School of Physical Sciences (Phys-Sciences) Collections

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    Fluvial geomorphology of the turaco prospect, Semliki Basin, South-Western Uganda
    (Makerere University, 2025) Kimumwe, Steven Zackayo
    Turaco Prospect was identified in the Semliki Basin located south of Lake Albert. Turaco-1, 2 and 3 wells were drilled by Heritage Oil and Gas Limited (HOGL) in 2002, 2004 and 2005 respectively and the location selected on the basis of a 2-D seismic dataset. Although the three (3) wells were largely unsuccessful, the Turaco-3 well which was drilled to a Total depth (TD) of 2960m encountered hydrocarbon bearing Formations. A 3-D seismic data was later acquired in 2005 over the Turaco Prospect area but was not significantly utilized to better understand the Prospect. This research utilized attributes derived from the 3-D seismic and well data that exists over the Turaco Prospect, RGB blending and geobody extraction to study the fluvial geomorphology of the area. The four (4) 3-D seismic attributes, namely; RMS amplitude, Sweetness, Variance and Envelope have been evaluated and used in the analysis of facies and depositional environment in the basin together with Gamma Ray well logs. Four seismic events or horizons were picked and interpreted. The choice of the seismic events was based on the quality of the seismic-well ties along with interpretive judgment on the reservoir targets that have been well defined by the Turaco-1, 2 and 3 wells. The Formation s interpreted were the Nyaburogo, Oluka, Kakara and Kisegi. The seismic attribute maps for the different Formation s were generated using different extraction methods in petrel software; this was followed by RGB blending and geobody extractions to create maps for interpretation and analysis to identify seismic facies, depositional environment and their lateral variation Eight (8) primary facies associations have been identified and interpreted. These are Crevasse Channels, Distributary Channels, Mouth Bars, Bifurcation Bars and Point Bars which are associated with Fluvial Environment as per the grouping and interpretation from Gamma Ray log interpretation, and Delta Front, Lower Delta Plain and Upper Delta Plain which are associated with the Delta and Lacustrine Environments also as per the grouping and interpretation from Gamma Ray log interpretation. The mapping and inference of facies from seismic attribute maps was entirely based on the variation in attribute values which is depicted by colors after RGB color blending. From the attribute maps, three sediment lithologies have been interpreted that is: sands, silts and clay.
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    Phytochemical study of Markhamia lutea and Securidaca longipedunculata
    (Makerere University, 1998) Sesaazi, Crispin Duncan
    This study describes the extraction and isolation of active principles from two local plants and an investigation of their chemical constitution and anti-bacterial properties. The two plants, Markhamia lutea and Securidaca longipedunculata, are found in Uganda. Markahamia lutea is widely distributed in Uganda and other parts of East Africa, but in Uganda Securidaca longipedunculata is only found in certain localised areas. Both plants are constituents of a herbal preparation, herein referred to as Formula H, which has been used by one prominent herbalist in the alleviation of HIV/AIDS symptoms. In all the extractions of both plants, only the roots were examined because they are the parts which are used by the herbalist to make the formula. Chemical analysis of the extracts of Markhamia lutea root revealed that they contained alkaloids and saponins which appeared to contribute to the pharmacological activity. Rhamnose, a sugar, is most likely to be found in this plant. Sterol and/or terpenes were found to be present. The phytochemical screening of Securidaca longipedunculata extract showed that the components are flavone aglycones, tannins and emodols. A shrimp litharity test was carried out on all the crude extracts of both plants. The results obtained compare very well with the accepted one for crude extracts. Anti-bacterial Activity Test (AAT) was done on three types of bacteria i.e. staphylococcas aureus, Escherichia coli and pseudomonas aeruginosa. It was found that the components of petroleum extract of Markhamia lutea showed the highest degree of activity towards the test organisms. Only one isolated component of the ethanol extract of Markhamia lutea showed considerable activity and only to one of the test organisms (Escherichia coli). Each isolated component of Securidaca longipedunculata showed activity towards at least one of the test organisms. An attempt to determine the structure of the different compounds using spectroscopic analysis was carried out but full interpretation of the data could not be achieved.
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    Structural elucidation, antimicrobial, antioxidant, and toxicity of compounds from selected Ugandan medicinal plants used in treating bacterial skin infections
    (Makerere University, 2025) Sekandi, Peter
    Many Ugandans rely heavily on medicinal plants for the treatment of bacterial skin infections. However, the efficacy of these medicinal plants for their pharmacological and phytochemical action are not known. The study aimed at evaluating the antibacterial, antioxidant, toxicity, and phytochemical composition of the extracts of Spermacoce princeae (K. Schum), Dolichopentas decora (S. Moore) and Rytigynia kigeziensis (De wild). The plant samples collected from Western region of Uganda and extracted by maceration sequentially using hexane, ethyl acetate, methanol, and distilled water. Antibacterial and antifungal activity of each extract and compound was carried out using an agar well diffusion and potato dextrose assay respectively against Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli and, Klebsiella pneumonie. The toxicity of the extracts was assessed using healthy albino rats according to OCED guidelines 402 and 410. Antioxidant activity of extracts was carried out using 2,2-diphenyl-1-picryl-hydrazyl radical scavenging assay. Compounds were isolated using a combination of chromatographic techniques and their structures were elucidated using a combination of spectroscopic techniques. Phytochemical analysis of S. princeae extracts led to the isolation and identification of 11 compounds which included; quercetin (1), kaempferol-3-O-rutinoside (2), rutin (3), myo-Inositol (4), asperulosidic acid (5), hexadecanoic acid (6), β-sitosterol (7), stigmasterol (8), campesterol (9), ursolic acid (10), β-sitosterol glucoside (11). Two novel compounds (a benzophenone 18 and cyano-compound 20) were isolated and identified from extracts from D. decora in addition to squalene (13) and protocatechuic acid (19). Phytochemical analysis of R. kigeziensis extracts led to the isolation and identification 12 known compound that included; pomolic acid (23), 23-hydroxyursolic acid (24), rotundic acid (25), heptyl coumarate (31), vomifoliol (34) and five novel triterpenoids (27, 28, 29, 30 and 33). Compounds 10 and 2 showed antibacterial and antifungal activity against S. aureus, P. aeruginosa, C. albicans, and A. flavu with ZOI ≥ 10.0 ± 0.1 mm. Kaempferol-3-O-rutinoside (2) showed good antioxidant activity (IC50 = 64.81µg/ml) and good sun protection factor (SPF = 26.83). The aqueous extract of S. princeae was not toxic at 8000 and 10,000 mg/Kg. The selected medicinal plants possessed good antibacterial, antioxidant, and sun protection agents. The aqueous extract of S. princeae was generally nontoxic. The novel compounds may present a vital template in pursuit of alternative antibacterial, antioxidant and sun protection agents.
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    Characterizing thinbeds for petroleum potential: a case study of the Ngaji prospect of Lake Edward Basin, South Western Uganda
    (Makerere University, 2025) Katana, Rhitah
    Thinbed reservoirs are widely neglected as exploration targets due to conventional exploitation techniques that focus on thick beds.Thin layers of sand between thick Formations trap hydrocarbons and can be delineated once interpreted well. During Formation evaluation, these thinbeds are neglected or missed out because of the poor resolution of conventional logging tools. These tools only give the average properties of these layers which gives an unsatisfactory prediction of the amount of oil or gas in the layers. However, with more efficient interpretation techniques like cross plots and seismic attributes, subtle details that could otherwise not be identifiable with conventional methods can be solved. Consequently, more reliable results are obtained to detail the realistic reserve estimates in thin bed reservoirs. In this research, thinbeds were identified at specified depths that is between 948 to 953 m, 1174 to 1182 m, 1331 to 1338 m, 1589 to 1595 m and 1615 to 1617 m of the Ngaji prospect using both seismic attributes and interpretation tools with better resolution. Cross plots of neutron-density and log combinations of neutron-density and neutron-sonic were used to generate Litho-M and Litho-N parameters (M-N cross plots) in order to identify the lithologies within the delineated thinbeds . Using Thomas Stieber methods, porosity computations were conducted using petrophysical logs including gamma ray, density, sonic and neutron logs to determine the pay zones within the thin bed intervals. Hydrocarbon saturation of oil was derived from water saturation using Archie’s equation to determine the reservoir quality. The neutron-density cross plots show presence of sandstone, dolomite and shales. The dorminant lithology is sandstone of which are potential reservoirs. The M-N cross plots show the presence of calcite to confirm secondary porosity in the Ngaji prospect. The effective porosity of thinbeds ranges from 0.3 - 0.35 which is an indication of good reservoirs. Hydrocarbon saturation of oil within thinbeds observed in Lake Edward Basin is 25% suggesting fair to good reservoir quality and pay.
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    Structural elucidation, antimicrobial, antioxidant, and toxicity of compounds from selected Ugandan medicinal plants used in treating bacterial skin infections
    (Makerere University, 2025) Sekandi, Peter
    Many Ugandans rely heavily on medicinal plants for the treatment of bacterial skin infections. However, the efficacy of these medicinal plants for their pharmacological and phytochemical action are not known. The study aimed at evaluating the antibacterial, antioxidant, toxicity, and phytochemical composition of the extracts of Spermacoce princeae (K. Schum), Dolichopentas decora (S. Moore) and Rytigynia kigeziensis (De wild). The plant samples collected from Western region of Uganda and extracted by maceration sequentially using hexane, ethyl acetate, methanol, and distilled water. Antibacterial and antifungal activity of each extract and compound was carried out using an agar well diffusion and potato dextrose assay respectively against Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli and, Klebsiella pneumonie. The toxicity of the extracts was assessed using healthy albino rats according to OCED guidelines 402 and 410. Antioxidant activity of extracts was carried out using 2,2-diphenyl-1-picryl-hydrazyl radical scavenging assay. Compounds were isolated using a combination of chromatographic techniques and their structures were elucidated using a combination of spectroscopic techniques. Phytochemical analysis of S. princeae extracts led to the isolation and identification of 11 compounds which included; quercetin (1), kaempferol-3-O-rutinoside (2), rutin (3), myo-Inositol (4), asperulosidic acid (5), hexadecanoic acid (6), β-sitosterol (7), stigmasterol (8), campesterol (9), ursolic acid (10), β-sitosterol glucoside (11). Two novel compounds (a benzophenone 18 and cyano-compound 20) were isolated and identified from extracts from D. decora in addition to squalene (13) and protocatechuic acid (19). Phytochemical analysis of R. kigeziensis extracts led to the isolation and identification 12 known compound that included; pomolic acid (23), 23- hydroxyursolic acid (24), rotundic acid (25), heptyl coumarate (31), vomifoliol (34) and five novel triterpenoids (27, 28, 29, 30 and 33). Compounds 10 and 2 showed antibacterial and antifungal activity against S. aureus, P. aeruginosa, C. albicans, and A. flavu with ZOI ≥ 10.0 ± 0.1 mm. Kaempferol-3-O-rutinoside (2) showed good antioxidant activity (IC50 = 64.81µg/ml) and good sun protection factor (SPF = 26.83). The aqueous extract of S. princeae was not toxic at 8000 and 10,000 mg/Kg. The selected medicinal plants possessed good antibacterial, antioxidant, and sun protection agents. The aqueous extract of S. princeae was generally nontoxic. The novel compounds may present a vital template in pursuit of alternative antibacterial, antioxidant and sun protection agents.