Thesis (Ph. D.)--University of Michigan.

Thesis (Ph. D.)--University of Wisconsin, 1964. / Abstracted in Dissertation abstracts, v. 25 (1964) no. 6, p. 3279-80. Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1959. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Bibliography: leaves 92-95.

A product must comply with pharmacopeial specifications at all times. If the drug in the tablet degrades to a therapeutically inactive (and sometimes toxic) substance, the patient will not receive the correct amount of drug and, more important, may be adversely affected by the degradation product. The stability characteristics of four products containing either p-aminosalicylic acid or sodium aminosalicylate were, therefore, determined in this laboratory. The products were selected at random and are currently being sold to pharmacies and hospitals in Canada. The products were analyzed and their disintegration times determined. All products complied with existing specifications. The products were then stored in a Vapor-Temp Controlled Humidity Chamber at various temperatures (30°C. to 60°C.) and at 65 % and 90 % relative humidity for varying periods of time. Tablets were withdrawn from the chamber at various times and analyzed. Using the data so obtained, rate constants were calculated for each product stored at the two basic conditions, that is, at 65 % and 90 % relative humidity. Products 1 and 4 were not affected by the environmental conditions in the humidity chamber. However, the drug in Products 5 and 7 degraded quickly to m-aminophenol when the tablets were exposed to temperatures in excess of 40°C and a relative humidity of 90 %. Product 7, in particular, was very susceptible to both heat and moisture. The product would, therefore, be unacceptable to the profession. It contains buffers and it is assumed that these substances are responsible for the product's instability. This then is a good example of poor product development. The data accumulated during this investigation was analyzed mathematically and it was concluded that the pseudo first-order reaction equation may be used to explain the degradation process. Arrhenius plots (that is, plots of the logarithm of the rate constant versus the reciprocal of the absolute temperature) were prepared for Products 5 and 7. On the basis of these plots, product stability at various temperatures and a relative humidity of 90 % was determined. As an example, Product 7 will contain only 90% of the drug claimed on the label if it is stored at a temperature of 25°C and a relative humidity of 90% for 70 days. Values at other temperatures and for Product 5 are given in this thesis. The data obtained during this investigation suggests that the following stability specification may be used to quickly evaluate a product containing p-Aminosalicylic acid or its sodium salt. Place 20 tablets in a petrie dish and transfer to a humidity chamber adjusted to 40°C and a relative humidity of 90%. Store in the chamber for ten days. Remove and assay the tablets. The mean potency of the 20 tablets must be not less than 90 % of the amount claimed on the label. The drug in products which do not meet this specification would degrade to m-aminophenol even if it is stored at normal temperatures for relatively short periods of time. Product 7 falls into this category. This study shows that humidity must be taken into consideration in any investigation on product stability. Moreover, it is not enough to determine the stability of the drug as such. The excipients (and other drugs combined with the anti-tubercular in the same dosage form) can influence the degradation process in the tablet. This abstract represents the true contents of the thesis submitted. / Pharmaceutical Sciences, Faculty of / Graduate

The diastereomeric tetrahydropyranyl (THP) and tetrahydrofuranyl (THF) ethers of a variety of α-hydroxyesters were synthesized and separated by column chromatography. The separability of the diastereomers was found to be a general phenomenon which allowed for wide variations in both the THP/THF ring and the α-hydroxyester. The resolved compounds could be deprotonated and alkylated diastereoselectively with a variety of electrophiles. The diastereoselectivity ranged from 1:1 to 12:1 depending on the α-hydroxyester, the alkylating agent, and the reaction conditions. In most cases the diastereomeric products of the alkylation were also separated by column chromatography. This alkylation method was used in the synthesis of the natural product (S)-frontalin and its enantiomer with optical purity. Modifications to the THP and THF rings were synthesized in an attempt to develop a "chiral THP". The (S)-methyl lactyl, (S)-methyl mandelyl, and (R)-pantolactyl 3-benzyloxytetrahydrofuranosides were synthesized and separated. Transacetalization to the methyl furanosides gave "chiral THF's" which were used in the resolution of other racemic α-hydroxyesters.

The dichloromethane extracts of twelve US Southwestern herbal remedies were tested against Staphylococcus aureus (9-29 UA), Bacillus subtilis (2-27 UA), Klebsiella pneumoniae (3-9 UA), and Candida brassicae (IFO 1664) in an agar dilution-streak bioassay at 1000 μg/ml. All twelve plants inhibited the growth of B. subtilis. Anemopsis californica, Berberis fendleri, Cacalia decomposita, and Eriodictyon angustifolium inhibited the growth of at least two organisms. Salvia apiana was the only plant in this study to completely inhibit the growth of all four test organisms. After a literature search led to the elimination of A. californica, B. fendleri, and C. decomposita from further study due to reports of their bioactive compounds, Eriodictyon angustifolium Nutt. and Salvia apiana Jeps. were subjected to a detailed bioassay directed chemical investigation. Compounds were isolated by solvent extraction, fractionation and standard chromatographic techniques. They were identified by infrared, mass, and nuclear magnetic resonance spectral analyses, comparison with published spectra and comparison with authentic samples when available. Benzyl-trans-4-coumarate was isolated from E. angustifolium following high performance reverse phase liquid chromatography and subsequently synthesized through the condensation of p-coumaric acid and benzyl alcohol. Estimated at 2.9% of the dichloromethane extract, benzylcoumarate was active against S. aureus (100 μg/ml), B. subtilis (50 μg/ml), and C. albicans (25 μg/ml). Also isolated from E. angustifolium were five flavanones: 4',5,7-trihydroxy-flavanone (naringenin), 4',5-dihydroxy-7-methoxy-flavanone (sakuranetin), 3'-methoxy-4', 5',7-trihydroxy-flavanone (homoeriodictyol), 4',5-dihydroxy-3',7-dimethoxy-flavanone, and 5,7-dihydroxy-3',4'-dimethoxy-flavanone. The dichloromethane extract of S. apiana gave an acid fraction from which the abietane diterpenes carnosic acid and its 16-hydroxy derivative were isolated as their methyl ester acetates. Unstable as free carboxylic acids, these compounds retained activity after methylation but lost activity upon acetylation. Methylation without prior acetylation lead to the formation of 11-methoxy-methylcarnosate, 12-methoxy-methylcarnosate, 16-hydroxy-methylcarnosate, 16-hydroxy-11-methoxy-methylcarnosate, 16-hydroxy-12-methoxy-methylcarnosate, and 11,12-dimethoxy-16-hydroxy-methylcarnosate. At 500 μg/ml 12-methoxy-methylcarnosate was inactive while 16-hydroxy-12-methoxy-methylcarnosate was active against S. aureus, B. subtilis, and C. albicans at 250 μg/ml. From this result it was inferred that the introduction of a 16-hydroxy group increased the bioactivity of carnosic acid.

No description available.

Chemokine receptor CCR5 (CCR5) is a G-protein coupled receptor (GPCR) predominantly expressed on leukocytes, or white blood cells.1–3 During inflammation, the body releases chemokines that bind to receptors such as CCR5 and attract leukocytes to the area of inflammation, leading to an immunological response.1 CCR5 is also an important receptor in the human immunodeficiency virus's (HIV-1) invasion of host cells, as CCR5 acts as a co-receptor that facilitates HIV-1 viral entry.4,5 The continued destruction of leukocytes as a result of HIV-1 viral entry produces a disease state called acquired immunodeficiency syndrome (AIDS).5 Of note, this receptor is also expressed on the glial cells of the central nervous system (CNS).6,7 The mu-opioid receptor (MOR) is also a GPCR is predominantly expressed in the central nervous system.8–10 It binds to signal molecules such as endorphins and produces analgesic effects upon activation.9 The protein binds to morphine and morphine derivatives, which are extracts from the opium poppy plant.10 Besides the analgesic effects produced from MOR activation, morphine and its derivatives are also highly addictive and can result in drug dependence.11 Like CCR5, MOR is also expressed on the glial cells of the CNS.8 The accelerated progression of AIDS-like symptoms, in particular HIV-associated neurocognitive disorders (HANDS), has been observed in opiate-addicted patients.6,7,12–14 It has been discovered that opiate-addicted patients who have AIDS are susceptible to higher levels of HIV-1 viral proliferation and a greater level of CNS host cell destruction.12–14 This is because the activation of MOR by opiates appears to increase the expression of CCR5 on glial cells and may alter CCR5's conformational state to one more susceptible to HIV-1 binding.15 Then, entry and subsequent destruction of glial cells by HIV-1 leads to the release of neurotoxic HIV-1 proteins that destroy primary neuronal cells.15 A bivalent ligand targeting the putative CCR5-MOR heterodimer was proposed to probe the interaction between the two proteins and act as a potential therapeutic ligand to combat neuroAIDS.16 A bivalent ligand attaching maraviroc, a CCR5 antagonist, with naltrexone, a non-selective opioid receptor antagonist, was synthesized and tested in vitro.16 The initial bivalent ligand was separated by a 21-atom spacer (Figure 1), the length of which was dictated by modeling studies and other bivalent ligands.17 The spacer was attached to the 6-position of 6β-naltrexamine, a modified variation of naltrexone replacing the 6 position ketone with an amino group, and the 4'-position of the maraviroc phenyl ring.16 These positions were chosen based on separate modeling studies of naltrexone and maraviroc docked in homology models of MOR and CCR5, respectively.18,19 From these studies, it appeared as if these positions were optimal given that they faced outward from their respective binding pockets and hence could tolerate spacer attachment.18,19 However, based on these modeling studies there was also room for structure optimization of the bivalent molecule.17–19 The original 21-atom spacer was subjected to numerous structural changes by our laboratory in an effort to increase CCR5 and MOR binding. The first type of structural modification included changing maraviroc's point-of-attachment to the spacer from the 4'- to the 3'-position. Based on results from calcium mobilization functional assays involving CCR5-transfected human acute lymphoblastic leukemia (MOLT-4) cells, the activity of the bivalent molecule decreased from an IC50 of 126.0 ± 28.0 to 1340.0 ± 110.0 when the point-of-attachment was changed to the 3'-position. Thus, the 4'-position was kept in future structural studies. After this, additional structural modification was pursued in the form of changing spacer length. We synthesized two additional bivalent ligands, i.e., 19-atom and 23-atom bivalents with their controls. It is important to note that each of these molecules had a separate synthetic route starting with a specified diamine spacer. For the 19-atom bivalent molecule and its controls, the starting material was 1,5-diaminopentane. For the 23-atom bivalent molecule and its controls, the starting material was a 1,9-diaminononane molecule. Once these molecules were synthesized, in vitro biological testing was conducted. The bivalent molecules and 6β-naltrexamine controls were subjected to a competitive radioligand binding assay involving hMOR membranes and then to a calcium mobilization functional assay involving hMOR-transfected chinese hamster ovarian (CHO) cells (Figure 2). The affinities from the radioligand binding assay were similar in order-of-magnitude to other modified opioid antagonists and had a fold-decrease in affinity relative to naltrexone ranging from 1.1 to 9.3. The IC50 values from the calcium mobilization assay were similar in order-of-magnitude to other modified opioid antagonists and had a fold-decrease in activity relative to naltrexone ranging from 7.6 to 32. Thus, it was concluded that spacer attachment to the 6-position of 6β-naltrexamine was tolerated in MOR-binding. The bivalent molecules and maraviroc controls were then tested in calcium mobilization assays involving CCR5-transfed MOLT-4 cells to assess CCR5 activity. Unlike in the hMOR-CHO calcium mobilization assay, the activity of the bivalent molecules for CCR5 was not similar in magnitude to the receptor's antagonist, maraviroc. The 23-atom bivalent and 19-atom bivalent had fold-decreases in activity relative to maraviroc of 1,100 and 250, respectively. Recently, the co-crystal structure of maraviroc bound to CCR5 was published in Science.20 Contrary to our previous understanding, it appeared as if modifications to the phenyl ring in maraviroc were not tolerated.20 After the biological testing, conformational analysis on the 19-, 21- and 23-atom bivalent compounds using Confort conformational modeling software was conducted. This was done to observe the possible viable conformations of each molecule. It was hypothesized that 1) the molecules could adopt viable conformations for binding to two different receptors simultaneously and that 2) the molecules could adopt similar conformations relative to each other. The first hypothesis was proposed to assess the realism of the project's design strategy whereas the second was to analyze whether significant conformational differences could account for differences in binding activity between the three molecules. Results from this experiment showed that the molecules all adopted viable conformations for binding to two receptors simultaneously and that the conformational differences between the three molecules were negligible enough to conclude that significant differences in binding were not because of conformational differences. In conclusion, our laboratory synthesized a set of bivalent compounds to probe the CCR5-MOR heterodimer and tested such compounds in vitro. While spacer modifications to the 6-position of naltrexone were tolerated in hMOR competitive radioligand binding assays and in hMOR-CHO calcium mobilization assays, spacer modifications to maraviroc's 4'-position on the phenyl ring were not tolerated very well in CCR5-MOLT-4 calcium mobilization assays. Therefore, future design strategies might focus on changing the spacer's point-of-attachment to the maraviroc molecule.

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science 6 February 2017, Johannesburg. / Polymorphism is not only limited to single component systems. Co-crystals have exhibited polymorphism and various polymorphic co-crystals have been reported. Polymorphism in co-crystals presents an expansion of the optimization space around a pharmaceutical compound and also offers the opportunity to develop novel patentable material. Polymorphism of pharmaceutical co-crystals was investigated by means of an exhaustive data mining survey and the formation of polymorphic co-crystals. The search was performed using the Cambridge Structural Database (CSD). The search aimed to find and tally neutral pharmaceutical co-crystals which are polymorphic. The survey of the CSD showed that 14% of the pharmaceutical co-crystals were polymorphic. The co-crystal of theophylline and 3,4-dihydroxybenzoic acid was found to be polymorphic and the novel polymorph was synthesized and characterized. The co-crystals were characterized by x-ray crystallographic techniques and Differential Scanning Calorimetry. The single crystals of carbamazepine and cinnamic acid was grown and characterized by SCXRD for the first time. The single crystal data was able to show that the hydrogen bonding packing that was modelled in the literature is incorrect. / MT2017

University of Macau / Institute of Chinese Medical Sciences