Quantitative Analysis of Bacoside A from Bacopa monnieri,Collected from Different Geographic Regions of India,by High-Performance Thin-Layer Chromatography-Densitometry

JPC – Journal of Planar Chromatography – Modern TLC - Bacoside A, a triterpenoid saponin, is a major constituent isolated from Bacopa monnieri (L.) Wettst. (Scrophulariaceae), used as a...     

Phase Transfer Catalysed Synthesis of Methyl α-Bromomethylacrylate

Methyl α-bromomethylacrylate 1 is an important intermediate both as a starting material for specifically functionalized polymers and for use in general organic synthesis. As an example of the former it has been used to prepare polymeric anthraquinoid dyes¹. Synthetically, its bifunctional reactivity towards nucleophilic attack has made it useful in the preparation of both spiro² and bicyclic^3,4 ring systems. Several reports of synthetic methods leading to α-methylenelactones, having potential antitumor activity, have also been reported which use α-bromomethylacrylate as a starting point⁵.     

Depletion interactions: a new control parameter for the self-assembly of diblock copolymer micelles

Small angle neutron scattering was performed on disordered mixtures of nonadsorbing homopolymer (A) chains and diblock (A-B) copolymer micelles in an A selective solvent. Increasing the molecular weight or concentration of A led to an increase in the aggregation number, and a decrease in the effective hard-sphere diameter of the micelles. Furthermore an intermicellar attractive force developed, which was successfully modeled by the Asakura-Oosawa depletion potential. Via an alternative model we also extracted information about mesoscopic clusters of micelles formed due to this attractive force.     

Kinetic and mechanistic studies of oxidation of alanine and phenylalanine by sodium N-chlorobenzene sulfonamide (chloramine-B) in hydrochloric acid medium

The kinetics of oxidation of alanine and phenylalanine by sodium N-chlorobenzene sulfonamide (CAB) has been investigated at 30°C in two ranges of acid concentrations. The reactions follow identical kinetics for both amino acids. At low acid concentration (0.03–0.10M), simultaneous catalysis by H⁺ and Cl^? ions is noted. The rate shows a first-order dependence on [CAB], but is independent of [substrate]. A variation of the ionic strength or the dielectric constant of the medium or the presence of the added reaction product benzene sulfonamide (BSA) has no pronounced effect on the rate. At [HCl] > 0.2M, the rate is independent of [H⁺], but shows a first-order dependence on [CAB] and a fractional-order dependence on [amino acid]. The addition of BSA or Cl^? ions, or a change in the ionic strength of the medium has no influence on the rate. Upon decreasing the dielectric constant of the medium, the rate increased, indicating positive ion–dipole interaction in the rate-determining step. The reaction was studied at different temperatures, and activation parameters have been computed. Rate laws in agreement with experimental results have been derived. Suitable mechanisms to account for the observed kinetics are proposed. The rate constants obtained from the derived rate laws as [H⁺], [Cl^?], and [substrate] vary are in excellent agreement with the observed rate constants, thus justifying the proposed rate laws and hence the suggested mechanistic schemes.     

Formulation and molecular docking simulation study of luliconazole nanosuspension–based nanogel for transdermal drug delivery using modified polymer

The purpose of study was to formulate nanosuspension-based nanogel of luliconazole (LLZ) for transdermal delivery to enhance its skin retention and effectiveness using modified starch ester. Nanosuspensions show promising results with size of 369.1–745.4 nm having PDI 0.193–0.344 and zeta potential 22–45 mV. These nanosuspensions form micelles and hydrophobic core of it provides the reservoir for LLZ with better drug loading and binding interaction. Drug loading was confirmed by percent drug entrapment efficiency (PDEE) and PDI. Molecular docking simulation (MDS) provides detail insight of LLZ polymer complexation at hydrophobic cavity of micelles and revealed that there was binding between drug and polymer in aqueous milieu having interaction energy ranges from ?7.1 to ?6.0 kcal/mol. Nanosuspensions so made were incorporated into gel by using Carbopol 934 ® and tested for % drug content, spreadability, pH, and viscosity with ranges of 101.62–97.71, 28.94–34.38 (gcm/s), 6.91–7.21, and 4802.62–9461.83 (cp), respectively. Nanogel also evaluated for stability and skin permeation study using human cadaver skin (HCS). In vitro skin permeation study indicated that the amount of LLZ permeated through skin from nanogel (71.042–83.818 μgcm ?2) was higher than standard cream (70.085 μgcm ?2). Nanogel increased the accumulation of LLZ in HCS ~3 times than standard cream. The transdermal flux was greater for standard cream (123.79 μgcm ?2), whereas smaller for nanogel (50.394–82.743 μgcm ?2) due to skin retention. Nanosuspension-based gel are able to especially favor LLZ accumulation into skin, provide better drug loading, improve stability, and efficacy. Thus, targeting older antibiotics such as LLZ and formulating into nanosystem utilized to expand its usefulness to physicians to treat illnesses caused by resistant fungal strains.     

Ameliorating effects of Tamarindus indica fruit extract on anti-tubercular drugs induced liver toxicity in rats

The study aimed to evaluate the hepatoprotective potential of aqueous extract of Tamarindus indica fruit against combination of two antitubercular drugs viz. Isoniazid and Rifampicin induced hepatotoxicity in rats. In vitro antioxidant activity of aqueous extract of T. indica by DPPH–HPLC method was found to be 81.48%. Treatment with aqueous extract of T. indica significantly reduced the elevated levels of biochemical markers such as SGOT, SGPT, ALP, bilirubin, TBARS and increased the albumin level as well antioxidant activities of SOD, CAT and GSH in intoxicated rats. The biochemical changes were supported by histological observations. Results of this study clearly demonstrate that aqueous extract of T. indica fruit protects against anti tuberculosis induced oxidative liver damage in rats and thus possess significant hepatoprotective activity. Further, it could be suggested that supplementation with this food extract might prove beneficial in the individuals on anti-TB drugs.     

Computational Identification of Dithymoquinone as a Potential Inhibitor of Myostatin and Regulator of Muscle Mass

The skeletal muscle (SM) is the largest organ in the body and has tremendous regenerative power due to its myogenic stem cell population. Myostatin (MSTN), a protein produced by SM, is released into the bloodstream and is responsible for age-related reduced muscle fiber development. The objective of this study was to identify the natural compounds that inhibit MSTN with therapeutic potential for the management of age-related disorders, specifically muscle atrophy and sarcopenia. Sequential screening of 2000 natural compounds was performed, and dithymoquinone (DTQ) was found to inhibit MSTN with a binding free energy of −7.40 kcal/mol. Furthermore, the docking results showed that DTQ reduced the binding interaction between MSTN and its receptor, activin receptor type-2B (ActR2B). The global energy of MSTN-ActR2B was found to be reduced from −47.75 to −40.45 by DTQ. The stability of the DTQ–MSTN complex was subjected to a molecular dynamics analysis for up to 100 ns to check the stability of the complex using RMSD, RMSF, Rg, SASA, and H-bond number. The complex was found to be stable after 10 ns to the end of the simulation. These results suggest that DTQ blocks MSTN signaling through ActR2B and that it has potential use as a muscle growth-promoting agent during the aging process.     

Development and Validation of a Stability-Indicating High-Performance Thin-Layer Chromatographic Method for the Simultaneous Quantification of Sparfloxacin and Flurbiprofen in Nanoparticulate Formulation

JPC – Journal of Planar Chromatography – Modern TLC - A simple, sensitive, precise, rapid, and reliable high-performance thin-layer chromatographic (HPTLC) method for the simultaneous...     

Photophysics and Rotational Dynamics of a Hydrophilic Molecule in a Room Temperature Ionic Liquid

We have studied the photophysics and rotational diffusion of hydrophilic solute 7‐(N, N′‐diethylamino)coumarin‐3‐carboxylic acid (7‐DCCA) in a room temperature ionic liquid methyltrioctylammonium bis(trifluoromethylsulfonyl) imide ([N₁₈₈₈][NTf₂]). Comparison of activation energies of viscous flow and nonradiative decay shows that the photophysical properties of 7‐DCCA are not guided by the bulk viscosity of the medium but are dependent on the specific solute solvent interaction and structural heterogeneity of the medium. The rotational relaxation behaviour of 7‐DCCA in [N₁₈₈₈][NTf₂] shows significant deviation from the Stokes Einstein Debye hydrodynamic model of rotational diffusion. This is indicative of the influence of specific solute solvent interaction on the rotational relaxation behaviour of 7‐DCCA. Comparison of activation energy of rotational relaxation with activation energy of viscous flow clearly reinforces our assumption that the structural heterogeneity of the medium and specific solute solvent interaction plays a dominant role on the rotational diffusion instead of bulk viscosity.     

A Validated Stability-Indicating TLC Method for Determination of Forskolin in Crude Drug and Pharmaceutical Dosage Form

A simple, accurate, selective, precise, economical and stability-indicating high-performance thin-layer chromatographic method for analysis of forskolin in crude drug and in pharmaceutical dosage form was developed and validated. The method was developed on TLC aluminium plates precoated with silica gel 60F-254 using solvent system benzene:methanol (9:1, v/v), which gives compact spot of forskolin (R _f value 0.25 ± 0.02). Densitometric analysis of forskolin was carried out in the absorbance mode at 545 nm after spraying with anisaldehyde sulphuric acid. The linear regression analysis data for the calibration plots showed good linear relationship with r = 0.994 and 0.994 with respect to peak height and peak area, respectively, in the concentration range 100–1,000 ng per spot. The limits of detection and quantification were 8.1 and 26.9 ng per spot, respectively. The proposed method was applied for determination of forskolin in Coleus forskohlii root and in capsule dosage forms, which showed 0.18 and 0.57% w/w of forskolin. Forskolin was subjected to acid and alkali hydrolysis, oxidation, photodegradation and heat degradation. It was observed that the drug is susceptible to acid, base hydrolysis, oxidation, photo-oxidation and heat degradation. Statistical analysis proves that the method is repeatable, selective and accurate for the estimation of forskolin in crude drug and in pharmaceutical dosage forms. The developed method effectively resolved the forskolin from components of C. forskohlii root, from excipients of capsule as well as the degradation products of forskolin hence, it can be employed for routine analysis and as a stability-indicating method.