RP-Department of Chemistry

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Biodegradable Superabsorbent Hydrogel from Activated Hydrochar-Glycerol Cross-linked with Maleic Acid
(American Journal of Polymer Science, 2025-08) Mukulu, Stanley M.; Mbuvi, Harun M.; Kasimu, Titus M.; Maingi, Francis
Superabsorbent hydrogels are polymer materials with a three-dimensional structure. They have the potential to absorb large amounts of water or aqueous solutions due to the presence of hydrophilic functional groups in their network structures. The increasing population, coupled with advanced technologies, has led to a fourfold increase in demand in industrial applications, technological fields, medical fields, and agriculture. This study reports on the synthesis and characterization of superabsorbent hydrogels derived from activated hydrochar. The preparation of hydrochar was done via the dehydration process of sugarcane bagasse, followed by activation using acidified potassium permanganate to form activated hydrochar (AH). The AH was then reacted with glycerol to form polymer units (AHGL). The polymeric units were then reacted with maleic acid to form a superabsorbent hydrogel (SAH). Characterization of the synthesized SAH was carried out using FT-IR, SEM, and XRD. The swelling capacity was optimized by varying contact time and doses of both glycerol and maleic acid. The FT-IR spectra showed a C=O carbonyl spectral absorption peak at 1711.85 cm⁻¹ in SAH, indicating successful crosslinking. The XRD analysis portrayed the amorphous nature of hydrochar and AH, while AHGL and SAH showed semi-crystalline and crystalline nature, respectively. SEM analysis showed dense porous surfaces in SAH compared to rigid surfaces with fewer and unevenly distributed pores in AHGL. The gravimetric technique showed that the maximum absorption capacity of the SAH was obtained at the optimum reaction mole ratio of AH:GL:MA of 10:4:1. The maximum absorption capacity of the synthesized superabsorbent hydrogel relative to its dry mass was found to be 905% and was achieved in a period of 8 hours. Crosslinking the hydrogel improved the water absorption capacity, and hence, it has potential application in agriculture in arid and semi-arid regions.
Evaluation of the Food Barrier and Mechanical Properties of Carrageenan-Starch Composite Films
(Wiley, 2024) Madivoli,E. S.; Kisato,J; Kimani, P. K.; Kamau, K
Single use plastics are a leading source of microplastics that have been detected along the food chain. This study evaluated the potential of starch (ST) and carrageenan (CRG) in packaging film formulation. CRG isolated from the seaweed (SW) Eucheuma denticulatam was blended with starch and cast to obtain films whose moisture content (MC), total soluble matter (TSM), degree of solubility (DS), water vapor permeability (WVP), opacity (O), contact angles (CA), moisture absorption (MA), and percent elongation (PE) were evaluated. The films’ morphology, crystallinity, opacity, thermal profile, and functional groups were then studied by scanning electron microscopy, powder diffraction, UV–Vis, thermal gravimetry, and infrared spectroscopy. From the results obtained, the SWF films exhibited a higher MC, DS, and TSM than CRG and CRG-ST films but lower DC values. The PE of CRG films was lower than that of SWF (30%) though incorporation of ST increased the PE of CRG-ST. However, SWF films had WVP of 2.25×10−7 gs−1m−1Pa−1, compared to 3.65×10−7 gs−1m−1Pa−1 of CRG, 2.73×10−7 gs−1m−1Pa−1 of CRG-ST and a moisture absorption of 29.29±3.5 as compared to 17.29±0.87 of CRG and 23.80%±4.12% of CRG-ST. The opacities were found to be 41.02, 79.89, and 42.23 for SWF, CRG, CRG-ST while the contact angles were found to be 72.86, 80.93, 65.57 for SWF, CRG, and CRG-ST, respectively. Moreover, the films were impermeable to vegetable oil, had carbohydrate functional groups, good thermal stabilities, and trace micronutrients. In conclusion, this study formulated packaging films with enhanced food barrier and mechanical properties that can potentially replace single use packaging films
Development of an Electrochemical Nano-biosensor for Rapid and Sensitive Diagnosis of Bilharzia in Kenya
(sabinet, 2018) Odundo,Joseph; Naumih, Noah; Andala,Dickson; Kiragu,Janet; Masika,Eric
Bilharzia, also known as schistosomiasis, is still affecting more than 250 million people, killing about 200 000 annually and leaving millions of others debilitated. Current diagnostic tools have extremely low validity and are not readily applicable for rapid diagnosis in rural and remote areas. In low-grade infections, microscopy, the most commonly used method, may have low sensitivity. For example, in suspected cases, up to five real sample specimens are recommended for increased sensitivity. The rise of nanotechnology has created the potential to significantly improve the current diagnostic approaches. Conjugating antibodies with nanoparticles pools the distinctive properties of the nanoparticles with the specificity and selectivity of the antibodies in the recognition of the antigen. This in return leads to a very versatile and specific mixed product with improved analytical signal which is important for fast, sensitive and real-time point-of-care diagnosis. In this work, we report the use of nanotechnology to develop a simple and sensitive nano-biosensor which consisted of a nano-strip with immobilized gold nanoparticles conjugated with bilharzia antibody, and demonstrated its potential for diagnosis of bilharzia antigen. A detection range of 1.13 × 101 ng mL–1 to 2.3 × 103 ng mL–1 of bilharzia antigen in stool samples and with a limit of detection of 8.3887 × 10–2ng mL–1 was attained, indicating the potential of the nano-biosensor to be used to detect bilharzia antigen in stool samples.
Acceptability of Germinated Porridges with Micronutrient Powder among Children (6-23 Months) in Kenya: A Parallel Siterandomized Feeding Trial
(African Journal of Agriculture and Food Science, 2025-05) Nyambaka, Hudson; Kimiywe, Judith; Susan, Momanyi-Nyasimi
Introduction: Foods prepared from germinated ingredients have lower antinutrients and thus suitable vehicles for Micronutrient powder (MNP). Unfortunately, home consumption of these food products is declining in Kenya. Methods: Three phase acceptability study: a seven-day phase one using a crossover design, a two-week parallel site-randomized feeding trial, and a focus group discussion with caregivers. Results: Caregivers reported significant differences in color and texture between germinated flour porridge and control porridge, but these differences did not impact overall acceptance. Significantly more non-germinated flour porridges were consumed during the sensory testing. Conversely, germinated flour sorghum porridge (p=0.003), maize (p=0.127), and millet (p=0.073) were consumed over a 2-week feeding phase. Significantly more germinated flour porridges compared to non-germinated flour porridges were consumed in the latter days compared to the initial days ((p<0.001). Caregivers gave positive feedback on the germinated porridges. Conclusion: The three germinated porridges were accepted and could serve as vehicles for MNP in Homa-bay County.
In-vitro Antibacterial and Antifungal Activities of the Stem Bark Extract and Fractions of Warbugia. ugadensis, Prunus africana and Albizia gummifera from Mt Kenya and Elgon Regions in Kenya
(asiapacificpublishers, 2025-02) Holland , Shoso Luvembe; Wanyonyi, Alphonse Wafula; Mwangi, Henry
Fungal and bacterial infections pose a major global public health challenge due to rising antimicrobial resistance. Over 50% of hospital infections now involve pathogens resistant to multiple drugs, contributing to higher death rates, longer patient illness, and increased/prolonged hospital stays. Exploration of medicinal plants' phytochemical properties provides one avenue for developing new treatment options outside the traditional drug development process to address the intensifying antimicrobial resistance crisis. The plant materials were subjected to cold maceration followed by liquid-liquid partitioning using hexane, dichloromethane (DCM), and ethyl acetate in order of increasing polarity. The derived methanol extracts were screened for phytochemicals using standard procedures. The disk diffusion method evaluated the antimicrobial activity of 50mg/mL of W. ugadensis, P. africana, and A. gummifera against S. aureus, E. coli, and C. albicans. The study qualitatively and quantitatively assessed antibacterial and antifungal activities by observing inhibition zones and determining minimum inhibitory concentration (MIC) values. Several bioactive compounds were detected in the methanolic extract of these plants such as saponins, alkaloids, terpenoids, tannins, flavonoids, phenols, and glycosides. Preliminary disk diffusion screening revealed that W. ugadensis DCM extract exhibited the strongest antimicrobial activity against C. albicans, E. coli, and S. aureus, with mean inhibition zones of 21.0, 10.3, and 15.7mm respectively. MIC analyses with 96-well microliter plate assays confirmed S. aureus as the most susceptible and E. coli as the least vulnerable to the extracts. Tukey’s Multiple Comparison Test (P < 0.05) demonstrated significant differences in antimicrobial activity among A. gummifera, W. ugandensis, and P. africana. The inhibition of the various plant extracts against the tested microorganisms indicates that further study could reveal their potential use in treating infections caused by these microorganisms. Additional research is required to fully elucidate their therapeutic potential and explore practical applications for combating microbial infections.
Controlling Rate of Release of Tsetse Fly Repellent Blend byEncapsulating in β-Cyclodextrin Nanoparticles
(Journal of Nanotechnology, 2025-05) Ratemo, Bernadatte M.; Wachira, Benson M.; Masika, Eric; Ng’ang’a, Margaret M.; Hassanali, Ahmed; Mireji, Paul O.
Tsetse flies are major vectors of African trypanosomiasis, with devastating medical and veterinary consequences in sub-Saharan region of Africa. Insect repellents are promising tool for control of tsetse flies in the region. A four-component tsetse-repellent blend (δ-nonalactone, heptanoic acid, 4-methylguaiacol, and geranyl acetone) previously formulated and optimized was encapsulated in β-cyclodextrin for a slow controlled release. Here, we explored various methods of microencapsulating (kneading, coprecipitation, heating, or freeze-drying) tsetse fly repellent blend in β-cyclodextrin nanoparticles. We assessed release kinetics of the blends and individual compounds using gas chromatography linked with flame ionization detector and evaluated laboratory and field responses (repellence) of the flies by the encapsulated blends. We compared individual performances of releases kinetics of the encapsulated blend relative to nonencapsulated composites. Overall, kneading, coprecipitation, heating, and freeze-drying microencapsulation techniques retained 72.0%, 61.0%, 59.5%, and 57.3% of the blend, respectively. Release rates of blends in 400- and 200-microns thick polythene sachets were 6.73 and 11.82 mg/h, respectively, significantly higher (p < 0.05) than that of the kneaded encapsulated blend (5.35 mg/h). Laboratory and field responses of tsetse flies to the unencapsulated native (sachet) and kneaded encapsulated odor blends confirmed our laboratory findings. Microencapsulation technology of repellent odors can be used for controlled release of active molecules in order to give an extended protection period, potentially reducing operational cost in programs for control of tsetse flies and related insect vectors.
Removal of Nitrites from Wetland Waters Based on Diazonium Silica
(SAP, 2025) Kathambi Aquiline; Njoroge Peter W.; Opiyo Sylvia A.; Waweru Isaac; Mwangi Benson M.
Diazonuim silica was prepared and used to remove nitrites in wetland waters. Raw silica was chlorinated using phosphorous pentachloride (PCl5). Chlorinated silica was further reacted with ethylenediamine (EDA) under reflux to give aminated silica. Thereafter, aminated silica was protonated to yield diazonium silica which was used as the adsorbent. The prepared diazonium silica material was characterized using Fourier Transform Infrared (FT-IR) showing bands at wavenumbers 1049 and 791 cm-1 of the anti-symmetric and symmetric stretching modes (Si-O-Si) of SiO4. The shift in spectra band of Si-O-Si from 1051cm-1 in raw silica to 1049cm-1 , was attributed to diazonium silica. Additionally, a new open chain azo (N=N) group band was found in the region 1575cm-1 -1630cm-1 . The physical adsorption parameters examined using batch adsorption system including: pH, initial concentration, contact time and temperature were made using sorption models, adsorption kinetics and thermodynamics. The results obtained showed 3.0 as the optimal pH for adsorption of NO2 - , 303K as the optimal temperature, optimum contact time as 60 minutes and optimal initial concentration as 20ppm. The adsorption capacity of nitrites using diazonium silica adsorbent was achieved at 16.45mg/g. For sorption of nitrites in diazonuim silica, Langmuir isotherm model was obeyed according to correlation coefficient R2 = 0.97182 close to unity. Adsorption kinetics of nitrites in diazonium silica pseudo second order was best obeyed while, thermodynamic parameters revealed that the sorption of nitrites into diazonium silica was exothermic in nature. From the results obtained, diazonium silica is an efficient adsorbent for adsorption of nitrites compared to raw silica
Levels of Cadmium, Copper, and Lead in Soils and Cassava Tubers Grown in Machakos County, Kenya
(Applied and Environmental Soil Science, 2024-08)
Dietary Mycotoxins: An Overview on Toxicokinetics, Toxicodynamics, Toxicity, Epidemiology, Detection, and Their Mitigation with Special Emphasis on Aflatoxicosis in Humans and Animals
(MDPI, 2024-11) Kibugu, James; Munga, Leonard; Mburu, David; Maloba, Fredrick; Auma, Joanna E.; Delia, Grace; Lindahl, Johanna F.
Mycotoxins are secondary metabolites of filamentous fungi and ubiquitous dietary contaminants. Aflatoxins, a group of mycotoxins with high prevalence and toxicity, have raised a high level of public health concern, the most prevalent and toxic being aflatoxin B1 (AFB1). Many aspects appertaining to AFB1 poisoning are not well understood. Yet this information is necessary to devise appropriate surveillance and mitigation strategies against human and animal aflatoxicosis. This review provides an in-depth update of work carried out on mycotoxin poisoning, particularly aflatoxicosis in humans and animals, to identify gaps in knowledge. Hypotheses explaining the functional significance of mycotoxins in fungal biology and their dietary epidemiological data are presented and briefly discussed. The toxicology of aflatoxins and the challenges of their mitigation are discussed in depth. It was concluded that the identification of potential mycotoxin-hazard-prone food items and quantification of the associated risk of cancer ailments in humans is a prime priority. There is a dearth of reliable sampling methodologies for estimating AFB1 in animal feed. Data update on AFB1 in animal feed and its implication in animal production, mitigation strategies, and elucidation of risk factors to this hazard is required. To reduce the burden of aflatoxins, surveillance employing predictive technology, and biocontrol strategies seem promising approaches.
Analysis of Physico-Chemical Parameters and Selected Heavy Metals in Aquatic Ecosystems.
(IOSR-JAC, 2023-09) MunenePaul M.; Mbugua, Gerald W.; Wanjau, Ruth N.; Ndiritu, N. James
The quality of aquatic ecosystems is of great concern. Elevation of pollutants in water could cause health disorders in human and destabilize the aquatic ecosystem. The case study investigated quality of water from five sites of Lake Turkana selected based on proximity to potential anthropogenic pollution sources. Temperature, pH, electrical conductivity (EC), dissolved oxygen (DO), salinity, total dissolved solids (TDS) and OxidationReduction Potential (ORP) were measured at the site using YSI Pro 1030 Multiparameter electrode while nitrates and phosphates were determined at Kenyatta University’s food science laboratory using Vis 130 Spectrophotometer. Selected heavy metals (lead, cadmium and chromium) were determined using flame atomic absorption spectroscopy. Sampling was performed in triplicates during the dry season. The results were: temperature (28.24±0.96 to 28.86±0.38°C), pH (9.04±0.21 to 9.46±0.06), electrical conductivity (281.57±0.41 to 289.46±3.95 Ωcm-1 ), dissolved oxygen (6.3±0.79 to 7.04±0.05 mg/L), salinity (1.67±0.00 to 1.70±0.01 ppt), TDS (2093.4±0.39 to 2135.8±4.86 mg/L), ORP (-54.22±0.12 to 588.14±0.51 mV), nitrates (5.52±0.31 to 10.04±1.82 mg/L) and phosphates (0.47±0.06 to 0.72±0.15 mg/L). Water lead (0.11±0.01 to 0.12±0.00 mg/L), cadmium (0.00±0.00 to 0.03±0.00 mg/L) and chromium (0.01±0.00 to 0.03±0.01 mg/L). The results showed that pH and TDS were beyond WHO standard of 6.5-8.5 and 600.0 mg/L respectively while phosphates exceeded USEPA limit of 0.024 mg/L in all sites. The electrical conductivity and nitrates complied with WHO standards of 400.0 Ωcm-1 and 50.0 mg/L respectively while the other parameters were not guided by WHO. The lead levels in water exceeded WHO standard of 0.01 mg/L in all sites. The cadmium levels in Impressa and Long’ech beaches in the upstream section exceeded WHO standard of 0.003 mg/L. However, chromium complied with WHO standard of 0.05 mg/L in all sites. These calls for measures keep all the parameters under surveillance to ensure water quality is maintained.
Bioavailability of Antioxidant Vitamins in Selected Indigeneous Vegetables and their Potential use in Management of HIV/AIDS in Butula, Busia, Kenya
(ACRI, 2024-04) Nambafu, Rachel Wanjiru
The study investigated feeding pattern of PLWHA in Butula division, determined vitamin A, C and E content and bioavailability in selected indigenous foods for use in the management of HIV and AIDS. Animal and plants foods accounted for 45.17 %, 21.9 %, 17.48 % and 73 % respectively of total foods consumed. Fresh blanched vegetables, contained high levels of β-carotene; 4000- 9700µg/100g and α-tocopherol; 3000-7350µg/100g. Solar dried vegetables contained β-carotene of range 572-854µg/g DW and α-tocopherol of 281-673µg/g DW which is significantly lower (P<0.05) than fresh vegetables determined by HPLC. L-ascorbic acid content in fresh vegetables and fruits determined by redox titration ranged from 6 to 65mg/100g. Mean serum retinol, αtocopherol and β-carotene levels were 0.937, 0.144 and 17.787µmol/l respectively determined using HPLC. CD4+ cell counts in blood determined using flow cytometer were within the normal range of 500-1500 cells/µl while the CD8+ cell count was in the range of 300-3300 cell/µl of blood. Hb was less than 12 g/dL and RDW was less than 15.2% indicating anaemia. 88.35% of the subjects had a CD4/CD8 ratio of less than 1, 9.71% had a CD4/CD8 ratio range of 2-3 and 1.94% had a ratio greater than 4.77.95% of the subjects had a normal weight, 11.81% were underweight, 8.66% were overweight and 1.57% were obese. Bioavailability in foods estimated using algorithm indicated a +2.17 change in serum β-carotene and +7.776 changes in serum α-tocopherol levels indicating that consumption of the foods would result to improving bioavailability of these nutrients in PLWHA in Butula.
Method Development and Optimization of Liquid Liquid Microextraction Based on the Decomposition of Deep Eutectic Solvent for the Determination of Chromium (VI) in Spinach: Assessment of the Greenness Profle Using Eco scale, AGREE, and AGREEprep
(Springer, 2024-01) Moema, D.; Makwakwa, TA.; Nyambaka, H. N.; Dube, S.; Nindi, MM
A simple, efective, and ligandless liquid-liquid microextraction (LLME) procedure based on the decomposition of hydrophobic deep eutectic solvents (HDES) was developed for the separation and pre-concentration of chromium (VI) ions in spinach leaves, before the determination by fame atomic absorption spectrophotometry. In the proposed study, the frst stage involved the leaching of chromium (VI) from spinach leaves with 0.1 M Na2CO3, and in the second stage, chromium (VI) extract was preconcentrated with the LLME procedure using a DES prepared from the combination of DL-menthol and formic acid as a chelating agent and extraction solvent. The DES decomposed in an aqueous donor phase resulting in the dispersion of menthol and extraction of Cr (VI) ions. Under optimal experimental conditions, the limits of detection (LOD) and quantifcation (LOQ) were 0.63 and 2.1 µg L−1, respectively. The relative standard deviation (RSD) was less than 7%, and the pre-concentration factor (PF) was found to be 31.25. The accuracy of the present methodology was tested by recovery experiments. The greenness of the developed method was assessed using three quantitative green metrics tools: Analytical Eco-scale, AGREE, and AGREEprep, with only Analytical Eco-scale qualifying the proposed method as green.
Green Superabsorbent Hydrogel Derived from Activated Charcoal and Glycerol with Maleic Acid as a Cross-Linker
(Journal of Experimental Sciences, 2024-02) Kasimu, Titus M.; Mbuvi, Harun M.; Maingi, Francis M.
Superabsorbent hydrogels characterize a set of polymeric materials with three-dimensional structures capable of absorbing large amounts of water due to their hydrophilic functional groups on their surface. Their application in industries, agriculture, and the environment is of primary significance. This study reports the synthesis and characterization of green superabsorbent hydrogels derived from activated charcoal. The process involved a polymerization reaction between activated charcoal (AC) with glycerol (G) using sodium hydroxide as an initiator in the absence and presence of maleic acid as a crosslinker to synthesize HCG-1 and HCG-2 superabsorbent hydrogel respectively. Characterization of the hydrogels was done using Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscope (SEM), and X-ray diffraction (XRD). Optimization conditions were done by synthesizing hydrogel with varying dosages of both activated carbon and maleic acid as well as swelling time. The FT-IR results showed the appearance of strong sharp peaks at 1591.34 cm-1 and 1400.28 cm-1 in HCG-1 associated with -COO¯ symmetric stretching and asymmetric bending vibrations, indicating interlink between reacting monomers. Anew absorption band at 1639.48 cm-1 associated with -COO¯ bending in non-conjugated ester indicates ester-crosslink in HCG-2 hydrogel. XRD analysis showed a phase shift from semi-crystalline to crystalline structure upon crosslinking. SEM analysis showed a crystalline intact, rigid structure without voids and pores on its surface in HCG-1 compared to the smooth irregular pores and lamina structure observed in HCG-2 hydrogel. The dosage ratio of AC: G: maleic acid of 8:5:1 produced hydrogel with an optimal water absorption capacity of 1255.80±0.70%. Maleic acid was found to improve the water absorption capacity of the superabsorbent. The study is an eye opener towards the application of biodegradable hydrogels in agriculture, especially in semi and arid regions.
Effect of Processing Methods on Nutrient and Anti-Nutrient Composition of Grasshopper and Termites
(Tylor and Francis, 2023-11) Gachihi, Anne; Tanga, Chrysantus; Nyambaka, Hudson; Kimiywe, Judith
Different processing methods could impact on the nutritional and anti-nutritional composition of edible insects. This study involved the analysis of nutrients and anti-nutrients in fresh and processed grasshopper (Ruspolia differens) and winged termites (Nasutitermes spp) in Kenya. Proximate analysis was done using AOAC methods, minerals analysis using AAS and anti-nutrients analysis using UVVIS and titration. Moisture content reduced significantly to less than 10% on processing, while ash content increased significantly by more than 50% on processing. Processing did not affect the crude fibre content but it led to a 0.2–90% decrease in crude fat. Processing increased significantly the protein content but did not significantly influence mineral levels; however calcium content was reduced considerably. Anti-nutrient levels decreased significantly on processing by 2%–70% with oxalates and phytates having the highest decrease. These results show that oven-drying and defatting methods retained higher nutrient composition in the edible insects.
Review of the Effect of Grinding Aids and Admixtures on the Performance of Cements
(Hindawi, 2023-11) Muthengia, Jackson Wachira; Munyao, Onesmus Mulwa; Mutitu, Daniel Karanja; Musyoki, David Munyao
Grinding aids (GAs) are polar chemicals introduced in cement mills in either liquid or powder form to improve on mill grindability efficiency. Studies have shown that some GAs not only help in grinding efficiency but also play vital roles in improving the product particle size distribution, product ability to flow in the mill, grinding energy reduction, and improvement on the separator efficiency. This review investigated the impacts of the GAs on the performance of some properties of cement when used as either mortar and/or concrete. The influence of the GAs incorporation in cement grinding on properties such as workability and setting times of the placed concrete and/or mortar has been covered in this review. The performance of GAs on ordinary portland cement (OPC) and blended cements with other supplementary cementitious materials such as pozzolana, fly ash, and slag has also been discussed. This is in view to tapping the maximum benefits of using GAs in cement production and use. This review work established that GAs have a positive influence on mill performance when properly applied. It further established that blended cements work better when dosed with additives such as GAs and/or quality improvers when compared to OPC. The review work demonstrated that some superplasticizers help in lowering the water demand in highly blended pozzolanic-based cements. The review finally recommended that the future course of action in the production of blended cements should apply GAs. This is in order to help produce highly replaced blended cements that are sustainable.
Antimicrobial Activities of Some Constituents Isolated from a Kenyan Medicinal Plant, Capparis fascicularis DC
(Hindawi, 2023-10) Kagika, Mary W.; Chhabra, Sumesh C.; Nonoh, James O. M.; Hassanali, Ahmed
Background of the Study. Capparis fascicularis DC. is an indigenous medicinal plant belonging to the family Capparaceae found in Nyandarua County, Nairobi, Kenya, and many parts of Africa. It is a shrub whose roots are used traditionally to treat colds. Aim. The aim of the present study is to carry out antimicrobial activities of solvent extracts of diferent parts of Capparis fascicularis, characterize the phytochemical constituents of the most active extract, and identify the most active compounds. Place and Duration of the Study. All the experiments were carried out in the departments of Chemistry and Microbiology, Kenyatta University, Nairobi, Kenya. Methodology. Petroleum ether, ethyl acetate, methanol, and water extracts from the leaves, stem bark, and root bark of C. fascicularis were screened against selected strains of both Gram-positive (Staphylococcus aureus and Bacillus subtilis) and Gram-negative (Salmonella typhimurium and Escherichia coli) bacteria using disc difusion and tube dilution methods. Fractionation of the most active crude extract was carried out by column chromatography, and the fractions together with the most active crude extract were screened against the selected bacterial strains. Te most active fraction was further fractionated, and the subfractions were screened against the bacterial strains to test for possible synergistic efects between the subfractions and their constituents. Te most active fraction was then analysed by GC-MS and LC-ESI-MS methods to identify the major constituents. Results. Te ethyl acetate extract of C. fascicularis root bark (CFR2) showed a signifcant in vitro antibacterial activity. From the seven fractions of CFR2 obtained, fraction 2 (F2) had the lowest MIC value and was thus most active. Moreover, F2 was found to be more active compared to the four subfractions obtained from it. Tis suggested that constituents of F2 worked in synergy. Fraction 2 contained phenols, terpenes, and favonoids. Two compounds were identifed by GC-MS as 2,4-di-tert-butylphenol and (E,E)-2,4-decadienal, while three compounds were identifed by LC-ESI-MS as tanshinone II A, cryptotanshinone, and danshensu. Conclusion. Te study revealed that CFR2 is the most active extract on bacteria, suggesting that most antimicrobial compounds are concentrated in the roots of C. fascicularis. A follow-up study is directed towards chromatographic separations to obtain the other chemical constituents and screen them against various strains of bacteria.
Ethnobotany of Some Members of the Genus Cassia (Senna)
(Novelty Jourrnals, 2023-09) Osunga, Salome; Amuka, Omari; Machocho, Alex K.; Getabu, Albert
The Genus Cassia, also known as Senna, is a large group of leguminous plants belonging to the family of Fabacea. They have a wide range of ethnobotanical uses, including medicinal, ornamental, and industrial applications. In traditional medicine, the Genus has been used in the treatment of various diseases all over the world. Various pytochemicals with diverse bioactivities have been isolated from the Cassia species. However, this has not been done exhaustively in all the species. This review relates the ethnobotanical uses of various Cassia species and emphasizes the importance of doing scientific research on these secondary metabolites for the benefit of the general public.
Comparative Responses of Ovipositing Anopheles Gambiae and Culex Quinquefasciatus Females to the Presence of culexegg Rafts and Larvae
(Medical and Veterinary Entomology, 2010-11) Wachira, W.; Ndung’u, M.; Njagi, P.G.N.; Hassanali, A.
Field observations have demonstrated that gravidAnopheles gambiaeGiless.s. (Diptera: Culicidae) are selective in their choice of oviposition sites. Forexample, immature stages ofAn. gambiae s.s.are rarely found in water that containsCulex quinquefasciatusSay immatures. The possibility that this may, in part at least,reflect a response by ovipositingAn. gambiae s.s.females to volatile signals associatedwithCulexjuveniles was evaluated by testing the response ofAn. gambiae s.s.femalesto varying densities ofCx. quinquefasciatusegg rafts and/or larvae in ovipositionchoice assays. For comparison, the oviposition choices ofCx. quinquefasciatusto conspecific egg rafts and/or larvae were similarly assayed. At a low densityofCx. quinquefasciatusegg rafts (1–15 egg rafts/100 mL water),An. gambiae s.s.females laid more eggs in the treatment water than in the control, with a maximumof twice as many in the treatment water at 5 egg rafts/100 mL water. At higheregg raft densities and in all treatments that includedCx. quinquefasciatuslarvae,oviposition decreased significantly in the treatment dishes in a density-dependentmanner. As previous studies have indicated, ovipositingCx. quinquefasciatusfemaleswere attracted to and laid egg rafts in dishes containing conspecific egg rafts and,interestingly, also in dishes containing larvae.
Novel Cross-Stage Solitarising Effect of Gregarious-Phase Adult Desert Locust (Schistocerca Gregaria (Forska ˚l)) Pheromone on Hoppers
(Elsevier Ltd, 2010-01) Bashira, Magzoub O.; Hassanali, Ahmed
Previous studies had demonstrated stage differentiation in the cohesion (aggregation) pheromone systems of the desert locust, Schistocerca gregaria. In laboratory arena, the nymphal and adult stages responded aggregatively to their own pheromone, but dispersed evenly within the arena in the presence of the other. In the present study, we explored the effects of longer-term contact of ﬁeld gregarious hopper bands and laboratory crowd-reared nymphs with the major constituent of the adult pheromone. During the ﬁrst few days, hoppers in treated bands became relatively hyperactive. Over the next few days, their movements became random and they stopped marching as coherent groups, they started to roost for longer periods on vegetations, and they fragmented into smaller and smaller groupings and individuals. When attacked by birds, they demonstrated subdued levels of collective defensive behaviour compared to normal hoppers, and there were clear signs of increased predation and cannibalism at the roosting sites. In cage experiments, crowd-reared nymphs treated with the pheromone component became hyperactive, showed abnormal diel patterns and reduced feeding on plants but increased cannibalism. Our observations show that the major adult pheromone constituent has asolitarising effecton gregarious hoppers. The mechanism underlying this effect and the potential of the agent in desert locust control are discussed.
Antimosquito and Antimicrobial Clerodanoids and A Chlorobenzenoid from Tessmannia Species
(Natural Product Communications, 2009-08) Kihampaa, Charles; Nkunya, Mayunga H.H.; Joseph, Cosam C.; Magesad, Stephen M.; Hassanalic, Ahmed; Heydenreiche, Matthias; Kleinpeter, Erich
The clerodane diterpenoids trans-kolavenolic acid, 18-oxocleroda-3,13(E)-dien-15-oic acid, ent-(18-hydroxycarbonyl)-cleroda3,13(E)-dien-15-oate, 2-oxo-ent-cleroda-3,13(Z)-dien-15-oic acid and trans-2-oxo-ent-cleroda-13(Z)-en-15-oic acid, and the chlorobenzenoid O-(3-hydroxy-4-hydroxycarbonyl-5-pentylphenyl)-3-chloro-4-methoxy-6-pentyl-2-oxybenzoic acid were isolated from Tessmannia martiniana var pauloi and T. martiniana var matiniana. Structures were established based on interpretation of spectroscopic data. Some of the compounds exhibited significant antimosquito, antifungal and antibacterial

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