Md. Zakir Sultan

Labdane-Type Diterpenes Active against Acne from Pine Cones (Pinus densiflora)

Bioassay-guided extraction and fractionation of the aqueous methanolic extract of the cones of Pinus densiflora (Pinaceae) afforded one new labdane-type diterpene aldehyde, 15-nor-14-oxolabda-8(17),12 E-diene-18-oic acid, along with eight known diterpenes. Their structures were elucidated using spectroscopic methods as well as by comparison with previously reported data. The isolates showed antibacterial (Propionibacterium acnes) and antifungal activities.

Anti-acne activities of pulsaquinone, hydropulsaquinone, and structurally related 1, 4-quinone derivatives

Quinone type compound, pulsaquinone 1, isolated from the aqueous ethanol extract of the roots of Pulsatilla koreana exhibited antimicrobial activities against an anaerobic non-spore-forming gram-positive bacillus, Propionibacterium acnes, which is related with the pathogenesis of the inflamed lesions in a common skin disease, acne vulgaris. Compound 1 was unstable on standing and thus converted to more stable compound 2, namely hydropulsaquinone by hydrogenation, whose activity was comparable to mother compound 1 (MIC for 1 and 2 against P. acnes: 2.0 and 4.0 μg/mL, respectively). Other structurally-related quinone derivatives (3–13) were also tested for structure-activity relationship against anaerobic and aerobic bacteria, and fungi. The antimicrobial activity was fairly good when the quinone moiety was fused with a nonpolar 6- or 7-membered ring on the right side whether or not conjugated (1,4-naphtoquinone derivatives 3–5), while simple quinone compounds 6–9 showed poor activity. It seems that the methoxy groups at the left side of the quinone function deliver no considerable antimicrobial effect.

An In Vitro Study of Binding of Aceclofenac and Pantoprazole with Bovine Serum Albumin by UV Spectroscopic Method

An In Vitro Study of Binding of Aceclofenac and Pantoprazole with Bovine Serum Albumin by UV Spectroscopic Method Plasma protein binding is one of the most important pharmacokinetic parameter of drug. The study was designed to determine the binding of Aceclofenac and Pantoprazole to Bovine Serum Albumin. The study was conducted by equilibrium dialysis method followed by measurement using a spectrophotometer at pH 7.4 and 37°C

Interaction of nalbuphine hydrochloride with deoxyribonucleic acid measured by fluorescence quenching.

The interaction of nalbuphine hydrochloride with calf thymus deoxyribonucleic acid was investigated by absorption and fluorescence titration techniques. Hypochromic effect was observed in the absorption spectra of nalbuphine. The fluorescence quenching of nalbuphine by DNA was found to be static according to Stern-Volmer constant at different temperature (2.257×103 L/mol and 1.678×103 L/mol at 298 K and 308 K respectively; binding constants (K) between calf thymus DNA and nalbuphine were 2.081×103 and 8.26×101 at 298 K and 308 K respectively). The binding numbers (n) were 0.9955 and 0.6762 with the standard deviation of 0.225 at 2 different temperatures which indicates mol ratio of Nalbuphine and DNA remains unchanged at different temperatures (298 K and 308 K). The binding affinity of nalbuphine to DNA was calculated at different temperatures and the stoichiometry of binding was characterized to be about 1 nalbuphine molecule per nucleotide. Calibration for nalbuphine, based on quenching titration data, was linear in the concentration range 6.3×10-6 to 6.4×10-4 mol/L. And these binding forces also indicate the binding site of Nalbuphine to be at the minor groove of DNA.

Fluorescence Spectroscopic Study of Interaction between Olanzapine and Bovine Serum Albumin

The binding capacity of an antipsychotic drug, olanzapine with bovine serum albumin (BSA) was studied. The experiment was designed to investigate the interaction between olanzapine and BSA using fluorescence spectroscopy at different temperatures (298 K and 308 K). Fluorescence quenching constant was determined from Stern-Volmer equation. Van’t Hoff equation was used to determine the thermodynamic parameters such as free energy (ΔG), enthalpy (ΔH) and entropy (ΔS). A strong quenching was observed in the fluorescence spectrum. The quantitative analysis revealed that olanzapine bound with BSA via a dynamic quenching through hydrophobic interactions, where binding constant Kb at 280 nm was 10.28x104 μM-1 and 10.739x104 μM-1 at 298 and 308 K, whereas it was 19.31x104 μM-1 and 18.923x104 μM-1 when the study was conducted at 293 nm, respectively. The number of bound olanzapine molecules per BSA protein was ~0.5 at both the temperatures. The Kb value in different temperatures suggested that the stability of BSA-olanzapine complex increased with the increase of temperature at 280 nm but reversed effect was observed in excitation wavelength of 293 nm. Positive ΔHo and ΔSo were the distinctive characteristics that allowed us to suggest that the interaction was mostly hydrophobic in nature.

A Novel Ion-Pair RP-HPLC Method for Simultaneous Quantification of Naproxen and Esomeprazole in Pharmaceutical Formulations

A rapid, sensitive and stability indicating ion-pair reversed-phase high-performance liquid chromatographic method was developed for simultaneous estimation of naproxen (NPX) and esomeprazole (ESP) in pharmaceutical preparations. In our study, this new method was used to overcome the instability problem of ESP during high-performance liquid chromatographic analysis in the presence of acidic drugs such as NPX. The method was validated according to ICH, FDA and USP guidelines with respect to accuracy, precision, specificity, linearity, solution stability, robustness, sensitivity and system suitability. The method was developed by using an isocratic condition of mobile phase comprising buffer [tetrabutylammonium hydroxide (0.0077 M) and n-heptane sulfonic acid-Na salt (0.002 M), pH 7.6], acetonitrile and methanol in a 60 : 20 : 20 v/v/v ratio at a flow rate of 1.5 mL/min over a C-18 (Octadecyl-silica, 5 µm, 250 × 4.6 mm) column at ambient temperature. The recovery for both drugs was found to be >99% which demonstrated the accuracy of this method. Intra- and inter-day precision studies of the new method were less than the maximum allowable limit [% relative standard deviation (RSD) ≤2.0 according to FDA]. The method showed linear response with a correlation coefficient (r(2)) value of 0.999 for both drugs. More importantly, ESP was quite stable in diluting solvent and mobile phase in the presence of NPX for >3 days. Therefore, it was found to be an accurate, reproducible, sensitive and highly stability-indicating method and can be successfully applied for routine analysis of simultaneous assay of NPX and ESP in pharmaceutical dosage forms.

In vitro Study of Interactions of Sildenafil Citrate with Bovine Serum Albumin in Presence of Bisoprolol Fumarate and Metformin Hydrochloride by Fluorescence Spectrophotometry

Aims: This paper describes the In vitro study of protein binding by sildenafil citrate (SC) in presence of bisoprololfumarate (BF) and metformin hydrochloride (MH). Study Design: Study was designed to assess In vitro of quenching of bovine serum albumin (BSA) by sildenafil citrate (SC) in presence of bisoprolol fumarate (BF) and metformin hydrochloride (MH) by fluorescence spectrophotometry. Place and Duration of Study: Drug Analysis and Research Laboratory, Centre for Advanced Research in Sciences, University of Dhaka, Dhaka-1000, Bangladesh between December 2013 and March 2014. Methodology: In the present work, the In vitro study of quenching of BSA by SC in presence of BF Original Research Article Rokonujjaman et al.; BJMMR, 5(3): 362-375, 2015; Article no.BJMMR.2015.040 363 and MH have been studied by fluorescence emission spectroscopy under different conditions. At first, the BSA solution (20 μM) was prepared in phosphate buffer (pH =7.4) in eight test tubes and different amounts of sildenafil citrate was added to each BSA solution to obtain the final concentrations as 0, 20, 40, 80, 120, 160,240 and 320 × 10 -6 molL -1 , respectively. Then the fluorescence emission spectra of BSA-SC system were recorded for eight test tubes at two excitation wavelengths of BSA (λExmax= 280 nm and λExmax=293 nm) at 298 K and 308 K. Similarly, the fluorescence emission spectra of BSA-(SC+BF), BSA-(SC+MH) and BSA-(SC+BF+MH) systems were recorded at 280 nm and293 nm at 298 K and 308 K. Quenching constants were determined using the Stern-Volmer equation to provide a measure of the strength of quenching of BSA by SC in presence of BF and MH in all the systems. Results: The quenching of BSA by SC was increased in presence of BF and MH but remained close in presence of both BF and MH. Quenching constants were larger for the BSA-(SC+BF) system and ranked in the order as BSA-(SC+BF)>BSA-(SC+MH)>BSA-(SC+BF+MH)≈ BSA-SC at 280 nm at two different temperatures, respectively. But quenching at the excitation wavelength of 293 nm was ranked in order as BSA-(SC+BF) >BSA-(SC+MH) >BSA-(SC+BF+MH)>BSA-SC at 298 K and 308 K, respectively. Conclusion: It was found that BSA quenched by SC in presence of BF and MH, which indicated that the effectiveness of SC might be predominately influenced by these drugs.

Evaluation of antinociceptive, anti-inflammatory and anxiolytic activities of methanolic extract of Terminalia citrina leaves

Abstract Objective To investigate the antinociceptive, anti-inflammatory and anxiolytic effects of methanolic extracts of Terminalia citrina (T. citrina) leaves (Family: Combretaceae). Methods The antinociceptive activity was evaluated by acetic acid induced writhing method and radiant heat tail flick method while anti-inflammatory activity was evaluated by human red blood cell membrane stabilization method and anxiolytic activity by elevated plus maze model. Results The methanolic extract of T. citrina leaves showed significant antinociceptive, anti-inflammatory and anxiolytic effects in dose dependent manner compared to their respective standard drugs. Conclusions The present study demonstrated that T. citrina possesses antinociceptive, anti-inflammatory and anxiolytic effects.

A Study of Prophylactic Effect Against Diabetes of Two Ayurvedic Drugs ‘Jambadyarista’ and ‘Bohumutrantak Ras’ in Normal as well as Alloxan-induced Diabetic Rats

Aims: The present study was designed to evaluate the anti -diabetic as well as prophylactic activity of Jambadyarista and Bohumutrantak Ras in alloxan -induced diabetic rats. Study Design:Study the prophylactic and antiglycemic effects against diabetes of two

Study of Interaction between Febuxostat and Bovine Serum Albumin byFluorescence Spectroscopy

The interaction of an anti-gout drug, febuxostat was studied with bovine serum albumin (BSA) applying fluorescence quenching method for the first time. Interaction parameter and magnitude of the force indicated for both, dynamic and static quenching in between febuxostat and BSA protein. Thermodynamic studies indicated for both hydrogen and hydrophobic interactions, observed at 280 nm and only hydrophobic at 293 nm excitation wavelength. Negative ΔHo and positive ΔSo, indicated for distinctive characteristics for the existence of both, hydrogen and hydrophobic binding throughout the interactions. The binding constant Kb at λex=280 nm was 3.467 × 103 μM-1 and 4.943 × 103 μM-1 at 298 and 308 K temperature whereas, 5.54 × 103 μM-1 and 4.44 × 103 μM-1 was noted during excitation at λex=293 nm wavelength. The Kb values in different temperatures assumed that the stability of binding increased with the increase of temperature at λex=280 nm, but reverse effect was experienced at an excitation wavelength of λex=293 nm. The number of bound febuxostat molecules per BSA protein was found ~1.5 at both 298 and 308 K.