Preparation and characterization of cyclodextrin inclusion complex of naringenin and critical comparison with phospholipid complexation for improving solubility and dissolution

Naringenin, a flavonoid specific to citrus fruits shows a variety of therapeutic effects like anti-inflammatory, anticarcinogenic, and antitumour effects. But it is associated with some limitations like poor water solubility, poor dissolution, lower half-life, and rapid clearance from the body. With the aim of improving amorphous nature, water solubility, and dissolution profile of naringenin and its complexes were prepared with β-cyclodextrin in three different molar ratios (1:1, 1:2, and 1:3) by solvent evaporation method. These complexes were characterized for solubility, drug content, chemical interaction (using FTIR), phase transition behavior (using DSC), crystallinity (using XRPD), surface morphology (using SEM), and in vitro dissolution study. The results were also critically compared with the results obtained from naringenin-phospholipid complexes (from author’s previous study). The prepared complexes showed high drug content (ranging from 69.53 to 84.38 %) and about two fold improvement in water solubility (from 41.81 to 76.31 μg mL^?1 in the complex with 1:3 ratio). SEM of the complexes showed irregular and rough surface morphology. FTIR, DSC, and XRPD data confirmed the formation of the complex. Unlike the free naringenin which showed a total of only 48.78 % drug release at the end of 60 min, the complex showed 98.0–100 % in dissolution study. Thus it was concluded that the β-cyclodextrin of naringenin may be of potential use for improving bioavailability of poorly soluble phytoconstituents/herbal drugs. On critical comparison with the phospholipid complex of naringenin both the techniques were found almost equally effective in improving the solubility and the dissolution performance of naringenin in the complex form.     

Response Factor Correction for Estimation of Ester Content in Biodiesel

EN 14103 is generally used for quantification of ester content in biodiesel free of heptadecanoate ester (C17:0) or methyl nonadecanoate (C19:0), which are employed as internal standards. It was observed that ester content obtained by EN 14103 method did not match with theoretical value of biodiesel, as the method did not take care of response factors of each component to compensate for changes in detector sensitivities. In this study, the whole range of fatty acid (C₆–C_24:1) methyl esters have been taken into consideration for the calculation of the ester content. Methyl nonadecanoate (C19:0) was used as an internal standard. The response factors of both the saturated and unsaturated methyl esters in the range C₆–C_24:1 were estimated and found in the range 0.97–1.16. The ester content was calculated after applying the response factors of each methyl ester. The results obtained by this method agreed well with the theoretical value as compared to estimated value using EN14103 method. The results obtained from this method also show good correlation (R ² = 0.98) with ¹H-NMR method. Further, this method does not depend on nature of biodiesel feed stock and is applicable to all methyl biodiesel samples obtained from different raw materials.     

Mechanistic aspects for the oxidation of brilliant green dye by chloramine-T in the presence of perchloric acid: a spectrophotometric kinetic approach

The kinetics of a triarylmethane dye, brilliant green (BG), by sodium N-chloro-p-toluenesulfonamide or chloramine-T (CAT) was studied spectrophotometrically in HClO₄ media at 303 K. Under identical experimental conditions, the rate law was ?d [BG]/dt = k [BG] [H⁺]. Variations in ionic strength (μ) of the medium had no effect on the oxidation velocity. Addition of p-toluenesulfonamide, the reduction product of CAT and Cl^?, had no significant effect on the rate of reaction. The values of rate constants observed at five different temperatures (298, 303, 308, 313, and 318 K) were utilized to calculate the activation parameters. The observed results have been explained by a general mechanism and the related rate law has been obtained. The process demonstrated in this study is cost effective, which holds great promise in potential application for pollutant control.     

Crystallographic evidence of hexacoordination at phosphorus via intramolecular coordination of donor groups on phosphane and phosphane sulphide

The X-ray structure analysis of bis(8-dimethylamino-l-naphthyl)phenylphosphane (3) and of the corresponding sulphide 4 has revealed hexacoordination at phosphorus in both cases, the N … P separations being less than the sum of the van der Waal radii. Furthermore, in both cases the overall geometry corresponds to a distorted bicapped tetrahedron. The optimum geometry calculated for 4 via the program developed by Autodesk (MM + method) suggests that the structure of the molecule is a function not only of steric requirements but also of electronic effects.     

Complexes of N-aroyl-N′-thiobenzohydrazide with cobalt(II), nickel(II) and zinc(II)

Summary New potential tetradentate ligands, N-benzoyl-N-thiobenzohydrazide (H₂BTBH) and N-salicyl-N-thiobenzohydrazide (H₂SBTH) have been prepared and characterized. Their complexes with Co^II, Ni^II and Zn^II have been prepared and characterized on the basis of elemental analyses, magnetic susceptibility measurements, and u.v.-vis., i.r. and ¹H-n.m.r. spectral studies. The bonding and stereochemistries of the complexes are discussed. H₂BTBH, H₂SBTH and the complexes have been screened towards a number of bacteria.     

E.s.r. studies on acylhydrazine and hydrazone copper(II) sulfate complexes

Summary Cu^II complexes of the [CuL₂(SO₄)]·nH₂O and [CuL(SO₄)(H₂O)₂]·nH₂O type, where L = benzoylhydrazine (PhCONHNH₂; BH) or iso-propanone benzoylhydrazone (PhCONHN:CMe₂; IBH), L= iso-nicotinoylhydrazine (NC₅H₄CONHNH₂; INH) or isopropanone iso-nicotinoylhydrazone (NC₅H₄CONHN: CMe₂; IINH); n = 0–2, were prepared and characterized by elemental analyses, molar conductances, and electronic, e.s.r. and i.r. spectral measurements. The electronic and e.s.r. spectra suggest a tetragonally distorted octahedral geometry in the solid state as well as in DMSO solution. The e.s.r. data also reveal an axial symmetry for most of the complexes in the solid state and in DMSO solution at 300 and 77 K, while the complex of IBH is isotropic at 300 K. The M_s = 2 transition observed for this complex suggests that it is a dimer. BH and INH bond to Cu^II through the C-O and NH₂ groups, whereas IBH and IINH bond through C-O and C-N groups.     

Electric field gradients in various chemical environments of133Ba by the sum peak method

The sum peak at 437 keV (356+81 keV) has been measured in various chemical and physico-chemical environments. The fact that the intensity ratio of the sum peak to its single peak changes with the circumstances in which the radioactive source is placed is used to observe the effect of the chemical environment on directional correlation coefficients of 351–81 keV cascade in¹³³Ba−¹³³Cs decay and to detect the variations in the electric field gradient in different barium compounds. The sum peak method has been found to be useful in describing the chemical influences onG ₂₂ parameters and hence in the study of electric field gradients.     

Novel Process Applications Using PHI-TEC II Adiabatic Calorimeter

This paper presents several applications of the PHI-TEC II that are not commonly associated with adiabatic calorimeters but which have proved to be extremely valuable. These include simulation of a deep oil well for enhanced oil recovery, isothermal calorimetry of a semibatch reaction, catalyst research using flow through reactors (both plug flow and CSTR) with controlled feeds of high pressure liquid and gas.This revised version was published online in November 2005 with corrections to the Cover Date.