biological activity. A tri-parametric QSAR model has been generated upon rigorous statistical treatment.

Efficient Synthesis of N‐Cyano α and β‐Amino Esters

Abstract A versatile method for the synthesis of N‐cyano α and β‐amino esters is described. Reaction of different amino esters with cyanogen bromide in dry ether gave the corresponding N‐cyano α and β‐amino esters in excellent yields.

CHEMOSELECTIVE AND CHEMOSPECIFIC PROTECTION AND DEPROTECTION OF A CARBONYL GROUP USING POLYSTYRENE DIVINYLBENZENE SULFONIC ACID

Chemospecific protection of one carbonyl group of two identical carbonyls of 2,2-dialkyl-1,3-cyclohexanedione and chemoselective protection of aliphatic or aromatic carbonyls in the presence of conjugated carbonyl compounds using cross-linked polystyrene divinyl benzene sulfonic acid (SPS) as a heterogeneous catalyst has been demonstrated.