Metabolic N-Dealkylation and N-Oxidation as Elucidators of the Role of Alkylamino Moieties in Drugs Acting at Various Receptors

Metabolic reactions that occur at alkylamino moieties may provide insight into the roles of these moieties when they are parts of drug molecules that act at different receptors. N-dealkylation of N,N-dialkylamino moieties has been associated with retaining, attenuation or loss of pharmacologic activities of metabolites compared to their parent drugs. Further, N-dealkylation has resulted in clinically used drugs, activation of prodrugs, change of receptor selectivity, and providing potential for developing fully-fledged drugs. While both secondary and tertiary alkylamino moieties (open chain aliphatic or heterocyclic) are metabolized by CYP450 isozymes oxidative N-dealkylation, only tertiary alkylamino moieties are subject to metabolic N-oxidation by Flavin-containing monooxygenase (FMO) to give N-oxide products. In this review, two aspects will be examined after surveying the metabolism of representative alkylamino-moieties-containing drugs that act at various receptors (i) the pharmacologic activities and relevant physicochemical properties (basicity and polarity) of the metabolites with respect to their parent drugs and (ii) the role of alkylamino moieties on the molecular docking of drugs in receptors. Such information is illuminative in structure-based drug design considering that fully-fledged metabolite drugs and metabolite prodrugs have been, respectively, developed from N-desalkyl and N-oxide metabolites.     

Solubility of Solid Pentane, 2-Methylbutane, and Cyclopentane in Liquid Argon at 87.3 K

The solubilities of solid pentane, 2-methylbutane (isopentane), and cyclopentane in liquid argon at 87.3 K have been measured by the filtration method. The C₅ hydrocarbon content in solution was determined using gas chromatography. The solubilities of the C₅ hydrocarbons in liquid argon at 87.3K vary from 0.61 × 10^–7 mole fraction for cyclopentane, to 1.37 × 10^–7 mole fraction for pentane, and 8.83 × 10^–6 mole fraction for 2-methylbutane. The Preston–Prausnitz method was used for calculation of the solubilities of solid C₅ hydrocarbons in liquid argon in the temperature range 84–110 K and in liquid nitrogen in the range 64–90K. The values of the solvent–solute interaction constant l ₁₂ were also calculated.     

Inclusion Complexation and Dissolution Properties of Nimesulide and Meloxicam–hydroxypropyl-β-cyclodextrin Binary Systems

The purpose of the work is physicochemical characterization of nimesulide (NI) and meloxicam (ME)–hydroxypropyl-β-cyclodextrin (HP-β-CD) binary systems both in solution and solid states and to improve the pharmaceutical properties of NI and ME via inclusion complexation with HP-β-CD. Binary systems of NI and ME with HP-β-CD have been characterized both in solution and solid state by different physicochemical methods. Three types of drug–HP-β-CD binary systems, namely physical mixtures (PM), kneaded systems (KS) and co evaporated systems (CS) in 1:1 and 1:2 molar ratios (1:1 and 1:2 M) were prepared. Phase solubility and ¹H-NMR spectroscopic studies in solution state revealed 1:1 M complexation of NI and ME with HP-β-CD. A partial inclusion of NI with HP-β-CD at both molar ratios of kneaded and co evaporated systems and a true inclusion of ME with HP-β-CD at both molar ratios of co evaporated systems in solid state was confirmed by differential scanning calorimetry (DSC), powder X-ray diffractometry (powder X-RD) and scanning electron microscopy (SEM) studies. Dissolution properties of NI and ME–HP-β-CD binary systems were superior when compared to corresponding pure drugs. The aqueous solubility and dissolution properties of NI and ME can be improved by inclusion complexation with HP-β-CD. Author for correspondence: E-mail: nbnaid2@E-mail.uky.edu     

高取代度淀粉磷酸酯的理化性质及结构表征

以磷酸二氢钠、磷酸氢二钠的混盐为酯化剂,干法制备高取代度木薯淀粉磷酸酯(CSP-HDS)。研究表明,取代度不同时,产物的表观粘度、糊透明度、凝沉性、冻融稳定性均不相同。与木薯淀粉相比,酯化反应后产物粘度增大,糊透明度、凝沉性及冻融稳定性得到改善。XRD分析表明酯化反应主要发生在淀粉分子的非结晶区,对结晶区破坏不明显;SEM分析显示酯化后大部分淀粉颗粒保持原来形貌,仅少数团粒受到侵蚀。     

Physicochemical,structural, and digestive properties of pea starch obtained via ultrasonic-assisted alkali extraction

As a new and clean extraction technology, ultrasonic extraction has been demonstrated with great potential in the preparation of modified starch. In order to increase its added value, it is necessary to modify pea starch to enlarge its application. In this study, the efficiency of combining ultrasonic with alkali in the extraction of pea starch was evaluated and compared to conventional alkali extraction. Ultrasonic-assisted alkali extraction conditions were optimized using single-factor experiments and response surface methodology. The results revealed that maximum yield of pea starch (54.43 %) was achieved using ultrasound-assisted alkali extraction under the following conditions: sodium hydroxide solution with a concentration of 0.33 %, solid/alkali solution ratio of 1:6 (w/v), ultrasonic power of 240 W, temperature of 42 °C, and extraction time of 22 min. The ultrasound-assisted alkali extraction yielded 13.72 % greater pea starch than conventional alkali extraction. On the other hand, morphological, structural, and physicochemical properties of the obtained starch isolates were evaluated. The ultrasound-assisted alkali extraction resulted in pea starch with greater amylose content, water-solubility, swelling power, and viscosity compared with conventional alkali extraction. Furthermore, ultrasonication influenced the morphological properties of pea starch granules, while the molecular structure and crystal type were not affected. Moreover, the ultrasonic-assisted extraction produced starch with a slightly greater resistant starch content. Therefore, ultrasonic-assisted extraction can be suggested as a potential method for extracting pea starch with improved functional properties.     

三种C240异构体分子的AM1研究

采用RHF水平的AM1半经验量子化学方法,计算了线性4C60富勒烯聚合体、花生壳状4C60富勒烯聚合体,以及C240纳米碳管等三种C240异构体分子的几何构型、电子结构、分子能量,以及疏水常数LogP、极化率、偶极矩等物理化学特性,讨论了三种C240异构体分子的几何构型、前线分子轨道及能级、净电荷分布与静电势、分子能量等特性的差异.研究表明,三种C240分子的生成均为吸热,它们的稳定性依次排序为:C240纳米碳管>花生壳状4C60>线性4C60.     

Characterisation of commercial Perna canaliculus samples and development of extemporaneous oral veterinary paste formulations containing Perna

Perna canaliculus is a nutritional supplement recently studied and highly recommended for its anti-inflammatory effects in both animals and humans. In this study, the physicochemical properties, the microbiological quality, the total lipid content and fatty acids composition of three commercial samples of Perna powder were determined. Subsequently, three simple formulations of extemporaneous oral pastes containing Perna were prepared and designed for veterinary use. Their microbiological stability was assessed after 1-month storage at either room temperature or 35 °C. The results demonstrated that commercial Perna samples lack homogeneity, in regard to some technological properties and fatty acid composition; therefore, a preliminary characterisation of commercial Perna samples is recommended to assure the quality of formulations containing this nutritional supplement. Oral paste formulations are easy and simple to prepare and show good physical and microbiological stability, suggesting their large-scale production.