Simultaneous Quantitation of Minoxidil and Tretinoin in Magistral and Pharmaceutical Preparations by First Derivative Spectrophotometry

Abstract

A first derivative spectrophotometry method has been developed for the simultaneous quantitation of minoxidil and tretinoin. The method is based on measuring the first derivative signals (D₁) of minoxidil and tretinoin at 290 and 351 nm, respectively, without any interference from each other, or any other coexisting materials. Beer's law was valid over the concentration range 2–10 μg/ml of minoxidil and 0.25–1.25 μg/ml of tretinoin. The proposed method has been applied successfully to the determination of some magistral and pharmaceutical preparations. Relative standard deviations for the assay of both drugs were less than 0.95%.     

Determination of phenolic compounds,in vitro antioxidant activity and characterization of secondary metabolites in different parts of Passiflora cincinnata by HPLC-DAD-MS/MS analysis

Abstract

Ethanol extracts of different parts of Passiflora cincinnata were obtained by maceration. The total phenolic and flavonoid contents were evaluated. The antioxidant activities were determined by β-carotene-linoleic acid bleaching test, 2,2-diphenyl-1-picrylhydrazil (DPPH), and 2,2’-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical scavenging. The crude ethanol stem extract showed the highest amount of total polyphenols (45.53?mg gallic acid equivalent/g) while the highest total flavonoid contents (1.42?mg of quercetin equivalent/g) were observed in the leaf extract. The lowest IC₅₀ (25.65?μg/ml) by the DPPH method was observed for the stem extract. The ABTS method showed a significant antioxidant activity for all investigated extracts. The secondary metabolite composition of ethanol extracts was assessed by HPLC-DAD-MS/MS analysis, leading to the identification of fourteen secondary metabolites in P. cincinnata extracts. These results showed the potentiality of this species as a source of phenolic compounds and antioxidants.     

Analysis of Metal Ions in Environmental Samples - III Synergistic Determination of Vanadium (V) As its Mixed Complex with N-0-Methoxyphenyl-2-Thenohydroxamic Acid and 3-(0-Carboxyphenyl)-1-Phenyltriazine-N-0Xide

Abstract

A highly sensitive, selective, and rapid method for the spectrophotometry determination of vanadium(V) at trace levels is described. The method is based on the selective extraction of vanadium(v) from strongly acidic (3–6 M hydrochloric acid) met ium with solution of N-0-methoxyphenyl-2- thenohydroxamic acid (0MTHA) in chloroform. The extract is then equilibrated with 3-(0-carboxyohenyl)-1-phenyltriazine-N-oxide(CPPTNO) at pH ? 1.5 and the resulting colour is measured at 445 nm. The colour system obeys Beer's law over the range 0–20 -μg/ml of vanadium; the molar absorptivityat the wavelength of maximum absorption (445 nm), and the Sandell sensitivity of the method are 1.1 × 10⁴1. mole^?1 cm^?1 and 0.005 μg/ml respectively.     

New Rapid Assay for Nafcillin by Spectrofluorimetry in Pharmaceutical Dosage

Abstract

A method for the spectrofluorimetric determination of nafcillin is proposed (λ_ex = 226 nm, λ_em = 366 nm), for concentrations between 0.10 and 1.0 μg mL^?1. The method was performed in ethanol/water medium (30% V/V), at apparent pH 6.0 provided by adding of phosphate buffer solution with pH = 6.20.

The obtained values of detection and determination limits are 0.016 and 0.054 μg mL^?1, respectively.

The method was successfully applied to assay a commercial injection containing nafcillin sodium monohydrate.     

A silver nanoparticles-catalyzed efficient three-component synthesis of polysubstituted 4H-chromenylphosphonates and their antioxidant activity

Abstract

A simple and efficient protocol for one-pot three-component synthesis of structurally diverse dialkyl 2-amino-3-cyano-4H-chromen-4-ylphosphonates from the condensation of salicylaldehydes, malononitrile, and trialkyl phosphite using silver nanoparticles as catalyst in ethanol at reflux has been developed. Selected new compounds were evaluated for their antioxidant activity by free radical screening using 2,2-diphenyl-1-picrylhydrazyl (DPPH) method. Among the compounds employed, 5a, 5?b, and 5?h showed promising DPPH radical scavenging activities compared to the experimental standards at low concentration (100?µg/mL) after 24?h incubation.     

Utility of Derivative Spectrophotometry in the Determination of Carbochromen Hydrochloride and Dipyridamole in the Presence of Their Oxidative Degradation Products

Abstract

Direct spectrophotometric methods for the determination of carbochromen hydrochloride and dipyridamole, each in the presence of its oxidative degradation products, are presented. the methods are based on the first derivative (D₁) and second derivative (D₂) spectrophotometric measurement (absolute trough, U) at 336 nm and (Peak-trough, Y) at 309–342 nm for carbochromen hydrochloride and at 240–260 nm(U) and 246–268 nm(Y) for dipyridamole. Plots of D₁ or D₂ versus concentration were linear over the concentration range of 8.00–16.00 μg/ml for carbochromen hydrochloride and 4.00–12.00 μg/ml for dipyridamole. Oxidative degradation of these drugs has been optimized with respect to hydrogen peroxide concentration. Determining the intact in coexistence with its oxidative degradation product, the proposed derivative spectrophotometric methods proved to be of high potential in correcting the systematic error appearing in the results of the A_max method due to the latter. Assaying the commercial tablets, the proposed method gave results of high accuracy and reproducibility.     

Spectrophotometric Assay of Certain Cephalosporins Based on Formation of Ethylene Blue

Abstract

The hydrolytic degradation of antibiotics is very often used as a preliminary step in the analytical procedures for their determination. Therefore, a procedure was developed for measuring small amounts of cefadroxil and cefotaxime in pure samples as well as in formulations.

The method depends on forming a vis-absorbing compound with N,N-diethyl-p-phenylenediamine sulphate (N,N-DPPD) (ethylene blue dye), after the hydrolysis of cefadroxil and cefotaxime in sodium hydroxide solution to give hydrogen sulphide. The method is selective for cephalosporins, since other β-lactam compounds such as penicillins do not give hydrogen sulphide under alkaline hydrolysis. Variables such as pH, temperature, reagent concentrations and stability of the colour produced have been evaluated to permit selection of the most advantageous technique. Beer's law obeyed over the concentration range 0.5–10 μg/ml and 0.5–7 μg/ml for cefadroxil and cefotaxime, respectively. The detection limit being 0.1 μg/ml and 0.05 μg/ml (defined as the amount of the drug that gave a signal of twice the background noise) for cefadroxil and cefotaxime, respectively. The method has been successfully applied to the analysis of some pharmaceutical formulations.

The results have been statistically compared with those obtained by the official method. The relative standard deviation (for 10 replicates) was 1.12 (9 μg/ml) and 0.49% (5 μg/ml) for cefadroxil and cefotaxime, respectively. Procedural details and data for the effect of operating parameters are presented.     

The [DPPH●/DPPH-H]-HPLC-DAD Method on Tracking the Antioxidant Activity of Pure Antioxidants and Goutweed (Aegopodium podagraria L.) Hydroalcoholic Extracts

The 2,2-diphenyl-1-picrylhydrazyl (DPPH)-reverse phase (RP)-HPLC-diode array detector (DAD) method was tested on standard antioxidants (AOs), i.e., reduced glutathione (GSH), ascorbic acid (vitamin C), and alcoholic extracts of A. podagraria L. An elaborated HPLC procedure enabled the simultaneous measurement of the redox couple DPPH-R (2,2-diphenyl-1-picrylhydrazyl radical)/DPPH-H (2,2-diphenyl-1-picrylhydrazine). Both forms were fully separated (R_s = 2.30, α = 1.65) on a Zorbax Eclipse XDB-C18 column eluted with methanol–water (80:20, v/v) and detected at different wavelengths in the range of 200–600 nm. The absorbance increases of the DPPH-H as well as the DPPH-R peak inhibition were measured at different wavelengths in visible and UV ranges. The chromatographic method was optimized, according to reaction time (slow, fast kinetics), the linearity range of DPPH radical depending on the detection conditions as well as the kind of the investigated antioxidants (reference chemicals and the ground elder prepared from fresh and dry plants). The scavenging capacity was expressed by the use of percentage of peak inhibition and the IC₅₀ parameters. The evaluated extracts displayed antioxidant activity, higher than 20% inhibition against 350 µM DPPH free radical. The results show that extract prepared from dry plants in the ultrasonic bath exhibits the highest antioxidant potential (IC₅₀ = 64.74 ± 0.22 µL/mL).     

DNA cleavage,cytotoxic and antioxidant properties of Cistus laurifolius L. extracts

In this study, extracts of the root, branch and leaf parts of Cistus laurifolius L. were prepared using hexane, methylene chloride and ethanol solvents. DNA cleavage, cytotoxic and antioxidant properties of the prepared extracts were then investigated. The cytotoxic properties of the extracts were investigated in A549, DU-145, PNT-1A, MDA-MB231, CRL-4010 and HCT-116 cell lines. Among all prepared extracts, T4 (seed–methylene chloride) extract showed cytotoxic effects on more cancer cell lines compared to other extracts. Antioxidant tests were performed by DPPH (2,2-diphenyl-1-picrylhydrazil) radical scavenging and Folin-Ciocalteu methods. In both tests, it was determined that T7 (seed–ethanol) extract has a very strong antioxidant effect (IC₅₀ = 0,000015 μg/ml for the DPPH method). In DNA cleavage studies, the results obtained confirm the protection of DNA from hydroxyl radical damage in the presence of methanolic plant extracts. Consequently, we determined that some of the Cistus laurifolius L. extracts have significant biological properties on the studied cell lines.     

Optimization of extraction process and the antioxidant activity spectrum–effect relationship of Angelica dahurica

Despite the large number of studies indicating that Angelica dahurica has strong antioxidant capacity, there are no clear details on the specific antioxidant components involved. In this study, the chromatograms and antioxidant activity of A. dahurica were obtained by gas chromatography–mass spectrometry (GC–MS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and ferric ion reducing antioxidant power (FRAP) methods. The factors affecting free radical scavenging were investigated under different extraction conditions, on the basis of the single-factor experiment. The results showed that the optimum conditions for the DPPH method were ultrasonic extraction, using 80% methanol as extract the extraction solvent, a 20:1 (ml/g) ratio of liquid to material and an extraction time of 30 min. Furthermore, the spectrum–effect relationship between the GC–MS chromatograms and the antioxidant effect of A. dahurica was established to evaluate the antioxidant components of A. dahurica using multiple data analysis methods. Isoimperatorin and byakangelicol made the greatest contribution to scavenging DPPH free radicals and ferric-reducing antioxidant power. This result may provide the basis for developing new and effective products based on the antioxidant ingredients of A. dahurica.     

Spectrophotometric Determination of Trace Amounts of Ascorbic Acid

Abstract

Colourless silver-gelatin complex is quantitatively reduced by ascorbic acid to yellow silver sol in water within the pH range 7.5–10.0 at room temperature. The determination of 1–10μg/ml of ascorbic acid is possible at 415 nm in the presence of glycine, alanine, fructose, sucrose, citric, tartaric, oxalic, malic, succinic acids and also in the presence of various reducing agents. The molar absorptivity of ascorbic acid at the δ_max is found to be 21500 lit mol^?1 cm^?1 and the Sandell sensitivity of the sol is 8.18x10^?3 μg ascorbic acid cm^?2 for 0.001 absorbance. The relative standard deviation is ±0.22% and the confidence limit (20 determinations, 95%) being 8.806±0.0093%.     

Simultaneous Determination of Tinidazole and Furazolidone in Suspension by HPTLC and HPLC

Abstract

High performance thin layer chromatographic (HPTLC) and high performance liquid chromatographic (HPLC) methods were developed for the simultaneous determination of Tinidazole and Furazolidone in suspension.

In the HPTLC method the separation of Tinidazole and Furazolidone was carried out on silica gel 60F₂₅₄ HPTLC glass plate using chloroform:methanol:ammonia (9:1:0.1 v/v) as a mobile phase. Rf values obtained were 0.63 and 0.79 for Furazolidone and Tinidazole respectively. Densitometric evaluation was done at 335 nm. Linearity was obtained within the concentration range 10–50 μg/ml and 3.5–17.5 μg/ml for Tinidazole and Furazolidone respectively.

The second method is based on high performance liquid chromatography on a reversed phase column (μ Bondapak C₁₈) using a mobile phase comprised of water: acetonitrile: triethylamine (80:20:0.1 v/v) adjusted to pH = 3.0 with dil. phosphoric acid. Retention times were 5.24 and 7.82 min for Tinidazole and Furazolidone respectively at a flow rate of 1.5 ml/min. Detection was done at 335 nm. Linearity was obtained within the concentration range 30–180 μg/ml and 10.5–63 μg/ml for Tinidazole and Furazolidone resp.     

Use of Derivative Spectrophotometry for the in Vitro determination of Phenylbutazone and Oxyphenbutazone in Human Plasma

Abstract

Fourth derivative-difference (ΔD₄.) spectrophoto metry is presented for the simultaneous assay of phenylbutazone and oxyphenbutazone as metabolites of bumadizone either in laboratory made mixtures or in human plasma. Phenylbutazone and oxyphenbutazone are determined through the measurement of ΔD₄ signals at 293 and 282 nm, respectively. The linear relationship of these values versus concentration of both compoundsin the range 1–5 μg/ml for phenylbutazone and 3–8 μg/ml for oxyphenbutazone permits their determination with high accuracy and good reproducibility. The relative standard deviation is less than 1.35% The proposed method could be used for monitoring bumadizone metabolites.     

Biosynthesis and characterization of lead selenide semiconductor nanoparticles (PbSe NPs) and its antioxidant and photocatalytic activity

The current study fabricated novel lead selenide nanoparticles (PbSe NPs) by a simple biological benign process with Trichoderma sp. WL-Go. Ultraviolet–visible spectroscopy (UV–vis), Transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transfer infra-red (FTIR) spectroscopic analysis, Raman spectroscopy and Photoluminescence (PL) were used to characterize the physicochemical properties of the fabricated NPs. Synthesis at pH 8 with 0.5 g biomass of strain WL-Go and (1:1) mM of SeO₂: Pb(NO₃)₂ were the optimal synthesis conditions to achieving 10–30 nm cubic faced centered NPs. The PbSe NPs served as catalyst for investigating the antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and photodegradation ability of rhodamine B dye (10 mg/L). The results indicated that the NPs could eliminate up to 88.60% of free radicals after adding 600 g/mL NPs and could photodegrade 82% of rhodamine B in 30 min. Thus, this study provides new knowledge and strategies for the future use of an environmentally benign bio- catalytic PbSe NPs to efficiently eliminate free radicals and in treatment of persistent organic pollutants in wastewaters.     

Preparation of a simple biocompatible magnetite@citric acid: An efficient reusable solid acid catalyst for the rapid synthesis of antipyrine Schiff’s bases and study of their radical scavenging potential

Citric acid immobilized magnetic nanoparticles (MNPs@CA) have been synthesized and used for the preparation of bio-important antipyrine (1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one) derived Schiff’s bases (3a–k) in lesser reaction time with very high yield under ultrasonication. The catalyst was characterized by FT-IR, powder X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), and thermogravimetric analysis (TGA). The functionalized nanoparticles were easily separated using an external magnet during work-up procedure and show excellent reusability upto 8 cycles without any significant loss in catalytic activity. All the synthesized compounds (3a–k) were screened by DPPH (2,2-diphenyl-1-picrylhydrazyl) method with respect to ascorbic acid for their antioxidant activity and some of them gave promising results.     

Simultaneous Analysis of Pyridoxine and Melatonin in Tablet Formulation by Derivative Ultraviolet Spectroscopy

Abstract

A method for simultaneous analysis of pyridoxine and melatonin by second and third derivative UV - spectroscopy, the “zero - crossing” technique, is described. The determination has been carried out in 0.1 mol dm^?3 hydrochloric acid solution and the concentration range of 2 – 10 μg/ml pyridoxine and 0.5 – 3.5 μg/ml melatonin. Lower limits of detection at the 95% confidence level were 0.26 μg/ml for pyridoxine and 0.05μg/ml for melatonin The advantages of the proposed method include its application for the assay and in-vitro dissolution studies of pyridoxine and melatonin from two different tablet formulations.     

A Fluorimetric Method for the Determination of Atmospheric Sulphur Dioxide With 2′, 7′—Dichlorofluorescein∗

Abstract

A rapid, simple and sensitive fluorimetric method has been developed for the determination of atmospheric sulphur dioxide with dichlorofluorescein as fluorogenic reagent (λ_ex = 505 nm, λ_em = 520 nm) at pH 4.0–6.0. A linear calibration curve was obtained in the range 0.01–0.40 μg SO₂/25 ml. The detection limit is 0.01 μg SO₂/25 ml. Nitrogen dioxide does not interfere with the method. The method was successfully applied to the determination of atmospheric sulphur dioxide.

     

A Fluorimetric Method for the Determination of Cyanide with Fluorescein and Iodine∗

Abstract

A rapid, simple and sensitive fluorimetric method has been developed for the determination of cyanide with fluorescein as fluorogenic reagent (λ_ex = 494 nm, λ_em = 514 nm) at pH 6.0–7.0. A linear calibration curve was obtained in the range 0.004–2.0 μg CN^?/25 ml. The detection limit is 0.004 μg CN^-/25 ml. The method was successfully applied to the determination of cyanide in waste water.

     

Antioxidant activityofaromatic alkaloids from the marine sponges <Emphasis Type="Italic">Aaptos aaptos</Emphasis> and <Emphasis Type="Italic">Hyrtios</Emphasis> SP.

Aaptamine (1) and isoaaptamine (2) were isolated from the marine sponge Aaptos aaptos; 6-bromo-2′-de-N-methylaplysinopsin (3) from the marine sponge Hyrtios sp. Alkaloids 1–3 were tested for the ability to trap 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical, to reduce Folin–Ciocalteau reagent (FCR), and to inhibit oxidation of linoleic acid (LA) induced by peroxide radicals. Compounds 1 (IC₅₀ 18 μM), 2 (IC₅₀ 16 μM), and 3 (IC₅₀ 18 μM) reacted strongly with DPPH, comparable with trolox (IC₅₀ 16 μM) and showed high reducing ability for FCR. The inhibition of LA oxidation by 1–3 was comparable with that of ionol (BHT). It was shown that the antioxidant activity of 1–3 was related to their ability to release both electrons and H atoms.     

Hypocrol A,a new tyrosol derivative from a sponge-derived strain of the fungus Hypocrea koningii

In continuation of our search for new antibacterial and antioxidant metabolites from sponge-derived fungi, one new tyrosol derivative, hypocrol A (1), together with four known congeners, trichodenol B (2), 4-hydroxyphenethyl acetate (3), 4-hydroxyphenethyl tetradecanoate (4) and 1-oleyltyrosol (5), was isolated from the strain Hypocrea koningii PF04. Their planar structures were unequivocally elucidated by spectroscopic methods and comparison with the literature data. All the compounds displayed weak antibacterial activities against Staphylococcus aureus, methicillin-resistant S. aureus and Escherichia coli, whereas compounds 1 and 2 exhibited a moderate antioxidant efficacy in the DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging assay with IC₅₀ values of 48.5 and 97.4 μg/mL, respectively.