Theses (MSc. Analytical & Pharmaceutical Chemistry)

Everolimus is a mammalian target of a rapamycin inhibitor drug approved for treating advanced-stage, metastatic cancer that is non-responsive to endocrine therapy. Like most chemotherapeutic drugs, everolimus comes with numerous side effects, and the severity of these side effects often varies from patient to patient. In hopes of curbing the side effects during the treatment process, it was reported that some patients default to complementary and alternative medicine (CAM) in the form of natural product-based dietary supplements. One of the natural product supplements that was reported to have been consumed by patients undergoing everolimus treatment is curcumin. Following the consumption of curcumin during everolimus treatment is a significant fall in everolimus blood concentration levels (Cmin.). It was speculated that curcumin induces CYP3A4 activity, thus increasing everolimus metabolism. However, whether the effects of curcumin on everolimus metabolism are CYP3A4-related is yet to be proven, as there are other possible ways for curcumin to be involved in decreasing everolimus Cmin in patients. One of them includes the possibility of physicochemical interaction. The primary objective of this project was to investigate the potential chemical interaction(s) that could occur between everolimus and certain selected natural compounds (rutin, quercetin and curcumin) when present in an aqueous matrix under different physiological pH environments via HPLC. The occurrences of said interactions are depicted by the appearance of unknown peaks in sample chromatograms whereby everolimus was paired with other foreign compounds. These unknown peaks were not detected in the control samples, whereby everolimus stands as the lone compound. Not all peaks present in the sample chromatograms are integrated and quantified. As a pre-requisite, the unknown peaks that are isolated in sample chromatograms mustn’t be present in blanks or controls. Only the unknown peaks that share the same spectral profile as the primary molecule, everolimus are captured and quantified. Based on the findings of this investigation, everolimus is most unstable in the presence of the natural compounds when incubated in pH 6.8 medium. The degree of instability of everolimus was depicted by the number of unknown peaks present. This indicates that more chemical interactions take place between everolimus and the natural compounds at a pH 6.8 environment compared to other pHs. Also, in pH 6.8, everolimus is most unstable and degrades rapidly when paired individually with the natural compound quercetin. The extent of interaction that takes place between everolimus and each natural compound differs. When in the presence of all three natural compounds at once, the rate of degradation of everolimus is highest at pH 6.8. The rate of degradation is interpreted as the formation of unknown peaks per unit time. However, in a pH 4.5 environment, everolimus has the most interaction when individually paired with curcumin. Most of the unknown peaks observed in single-paired samples are not found in the control sample. Based on the evidence gathered, the stability of everolimus in different pH environments is highly affected by the presence of natural compounds.

Nanofibers for wound dressing application has become the research hotspot due to their excellent properties to make wound dressing. The nanofibers can be loaded with the drugs to kill or inhibit the bacteria on wound area. This study demonstrated the preparation and formulation of polycaprolactone (PCL) nanofibers loaded with curcumin, titanium dioxide and zinc oxide using electrospinning method. Optimisation of the PCL nanofibers for each parameter of electrospinning was done before preparing curcumin-titanium dioxide/zinc oxide nanofiber. Scanning electron microscopy (SEM), attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, and differential scanning calorimetry (DSC) were then used to characterise the nanofibers. Surface properties measurement, degradation analysis, in-vitro release of drug test, in-vitro cytotoxicity study, and antibacterial activity were evaluated on nanofibers. The optimised parameters to produce smooth nanofibers were found to be 12 wt% polymer concentration, a 6:4 mixture of chloroform and dimethylformamide at room temperature, 15 kV applied voltage, 0.5 mL/h flow rate, and a 20 cm working distance. The addition of curcumin, titanium dioxide nanoparticles, and zinc oxide nanoparticles into the nanofibers can increased the diameter and hydrophobicity of the PCL nanofibers but decreased its crystallisation and melting temperature. The degradation test showed that the PCL nanofibers were able to degrade completely within 14 days with the presence of lipase. In drug release study, the nanofiber exhibited a burst release of curcumin at the beginning of time, then sustained release. In cytotoxicity study, 1 and 3% w/w of curcumin in nanofibers do not show cytotoxic effect to HaCaT cells. The addition of curcumin-titanium dioxide/zinc oxide can suppress the activity of Staphylococcus aureus and Pseudomonas aeruginosa in antimicrobial tests. The curcumin-titanium dioxide and zinc oxide nanofibers with 1 and 3% w/w of curcumin show potential application in wound healing, as they do not harm the cells and able to inhibit the activity of bacteria, which will be useful to protect the wound.

Introduction: Photodynamic therapy is an alternative treatment to established standard treatments for cancer and antibiotics for bacterial infections. Although the potential of platinum-based drugs as antibacterial and anticancer agents has been studied for years, due to severe side effects that have limited their further development, ruthenium compounds are now emerging as one of the most promising therapeutic options in terms of targeting cancer and bacterial infections. Objectives: The objective of this work is to prepare and characterize a series of ruthenium complexes, followed by in vitro determination of their antibacterial and anticancer activity. Materials and Methods: Three ruthenium(II) Schiff base {[Ru(bpy)2(SB4CB)]PF6, [Ru(bpy)2(SBFH)]PF6, [Ru(bpy)2(SB4EB)]PF6} and two ruthenium(II) polypyridyl complexes { [Ru(bpy)2(bpy-COOH)](PF6)2, [Ru(bpy)2(bpy-(COOH)2)](PF6)2} were synthesized. FT-IR, UV-Vis, HPLC, NMR, ESI-MS, and elemental analysis were used to characterize the synthesized compounds. The antibacterial activity of the compounds was tested against susceptible strains of gram-negative bacteria Pseudomonas aeruginosa ATCC 27853, Escherichia coli ATCC 25922 (BSL 1), Acinetobacter baumannii ATCC 19606, and gram-positive Staphylococcus aureus ATCC 35923 (BSL 2). The anticancer activity of the compounds was tested against MDA-MB-231, A549, HT29, MeL28, SW1990 cancer cell lines, and non-cancerous MRC5 cell line. Finally, a combination study of the most promising compound with cisplatin was conducted to determine if there is synergistic anticancer effect. Results: [Ru(bpy)2(SB4CB)]PF6, and [Ru(bpy)2(SBFH)]PF6 were effective against Staphylococcus aureus, with MIC values of 16 μM when tested on irradiated plates and 16 μM and 8 μM, respectively, for non-irradiated plates. In the anticancer assay, SB4EB was active only in the MDA-MB-231 cell line with IC50 of 37.52 μM for light and 39.59 μM for dark. However, [Ru(bpy)2(bpy-COOH)](PF6)2 was inactive towards all the cell lines. The combination of [Ru(bpy)2(SB4CB)]PF6 with cisplatin did not show any synergistic effect on MDA-MB-231 and MeL28 cell lines, but an antagonistic effect was observed for the non-cancerous MRC5 cell line. Conclusion: [Ru(bpy)2(SB4CB)]PF6, and [Ru(bpy)2(SBFH)]PF6 exhibited favorable activity against Staphylococcus aureus. The most promising anticancer results were obtained for [Ru(bpy)2(SB4CB)]PF6 against MDA-MB-231 cell line. However, it’s combination with cisplatin did not show any synergistic effect on MDA-MB-231 and MeL28 cell lines.

Zingiber officinale Roscoe is the plant from which ginger is derived. This is a popular condiment around the world and is recognized for its rich chemical composition, which includes gingerols, gingerdiols, shogaols, paradols, and zingerones. Antibiotic resistance is a serious hazard to public health, hence developing novel antibacterial drugs is urgently needed. Due in large part to its bioactive components, 6-gingerol, and 6-shogaol, ginger shows great promise as a source. A major contributor to ginger's antibacterial qualities is shogaol. The purpose of this study is to investigate the antibacterial properties of several shogaol derivatives, specifically 3-, 4-, 5-, and 6-shogaol. Aldehyde, zingerone, and dimethylammonium dimethyl carbamate (DIMCARB) were used in the synthesis of these compounds, which were then evaluated against four targeted bacteria: Staphylococcus aureus ATCC 43300, Enterococcus faecalis ATCC 51299, Acinetobacter baumannii ATCC 19606, and Klebsiella pneumoniae ATCC BAA 1705. Using micro broth dilution and the disc diffusion method, concentrations of tested shogaols ranging from 250 μg/mL to 5000 μg/mL were used for the antibacterial properties screening. With zone inhibition values of 2.1 cm and 1.5 cm, 3-shogaol, notably, demonstrated the greatest efficacy and considerable zone inhibition against S. aureus. Moreover, 3-shogaol showed the lowest minimum inhibitory concentration (MIC) of 64 μg/mL of all the compounds might be due to its smaller molecular size and higher lipophilicity, which enhance its cellular penetration and bioavailability. According to these results, various shogaols with different side chain lengths could potentially be sources of lead compounds with antibacterial properties, in addition to the well-researched 6-shogaol. 3-shogaol has been subjected to molecular docking studies against S. aureus dihydrofolate reductase (DHFR) antibacterial drug target and predicts the binding properties of the ligand-protein complex. Determine the relationship between the reported virtual binding qualities that have been confirmed by experimental data based on the literature. Keywords: Antimicrobial, Zingiber officinale, Nutraceutical, Shogaols.

Resveratrol (RSV) is an essential non-flavonoid polyphenolic compound that is frequently present in numerous botanical species. RSV exhibits properties that are associated with anticancer, antioxidant, anti-inflammatory, and cardioprotective effects. Nevertheless, the systemic absorption of the substance is constrained as a result of its lowered water solubility, which consequently reduces its oral bioavailability and its natural chemical instability. Using resveratrol as a model drug, resveratrol-loaded niosomes with two levels of RSV loading concentration (2 mg/mL and 4 mg/mL) were prepared by the thin-film hydration method with different molar ratios of Span 60 (SP 60) / Tween 60 (TW 60) mixed non-ionic surfactants to vitamin D3 (VD3) and to cholesterol (CHL) as vesicular stabiliser, respectively. Their physicochemical properties including shape, vesicle size, polydispersity index (PDI), zeta potential, and stability study, were characterized by zeta sizer and scanning electron microscopy (SEM), while encapsulation efficiency and drug release profile were measured by RP-HPLC and UV-vis spectrophotometer, respectively. It was found that the ratio of stabiliser-to-the mixed non-ionic surfactant and the RSV loading concentration affected particle sizes (125.5 nm to 934.2 nm), PDI (0.492 to 0.794), and zeta potential (-29.9 mV to -42.1 mV) to various extent, with niosomes prepared from resveratrol solution loading concentration of 2 mg/mL having more significant impact. Specifically, VD3-stablised resveratrol-loaded niosomes had a smaller mean particle size and a lower negative zeta potential value than CHL-stabilised ones, suggesting that the type of stabiliser and drug concentration affect the zeta potential but not the stability of the niosomes. The SEM images of selected VD3- stabilised niosomes (Formulation F3; 4 mg/mL RSV) exhibited a quasispherical surface shape, while the CHL-stabilised niosome (Formulation F3; 4 mg/mL RSV) showed a spherical shape. Although the RSV entrapment efficiency (%EE) of the VD3-stabilised niosomes were significantly lower compared with those of CHL-stabilised niosomes prepared at both RSV loading concentrations, the VD3-stabilised niosomes had significantly faster RSV release rate (64.1%) than CHL-stabilised niosomes (56.7%) at 12 hours (F2, RSV = 4 mg/mL loading conc). In the niosomal stability study, the VD3- stabilised niosomes have shown better stability when kept at 4°C than at 25°C over 90 days. Therefore, it can be concluded that VD3 performed better in enhancing favorable characteristics with regard to particle size, stability, and in vitro drug release rate, making it an appropriate replacement for CHL as a stabiliser.