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The present study aims at developing a simple, sensitive and specific liquid chromatography-tandem mass spectrometry (LC–MS/MS) method for simultaneous quantification of sildenafil and its metabolite N-desmethyl sildenafil in human plasma using sildenafil-d8, N-desmethyl sildenafil-d8 as internal standards (IS). Chromatographic separation was performed on Zorbax SB C18, 4.6 × 75 mm, 3.5 μm column with an isocratic mobile phase composed of 10 mM ammonium acetate and acetonitrile (5/95 v/v), at a flow-rate of 0.6 ml min−1. Sildenafil, sildenafil-d8, N-desmethyl sildenafil and N-desmethyl sildenafil-d8 were detected with proton adducts at m/z475.2 → 283.4, 483.4 → 283.4, 461.3 → 283.4 and 469.4 → 283.4 in multiple reaction monitoring (MRM) positive mode respectively. Both drug, metabolite and internal standards were extracted by liquid–liquid extraction. The method was validated over a linear concentration range of 1.0–1000.0 ng ml−1for sildenafil and 0.5–500.0 ng ml−1for N-desmethyl sildenafil with correlation coefficient (r2) ≥ 0.9998 for sildenafil and (r2) ≥ 0.9987 for N-desmethyl sildenafil. This method demonstrated intra and inter-day precision within 1.5 to 5.1 and 2.2 to 3.4% for sildenafil and within 1.3 to 3.1 and 2.8 to 4.3% for N-desmethyl sildenafil. This method demonstrated intra and inter-day accuracy for sildenafil within 97.3 to 98.3 and 96.7 to 97.2% and for N-desmethyl sildenafil within 95.3 to 96.3 and 95.0 to 97.2%. Both analytes were found to be stable throughout three freeze/thaw cycles, bench top and postoperative stability studies. This method was used successfully for the analysis of plasma samples following oral administration of 100 mg in 43 healthy Indian male human volunteers under fasting conditions.

Acetyl nitronates (acetic nitronic anhydrides), readily obtainable from ketones and nitroalkenes, have been demonstrated to serve as potentially useful intermediates for the synthesis of 2,5-dialkylpyrrolidines and 2,5-dialkylpyrrolines, and a short-step synthesis of some ant venom alkaloids has been accomplished via these acetyl nitronates.

A facile synthesis of various substituted α,β-unsaturated ketones utilizing nitroalkenes and sulfones are described, in which conjugate addition of sulfonyl carbanions to nitroalkenes, ozonolysis or acid treatment of the resulting lithium nitronates, and subsequent elimination of sulfinic acid from keto sulfones by DBU are involved.

GC-MS analysis of the hydrodistilled oil of Erigeron mucronatusDC was carried out, after the separation of a crystalline compound, lachnophyllum cumulene. Twenty-four components were identified. The oil contained 59.6% sesquiterpenoids, 16.1% monoterpenoids and 24.3% polyacetylenic esters. Among the mono and sesquiterpenoids, limonene (10.3%) and caryophyllenes (11.4%) were the major constituents. The essential oil also revealed the unusual presence of both cis(8.3%) and trans(1.1%) methyl lachnophyllum esters. Seasonal variation in the yield of E. mucronatusoil was observed. The yield varied from 0.49 to 0.58%, being highest during the rainy season. Antimicrobial activity was assessed using a method based on zones of inhibition; the oil exhibited maximum anti- bacterial activity against both Staphylococcus aureusand Escherichia coli, but moderate activity against Pseudomonas aeruginosa.Genotoxicity of the oil was determined in AB blood serum at different concentrations and hours of exposure. The antibacterial activity of the oil and its insignificant genotoxicity at low concentrations make the oil a good candidate as a curative agent.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.