Surendra Singh

Lanthano-phosphotungstate: A water soluble and reusable catalyst for oxidation of alcohols using H2O2 as an oxidant

A series of water soluble lanthano-phosphotungstate K11[Ln(PW11O39)2]·xH2O [Ln = Pr(III), Nd(III), Eu(III), Gd(III), Tb(III), Dy(III), Ho(III), Er(III), Tm(III) and Yb(III)] catalysts were synthesized. These catalysts (0.24 mol%) were screened for oxidation of primary and secondary alcohols using H2O2 as an oxidant in water. The Pr-POM catalyst retained its activity after being recycled and reused upto five cycles.

Synthesis of MacMillan catalyst modified with ionic liquid as a recoverable catalyst for asymmetric Diels–Alder reaction

MacMillan catalyst was modified with imidazolium ionic liquid by ester linkage and acts as recoverable and reusable catalyst for asymmetric Diels–Alder reactions. A Diels–Alder reaction between cyclopentadiene and crotonaldehyde was carried out using MacMillan catalyst modified with ionic liquid (5 mol%) using trifluoroacetic acid (5 mol%) as co-catalyst in acetonitrile–water (95 : 5) at room temperature, to give 94% conversion of Diels–Alder adduct with exo/endo (1 : 1.1) and 90% ee of endo product. The catalyst was recovered and reused up to 5 cycles with a slight decrease in ee and product conversion.

Revisiting hemophilia management in acute medicine.

The World Federation of Hemophilia estimates that more than 350,000 people globally have a form of the disease. Hemophilia A is a bleeding disorder that has a spectrum of manifestations ranging from persistent bleeding after minor trauma to spontaneous hemorrhage. We report a case of a male patient with hemophilia A who received general anesthesia for removal of foreign body from the nose. There was no excessive blood loss during surgery. Perioperatively, the patient received recombinant factor VIII coverage. Rest of the postoperative course was uneventful. Literature on the clinical management of patient with hemophilia A are reviewed and considerations for perioperative preparation and management of hemophilic patient are presented.

(L)-Prolinamide imidazolium hexafluorophosphate ionic liquid as an efficient reusable organocatalyst for direct asymmetric aldol reaction in solvent-free condition

We have designed a new hydrophobic ionic liquid derived from bromoester of trans-4-hydroxy-(L)-prolinamide and N-methylimidazole. (L)-Prolinamide imidazolium hexafluorophosphate ionic liquid (2 mol%) found to be an excellent organocatalyst for direct asymmetric aldol reaction between 4-nitrobenzaldehyde and cyclohexanone using acetic acid (2 mol%) as an additive at −15 °C in solvent-free condition, the aldol product was afforded in excellent yield with diastereomeric ratio (anti/syn; 97 : 3) and 94% ee of anti-aldol product. Ionic liquids can catalyze the direct aldol reaction between benzaldehyde derivatives and cycloalkanones and the best dr (anti/syn; 99.9/0.01) and 99% ee was obtained for aldol product of 2-trifluoromethyl benzaldehyde and cyclohexanone. (L)-Prolinamide imidazolium hexafluorophosphate ionic liquid was reused up to 6 continuous cycles without decrease in the conversion of the product with 92% ee and found to be superior than its counterpart trans-4-hydroxy-(L)-prolinamide. Continuous cycle experiments do not require isolation of the catalyst after each cycle. The results of reusability of the ionic liquid catalyst were found to be better than most of other reported reusable catalysts.

N-Fluorobenzenaminium tetrafluoroborate generated in situ by aniline and Selectfluor as a reusable catalyst for the ring opening of epoxides with amines under microwave irradiation

The ring opening of epoxides with aromatic and aliphatic amines was carried out under solvent free conditions using N-fluorobenzenaminium tetrafluoroborate (2 mol%) generated in situ by the reaction of aniline and Selectfluor as a catalyst with microwave irradiation. Excellent yields of β-amino alcohols were obtained. The catalyst also results in the retention of the stereochemistry for the ring opening of enantiopure epoxide with amine. The catalyst was recovered and reused up to 4 cycles for the ring opening of cyclohexene oxide with aniline.

Novel biotin-functionalized lipidic nanocarriers for encapsulating BpT and Bp4eT iron chelators: evaluation of potential anti-tumour efficacy by in vitro, in vivo and pharmacokinetic studies in A549 mice models

Tumour cells have a high demand for iron (Fe) due to their rapid rate of proliferation. Strategies to target intracellular iron for antitumour therapy have not been systematically explored. The benzoylpyridine thiosemicarbazone (BpT) group of Fe-binding drugs represent a promising class of anti-tumour agents; however, their low aqueous solubility and high protein binding limit their clinical efficacy. In this work, we have explored the possibility of using solid lipid nanoparticles (SLNs) to develop a nanocarrier system that can deliver a drug cargo of BpT drugs to tumour sites. Herein, we prepared targeted biotinylated stearic acid based PEGylated SLN formulations for entrapment of benzoylpyridine thiosemicarbazone (BpT) and its analogue 4-ethyl benzoylpyridine thiosemicarbazone (Bp4eT) by the ultrasonication method, resulting in BpT-PB-SLNs and Bp4eT-PB-SLNs (size 115 to 120 nm, zeta potential −28 to −36 mV) with EEs of 72%. These formulations had negligible hemolytic activity and sustained drug release for 7 days. Radiolabeling with technetium-99m (99mTc) radionuclide facilitated the evaluation of their biological parameters both ex vivo and in vivo. Their blood kinetics profile showed prolonged systemic circulation compared to native drugs (BpT and Bp4eT) in New Zealand albino rabbits. The biodistribution studies performed in A-549 xenografted athymic mice depicted higher tumour uptake and lower non-specific uptake than native drugs as confirmed through whole body SPECT imaging by semi-quantitative analysis. This research presents for the first time a novel lipidic nanocarrier system in the form of biotin functionalised PEGylated SLNs that can help deliver iron chelators in a highly sustained manner and therefore hold potential to enhance their intracellular uptake and hence their antitumour efficacy.

Synthesis, crystal structure and catalytic activity of the guanidinium cation directed nickel(II)-containing open Wells–Dawson 19-tungstodiarsenate(III) [{Ni(H2O)4}2{Na(H2O)}As2W19O67(H2O)]9−

A new example of an open Wells–Dawson type 19-tungstodiarsenate(III) [{Ni(H2O)4}2{Na(H2O)}As2W19O67(H2O)]9− polyanion 1 has been synthesized in a single step reaction protocol, on the interaction of nickel chloride with the sodium salt of the trilacunary [B-α-AsW9O33]9− ligand in aqueous solution (pH ∼ 5.8), in the presence of pyridine-2,6-dicarboxylic acid. The guanidinium cation plays a structure-directing role to crystallize polyanion 1 as a mixed salt of sodium and guanidinium salt in the triclinic space group P. The solid state structure shows an open Wells–Dawson type [As2W19O67(H2O)]14− anion containing two nickel atoms in octahedral geometry. The mixed sodium and guanidinium salt of polyanion 1 was further characterized by FT-IR, single crystal X-ray diffraction, thermogravimetric analysis, and vibrating sample magnetometry (VSM). Polyanion 1a was screened as a catalyst for the oxidation of styrene.

Comparison of efficacy of palonosetron-dexamethasone combination with palonosetron or dexamethasone alone for prophylaxis against post-operative nausea and vomiting in patients undergoing laparoscopic cholecystectomy

Background and Aims: Post-operative nausea and vomiting (PONV) is highly distressing and unpleasant symptom. Dexamethasone and palonosetron are effective antiemetics with minimal side effect profile. This study compares the efficacy of palonosetron or dexamethasone alone and their combination (palonosetron plus dexamethasone) for prevention of PONV after laparoscopic cholecystectomy. Methods: This prospective, randomised, double-blind trial was done on 187 adults, American Society of Anesthesiologists Grade I and II patients, aged 18–75 years undergoing laparoscopic cholecystectomy. They were allocated to three groups which were to receive either of the three treatment regimens: dexamethasone 8 mg (Group D, n = 57), palonosetron 0.075 mg (Group P, n = 66) or dexamethasone 8 mg plus palonosetron 0.075 mg (Group PD, n = 64). The primary outcome was incidence of PONV in 24 h and the secondary outcome was a number of rescue antiemetic required. One-way ANOVA test was used to compare the means amongst three groups. To compare the proportions in the groups, Chi-square test/Fishers exact test/Two proportions Z-test was applied as appropriate. Results: Overall incidences of PONV in the study 24 h postoperatively were 23.4% in PD, 27.2% in P group and 56.14% in D group (P < 0.001). Requirement of rescue antiemetic was more in dexamethasone group than other two groups (PD = 1 time, P = 1.38 times and D = 1.5 times). Conclusion: Palonosetron alone and palonosetron-dexamethasone combination were equally effective in the prevention of PONV. Dexamethasone alone was least effective amongst the three groups. There is no difference between palonosetron and palonosetron-dexamethasone for PONV prevention.