Interaction of cyproheptadine hydrochloride with human serum albumin using spectroscopy and molecular modeling methods

The interaction between cyproheptadine hydrochloride (CYP) and human serum albumin (HSA) was investigated by fluorescence spectroscopy, UV–vis absorption spectroscopy, Fourier transform infrared spectroscopy (FT‐IR) and molecular modeling at a physiological pH (7.40). Fluorescence of HSA was quenched remarkably by CYP and the quenching mechanism was considered as static quenching since it formed a complex. The association constants K_a and number of binding sites n were calculated at different temperatures. According to Förster's theory of non‐radiation energy transfer, the distance r between donor (human serum albumin) and acceptor (cyproheptadine hydrochloride) was obtained. The effect of common ions on the binding constant was also investigated. The effect of CYP on the conformation of HSA was analyzed using FT‐IR, synchronous fluorescence spectroscopy and 3D fluorescence spectra. The thermodynamic parameters ΔH and ΔS were calculated to be ?14.37 kJ mol^?1 and 38.03 J mol^?1 K^?1, respectively, which suggested that hydrophobic forces played a major role in stabilizing the HSA‐CYP complex. In addition, examination of molecular modeling indicated that CYP could bind to site I of HSA and that hydrophobic interaction was the major acting force, which was in agreement with binding mode studies. Copyright © 2012 John Wiley & Sons, Ltd.     

REACTION Of GLYCOSYL ISOTHIOCYNATES WITH 3-INDOLYLAMINOMETHYL-KETONE HYDROCHLORIDE

ABSTRACT

Reaction of glycosyl isothiocyanate 1a-c with 3-indolylaminomethyl-ketone hydrochloride(2) yielded glycosylthiourea derivatives 3a-c. Cyclodehydration of 3a-c with acetic anhydride afforded 5-(indol-3-yl)-2-[N-per-O-acetyl-D-glycopyranosyl)amino]thiazoles 4a-c. Deacetylation of 4a-c gave 5-(indol-3-yl)-2-[N-(D-glycopyranosyl) amino]thiazoles 5a-c.     

Calcium ions and osteoclastogenesis initiate the induction of bone formation by coral‐derived macroporous constructs

Coral-derived calcium carbonate/hydroxyapatite macroporous constructs of the genus Goniopora with limited hydrothermal conversion to hydroxyapatite (7% HA/CC) initiate the induction of bone formation. Which are the molecular signals that initiate pattern formation and the induction of bone formation? To evaluate the role of released calcium ions and osteoclastogenesis, 7% HA/CC was pre-loaded with either 500 μg of the calcium channel blocker, verapamil hydrochloride, or 240 μg of the osteoclast inhibitor, biphosphonate zoledronate, and implanted in the rectus abdominis muscle of six adult Chacma baboons Papio ursinus. Generated tissues on days 15, 60 and 90 were analysed by histomorphometry and qRT-PCR. On day 15, up-regulation of type IV collagen characterized all the implanted constructs correlating with vascular invasion. Zoledronate-treated specimens showed an important delay in tissue patterning and morphogenesis with limited bone formation. Osteoclastic inhibition yielded minimal, if any, bone formation by induction. 7% HA/CC pre-loaded with the Ca⁺⁺ channel blocker verapamil hydrochloride strongly inhibited the induction of bone formation. Down-regulation of bone morphogenetic protein-2 (BMP-2) together with up-regulation of Noggin genes correlated with limited bone formation in 7% HA/CC pre-loaded with either verapamil or zoledronate, indicating that the induction of bone formation by coral-derived macroporous constructs is via the BMPs pathway. The spontaneous induction of bone formation is initiated by a local peak of Ca⁺⁺ activating stem cell differentiation and the induction of bone formation.     

Preparation and in vitro evaluation of xanthan gum facilitated superabsorbent polymeric microspheres

Interpenetrating polymer network (IPN) hydrogel microspheres of xanthan gum (XG) based superabsorbent polymer (SAP) and poly(vinyl alcohol) (PVA) were prepared by water-in-oil (w/o) emulsion crosslinking method for sustained release of ciprofloxacin hydrochloride (CIPRO). The microspheres were prepared with various ratios of hydrolyzed SAP to PVA and extent of crosslinking density. The prepared microspheres with loose and rigid surfaces were evidenced by scanning electron microscope (SEM). Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analysis confirmed the IPN formation. Differential scanning calorimetry (DSC) study was performed to understand the dispersion nature of drug after encapsulation. The in vitro drug release study was extensively evaluated depending on the process variables in both acidic and alkaline media. All the formulations exhibited satisfactory physicochemical and in vitro release characteristics. Release data indicated a non-Fickian trend of drug release from the formulations. Based on the results, this study suggest that CIPRO loaded IPN microspheres were suitable for sustained release application.     

Effect of Oxidized Arachidonic Acid and Hexanal on the Mouse Taste Perception of Bitterness and Umami

The oxidization of fatty acids generates many volatile compounds forming an aroma, but little is known whether mammals use gustatory sense to detect the oxidized products as a taste or only use olfactory sense to detect as an aroma. We examined in this study the effect of aqueous extracts of the compounds from autoxidized arachidonic acid (AA) ethyl ester or hexanal which is the predominant component generated from oxidized AA by the anosmic mouse licking performance to a tastant. The addition of the water extract from oxidized AA or hexanal to a quinine hydrochloride (QHCl) solution decreased the anosmic mice licking frequency at several concentrations of QHCl. Hexanal also reduced the licking frequency of anosmic mice conditioned to avoid MSG at several concentrations of monosodium glutamate (MSG). These results suggest that hexanal would affect mouse taste perception to QHCl and MSG via the gustatory sensation.     

High-level SUMO-mediated fusion expression of ABP-dHC-cecropin A from multiple joined genes in Escherichia coli

The antimicrobial peptide ABP-dHC-cecropin A is a small cationic peptide with potent activity against a wide range of bacterial species. Evidence of antifungal activity has also been suggested; however, evaluation of this peptide has been limited due to the low expression of cecropin proteins in Escherichia coli. To improve the expression level of ABP-dHC-cecropin A in E. coli, tandem repeats of the ABP-dHC-cecropin A gene were constructed and expressed as fusion proteins (SUMO-nABP-dHC-cecropin, n = 1, 2, 3, 4) via pSUMO-nABP-dHC-cecropin A vectors (n = 1, 2, 3, 4). Comparison of the expression levels of soluble SUMO-nABP-dHC-cecropin A fusion proteins (n = 1, 2, 3, 4) suggested that BL21 (DE3)/pSUMO-3ABP-dHC-cecropin A is an ideal recombinant strain for ABP-dHC-cecropin A production. Under the selected conditions of cultivation and isopropylthiogalactoside (IPTG) induction, the expression level of ABP-dHC-cecropin A was as high as 65 mg/L, with ∼21.3% of the fusion protein in soluble form. By large-scale fermentation, protein production reached nearly 300 mg/L, which is the highest yield of ABP-dHC-cecropin A reported to date. In antibacterial experiments, the efficacy was approximately the same as that of synthetic ABP-dHC-cecropin A. This method provides a novel and effective means of producing large amounts of ABP-dHC-cecropin A.     

Interaction between fasudil hydrochloride and bovine serum albumin: spectroscopic study

The interaction between fasudil hydrochloride (FSD) and bovine serum albumin (BSA) was investigated using fluorescence and ultraviolet spectroscopy under imitated physiological conditions. The Stern–Volmer quenching model has been successfully applied and the results revealed that FSD could quench the intrinsic fluorescence of BSA effectively via static quenching. The binding constants and binding sites for the BSA–FSD system were evaluated. The corresponding thermodynamic parameters obtained at different temperatures indicated that hydrophobic force played a major role in the interaction of FSD and BSA. The distance between the donor (BSA) and the acceptor (FSD) was obtained according to fluorescence resonance energy transfer (FRET). Synchronous fluorescence spectroscopy and FT‐IR spectra showed that the conformation of BSA was changed in the presence of FSD. Copyright © 2015 John Wiley & Sons, Ltd.     

Effect of guanidine hydrochloride and urea on the interaction of 6-thioguanine with human serum albumin: a spectroscopic and molecular dynamics based study

6-thioguanine (6-TG) is an antineoplastic, nucleobase guanine, purine analog drug belongs to thiopurine drug-family of antimetabolites. In the present study, we report an experimental approach towards interaction mechanism of 6-TG with human serum albumin (HSA) and examine the chemical stability of HSA in the presence of denaturants such as guanidine hydrochloride (GdnHCl) and urea. Interaction of 6-TG with HSA has been studied by various spectroscopic and spectropolarimeteric methods to investigate what short of binding occurs at physiological conditions. 6-TG binds in the hydrophobic cavity of subdomain IIA of HSA by static quenching mechanism which induces conformation alteration in the protein structure. That helpful for further study of denaturation process where change in secondary structures causes unfolding of protein that also responsible for severance of domain III from rest of the protein part. We have also performed molecular simulation and molecular docking study in the presence of denaturating agents to determine the binding property of 6-TG and the effect of denaturating agents on the structural activity of HSA. We had found that GdnHCl is more effective denaturating agent when compared to urea. Hence, this study provides straight evidence of the binding mechanism of 6-TG with HSA and the formation of intermediate or unfolding transition that causes unfolding of HSA.     

Determination of oxytetracycline hydrochloride in milk and egg white samples using Ru(bipy)32+–Ce(SO4)2 chemiluminescence

A novel, rapid and sensitive chemiluminescence (CL) method for the determination of oxytetracycline hydrochloride (OTCH) is described in this paper. The presented method was based on the fact that OTCH could immensely enhance the CL of the reaction of cerium sulfate and tris(2,2‐bipyridyl) ruthenium (II) in acidic medium. Under optimal experimental conditions, CL intensity was favorably linear for OTCH in the range 5.0 × 10^?7 to 5.0 × 10^?5 g/ml, with a detection limit of 1.5 × 10^?7 g/ml (S/N = 3). The relative standard detection was 4.76% for 5.0 × 10^?6 g/ml (n = 11). This method was successfully applied to the analysis of OTCH in milk and egg white samples. According to the results of the kinetic curves for OTCH in the Ru(bipy)₃²⁺–Ce(SO₄)₂ CL system, together with CL and ultraviolet (UV)–visible spectra, the possible mechanism of the CL reaction is discussed briefly.     

Effect of stachydrine hydrochloride to the prostate hyperplasia model in mice

Study the effect of stachydrine hydrochloride to prostatic hyperplasia in mice which made of the urogenital sinus implantation. KM male mices were selected.The group was given the respective drugs for gavage, the group of BG and MG were given the distilled water which the same amount as the drugs group for 21 consecutive days. The level of DHT, ACP, Non PACP were measured in serum, the average wet weight of the prostate and prostate index were calculated, the expression of bFGF, EGF, IGF-I, TGF-β in prostate tissue were measured, the pathological changes of the prostate, kidney, thymus, spleen were observed by HE staining. Compared with MG, stachydrine hydrochloride high (SHH), medium (SHM) and low (SHL) group could reduced the level of DHT and PACP in serum significantly (P < 0.01); SHM and SHL could increased the express of TGF-β1 significantly (P < 0.05); SHH, SHM, SHL could reduced the express of EGF significantly (P < 0.01); SHM could reduced the express of IGF-Ⅰ significantly (P < 0.01); Compared with MG, SHH, SHM, SHL could reduced the pathological changes of prostate significantly (P < 0.01); FG could reduced the kidney pathological changes significantly (P < 0.01). Stachydrine hydrochloric had no significant effect on the kidney. Stachydrine hydrochloride had the effect of improve thymus, spleen pathological changes. Stachydrine hydrochloride has a good inhibition effect on prostatic hyperplasia model in mices.