Binding of Beta-site Amyloid Precursor Protein Cleaving Enzyme 1 (BACE1) Inhibitor Aminoquinoline (68K) for Possible Treatment of Alzheimer\u27s Disease

Alzheimer’s Disease (AD), affecting approximately 24 million people worldwide, is characterized by the formation of amyloid-β plaques within the brain. Alzheimer’s research has been focused on limiting amyloid-β production through developing inhibitors for the enzymes needed within the amyloid cascade. This project focuses on the aminoquinoline class of inhibitors, of which 68K (PDB: 5i3Y) is the most effective because of its strong Kd and IC50 values. The students of the Honors Protein Modeling class at Nova Southeastern University modeled the interaction between Beta-site Amyloid Precursor Protein Cleaving Enzyme 1 (BACE-1) and 68K. Using Jmol a model was developed, and 3D printed to show how the inhibitor (68K) fit into the enzyme’s active site. This model highlights important aspects of the interactions between the ligand and the BACE-1 enzyme. 68K has strong interactions with 32 amino acid residues in BACE1, some of which are intertwined with one another. For example, BACE-1’s residues Val69, Pro70, and Tyr71 are known collectively as “the flap”. “The flap” is a β-hairpin loop structure that is positioned directly over BACE-1’s catalytic dyad, a group of amino acids within the active site of the enzyme. “The flap” is also responsible for regulating access to the enzyme’s catalytic dyad (Asp 32 and Asp 228) by a given substrate (or inhibitor). Researchers found the inhibitor 68K to have interactions with the flap which maximizes the strength of the interaction with BACE-1 residues, thus minimizing the distance between the inhibitor’s various functional groups and accommodating their specific polarities. Being able to visualize the protein structure using a 3D model aids in the understanding of how the ligand inhibits this enzyme leading to the progression of AD.https://nsuworks.nova.edu/protein_modeling_reports/1011/thumbnail.jp

Enhanced dissolution and bioavailability of gliclazide using solid dispersion techniques

Gliclazide is practically insoluble in water and its bioavailability is limited by dissolution rate. To enhance the dissolution rate and bioavailability the present study was aimed to formulate solid dispersions using different water soluble polymers such as polyethylene glycol 4000 (PEG 4000), polyethylene glycol 6000 (PEG 6000) using fusion method and polyvinyl pyrrolidone K- 30 (PVP K 30) by solvent evaporation method. The interaction of gliclazide with the hydrophilic polymers was studied by Differential Scanning Calorimetry (DSC), Fourier Transformation-Infrared Spectroscopy (FTIR) and X-Ray diffraction analysis. Solid dispersions were characterized for physicochemical properties like drug content, surface morphology and dissolution studies. Various factors like type of polymer and ratio of the drug to polymer on the solubility and dissolution rate of the drug were also evaluated. Pharmacokinetic studies of optimized formulation were compared with pure drug and marketed formulation in wistar rats. The dissolution of the pure drug and solid dispersion prepared with PVP K 30 (1:1) showed 38.3 + 4.5 % and 95 + 5.2 % release respectively within 30 min. Peak plasma concentration of pure drug, solid dispersion (PVP K 30) and marketed formulation was found to be 8.76 + 2.5, 16.04 + 5.5 and 9.24 + 3.6 μg/ml respectively, from these results it was observed that there is two fold increase in peak plasma concentration compared to pure drug. Solid dispersion is an effective technique in increasing solubility, dissolution rate and bioavailability of the poorly soluble drugs.Keywords: Gliclazide; solubility; solid dispersion; pharmacokinetics; peak plasma concentration; half lif

Liposomi rivastigmina za isporuku u mozak intranazalnim putem

The present study is mainly aimed at delivering a drug into the brain via the intranasal route using a liposomal formulation. For this purpose, rivastigmine, which is used in the management of Alzheimer’s disease, was selectd as a model drug. Conventional liposomes were formulated by lipid layer hydration method using cholesterol and soya lecithin as lipid components. The concentration of rivastigmine in brain and plasma was studied in rat models after intranasal and oral administration of liposomes and free drug. A significantly higher level of drug was found in the brain with intranasal liposomes of rivastigmine compared to the intranasal free drug and the oral route. Intranasal liposomes had a longer half-life in the brain than intranasally or orally administered free drug. Delivering rivastigmine liposomes through the intranasal route for the treatment of Alzheimer’s disease might be a new approach to the management of this condition.Glavni cilj rada je razvoj liposoma za intranazalnu primjenu za isporuku lijeka u mozak. U tu svrhu izabran je rivastigmin kao modelni lijek koji se upotrebljava u terapiji Alzheimerove bolesti. Liposomi su pripravljeni metodom hidratacije lipidnog sloja koristeći kolesterol i lecitin iz soje kao lipidne komponente. Praćena je koncentracija rivastigmina u mozgu i plazmi nakon intranazalne i peroralne primjene liposoma i slobodnog lijeka. S intranazalnim liposomima rivastigmina postignuta je značajno veća koncentracija lijeka u mozgu. Osim toga intranazalni liposomi imaju dulje vrijeme poluživota u mozgu. Intranazalna primjena liposoma rivastigmina mogla bi predstavljati novi pristup terapiji Alzheimerove bolesti

177Lu-Bombesin-PLGA (paclitaxel): A targeted controlled-release nanomedicine for bimodal therapy of breast cancer

The gastrin-releasing peptide receptor (GRPr) is overexpressed in>75% of breast cancers. 177Lu-Bombesin (177Lu-BN) has demonstrated the ability to target GRPr and facilitate efficient delivery of therapeutic radiation doses to malignant cells. Poly(D,L‑lactide‑co‑glycolide) acid (PLGA) nanoparticles can work as smart drug controlled- release systems activated through pH changes. Considering that paclitaxel (PTX) is a first-line drug for cancer treatment, this work aimed to synthesize and chemically characterize a novel polymeric PTX-loaded nanosystem with grafted 177Lu-BN and to evaluate its performance as a targeted controlled-release nanomedicine for concomitant radiotherapy and chemotherapy of breast cancer. PLGA(PTX) nanoparticles were synthesized using the single emulsification-solvent evaporation method with PVA as a stabilizer in the presence of PTX. Thereafter, the activation of PLGA carboxylic groups for BN attachment through the Lys1-amine group was performed. Results of the chemical characterization by FT-IR, DLS, HPLC and SEM/TEM demonstrated the successful synthesis of BN-PLGA(PTX) with a hydrodynamic diameter of 163.54 ± 33.25 nm. The entrapment efficiency of paclitaxel was 92.8 ± 3.6%. The nanosystem showed an adequate controlled release of the anticancer drug, which increased significantly due to the pH change from neutral (pH=7.4) to acidic conditions (pH=5.3). After labeling with 177Lu and purification by ultrafiltration, 177Lu-BN-PLGA(PTX) was obtained with a radiochemical purity of 99 ± 1%. In vitro and in vivo studies using MDA-MB-231 breast cancer cells (GRPr-positive) demonstrated a 177Lu-BNPLGA( PTX) specific uptake and a significantly higher cytotoxic effect for the radiolabeled nanosystem than the unlabeled BN-PLGA(PTX) nanoparticles. Using a pulmonary micrometastasis MDA-MB-231 model, the added value of 177Lu-BN-PLGA(PTX) for tumor imaging was confirmed. The 177Lu-BN-PLGA(PTX) nanomedicine is suitable as a targeted paclitaxel delivery system with concomitant radiotherapeutic effect for the treatment of GRPr-positive breast cancer.This study was partially supported by the National Council of Science and Technology (CONACyT-CB-A1S38087) and the International Atomic Energy Agency (CRP-F22064, Contract 18358). It was carried out as part of the activities of the “Laboratorio Nacional de Investigación y Desarrollo de Radiofármacos, CONACyT

Transpapillary Drug Delivery to the Breast

<div><p>The study was aimed at investigating localized topical drug delivery to the breast via mammary papilla (nipple). 5-fluorouracil (5-FU) and estradiol (EST) were used as model hydrophilic and hydrophobic compounds respectively. Porcine and human nipple were used for in-vitro penetration studies. The removal of keratin plug enhanced the drug transport through the nipple. The drug penetration was significantly higher through the nipple compared to breast skin. The drug’s lipophilicity had a significant influence on drug penetration through nipple. The ducts in the nipple served as a major transport pathway to the underlying breast tissue. Results showed that porcine nipple could be a potential model for human nipple. The topical application of 5-FU on the rat nipple resulted in high drug concentration in the breast and minimal drug levels in plasma and other organs. Overall, the findings from this study demonstrate the feasibility of localized drug delivery to the breast through nipple.</p></div

Experimental set-up for in-vitro drug penetration study.

<p>Experimental set-up for in-vitro drug penetration study.</p

In-vitro penetration parameters of 5-FU in porcine and human tissue.

<p>L is lag time; J_ss is flux at steady state; Q₄₈ is cumulative amount of drug permeated per cm² of the tissue at 48 hrs; C_T is tissue drug amount at 48 hrs. Results are presented as mean ± SEM (n = 3–4); ‘a’ is significant in comparison to porcine skin; ‘b’ is significant in comparison to human nipple with keratin plug; ‘c’ is significant in comparison to human skin. The values are significant at p<0.05 by one-way ANOVA.</p><p>In-vitro penetration parameters of 5-FU in porcine and human tissue.</p

Permeation of 5-FU through excised breast tissue.

<p>In-vitro permeation of 5-FU through porcine (A) and human (B) nipple after removing the keratin plug (KR), nipple with keratin plug, and breast skin. Each data point is represented as mean ± SEM (n = 3–4). † is significant in comparison to the results from nipple with keratin plug; *is significant in comparison to skin. The values are significant at p<0.05, by one-way ANOVA.</p

Confocal microscopic images of porcine nipple.

<p>(A) Cross section of porcine nipple after staining with hematoxylin-eosin. (Bar = 200 µm), (B) Confocal laser scanning microscopic images of porcine nipple, after treatment with hydrophilic dye sulforhodamine (SRB; upper panel) and hydrophobic dye Nile red (NR; lower panel). Image on the left panel is a cumulative xyz image of optical sections from 0 to 500 µm in the tissue. Images on the right panel are xz images from 0 to 500 µm (Bar = 100 µm).</p

Fluorescence microscopic images of nipple.

<p>Fluorescence microscopic images of 7–8 µm thick cryosections of porcine (A) and human (B) nipple after treatment with the fluorescent dyes, SRB (upper panel in A and B) and NR (lower panel in A and B). Sections were taken from the entire length of the nipple starting from the tip to the base of the nipple. (Bar = 100 µm); SRB- sulforhodamine; NR- Nile red.</p