Lung cancer is the leading cause of cancer-related death worldwide. Exclusively found in citrus peels, the inhibitory effects of polymethoxyflavones (PMFs) on 3 human non-small cell lung cancer cells have been investigated. Results showed that monodemethylated PMFs at 5-position potently inhibited lung cancer cells than those of their permethoxylated counterparts. The inhibition of cancer cells caused by monodemethylated PMFs was associated with both extensive cell cycle arrest and apoptosis as a result of modulation of key oncogenic signaling proteins. Treatment with different bioactive compounds in combination may enhance inhibitory effects on lung cancer due to their synergistic interaction among these agents. Results showed that both nobiletin/atorvastatin (NBT/ATST) and tangeretin/atorvastatin (TAN/ATST) co-treatments at low doses exerted strong synergy as confirmed by isobologram analysis, and also produced much stronger inhibitory effects on lung cancer cells in comparison to those produced by NBT, TAN, or ATST alone at higher doses. Flow cytometry analysis showed both NBT/ATST and TAN/ATST co-treatments significantly induced cell cycle arrest and apoptosis, and these molecular events were involved with prenylation of RhoA which subsequently resulted in alteration of key signaling proteins. Supplementation of mevalonate or geranylgeranyl pyrophosphate significantly counteracted the effects caused by NBT/ATST. Inhibitory effects of metabolites of PMFs against lung cancer cells were significantly stronger than those produced by their parental compounds. Treatments of PMFs significantly inhibited lung tumorsphere formation and aldehyde dehydrogenase bright cells implicating the potential utilization of these compounds to target lung cancer stem cells.

Background: Dental filling materials are used on a regular basis by dentists. Commonly used filling materials on the current market are resin composites and glass ionomers cements. However, new materials continue to be presented on the market with claimed improved physical and chemical properties, among them Predicta Bioactive Bulk.    Aim: The aim of this study was to investigate the surface roughness and ion release properties of a bioactive restorative material.   Methods: Surface roughness and ion release properties of a new material, Predicta Bioactive Bulk, was compared to Ceram.X Spectra ST and Fuji LC II. The results were analyzed using Microsoft Office Excel and IBM SPSS Statistics software.    Results: The material with the lowest surface roughness at baseline was Predicta Bioactive Bulk and Ceram.X Spectra ST had the highest value. After polishing/finishing CeramX showed the lowest surface roughness and Fuji II LC had the highest value. After the water aging-test, submerged for two weeks, Ceram.X Spectra ST exhibited the lowest value of surface roughness and Fuji II LC showed the highest value. The material with the highest fluoride release after two and seven days was Fuji II LC and Predicta Bioactive Bulk hade the lowest.    Conclusion: The surface roughness of Predicta Bioactive Bulk was comparable to CeramX in the test regarding surface roughness. Therefore, it can be concluded the surface roughness is neither better nor worse than CeramX. From the study it can also be concluded that Predicta Bioactive Bulk had very low fluoride ion release properties.

Wound care is a field with many treatment methods and products on the market. The healing period varies, some wounds become difficult to heal and chronic, in many cases a connection can be drawn to underlying diseases. Diabetes is a disease that could cause foot ulcers that are difficult to heal. Bioactive materials in wound care have not yet been studied to a greater extent, however it is of interest for development of new products with improved functions. Fibroblasts in the connective tissue have an important role in building and regenerating the tissue. Former studies show that the bio-ceramic calcium silicate (CS) induce tissue regeneration and promote reepithelization. It has also shown improvement of the biological functions of human epidermal stem cells and positive effects on cells in in vitro studies. The purpose of this project is to be a pre-study for further analysis of CS in wound care. The aim is to investigate additive material’s potential role in wound healing, one part will be a literature study to get an overview of the healing process of wounds and wound treatment. The other part of the study is based on three minor experiment to obtain information about how calcium silicate (CS) and CS/ β-tricalcium phosphate (β-TCP) effect human dermal fibroblasts. The method and results of literature study: The litterature study gathers information from literature and studies within the subject using the searchwords: wound, healing, biomaterials, calcium silicate, alamar blue, cell migration, recent trends, skin regeneration and diabetes. The results from the literature study demonstrates that the wound healing process is very complex and many factors must interact for good healing, some factors accelerate and inhibit healing. Furthermore, healing products with additives are already used for treatment of wounds with antibacterial and pain-relieving effects. However, only a little information about bioactive materials can be found which shows that there is lack of studies in this field. The method and results of experiments: Preparation of the two main samples: [1:10] CS in PBS together with pure water and [1:10] CS + β-TCP in PBS and pure water. The first experiment was the Inductively Coupled Plasma Optic Emission Spectroscopy (ICP-OES) made in an Optical Emission Spectrometer which detected the elements Ca 317,933 (mg/L) and Si 251,611 (mg/L) in the main samples. The second experiment was Alamar Blue which produce data about the cell survival in quantitative numbers to determine the toxicity of the diluted samples. One pre-test and two final tests (24 h apart) was made. The pre-test used the dilutions 1:2, 1:10, 1:100, and two Control Media, the pre-test indicated that CS diluted 1:2 is slightly toxic. The first final test used the dilutions 1:2, 1:10, 1:100, 1:1000, 1:10000 and one Control Media. The first final test indicated that CS diluted 1:2 is almost toxic. The second final used the dilutions 1:2, 1:10, 1:100, 1:1000, 1:10000 and one Control Media. The second final test indicated that CS diluted 1:2 is toxic. The third experiment was a Scratch Healing assay. This experiment struggled with learning how to count cells which made the analysis of this experiment difficult. The results of the Scratch healing assay shows cell migration through a before-picture right after the simulated scratch is made and a picture 24 hours after. In conclusion, two important parameters while investigating the direction of further research are toxicity and cell survival. CS as a bioactive material and additive in wound treatment could be possible but should be avoided when diluted 1:2 due to its toxicity shown in the Alamar blue test. The scratch healing assay showed that the fibroblasts migrate to some extent while interacting in solutions of CS.

<p>  </p> <p>Actinobacteria are a large and diverse group of bacteria that are known to produce a wide range of secondary metabolites, many of which have important biological activities, including antibiotics, anti-cancer agents, and immunosuppressants. The biosynthesis of these compounds is often highly regulated, with many natural products being produced at very low levels in laboratory settings. Environmental factors, such as small molecule elicitors, can induce the production of secondary metabolites. These elicitors can be natural products, including antibiotics or hormones, or synthetic compounds. The use of small molecule elicitors to induce the production of secondary metabolites has several advantages. First, addition of elicitors to fermentation media can result in increased titers of known natural products. Second, elicitors can enable the discovery of novel natural products typically produced at undetectable levels. In recent years, there has been a growing interest in the use of small molecule elicitors to induce the production of secondary metabolites from actinobacteria, especially for the discovery of “silent” natural products. In this work, we sought to expand on the method of chemical induction by utilizing oxytetracycline at a sub-MIC concentration to induce secondary metabolite production in Streptomyces. We have shown that translation-inhibiting antibiotics, specifically oxytetracycline, have a profound effect on the production of coeliomycin P1, actinorhodin, and calcium-dependent antibiotics (CDAs) in S. coelicolor and S. lividans. The expression of actinorhodin in S. lividans under these conditions is unique, unlike its counterpart, S. coelicolor, which can produce actinorhodin under standard conditions. In addition to the increased production of known secondary metabolites, we have also demonstrated the induction of BGCs in several other strains of Streptomyces, which were observed via LC-MS. </p> <p>In addition to exploring antibiotics as elicitors we have explored the traditional approach of natural product discovery by taking an bioactivity guided approach. Several strain that we isolated from soil collect of Hawaii were screened for activity against several pathogenic strains primarily looking for which strain will inhibit the growth of a. baumannii, which is an intriguing target because the rate of resistance to common antibacterial medication is rising and it’s membrane composition is vastly different compared to other gram negative bacterium like E.coli. From this preliminary screening 1 strain (Streptomyces sp. CS62) out of the 8 that tested exhibited the desired biological activity. The supernatant of Streptomyces sp .CS62 was processed and screen by LC-MS to gain insight on the type of molecules that Streptomyces CS62 could produce. Upon our initial screening process none of the masses observed in the mass spec were matched to knowns. However, after 2D NMR analysis and genomic analysis it was unveiled that Streptomyces sp. CS62 produces factumycin a known antibacterial agent that targets A.baumannii .This unfourtunate turn of events illustrates the issues with natural product discovery and the need to improve natural product databases.</p> <p>In conjunction to discovering a novel producer of factumycin we are also investigating the production of antifungal compounds from Staphylococcus lugdunensis  a commensal strain that modulates the microbiome by producing lugdunin. The supernatant collected of Staphylococcus lugdunensis  is exclusively being test against Candida auris due to the immense health risk it possess to society because of its innate resistance to many antifungal drugs and its ability to rapidly gain resistance to other classes of antifungals.</p> <p>In addition to exploring the influence of antibiotics on secondary metabolite production and using bioactivity as a guide to discovering antibiotics. We are evaluating the soils collected from unique environments as potential sources for novel natural products. Specifically, we are evaluating the biosynthetic potential of bacteria from ore-forming environments, specifically fluorspar and topaz mines. Soils from ore-forming environments tend have low pH, high saline content, low water holding capacity, and poor nutrient availability. Therefore, ore-forming environments pose a hostile environment for life. To date, no one has explored the natural product potential, or the bacterial diversity, exhibited in these harsh environments. To assess the bacterial diversity, bacteria were isolated from various ore-forming environments using a procedure that is selective for actinobacteria. Following bacterial isolation, genomic DNA was isolated and 16s rRNA gene sequencing was performed to gauge the type of bacteria that were isolated. To stimulate secondary metabolite production, bacteria were then subjected to 7 different media conditions. The supernatant collected from these media conditions were tested against ESKAPE pathogens utilizing the CTSI broth microdilution assay. LC-MS MS analysis was performed for samples exhibiting biological activity. GNPS molecular networking was then utilized to determine potential molecules present in each sample.  Through this process we were able to identify one strain, which we named Streptomyces sp. S1A that exhibited a board range of biological activity (anticancer and antibacterial) and possess a wide array of biosynthetic gene clusters ranging complex macrolides (PKS and NRPS) to terpenes. </p> <p>In summary this multifaced approach to natural product discovery may lead to the discovery of novel antibiotics, enable us to increase production of known or unknown antibiotics through chemical induction, and the characterization of metabolites from Streptomyces sp. S1A will shed insight on the biochemical potential of organisms that inhabit ore-forming environments </p>

<p dir="ltr">Phosphatidylinositol phosphates (PIPs) and soluble inositol phosphates (IPs) serve as critical secondary messenger molecules that regulate cellular processes. The INPP5 family of phosphatases play an essential role in regulating levels of PIP-5’ and IP-5’ molecules. Src homology 2-containing-inositol phosphatases (SHIP), are a subgroup of the INPP5 family that consists of two members, SHIP1 and SHIP2. Both SHIP proteins have been identified to hydrolyze PI(3,4,5)P3 into PI(3,4)P2. Interestingly, the dysregulation of PI(3,4,5)P3 and SHIP proteins have been observed in multiple diseases, such as cancer, diabetes, and neurodegenerative disease. Recently, SHIP1 was identified as a potential risk factor for the development of Late-onset Alzheimer’s Disease (LOAD). Furthermore, knockdown and inhibition of SHIP1 using small-molecule inhibitors were shown to reduce phenotypes associated with LOAD. Taking these studies together suggests SHIP1 to be a potential therapeutic target for the treatment of LOAD.</p><p dir="ltr"><br></p><p dir="ltr">Despite SHIP1’s therapeutic potential, the development of specific small-molecule inhibitors that target SHIP1 has been challenging. One explanation for this challenge is that very little is known about the overall structure and function of SHIP1. In this thesis I will discuss in detail how we generated multiple SHIP1 constructs to improve our understanding of SHIP1’s overall structure and function in an <i>in vitro </i>setting.</p><p><br></p><p dir="ltr">Efficient protein production is essential for studying enzyme structure and function. The choice of expression system can impact protein yield and stability. The E. coli (BL21) and Baculovirus expression systems are two commonly used systems for protein production. While E. coli is cost-effective and can yield a large amount of protein, the Baculovirus system offers advantages in terms of protein folding and post-translational modifications. Using both systems to generate SHIP1 protein, we demonstrate that the Baculovirus system significantly enhances SHIP1 solubility for all generated constructs, making it the preferable choice for investigating the structure and function of SHIP1.</p><p><br></p><p dir="ltr">SHIP1, a 133 kDa protein, which comprises five established domains: an N-terminal Src Homolgy 2 (SH2) domain, 2.) a pleckstrin homology-related (PH) domain, 3.) an inositol phosphatase catalytic (Ptase) domain, 4.) a C2 domain, and 5.) a C-terminal domain containing proline-rich regions (PXXP) and tyrosine phosphorylated (NPXY) motifs. Despite their regulatory roles in phosphatase activity, protein-protein interactions, and membrane association, limited information is available about their structures and how they contribute SHIP1’s biochemical functions. In this study, we utilized baculovirus-expressed SHIP1 constructs to investigate the impact of each domain on macromolecular structure. Interestingly, a previously unrecognized domain within SHIP1 that directly impacts the enzyme's oligomeric state was identified. This work highlights that SHIP1's individual domains can significantly impact its overall structure and function, providing valuable insights for the development of potential therapeutics in the treatment of LOAD.</p><p><br></p><p dir="ltr">Accurate determination of phosphatase kinetics is vital for understanding the enzymatic activity and its potential involvement in disease. Using our baculovirus generated SHIP1 constructs, we employed in-vitro assays, including the malachite green (MG) and the 2-amino-6-mercapto-7-methylpurine riboside (MESG) coupled enzyme assays, to gain insight into SHIP1 kinetics. Results from the MG assay shows that SHIP1 can hydrolyze the PI(3,4,5)P3 diC8 substrate more efficiently than I(1,3,4,5)P4. Additionally, SHIP1’s PH domain was observed to increase the turnover of PI(3,4,5)P3 diC8. Furthermore, dimerization of SHIP1 was not observed to alter SHIP1 kinetics in any way. Lastly, no major differences in I(1,3,4,5)P4 kinetics were observed with the addition of SHIP1’s N-terminus. These results offer the first comprehensive biochemical characterization of SHIP1 across its substrates and N-terminal domains.</p><p><br></p><p dir="ltr">The development of potent and specific small-molecule inhibitors that target SHIP1 remains challenging. One potential cause for this challenge is that no structures of SHIP1 have been solved in complex with active compounds, making structure-based drug design impossible. In this study, we developed a covalent compound, <b>TAD-58547</b>, from a previously published fragment-based screen that was conducted on SHIP1’s Ptase and C2 domain. <b>TAD-58547 </b>was shown to effectively inhibited SHIP1's Ptase and C2 domains at modest potency. Using X-ray crystallography, this compound was observed to form a covalent interaction with a cysteine residue near the Phosphatase-C2 domain interface. Intriguingly, the inhibitor's potency was observed to be reduced in the presence of the SH2 domain. In addition to testing <b>TAD-58547</b> against our SHIP1 constructs, we investigated the effect of SHIP1’s N-terminus on the potency of a literature compound, <b>TAD-58616</b>. This compound was shown to inhibit all our tested constructs at low µM concentrations. Furthermore, using x-ray crystallography <b>TAD-58616 </b>was solved in complex with SHIP1’s Ptase and C2 domain. Intriguingly, density for <b>TAD-58616 </b>was shown to interact with a site previously identified from the fragment-based screen. While we initially determined this site to be a result of crystal packing, fragments bound to this site may have the potential to inhibit SHIP1. The work presented in this study reinforced the importance of testing inhibitors against physiological relevant forms of SHIP1, when developing potential therapeutics.</p><p><br></p><p dir="ltr">Lastly, new evidence has suggested that the binding of phosphorylated immunoreceptor tyrosine-based activation motifs (p-ITAM) and immunoreceptor tyrosine-based inhibitory motifs (p-ITIM) to SHIP1’s N-terminal SH2 domain is essential for its “Anchorage and Activation” at the plasma membrane (PM). With this model it is believed that SHIP1’s SH2 domain, places the phosphatase into an auto-inhibited state. Upon binding to immune receptor proteins and adaptor proteins that contain ITAM/ITIM sequences, SHIP1 becomes un-auto-inhibited, allowing it to efficiently hydrolyze PI(3,4,5)P3 embedded in the PM. While this model does support the notion that SHIP1 activity is mediated by its PM localization, our biophysical and biochemical characterization add another level of complexity to this regulatory event. Taking all these results together, we propose a novel model for SHIP1 called “Anchorage and Assist” and suggest innovative therapeutic strategies for targeting SHIP1.</p><p><br></p><p dir="ltr">In conclusion, this thesis highlights the importance of choosing suitable expression systems for efficient protein production. Additionally, it offers insight into SHIP1's regulatory mechanisms through the discovery of a novel domain impacting its oligomeric state. Furthermore, the accurate determination of SHIP1 kinetics enhances our understanding of this phosphatase and its potential implications in disease. Also, the identification and crystallization of a novel and previously determined inhibitor scaffolds in complex with SHIP1 increases our ongoing efforts to develop a small-molecule inhibitor that specifically targets SHIP1. Lastly, using recently published data, detailing SHIP1 PM localization and activation, we proposed a new model for SHIP1 activity and suggest novel therapeutic strategies for targeting SHIP1.</p>

No description available.

The objective of this study was to compare time dependent micro-hardness of several bioactive cement compositions as compared to that of non-bioactive cement, a conventional glass ionomer. Materials & Methods: Three bioactive materials Ceramir Crown & Bridge Cement (CCB), Mineral Trioxide Aggregate (MTA), Biodentine (BD)], and a glass ionomer cement, Fuji I luting cement (F1), were utilized in this study. Samples of the materials were prepared in a standard cylindrical mold 1.5 mm in height and 12.0 mm in diameter and stored in Phosphate-Buffered-Saline (PBS) at 37 degrees C. prior to testing to determine Vickers micro-hardness in a CSM micro-indentation testing device. Micro-hardness values were collected via 2 x 2 micro-indentation matrices on the exposed surfaces of the specimens. All materials were tested at 24 hours and 2 months and 11 + 1 month's incubation time. The bioactive materials displayed significant differences in Vickers hardness as a function of storage time as compared the Vickers hardness values over the similar timeframe for the control material, the glass ionomer material Fuji 1. The control glass ionomer cement did not displayed significant changes in Vickers hardness after prolonged liquid storage. The experimental bioactive materials both demonstrated long-term trends with significant increases (CCB) and decreases (Biodentine) in Vickers hardness after storage in the simulated body fluid (PBS). The mean Vickers hardness of the calcium aluminate/glass ionomer (CCB) material was significantly greater than the mean Vickers hardness values for the other three materials tested at all time-points evaluated. The conclusions of this study were as follows: Unlike conventional glass ionomer cement, both the calcium silicate and calcium aluminate/glass ionomer cement displayed significant changes in surface micro-hardness after prolonged storage in a simulated body fluid (PBS) that has been demonstrated to induce the formation of a surface bioactive layer. The calcium silicate cement had a significant reduction in surface micro-hardness over a period up to year; while the calcium aluminate/glass ionomer cement displayed a significant increase in surface micro-hardness over that same time period. The formation of and changes in the bioactive surface layers formed on these materials may account for changes in the micro-hardness of these bioactive materials. / Oral Biology

El polen apícola es uno de los productos de la colmena más conocido. Las abejas melíferas (Apis mellifera L.) lo recolectan como una de sus principales fuentes de alimento. Si bien ha sido utilizado por las civilizaciones egipcia y griega atribuyéndole propiedades terapéuticas y “rejuvenecedoras”, no fue hasta después de la Segunda Guerra Mundial que comenzó a aumentar la producción y su consumo. Actualmente sus características composicionales lo constituyen en un excelente suplemento nutricional y debido a sus propiedades bioactivas es considerado un alimento funcional. Por otra parte, el polen es uno de los productos de la colmena que presenta mayor variabilidad composicional atribuido principalmente a las diferentes floraciones visitadas por las abejas. En este sentido, el análisis entomopalinológico es apropiado para clasificarlo como multi o monofloral siendo este último más estable composicionalmente, aunque también puede sufrir algunas variaciones según la zona de producción. Por esta razón, es imprescindible caracterizar al polen apícola fisicoquímicamente para poder asegurar su calidad endógena y brindar información completa al potencial consumidor. Así, el principal objetivo de este trabajo de tesis es desarrollar metodologías analíticas que permitan determinar la composición del polen de abeja recolectado en la zona centro de Argentina. Inicialmente la clasificación entomopalinológica de las muestras se realizó mediante la acetólisis de los granos de polen evitando la separación por colores de las cargas corbiculares, que es la etapa del proceso que demanda más tiempo. Desde el punto de vista físico-químico se desarrolló una metodología rápida y de bajo costo para la determinación de humedad y proteínas totales en un pool de cargas corbiculares empleando espectroscopía en el infrarrojo cercano (NIR) y técnicas quimiométricas tales como SPA-MLR e iSPA-PLS. Además, la utilización del modelo iSPA-PLS-DA permitió la clasificación de las muestras en relación a un contenido proteico de 20%. Por otra parte, se pusieron a punto técnicas de microanálisis para evaluar el contenido de polifenoles, flavonoides y proteínas en cargas corbiculares individuales estableciendo los respectivos coeficientes de variación. De esta manera se confirmó la elevada variabilidad que presentan los mencionados parámetros en la matriz apícola probablemente relacionados al origen botánico. Asimismo, se construyó un modelo quimiométrico en base a espectroscopía NIR para estimar el contenido de polifenoles totales en cargas individuales de polen corbicular. Finalmente, en relación al tratamiento poscosecha, se llevó adelante un ensayo cuantitativo in vitro de actividad antimicrobiana utilizando un extracto etanólico de propóleos como preservante de polen fresco como una alternativa de conservación de bajo costo. Los resultados obtenidos en esta tesis indican que el polen de abeja recolectado en la zona centro de Argentina presenta muy buenas características nutricionales y bioactivas en base al contenido de proteínas, polifenoles y flavonoides definidos principalmente por los taxones Brassicaceae (mayormente Diplotaxis tenuifolia), Eucalyptus sp. y Lotus sp. La incorporación de las metodologías desarrolladas en este trabajo para realizar el control de calidad de este producto apícola permitiría el correcto rotulado del producto comercial o, incluso definir su destino para las diferentes industrias (alimenticia, farmacéutica, cosmética). / Bee pollen is one of the best-known beehive products. Honey bees (Apis mellifera L.) collect it as one of their main food sources. Although it has been used by the Egyptian and Greek civilizations ascribing therapeutic and "rejuvenating" properties to it, it was after the Second World War that the production and consumption increased. Currently, its compositional characteristics make it an excellent nutritional supplement, and due to its bioactive properties, it is considered a functional food. On the other hand, bee-pollen is the hive product that presents the greatest compositional variability, attributed mainly to the different blooms visited by bees. In this sense, the entomopalynological analysis is suitable to classify it as multi or monofloral, being the latter more stable in its composition, although it may also undergo some variations depending on the production area. For this reason, it is essential to perform a physicochemical characterization of the bee-pollen to ensure its endogenous quality and provide complete information to the potential consumer. Thus, the main objective of this thesis is to develop analytical methodologies that allow determining the composition of the bee-pollen collected in central Argentina. Initially the entomopalynological classification of the samples was carried out through the acetolysis of the pollen grains, avoiding the separation by colours of the corbicular pellets, which is the stage of the process that requires more time. From the physicochemical point of view, a rapid and low-cost methodology was developed for the determination of moisture and total proteins in a pool of bee-pollen pellets using near-infrared spectroscopy (NIR) and chemometric techniques such as SPA-MLR and iSPA-PLS. Moreover, the use of the iSPA-PLS-DA model allowed the classification of the samples concerning a protein content of 20%. On the other hand, microanalysis techniques were developed to evaluate the content of polyphenols, flavonoids and proteins in individual corbicular loads, establishing the respective variation coefficients. In this way, the high variability of the mentioned parameters presented in the apicultural matrix was confirmed, probably related to botanical origin. Likewise, a chemometric model based on NIR spectroscopy was constructed to estimate the total polyphenols content in individual loads of corbicular pollen. Finally, concerning postharvest treatment, a quantitative in vitro antimicrobial activity test was carried out using an ethanolic extract of propolis as a preservative for fresh pollen as a low-cost conservation alternative. The results obtained in this thesis indicate that the bee-pollen collected in central Argentina has very good nutritional and bioactive characteristics based on the content of proteins, polyphenols, and flavonoids defined mainly by the Brassicaceae taxa (mostly Diplotaxis tenuifolia) , Eucalyptus sp. and Lotus sp. The incorporation of the methodologies developed in this work to carry out the quality control of this beekeeping product would allow the correct labelling of the commercial product or even define its destination for the different industries (food industry, pharmaceuticals, cosmetics).

Research was conducted to investigate the effect of phenolic compounds derived from inherently rich antioxidant grape extracts (GE) on α-glucosidase inhibitory activity in vitro and in vivo blood glucose control, oxidative stress, and inflammation associated with obesity-induced type 2 diabetes. Because intestinal α-glucosidase plays a key role in the digestion and absorption of complex carbohydrates, the inhibition of this enzyme is a metabolic target for managing diabetes by improving post-prandial blood glucose control. Initially, red Norton wine grape (Vitis aestivalis) and pomace extracts were evaluated and determined to have notable phenolic content and antioxidant properties. Next, grape skin (GSE) and pomace extract (GPE) were tested and both had in vitro yeast and mammalian α-glucosidase inhibitory activity. The GSE was 32-times more potent at inhibiting yeast α-glucosidase than acarbose, a commercial oral hypoglycemic agent. From HPLC and LC-MS analysis, three phenolics from the GSE (resveratrol, ellagic acid, and catechin) were identified as active inhibitory compounds. The acute administration of GPE (400 mg/kg bw) to mice reduced postprandial blood glucose level by 35% following an oral glucose tolerance test compared to the control. The daily supplementation (250 mg/kg bw) of GSE and GPE for 12-weeks to mice affected fasting blood glucose levels, oxidative stress, and inflammatory biomarkers associated with obesity and type 2 diabetes. At the end of the study, the GSE group gained significantly (P < 0.05) more weight (24.6 g) than the control, high fat, or GPE groups (11.2, 20.2, 19.6 g, respectively). Both GSE and GPE groups had lower fasting blood glucose levels (119.3 and 134.2 mg/dL, respectively) compared to the high fat group (144.6 mg/dL). The 12-week supplementation of GSE was associated with a higher plasma oxygen radical absorbance capacity (ORAC), lower liver lipid peroxidation as measure by TBARS, and lower levels of inflammation as measured by plasma C-reactive protein compared to the high fat group. In conclusion, our collective observations from these studies provide insight into the potential effects of antioxidant rich grape extracts on diabetes-related biomarkers through a dual mechanism of antioxidant protection and specific inhibition of intestinal α-glucosidases. / Ph. D.

The conformation of paclitaxel in the bound state on the protein has been proposed to be the T-taxol conformation, and paclitaxel analogs constrained to the T-taxol conformation proved to be significantly more active than paclitaxel in both cytotoxicity and tubulin polymerization assays, thus validating the T-taxol conformation as the tubulin-binding conformation. In this work, eight compounds containing an aza-tricyclic moiety as a mimic of the baccatin core of paclitaxel have been designed and synthesized as water-soluble simplified paclitaxel analogs, among which 3.50-3.52 and 3.55 were conformationally constrained analogs designed to bind to the paclitaxel binding site of tubulin, based on their similarity to the T-taxol conformation. The open-chain analogs 3.41-3.43 and 3.57 and the bridged analogs 3.50-3.52 and 3.55 were evaluated for their antiproliferative activities against the A2780 cell lines. Analogs 3.50-3.52 and 3.55 which were designed to adopt the T-taxol conformation showed similar antiproliferative activities compared to their open-chain counterparts. They were all much less active than paclitaxel. In the second project, a series of paclitaxel analogs with various thio-containing linkers at C-2′ and C-7 positions were designed and synthesized in our lab. These analogs were attached to the surfaces of gold nanoparticles by CytImmune Sciences for the development of mutifunctional tumor-targeting agents. The native analogs and the gold bound analogs were evaluated for their antiproliferative activities against the A2780 cell line. All the compounds tested showed comparable or better activities than paclitaxel. Stability studies were performed for selected analogs in hydrolysis buffer, which showed that the analogs released paclitaxel in buffer over time. In the third project, the synthesis of a conformationally constrained paclitaxel analog which was designed to mimic the REDOR-taxol conformation was attempted. Two synthetic routes were tried and significant progress was made toward the synthesis of the conformationally constrained analog. However, both of the current synthetic routes failed to produce the key intermediate that would serve as the precursor for a ring-closing metathesis reaction to furnish the macrocyclic ring. / Ph. D.