P. Sita Devi

Quantitative Determination of Sildenafil Citrate in Herbal Medicinal Formulations by High-Performance Thin-Layer Chromatography

A densitometric high-performance thin-layer chromatographic (HPTLC) method has been established for quantitative determination of sildenafil citrate in herbal medicinal formulations. Chromatography was performed on silica gel 60 F254 HPTLC plates, pre-washed with methanol, with toluene—acetone—methanol, 6 + 2 + 2 (v/v) as mobile phase. The plates were developed vertically, to a distance of 8 cm, in a saturated chamber, and densitometric quantitation was performed at λ = 312 nm by reflectance scanning. Recovery from the herbal medicinal powders and tablets was 83.17% and 99.41%, respectively. The standard sildenafil citrate calibration plot was linear (r = 0.9993) over the concentration range 100–600 ng per spot and the quantitative results showed the sildenafil content of the herbal formulations analyzed was in the range 76.4–85.0 mg ¦ (RSD < 3%). This HPTLC technique is complementary to other chromatographic methods and has potential use for routine quality-control analysis.

Validation of a High-Performance Thin-Layer Chromatographic Method with Densitometric Detection for Quantitative Analysis of Two Anticonvulsants in Tablets

A. quantitative densitometric high-performance thin-layer chromatographic (HPTLC) method has been established for analysis for two anti epileptic drugs, levetiracetam and oxcarbazepine in tablets. Separations on silica gel 60 F254 HPTLC plates with toluene-acetone-methanol, 6:2:2 (v/v), as mobile phase enabled satisfactory resolution of the two drugs. This system afforded well resolved compact bands for levetiracetam and oxcarbazepine at RF 0.45 ± 0.02 and 0.55 ± 0.02, respectively. Densitometric scanning was performed in absorbance/reflectance mode at 200 and 261 nm. The method was successfully validated for precision, robustness, ruggedness, and recovery. The drugs were also subjected to photodegradation studies; oxcarbazepine was degraded in 9 h and levetiracetam was not degraded even after a long period. The method was found to be accurate and compatible with the conditions used.

Comparison of conventional and supported liquid extraction methods for the determination of sitagliptin and simvastatin in rat plasma by LC–ESI–MS/MS

Three extraction methods were compared for their efficiency to analyze sitagliptin and simvastatin in rat plasma by LC–MS/MS, including (1) liquid–liquid extraction (LLE), (2) solid phase extraction (SPE) and (3) supported liquid extraction (SLE). Comparison of recoveries of analytes with different extraction methods revealed that SLE was the best extraction method. The detection was facilitated with ion trap-mass spectrometer by multiple reactions monitoring (MRM) in a positive ion mode with ESI. The transitions monitored were m/z 441.1→325.2 for simvastatin, 408.2→235.1 for sitagliptin and 278.1→260.1 for the IS. The lower limit of quantification (LLOQ) was 0.2 ng/mL for sitagliptin and 0.1 ng/mL for simvastatin. The effective SLE offers enhanced chromatographic selectivity, thus facilitating the potential utility of the method for routine analysis of biological samples along with pharmacokinetic studies.

Simultaneous Determination of Mirtazapine and its Three Main Impurities by a High Performance Thin Layer Chromatography/Densitometry Method

Abstract A quantitative densitometric high performance thin layer chromatography (HPTLC) method was developed for the simultaneous separation and quantification of Mirtazapine and its structurally related impurities. The three different impurities accounting for 3.3% were identified using TLC aluminium plates precoated with silica gel 60 F254 as the stationary phase. The mobile phase consisted of a saturated solution of toluene‐acetone‐methanol solution (6∶2∶2 v/v/v) and UV detection by absorbance reflectance at 285 nm facilitated the quantitative identification of the impurities along with the drug molecule. The minimum amount of Mirtazapine that could be authentically detected and quantified was 22.34 ng/spot and 74.47 ng/spot, respectively. The results of the present work showed that scanning densitometric HPTLC with online UV detection was simple, selective, accurate, and proved to be a valuable complementary method for quantitative evaluation of bulk drugs in the presence of their impurities.

In vitro cell culture of Charybdis congesta for enhanced production of secondary metabolites: Proscillaridin A, Scillaren A and Scilliroside

Callus cultures of Charybdis congesta were initiated in vitro and the effect of growth regulators was tested on callus growth and secondary metabolite production. Among several standard media formulated for use in the present study, MS and B5 were found to be potentially active and facilitated the calculation of callus induction frequency (CIF). The CIF was higher in both MS (70%) and B5 (63%) media supplemented with 1-naphthalene acetic acid (NAA) (9.0 μM) and benzyl amino purine (BAP) (0.9 μM). However, with indole-3-butyric acid (IBA) (9.0 μM) and BAP (0.8 μM), less amount (22.6%) of CIF was observed in MS medium but no callus formation was noticed in B5 medium. Rapid high performance thin layer chromatography (HPTLC) screening of callus extracts revealed that the callus established in MS medium supplemented with 4.5 μM NAA and 0.46 μM BAP produced the highest yield of Proscillaridin A (4.51 mg/g DW), Scilliroside (3.3 mg/g DW), Scillaren A (2.35 mg/g DW) and desacetylscilliroside (8.62 mg/g DW), which was higher than from the intact plants. The results obtained indicate that the in vitro cultures of C. congesta might be an excellent source of secondary metabolites and further metabolic profiling may provide insights into up scaling of the compounds which lead to greater commercial interest and continuous supply of cultures. Keywords : Squill, Charybdis congesta , bufadienolides, callus cultures, reflectance scanning densitometry African Journal of Biotechnology Vol. 12(15), pp. 1754-175