Rajvir Sharma

Preliminary brain-targeting studies on intranasal mucoadhesive microemulsions of sumatriptan

The aim of this investigation was to prepare microemulsions containing sumatriptan (ST) and sumatriptan succinate (SS) to accomplish rapid delivery of drug to the brain in acute attacks of migraine and perform comparative in vivo evaluation in rats. Sumatriptan microemulsions (SME)/sumatriptan succinate microemulsions (SSME) were prepared using titration method and characterized for drug content, globule size and size distribution, and zeta potential. Biodistribution of SME, SSME, sumatriptan solution (SSS), and marketed product (SMP) in the brain and blood of Swiss albino rats following intranasal and intravenous (IV) administrations were examined using optimized technetium-labeled (99mTc-labeled) ST formulations. The pharmacokinetic parameters, drug targeting efficiency (DTE), and direct drug transport (DTP) were derived. Gamma scintigraphy imaging of rat brain following IV and intranasal administrations were performed to ascertain the localization of drug. SME and SSME were transparent and stable with mean globule size 38±20 nm and zeta potential between −35 to −55 mV. Brain/blood uptake ratios at 0.5 hour following IV administration of SME and intranasal administrations of SME, SMME, and SSS were found to be 0.20, 0.50, 0.60, and 0.26, respectively, suggesting effective transport of drug following intranasal administration of microemulsions. Higher DTE and DTP for mucoadhesive microemulsions indicated more effective targeting following intranasal administration and best brain targeting of ST from mucoadhesive microemulsions. Rat brain scintigraphy endorsed higher uptake of ST into the brain. Studies conclusively demonstrated rapid and larger extent of transport of microemulsion of ST compared with microemulsion of SS, SMP, and SSS into the rat brain. Hence, intranasal delivery of ST microemulsion developed in this investigation can play a promising role in the treatment of acute attacks of migraine.

Analysis of metsulfuron-methyl residues in wheat field soil: a comparison of HPLC and bioassay techniques

BACKGROUND Metsulfuron-methyl is a low-application-rate sulfonylurea herbicide that is widely used to control broad-leaved weeds in wheat. Owing to its persistent nature, its residues may be present at phytotoxic levels for the next crop in rotation. Therefore, a comparative evaluation of HPLC and bioassay techniques was made for the analysis of this herbicide in wheat field soil. RESULTS Metsulfuron-methyl was applied to wheat crop at different rates (4, 8 and 12 AI ha(-1)) at 28 days after sowing as a post-emergence application, and the soil was analysed for metsulfuron-methyl residues by HPLC and lentil seed bioassay techniques. The bioassay was found to be the more sensitive technique. At the recommended rate of application, 4 g AI ha(-1), the bioassay technique could detect the residue up to 30 days in surface soil, while, with HPLC, residues were not detectable on the 15th day. The half-lives of metsulfuron-methyl by HPLC and bioassay were calculated as 6.3-7.8 and 17.5 days respectively. Under field conditions, residues of metsulfuron-methyl were also detected in subsurface soil by the bioassay technique at trace levels, but were not detected by the solvent extraction/HPLC method. CONCLUSION Lentil seed bioassay is a more sensitive technique than HPLC. Traces of residues detected in subsurface soil indicated the mobility of metsulfuron-methyl into lower layers.

Persistence of pyrazosulfuron in rice-field and laboratory soil under Indian tropical conditions.

BACKGROUND Pyrazosulfuron ethyl, a new rice herbicide belonging to the sulfonylurea group, has recently been registered in India for weed control in rice crops. Many field experiments revealed the bioefficacy of this herbicide; however, no information is available on the persistence of this herbicide in paddy soil under Indian tropical conditions. Therefore, a field experiment was undertaken to investigate the fate of pyrazosulfuron ethyl in soil and water of rice fields. Persistence studies were also carried out under laboratory conditions in sterile and non-sterile soil to evaluate the microbial contribution to degradation. RESULTS High-performance liquid chromatography (HPLC) of pyrazosulfuron ethyl gave a single sharp peak at 3.41 min. The instrument detection limit (IDL) for pyrazosulfuron ethyl by HPLC was 0.1 µg mL(-1) , with a sensitivity of 2 ng. The estimated method detection limit (EMDL) was 0.001 µg mL(-1) and 0.002 µg g(-1) for water and soil respectively. Two applications at an interval of 10 days gave good weed control. The herbicide residues dissipated faster in water than in soil. In the present study, with a field-soil pH of 8.2 and an organic matter content of 0.5%, the pyrazosulfuron ethyl residues dissipated with a half-life of 5.4 and 0.9 days in soil and water respectively. Dissipation followed first-order kinetics. Under laboratory conditions, degradation of pyrazosulfuron ethyl was faster in non-sterile soil (t(1/2) = 9.7 days) than in sterile soil (t(1/2) = 16.9 days). CONCLUSION Pyrazosulfuron ethyl is a short-lived molecule, and it dissipated rapidly in field soil and water. The faster degradation of pyrazosulfuron in non-sterile soil than in sterile soil indicated microbial degradation of this herbicide.

Evaluation of Diclosulam Residues in Soil at Harvest of Soybean

Introduction Diclosulam is a sulphonamide soil applied herbicide which controls broad-leaved weeds in peanuts, soybean and other crops. It is taken up by roots and foliage and inhibits the acetolactate synthesis. No information is available for its residual activity under Indian condition. Therefore a field experiment of soybean was taken with diclosulam to determine the residues of diclosulam in soil at the harvest of crop. Materials and Methods Preparation of standard solutions 10 mg of diclosulam was taken in 10 ml volumetric flask and solution was made with HPLC grade acetonitrile up to the mark to give 1000 μg/ml solution. From this working standard of 100 μg/ml, 10 μg/ml and 1μg/ml concentration were prepared by serial dilution with acetonitile. High performance liquid chromatography (HPLC) A reverse phase high performance liquid chromatography technique was used for quantitative analysis of diclosulam. A Hewlett Packard HPLC instrument (series 1100) connected with rheodyne injection system and a computer (model vectra) was used for analysis. The stationary phase consisted of lichrosphere on RP-18 packed stainless steel column (250mm × 4mm id). Chromatogram was recorded in a window 95 based HP Chemstation programme. International Journal of Current Microbiology and Applied Sciences ISSN: 2319-7706 Volume 6 Number 2 (2017) pp. 1459-1463 Journal homepage: http://www.ijcmas.com HPLC method for the analysis for diclosulam herbicide was standardized using acetonitrile : 0.1% ortho-phosphoric acid (40 : 60) at a flow rate of 1 ml/min at 204 nm wavelength using PDA detector. Recovery of diclosulam from soil were above 70%. Diclosulam was applied at 20 and 26 g/ha as pre-emergence application. Soil samples were extracted and analysed for diclosulam residues by HPLC at zero day and harvest. The residues were found below the detectable limits. K e y w o r d s Diclosulam, HPLC, Soybean, Residue. Accepted: 24 January 2017 Available Online: 10 February 2017 Article Info Int.J.Curr.Microbiol.App.Sci (2017) 6(2): 1459-1463 1460 The chromatographic condition were 1-Mobile phase Acetonitrile : 0.1% ortho-phosphoric acid (40 : 60) 2-Flow rate 1 ml min1 3-Wavelenght (λ max) 204 nm 4-Injection volume 20 μl 5-Column and solvent Ambient Temperature Standardization of method of analysis Suitability of technique for determining pesticide residues quantitatively in substrate require two basic things 1Calibration of the technique. 2Quantitative recovery of the pesticide Calibration of diclosulam by HPLC Determination of λ max The diclosulam standard solution was scanned in different wavelength automatically by HPLC using photodiode array and the wavelength, in which the absorbance was maximum, was selected for further studies. The optimum λ max selected was 204 nm to analyze diclosulam.

Control of complex weed flora in direct-seeded and transplanted rice (Oryza sativa L.) with early post-emergence herbicide

A field experiment was conducted during rainy season of 2010–11 at the Research Farm of the Indian Agricultural Research Institute, New Delhi to study the efficiency of new low dose herbicide penoxsulam on growth and development of rice, their associated weeds and micro flora. The results of experiment revealed that penoxsulam 24 SC at 25 g/haapplied at 10 DAS/DAT significantly reduced the weed population, increased growth, yield (4.86 t/ha) and yield attributes of rice crop. Herbicidal treatments provided a yield advantage of 65.98 to 72.63% over weedy check. Herbicides exerted a significant detrimental effect on soil bacteria, fungi and actinomycetes. The counts of bacteria, fungus and actinomycetes recorded at 10 DAS/DAT revealed that soil microbes were more sensitive to penoxsulam 25 g/ha applied at 10 DAS/DAT and pre-emergence application of pretilachlor @ 750 g/ha as evident from significant reduction in their population, eventually microbial density started to recover slowly.