Tanzania Journal of Science

Biomedical Potential of Natural Products from Selected Tanzanian Flora: A Review

Stephen S. Nyandoro — 2024-11-30

Natural products have been used for treatment of various diseases for thousands of years and served as sources of drug lead compounds for the improvement of livelihood. This paper presents a review on the biomedical potentials of selected natural products isolated from eight plant species indigenous to Tanzania. The review covers research work published between 2010 and 2023, and identifies 33 natural products with different pharmacological properties from Tanzanian plants. These bioactive natural products are discussed with other similar compounds isolated elsewhere from the same or different plant species to get further insights on the potential application in modern medicine based on information obtained from online search from different databases including Chemical Abstract, Google Scholar, MEDLINE, PubMed and Science Direct using different key words or phrases. The review includes antitubercular, anticancer and neuroprotective flavonoids from Erythrina schliebenii (Fabaceae), antitubercular and antioxidant metabolites from three mangrove species Heritiera littoralis (Sterculiaceae), Xylocarpus granatum (Meliaceae) and Sonneratia alba (Lythraceae). The review also covers antiplasmodial secoiridoids and iridoids from Morinda asteroscepa (Rubiaceae), antibacterial biflavonoids from two Ochna species (Ochnaceae), antiviral and antiplasmodial diterpenoids from Croton kilwae (Euphorbiaceae), and other constituents from these plant species. Most of these plants are rare, endemic or near endemic in Tanzania. Of these natural products, the catechinoid 13 (IC₅₀ 4.5 µg/mL) was four times more active than the positive control towards radical scavenging, the biflavonoid 31 (MIC 2.2 μM) was more potent in antibacterial assay than the standard drug, whereas diterpenoids 34-36 demonstrated strong anti-proliferative effect against the malaria parasite Plasmodium falciparum (80-100%, at 50 μM), making them promising candidates for drug development. The review argues about challenges associated with the realization of the full potential of biomedical agents such as scalability, toxicity, solubility, and bioavailability thereby calling for concerted research endeavors to address them to exploit effusively the potential that resides in the natural products towards drug development. The mode of actions of the lead compounds must be elucidated and clinical studies conducted for targeted disease treatments.

Tanzanian flora; antiplasmodial; anticancer; antioxidant; antiviral; antibacterial; neuroprotective; anti-inflammatory

Facile Fabrication of Water Filters with Desirable Properties for Removal of Pathogenic E. coli from Drinking Water at point-of-use

Godfrey Michael Shayo — 2024-11-30

The inevitable consequences of waterborne diseases caused by consuming contaminated water have prompted the development of low-cost water filtration technologies that surpass traditional purification methods in effectiveness. Ceramic water filters have been extensively researched due to their promising application in the filtration and purification of water to produce clean and safe drinking water. The present study reports the synthesis of ceramic filtration systems incorporating silver nanoparticles with desirable properties for water purification. The obtained samples were examined by XRD, XRF, and SEM analyses. XRD analysis showed that the samples had crystallite sizes ranging between 16 to 22 nm. XRF analysis revealed a high percentage of SiO₂ (94%) contributed by the high silica content from sand and rice husk. SEM analyses showed the formation of mainly spherical aggregates. The efficiency of the obtained samples was tested by their performance in filtering pond and river water. Prior to water treatment, E. coli counts and other physiochemical parameters were measured. The colorimetry results on E. coli removal by the prepared samples demonstrated good performance of up to 99.999% for samples of ratio 60:40:7.5 which were sintered at 850 °C. These results indicate that Ag-NPs/CWF samples are capable of removing a variety of pollutants, particularly E. coli and other physiochemical parameters making them a promising solution for water disinfection and purification.

Recovering Phosphorus and Nitrogen from Leachate Collected from Chidaya Sanitary Landfill Dodoma Tanzania for Fertilizer Production

Yasin Y. Kifwe — 2024-11-30

The demand for fertilizer is a global issue that poses a significant threat to future food security. Tanzania is among the countries which rely on agriculture for food production and contribute largely to the economy of the nation. However, farmers incur high production costs due to the utilization of expensive and environmentally insecure fertilizers. The present study investigated the potential of recovering nitrogen and phosphorus nutrients from leachate to produce fertilizer. Hanna pH meter (HI-98121) was used to determine the pH of leachate which was found to be 8.29 ± 0.33. The concentration of phosphorus and nitrogen was determined by using DR 4000 spectrophotometer and was found to be 305.24 ± 16.20 and 189.80 ± 0.165mg/L, respectively. Atomic Absorption Spectrophotometer was used in the determination of magnesium (13.13 ± 0.22 mg/L), potassium (3377 ± 123.4 mg/L), calcium (336 ± 3.65mg/L) and sodium (1270.6 ± 156.90 mg/L). The recovery of the nutrients was done through struvite precipitation, in which 74.01% of phosphorus and 57.27% of nitrogen were recovered under an optimal pH of 9.0 and magnesium-phosphorus molar ratio of 5:1. XRD patterns were analyzed by XRD Rietveld reﬁnement method, for phase quantitative and qualitative analysis. Results show that the precipitates formed were struvite and hydroxyapatite. The elemental composition of struvite was examined by using XRF in which plant nutrients including K, P, Mg, Na and Ca were identified. Production of fertilizer is feasible by using leachate from landfills, thus, to reduce the cost of production, alternative sources of magnesium from locally available materials should be explored.

Molecular docking simulation of Bioactive Compounds from Curcuma longa against Helicobacter pylori

Alex J. Mbise — 2024-11-30

Peptic ulcers are open sores that form on the lining of the stomach and upper small intestine and the primary causative pathogen is Helicobacter pylori. In this research, the inhibitory activities of bioactive compounds from Curcuma longa, against H. pylori (8H52) were studied. Eighty-three significant bioactive compounds were selected from the Zinc database and were initially screened using absorption, distribution, metabolism, excretion, and toxicity properties based on compliance with the Pfizer rule. Molecular docking studies were carried out with specific docking site dimensions of values x: -37.3658, y: -4.1028, and z: -22.8563, to identify the binding affinities and interactions. Ten phytoconstituents scored binding affinities between -7.8 and -10.1 kcal/mol. When compared to the control drug omeprazole (-8.8 kcal/mol), the compounds curcumin pyrazole (-10 kcal/mol), 4'-O-methylcatechin (-9.5 kcal/mol), and curcumin (-9.3 kcal/mol) displayed significant binding affinities and good interactions with alanine, valine, aspartic acid and glutamic acid amino acids respectively forming H-bonds with the phytochemicals. These results indicate that curcumin pyrazole, 4'-O-methylcatechin, and curcumin from C. longa can be used as potential inhibitors for H. pylori against peptic ulcers with no adverse effects.

Keywords: Helicobacter pylori; Peptic ulcers; Bioactive compounds; Molecular docking; Curcumin pyrazole

Stellar Properties from a self-consistent Analysis

Pius Privatus — 2024-11-30

Galaxies’ spectral energy distribution (SED) has been explored through the use of spectral synthesis codes. Most of the codes so far are solely stellar and assume a negligible nebular contribution. Fitting Analysis using Differential Evolution Optimisation (FADO) is the first spectral synthesis tool to consider the nebular contribution. The study examines how the primary stellar attributes are affected when FADO is applied to the Max Planck Institute for Astrophysics and Johns Hopkins University (MPA-JHU) data, namely the star-formation rate, metallicity, and stellar mass. The findings show that nebular emission results in the change of the slope of the equation of "the main sequence by 0.04 dex ", and " the vertical intercept by 0.3 dex ", and underestimates gas-phase metallicity of star-forming galaxies by 0.013.

First-Principles studies on the Electronic and Optical Properties of Corundum samples from the Tanga region

Esther J. Tarimo — 2024-11-30

The characteristics of corundum are significant as they provide accurate identification supporting its diverse applications, facilitating the development of advanced materials, and ensuring its optimal use across various fields. Corundum alumina (α-Al₂O₃) samples collected from the Tanga mining region were characterized for crystallographic information using XRD analysis. This crystallographic information was used to build the crystal system of the sample in Biovia Materials Studio modelling and simulation software. The electrical and optical properties of this sample were examined by applying first-principles density functional theory and Generalized Gradient Approximations. For the calculations, a sampling mesh of 6×6×2 k-points, with an energy cut-off of 600 eV, and an energy convergence within 1.0 x 10^-5 eV/atom were used. The band gap determined is 6.34 eV at the gamma point exhibiting an insulating property. By plotting their polarized dielectric function in various directions, the optical properties were evaluated. The reflectivity spectra exhibited anisotropic behaviour in the ultraviolet region, enhancing its performance in various electronic and photonic applications. Also, the absorption peaks observed are 64.81 nm along [001] crystalline direction and 65.29 nm along [100] and [010] crystalline directions.

Keywords: First-Principles studies; Corundum; Band gap; Polarized and anisotropic reflectivity

Exploring Dependence of Rapid Thermal Annealed Ag/ITO Bilayer Films Properties on the Systematic Ag Layer Thickness Increment for Bifacial CZTS Solar Cell Application

Emmanuel R Ollotu — 2024-11-30

This study investigated the impact of Ag layer thickness on the properties of rapid thermal annealed Ag/ITO bilayer films, aimed at addressing conductivity loss in ITO substrates used as a back contact for optoelectronic applications, such as bifacial CZTS solar cells. Ag layers of varying thickness (10 nm, 20 nm, 30 nm, and 40 nm) were sputter-deposited onto a commercially acquired ITO-coated glass substrate and rapidly thermally annealed. The samples’ characterization was performed using AFM, XRD, four-point probe, Hall Effect measurements, and UV-VIS-NIR spectrophotometry. Results indicated that thinner Ag layers exhibited relatively stable surfaces with uniformly distributed grains, smaller roughness, and higher electrical conductivity due to increased carrier mobility and concentration. The XRD analysis showed a preferential delafossite AgInO₂ structure for thinner Ag layers. Optical measurements revealed that the sample with thinner Ag layers had lower solar transmittance and bandgap narrowing, while thicker layers showed bandgap broadening. The samples had bandgaps within reported ITO bandgaps (3.38 to 4.15 eV). Ag/ITO films with thinner layers achieved a high average transmittance of 76%, lower sheet resistance of and enhanced micro-strain and crystallite size properties. These results suggest that thinner Ag/ITO bilayer films hold potential for use in optoelectronic applications, particularly as back contacts in bifacial CZTS solar cells.

Nutritional Composition of Mucuna pruriens var. utilis (Velvet bean) Seeds Grown in Nanyumbu District, Tanzania

Florence Boniface — 2024-11-30

In tropical countries, Mucuna seeds have been utilized to promote better health and ensure a stable food supply. The use of Mucuna pruriens var. utilis seeds in Tanzania has prompted an evaluation of the nutritional composition of two common cultivars grown in the Nanyumbu district. Mucuna seed samples (black-reddish brown and black-greyish) were collected and analyzed for their nutritional content using standard extraction and spectrophotometric techniques. Data analysis was conducted using GraphPad InStat 3.0 software, with a t-test employed to compare means at a 95% confidence level. The results indicated that the differences in nutritional parameters between the black-reddish brown and black-greyish Mucuna seeds were not significant (P > 0.05), except for crude lipid and carbohydrate content. The protein, lipid, carbohydrate, fiber, ash, vitamin C, beta carotene, lycopene, and energy content ranged from 48.13% to 46.50%, 2.13% to 1.39%, 26.75% to 23.12%, 15.99% to 14.51%, 3.23% to 3.21%, 0.98 to 0.84 mg/g, 0.011 to 0.004 mg/100 mg, 0.006 to 0.0058 mg/100 mg, and 1303.7 to 1243.1 kJ/100 g, respectively. Both cultivars of Mucuna seeds exhibit dietary qualities that can be explored as alternative food sources for the malnourished population in the country.

Carbon and Biodiversity Co-benefits in Tropical Forest and Agroforestry Ecosystems: A review

Anna N Mwambala — 2024-11-30

Global efforts to mitigate climate change are focused on the protection and restoration of forest carbon. These efforts do not only hold promise for climate protection but also other benefits including conservation of biodiversity, the majority of which is sheltered in the forest. These include actions to combat climate change and land degradation and actions to halt biodiversity loss through sustainable forest management. However, the challenge remains as to what extent forest conservation that optimizes carbon storage will conserve biodiversity. Understanding synergies between climate change mitigation and biodiversity conservation could be the basis for attaining sustainable development goals. Library catalogues and public database for studies that included carbon stock and biodiversity co-benefits/relationships in tropical forests were searched and included in a review. This review reveals that forest conservation for carbon is showing promising results for biodiversity in undisturbed/relatively disturbed tropical forest ecosystems. However, some areas with high biodiversity but low carbon may not benefit from carbon-based conservation. Given the tropical ecosystem dynamics, it is important to generate more data based on a specific ecosystem to ascertain the level of this co-benefit. This review forms the basis for considering biodiversity conservation in carbon-based conservation planning.

Inhibitory Activities of Phytoconstituents from Azadirachta indica and Murraya koenigii as Potential Drugs for Secondary Infection of Atopic Eczema Disease - In silico study

Mikidadi S. Gurisha — 2024-11-30

Atopic Eczema (AE) disease is a chronic inflammatory skin condition that is caused by a person’s inability to repair damage to the skin barrier. Staphylococcus aureus (SA) is a virulent pathogen that plays an important role in the progression of secondary infection in AE patients, thus intensifying the disease's virulence. In this study, the inhibitory activities of phytoconstituents from Azadirachta indica and Murraya koenigii against the SA (Protein Data Bank ID: 7TIO) using an in silico approach are presented. Site-specific docking analysis was carried out on the virulent pathogen with the docking center at X: 1.65044, Y: 1.7980, Z: 3.1878, for a box of dimension X: 64.2332, Y: 40.2828, Z: 41.8202. The natural compounds were chosen based on their absorption, distribution, metabolism, excretion, and toxicity characteristics, as well as other drug-like characteristics computed in Swiss ADME and pkCSM software. Four compounds, Gedunin (-7.2 kCal/mol), Curryanine (-7.1 kCal/mol), Mahanimbinine (-6.6 kCal/mol) and Mahanine (-6.5 kCal/mol) with good inhibition for the S. aureus pathogen were discovered to exhibit better docking scores compared to Prednisone (-6.1 kcal/mol) (control drug). The studied Phytoconstituents of A. indica and M. koennigii thus can be used as inhibitors of SA pathogen (7TIO) in the fight against AE disease.

Phytoconstituents; Staphylococcus aureus; Atopic Eczema; Azadirachta indica; Murraya koennigii.

A review on Ethnomedical use of Tephrosia vogelii Hook.f. and its potentiality towards the development of antimicrobial agents and pesticides

Stephano Hanolo Mlozi — 2024-11-30

Fish bean, Tephrosia vogelii Hook.f is among of potential medicinal plant species in the genus Tephrosia. It has been traditionally used to cure human and animal ailments including fungal and bacterial diseases though not exhaustively scientifically reported. Similarly, its extracts have been locally used to control vectors and pests in small scale farming though the drug development from its extracts and phytochemicals is not reported. Thus, this review focused to unveil its ethnomedical and pharmaceutical potentiality with emphasis towards development of antimicrobial agents and pesticides. Data collection for the review was based on the published paper searched globally in several sources including Web of Sciences, Google scholar, and publishers such as Elsevier, Springer, Taylor and Francis. Evidently, data from literature revealed various bioactivity studies which uncovered potentiality of this species towards development of pesticides and antimicrobial agents. This review hereby promotes the present bioactive secondary metabolites of Tephrosia vogelii, and thought-provoking emphases on either herbal formulation or development of pesticides and antimicrobial agents. The reported pharmacological value of various secondary metabolites such as terpenoids, steroids, tannins, flavonoids and rotenoids explains potentiality of this medicinal plant. Moreover, data generated from this review on medicinal value of the T. vogelii offer and emphasizes medicinal consciousness towards development of pesticides and antimicrobial agents for improvement of human health settings and agricultural production particularly management of crop pests and diseases.

Nutritional Potential and Antioxidant Activity of Dioscorea spp. Tubers from Mtwara Rural District, Tanzania

Tumsifu S. Mwanjala — 2024-11-30

The wild yam Dioscorea hirtiflora subsp. orientalis, native to the Mtwara rural district in Tanzania, remains underutilized despite its considerable nutritional and health benefits. This study aimed to assess the nutritional composition and antioxidant properties of its tubers. Standard AOAC procedures were employed to analyze dried tuber samples, while antioxidants and antioxidant capacity were evaluated. The tuber was found to have carbohydrates content ranging from 21.02% to 23.57%, crude protein from 1.0% to 1.5%, crude lipids between 0.46% and 0.68%, and crude fiber from 11.26% to 13.52%, with an energy value of 97.26 to 101.1 Kcal/100 g. Vitamin C content varied from 18.9 to 26.4 mg/100 g, beta-carotene from 4.15 to 17.8 µg/g, and lycopene from 6.89 to 9.10 µg/g. Methanol extracts revealed total phenolic content ranging from 60.28 to 122.51 mg GAE/g and flavonoids ranging from 599 to 1240.4 mg RUE/g, with notable DPPH radical scavenging activity, demonstrated an EC₅₀ of 0.04 mg/mL for brown tuber extract and 0.09 mg/mL for white tuber extract. These findings suggest that D. hirtiflora is a rich source of vital nutrients and antioxidants, with potential to enhance local diets and serve as a basis for developing antioxidant-rich supplements or functional foods. Future research should focus on refining extraction techniques and exploring the health applications of this valuable tuber.

Wild Yam (Dioscorea orientalis); Nutritional Composition; Phenolic; Flavonoid Content; Antioxidant Activity

Integrative human-mouse gene expression and phylogenetics analysis to prioritize genes of evolutionary and biomedical importance in the retina and retinal pigment epithelium

Edson Ishengoma — 2024-11-30

Mammalian models, such as mice, are often used to study human retinal diseases, but, owing to the evolutionary time-scale separating the two species, some physiological functions involved in vision differ between the two species. Here, public RNA-seq data sets were used to interrogate genome-wide gene expression patterns in mouse and human retina and retinal pigment epithelium in order to identify genes of significance underlying visual signal processing in the two species. Individual genes with distinct and conserved expression patterns across the retinal tissues were identified both within and between species, followed by an assessment of biomedical roles in visual functions, and their extent of sequence conservation among mammals. There was evidence that the conservation of expression patterns is linked to evolutionary sequence conservation, retinal cell-type specificity and disease association, suggesting that these parameters should be considered together when investigating the genetic and evolutionary underpinnings of mammalian eye function and pathology. The extent of sequence and expression pattern conservation observed at individual genes and at pathway level could highlight the relative importance of signaling pathways that control retinal cell development, differentiation and survival across species. This information may be crucial in providing the basis for which genes to prioritize in cross-species treatment testing, including gene therapy for retinal diseases, as well as providing deeper insights on the evolution of retinal diseases susceptibilities in different species.

Fixed Point Theorems and Sensitivity Analysis in Solving Nonlinear Matrix Equations: A Study Involving Partially Ordered Sets

Chacha Stephen Chacha — 2024-11-30

Nonlinear matrix equations of the form , where represents an unknown matrix, and and are given square matrices, are encountered in various fields. Understanding the characteristics and behaviour of these equations is essential for developing efficient computational methods and obtaining reliable solutions. This paper explores the use of partially ordered sets within fixed point schemes to solve the targeted equations. Furthermore, it derives perturbation estimates of the solutions and evaluates them computationally. Finally, the numerical simulations are provided to validate our theoretical claims and affirm the effectiveness of the proposed fixed-point scheme.

Keywords: Fixed point, partially ordered sets, Nonlinear matrix equation, Positive definite solution, Perturbation

A Mathematical Model for Malaria Transmission Dynamics in the Population with Different Immune Status

Neema S. Mbugi — 2024-11-30

Malaria is a febrile illness affecting a large population worldwide. Even though malaria is curable and preventable it continues to pose a significant health risk, economic effects, and social effects in the population. This study formulates a mathematical model to study the transmission dynamics of malaria in a population with different immune status. By dividing the population based on immune status, the model provides insights into how immunity influences the interaction between hosts and malaria parasites, particularly in terms of infection rates, immune responses, and propose appropriate control for effective elimination. The basic reproduction number is computed using the next-generation matrix approach. The analysis shows that the model can undergo forward bifurcation when the basic reproduction number , thus, the condition of necessary and sufficient for malaria elimination. The numerical simulation results indicate that non-immune individuals play a more significant role in malaria transmission compared to semi-immune individuals. This is because non-immune individuals, lacking strong immunity, are more susceptible to malaria infection. Moreover, the results highlight the effect of mosquito biting rates on the susceptible and infectious population. The findings underscore the importance of considering immune heterogeneity within the population when developing strategies to control and eventually eradicate malaria.

Modelling Malaria Dynamics in Children under Five Years, Pregnant Women and the Influence of Temperature

Paul K Robert — 2024-11-30

Malaria remains a major public health problem worldwide and it affects the livelihood of people particularly children under 5 years and pregnant women. This study formulates and analyzes a mathematical model that incorporates children under five years, pregnant women and influence of temperature on the transmission dynamics of malaria. The next generation matrix method is applied to compute the basic reproduction number . Analysis shows that malaria-free equilibrium point exists and it is globally asymptotically stable when . Numerical simulations show that the rate of infections in both human and mosquito populations increases as temperature increases. Higher temperatures generally increase the rate of infection in both human and mosquito populations, with distinct impacts on children under five years and pregnant women.

Keywords: Basic reproduction number, malaria-free equilibrium, model simulation, model analysis, temperature variations.