RP-Department of Chemistry

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    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.
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    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.
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    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.
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    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.
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    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.
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    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.
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    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.
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    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.
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    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.
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    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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    Biological cost of tolerance to heavy metals in the mosquito Anopheles gambiae
    (National Institute of Health, 2010-06) Mireji, P. O.; Keating, J.; Hassanali, A.; Mbogo, C. M.; Muturi, M. N.; Githure, J.I.; Beier, J.C.
    The global rate of heavy metal pollution is rapidly increasing in different habitats. Anopheles malaria vector species appear to tolerate many aquatic habitats with metal pollutants, despite their normal proclivity for ‘clean’ water (i.e., generally water free of organic matter). Investigations were conducted to establish whether there are biological costs for tolerance to heavy metals in Anopheles gambiae Giles sensu stricto (Diptera: Culicidae), and to assess the potential impact of heavy metal pollution on mosquito ecology. Anopheles gambiae s.s. were selected for cadmium, copper or lead tolerance through chronic exposure of immature stages to solutions of the metals for three successive generations. Biological costs were assessed in the fourth generation by horizontal life table analysis. Tolerance in larvae to cadmium (as cadmium chloride, CdCl2), copper (as copper II nitrate hydrate, (Cu (NO3)2. 2·5H2O) and lead (as lead II nitrate, (Pb (NO3)2), monitored by changes in LC50 concentrations of the metals, changed from, 6.07, 12.42 and 493.32 μg/L to 4.45, 25.02 and 516.69 μg/L, respectively, after 3 generations of exposure. The metal- selected strains had a significantly lower magnitude of egg viability, larval and pupal survivorship, adult emergence, fecundity and net reproductive rate than the control strain. The population doubling times were significantly longer and the instantaneous birth rates lower in most metal- selected strains relative to the control strain. Our results suggest that although An. gambiae s.s. displays the potential to develop tolerance to heavy metals, particularly copper, this may occur at a significant biological cost, which can adversely affect its ecological fitness
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    Adsorption of Lead (ii), Chromium (vi) and Manganese (ii) metal ions from water using modified Pennisetum purpureum Schumach plant stalk
    (2022) Murage, D.; Masika, E.; Wanyonyi, W. A.
    Water pollution is a global problem affecting humanity. Availability of clean water is a fundamental prerequisite to public health safety and the survival of the human race as well as animals. However, pollution of river water by heavy metal ions deposition is a grave environmental problem. Presence of the heavy metals in the water, pose a serious health risk particularly to rural populations which rely majorly on the river water for domestic purposes. Several methods for elimination of the heavy metal pollutants from river waters have been previously employed. However, most of these methods are expensive and cumbersome, hence not sustainable. This research explored the potential of modified Pennisetum purpureum Schumach plant adsorbent in removal of Lead (II), Manganese (II) and Chromium (VI) ions from spiked water samples by adsorption. Surface analysis of the adsorbent using FTIR Photometer confirmed presence of functional groups such as -NH2, C=O and O-H responsible for adsorption of heavy metal ions. Concentration of heavy metal ions in water samples was determined before and after adsorption process using Atomic Absorption Spectroscopy (AAS) and means concentration computed. Effect of changes in pH on adsorption was investigated by conducting adsorption at three different pH conditions of 5, 7 and 9. Modification of the adsorbent surface improved its adsorption capacity. For instance, at pH 5, adsorption of Cr+6 increased from 12% to 14.82% when modified adsorbent was used. The modified adsorbent achieved greater % adsorption in all the three metals. Increase in the pH of adsorption from 5 to 9 had a reducing effect on the percent adsorption. At pH of 5 the % adsorption of Pb+2 reduced from 90.26% to 73.75% at pH of 9. This reductions in percentage adsorption were recorded for Pb+2 and Mn+2 ions but not significant for Cr+6 ions. These results show the potential of P. purpureum plant for use as an adsorbent in purification/detoxification of river water which would present a cheaper and more readily available alternative to many current adsorbents and adsorption methods in use. However further research is needed to determine the optimal set of conditions as well as the most suitable modification treatment for maximum adsorption
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    Effects on Nanaofertilizers on Cd AND Pb Uptake in Kales Grown in Medially Polluted Experimental Soil.
    (IOSR Journal of Applied Chemistry (IOSR-JAC), 2020-03) Ngorwe, E.N.; Nawiri M.; Murungi J.; Nyambaka H.; Ongera T.
    Background: Most agriculturalists use excess commercial fertilizers with the notion that some will be eroded and leached eventually causing eutrophication and alters soil pH that increases Cd and Pb uptake in crops .Nanoparticles have numerous adsorption sites that reduce Cd and Pb uptake in crops and it has controlled release of nutrients guaranteeing longer interaction with the crops to ensure safer and higher crop yields to feed sporadic growing population. Materials and Methods: This study uses nanohydroxyapatite adsorbents from waste bones to synthesis nanofertilizers by encapsulating with DAP and NPK commercial fertilizers. Pots study in green house for contaminated soils were conducted with eight treatments in triplicate; DAP added, NPK added, NPK-DAP added, DAP nanofertilizer, NPK nanofertilizer, NPK-DAP nanofertilizer and non-treated control (ck) treatments, for sukuma wiki (kales) in Kitutu Chache south sub-county, Kisii County, Kenya. Nine pots were set for each treatment with one seedling each planted per pot. Nanofertilizers were applied at normal application rates during planting. Crops were left grown for 30 days to 90 days until they matured and harvested three times on a monthly basis. Harvested leaves were washed with distilled deionized water, oven dried and then acid digested and then analyzed by AAS for Cd and Pb. Data obtained was analyzed by ANOVA and t-test to compare means of various treatment, Cd and Pb in contaminated soils. Results: The nanofertilizers treatment recorded lowest levels of Cd and Pb in sukuma wiki harvested leaves. The bone ash (nHA added) had the lowest concentration levels of Cd (18.14±0.29) and Pb (15.91±0.57) with NPK nanofertilizers also recording lower concentration levels of Cd (27.29±0.50) and Pb (21.59±0.74). The DAP added fertilizers recorded highest concentration levels of Pb (56.74±5.75) while NPK added fertilizers recorded highest concentration levels of Cd (53.46±2.55). The bone nanofertilizer grown sukuma wiki had higher growth performance and lower levels of Cd and Pb to the permissible levels allowed by WHO/FAO in Kenyan vegetables. The bone ash nano treatment posted the lower heavy metals concentration levels of Cd (18.14±0.29) and Pb (15.91±0.57) while in synthetic experiments leaves harvested from synthetic ash nanofertilizer treated pots had Cd (23.71±1.92) and Pb (14.60±0.30). Cadmium concentration levels in kales harvested from bone ash recorded the highest reduction of 60.69% as compared with the non-treated control followed by bone NPK nanofertilizer with 30.70% cadmium uptake reduction. Lead uptake in bone set-up was most efficiently reduced by bone ash (nHA) by 59.25% while reduction by same treatment in synthetic experiment was 58.71%. The bone NPK nanofertilizer had 44.70% lead uptake reduction. However fertilizer amendment increased lead uptake with DAP added treatment hiking lead uptake in kales by 14.04%. Conclusion: The result is recommended for nanofertilizers to be used in growing other crops such as maize, beans, spinach potatoes, wheat, rice and other vegetative crops in medially polluted soils, especially in periurban farming to boost food productivity to feed ever growing population.
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    Characterization of Flavonoids from Candidate Striga Grass in Controlling Diet Legumes Cicer Arietinum and Vigna Radiata
    (BIOFARMASI J NAT PROD BIOCHEM, 2018-08) Akumu, Anyango Anna; Nyambaka, Hudson; Kuate, Serge Philibert; Torto, Baldwyn
    Akumu AA, Nyambaka H, Kuate SP, Torto B.2018. Characterization of flavonoids from candidate striga grass in controlling diet legumes Cicer arietinum and Vigna radiata.Biofarmasi J Nat Prod Biochem 16: 83-98. In Africa, intercropping of some legumes with cereal plants has been noticed to generate exceptional reduction of Striga invasion and enhanced production of cereal crop. Desmodium uncinatum administers Striga invasion in intercrop with cereals through an allelopathic technique, which includes post-sprouting accretion inhibitors emanated from the roots. Having a potential to be a new technique for grass administering, Allelopathy is a natural and environmentally friendly method. A standardized profiling technique based on Reverse Phase-High Performance Liquid Chromatography (RP-HPLC) and Liquid Chromatography coupled with Mass Spectrometry (LC/MS) was utilized to determine flavonoids in extracts of chickpea (Cicer arietinum) and mung bean (Vigna radiata), potential trap plants for Striga grass. Nine flavonoids involving mono-and diglycosyl derivatives of fisetin, baicalein, rhamnetin, isorhamnetin, formononetin, quercetin, isosakuranetin, and sakuranetin were temporarily distinguished. The obtained phenolics were available at concentrations higher than 0.001% of the dry materials. Many of these phenolic mixtures have been claimed to possess human health advantages. These glycosylated flavones are noted for the first time in these two species. The comprehensive analysis of the polar secondary metabolites in these leguminous plants was useful for comprehending their inhibitory chemistry and proposed biosynthesis by C-glucoside characteristics. All the segregated and described mixtures in the diet legume C. arietinum were O-glucosylated. While, Food legume V. radiata should be observed further to see if it can attain Desmodium’s allelopathic ability since it possesses inhibitory chemistry and proposed biosynthesis by C-glucosylation.
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    Antimicrobial Photodynamic Activity of Phthalocyanine Derivatives
    (Hindawi, 2018) Nyamu, Samuel N; Ombaka, Lucy; Masika, Eric; Ng’ang’a, Margaret
    Microbial pathogens have increasingly shown multidrug resistance posing a serious threat to the public health. Advances in technology are opening novel avenues for discovery of compounds that will mitigate the ever-increasing drug-resistant microbes. Use of photodynamic photosensitizer is one of the promising alternative approaches since they ofer low risk of bacteria resistance as they use generated reactive oxygen species to kill the microbes. Phthalocyanine (Pc) is one such photosensitizer which has already shown promising antimicrobial photodynamic therapeutic properties. Previous studies have shown efectiveness of the Pc against Gram-positive bacteria. However, its efectiveness toward Gram-negative bacteria is limited by the impermeability of the bacteria’s outer membrane which is made up of lipopolysaccharides layer. Te efectiveness of this photosensitizer is determined by its photophysical and photochemical properties such as singlet/triplet lifetimes, singlet oxygen quantum yields, and fuorescence quantum yield. Terefore, this review focuses on the recent signifcance advances on designing Pc that have this improved property by either conjugating with nanoparticles, quantum dots, functional groups in peripheral position, considering efect of cationic charge, and its position on the macrocycle.
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    Sonochemical Biosynthesis of Silver Nanoparticles Using Bridelia Micrantha and Evaluation of Their Antibacterial Activity
    (eijst, 2018) Kithokoi, Jackson Kilonzo; Ochoo, Lawrence; Maingi, John M.; Swaleh, Sauda; Njue, Wilson
    Metal nanoparticles have proven to have antimicrobial properties, but the chemical methods used in their production involve use harzodous chemicals. In this study, ecofriendly method was used for the synthesis of silver nanoparticles using B. micrantha. The reaction was done over ultrasonic bath. Formation of the nanoparticles was monitored by use of UV-VIS spectrophotometer and absorption peak at λmax 431 nm was obtained. EDX analysis showed the nanoparticles were pure silver. HRTEM analysis showed the nanoparticles had non uniform surface and were spherical with an average size of 16.07±3.192 nm. SAED showed distinct shiny spots, confirming crystallinity of the nanoparticles. FTIR analysis indicated the presence of biomolecules capping the nanoparticles. The silver nanoparticles inhibited growth of E.coli and S. aureus. The study contributes in designing novel methods geared towards development of drugs to combat pathogens by use of silver nanoparticles.
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    Ultrasonic Synthesis of Silver Nanoparticles Mediated by Prunus africana Plant Extracts and Their Antibacterial Activity
    (Modern Scientific Press, 2018) Kithokoi, J. Kilonzo; Ochoo, Lawrence; Maingi, John M.; Swaleh, Sauda; Njue, Wilson M.
    Metal nanoparticles possess unique properties influenced by their size, distribution and morphology. There is increasing interest and demand in metal nanoparticles due to their wide applications in various fields such as medicine, electronics, catalysis, cosmetics and energy. Chemical and physical methods used in synthesis of nanoparticles are costly and unfriendly to the environment due to toxic chemicals involved. Green synthesis is rapid; cost friendly and involve non-toxic chemicals. Plants provide unique platform for green synthesis of metal nanoparticles over other green synthetic methods as they stabilize and cap the nanoparticles with biomolecules. In this study, Prunus africana stem bark extract was used to synthesize silver nanoparticles (AgNPs) on ultrasonic bath. The formation of AgNPs was monitored visually through colour change and by UV-Vis spectroscopy. The Energy Dispersive X-ray (EDX) analysis showed that the AgNPs were pure silver. HRTEM analysis indicated evenly distributed, monodispersed and spherical AgNPs with the average size of 23±3.06nm. FTIR analysis showed the presence of hydroxyl and -C=C- groups an indication of presence of phenolic compounds. The antibacterial activity of the synthesized AgNPs was tested against E. coli and S. aureus and were found to be toxic against these pathogens with maximum zones of inhibition of 14.21±0.208mm and 16.03±0.204mm respectively. MIC for both E. coli and S. aureus was 0.25mM. No previous reports on synthesis of silver nanoparticles using P. africana. The study contributes towards application of P. africana extracts in generation of novel silver nanoparticles for development of drugs useful in fight against bacterial infections
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    Remediation of Fluoride Laden Water by Sorption using Kenyan Kisii Soapstone and Calcium Bentonite
    (IOSR-JAC, 2023) Omolo, Ted David; Wanjau, Ruth; Mbui, Damaris; Gerald, Mbugua
    Background: The aim of this study was to evaluate the adsorption potential of natural and locally available soapstone and Calcium bentonite clay for fluoride removal from aqueous solution and to determine the optimum conditions for use. Adsorption potential was anchored on the availability of hydroxyl and aluminum ions inherent in both minerals which have been established to have ability for fluoride adsorption in aqueous solutions. Adsorption potential was investigated using batch equilibrium experiments. Materials and Methods; Mineralogical characterizations were done using X-ray fluorescencespectroscopy. Fluoride ion selective electrode was used in determination of fluoride content in aqueous solution.Optimization studiesoninitial pH of the solution, contact time, initial fluoride concentration, adsorbent dose, and heat pretreatment of the adsorbent were done in batch adsorption experimentsat room temperature. Results:It was observed that calcium bentonite exhibited better adsorption capacity of 0.21mg/g while soapstone had 0.08mg/g at a contact time of 45 min and 5 min respectively.The optimum pH for both adsorbents was established at 3.6. The experimental data for bentonite fitted well with Langmuir isotherm indicating a monolayer adsorption while for Soapstone fitted better into Freundlich adsorption, indicating multilayer adsorption with heterogeneous energetic distribution of active sites. Conclusion:Based on these findings, the two adsorbents can be fitted into household defluoridation apparatus for domestic remediation of fluoride contaminated water.
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    Iron (III) Doped Titanium Dioxide Coated Dimensionally Stable Graphite Anode Electrode for Electro-Chemical Treatment of Domestic Wastewater
    (Elsevier Inc, 2021) Mwangi, I.W.; Kinyua, E.M.; Nthumbi, R.; Wanjau, R.N.; Swaleh, S.; Ngila, J.C.
    Availability of clean water is of concern due to pollution and diminishing supply pollution. However, purification is possible depending on the incorporated contaminants. Domestic wastewater contains dissolved organic matter and its remediation can be done by oxidation. The best oxidation can be achieved by electron transfer the same way metabolic processes occur. This study exploited the use of a film of iron (III) doped titanium dioxide applied on an electrode which was found to be effective. Natural light conditions generated electrons that migrated through the electrode leaving behind holes which oxidized the contaminants as the excess electrons were discharged at the cathode after passing through the casted proton exchange membrane (PEM) separating the two half cells of the prepared reactor. This electrochemical method has the advantage in that the organic pollutants are oxidized to carbon dioxide with no secondary pollutants and the inorganic pollutants into insoluble matter. The assembled cell was applied to purify both synthetic and real water samples of green leafy vegetable solution from the kitchen by clarification. The clarification process was monitored by UV-Vis using distilled water as a reference to compare the light that transmitted through a sample. It was observed that the electro-oxidation process took place showing a high potential 105 mV within the first 150 min followed by degradation at a high rate. The oxidation of the organic matter was confirmed by UV-Vis analysis as well as by cyclic voltametric analysis of iron released into the solution of the synthetic samples. The electro chemical treatment of the water was then applied to purify real water samples made from a sample of 4.5 g minced of green vegetables dispersed in one liter of water (4.5 g/l). The green leafy coloured solution was clarified after 154 h of continuous oxidation. The degradation process was confirmed to be independent of intermediates or other species present in solution as it was of first order reaction kinetics. The electrochemical oxidation of organic matter in water using iron (III) doped titanium dioxide coated graphite electrode has potential application on the purification of water.
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    Arsenic Contamination In Water From Selected Boreholes In Nairobi City County, Kenya
    (European Open Science, 2021) Kiplangat, Alice S.; Mwangi, Henry; Swaleh, Sauda; Njue, Wilson M.
    Arsenic is a metalloid, which may be found in surface water, ground water, plants and rocks. In high concentrations, its compounds are considered to be genotoxic and carcinogenic. Its levels in drinking water must be regularly monitored and controlled. The objective of study was to determine the concentration of arsenic in water with reference to WHO limits from selected boreholes in Nairobi County, Kenya. Water was randomly sampled from a total of 63 boreholes in five zones (Central, Eastern, Northern, Western and Southern) during dry and wet season. The arsenic was analyzed by Hydride Generation Atomic Absorption Spectrometer (HG-AAS). The results showed that the arsenic content in borehole water during dry season ranged between 0.00455±0.0022 and 0.01007±0.006 and in the range of 0.002057±0.0008 - 0.00744±0.0051 mg/L during the wet season. There was significant difference (P˂0.05) in arsenic content in borehole water samples in Central zone compared to the other zones. During the dry season, arsenic content in water from ten boreholes (16%) and four boreholes (6%) during wet season was found to be above the WHO recommended limit of 0.01 mg/L. The calculated contamination factor for the borehole water ranged from slightly arsenic contaminated in Central zone to very slightly contaminated in the other zones during dry season. During the wet season, the borehole water in all the five zones were very slightly contaminated with arsenic. The pollution index showed that the boreholes in all the five zones during both wet and dry seasons were not polluted with arsenic. Steps should be taken to monitor and treat borehole water for domestic purposes in order to mitigate the effect on human health due to arsenic contamination