Department of Chemistry and Biochemistry

PHYTOCHEMICAL ANALYSIS AND ANTIBACTERIAL ACTIVITY OF Guizotia scabra LEAF, STEM BARK AND ROOT EXTRACTS FOR DENTAL CARIES CONTROL

Wed, 01 Jan 2025 00:00:00 GMT

PHYTOCHEMICAL ANALYSIS AND ANTIBACTERIAL ACTIVITY OF Guizotia scabra LEAF, STEM BARK AND ROOT EXTRACTS FOR DENTAL CARIES CONTROL PAUL, ANJELINE JEPCHUMBA Medicinal plants offer promising alternatives for treating oral infections. This study investigated the phytochemical composition and antibacterial activity of Guizotia scabra tender leaf, stem bark, and root extracts against Streptococcus mutans and Streptococcus sobrinus, key pathogens in dental caries. Ethanol and acetone extracts were subjected to Standard laboratory tests for phytochemicals analysis, High- performance liquid chromatography (HPLC) for quantification of flavanoids, Fourier- transform infrared spectroscopy (FTIR) for determination of functional groups and antibacterial bioassays to assess antibacterial activity. Phytochemical tests revealed the presence of anthraquinones, alkaloids, terpenoids, flavonoids, steroids, saponins, and quinones. HPLC analysis confirmed the presence of myricetin and quercetin, with leaf extracts showing the highest concentrations (myricetin: 7.0013 ppm; quercetin: 0.901 ppm). Stem bark lacked myricetin but contained quercetin (2.4991 ppm), while root extracts had moderate levels of both (myricetin (2.0627 ppm) and quercetin (0.7027 ppm). FTIR spectra identified key functional groups, including O-H/N-H (3441 cm−1)1 linked to alkanoids (Quercetin ) (N-H /O-H group), C=O (1643 cm−1) which correlate to terpenoids, C-H/C-O (1396 cm−1) linked to alkaloids structure having N /O-H bond,2000 cm−1 to terpenoids /flavanoids and possible metal-ligand vibrations (538 cm−1). There is also a distinct C-N stretch (1250 cm−1) likely due to C-N stretching in alkaloids showed by leaf and root extracts. Antibacterial evaluation demonstrated that ethanol leaf extract had the highest inhibition against Streptococcus mutans (5.0 mm, 62.5%) and Streptococcus sobrinus (4.0 mm, 50%), followed by root extracts (3.0 mm, (37.5%) and 2.5 mm , (31.25%) respectively. Acetone extracts showed similar trends with the leaf extract at 4.6 mm, (57.5%) and 4.3 mm, (53.75%). However, commercial toothpastes showed superior inhibition (up to 7.0 mm, 87.5%) likely due to fluoride content and other additives. These findings suggest that Guizotia scabra possesses bioactive compounds with potential for natural oral healthcare applications. Further studies should optimize extraction; evaluate compound synergy, ensuring safety and efficacy for possible formulation of dental products.

PLASMID-MEDIATED ANTIBIOTIC RESISTANCE IN GRAM-NEGATIVE PATHOGENIC BACTERIA ISOLATED FROM RIVER SOSIANI AND WASTE WATER SYSTEMS IN UASIN GISHU COUNTY, KENYA

Wed, 01 Jan 2025 00:00:00 GMT

PLASMID-MEDIATED ANTIBIOTIC RESISTANCE IN GRAM-NEGATIVE PATHOGENIC BACTERIA ISOLATED FROM RIVER SOSIANI AND WASTE WATER SYSTEMS IN UASIN GISHU COUNTY, KENYA AUMA, SHARON The widespread of bacteria resistance to antibiotics poses an immense threat to the public health. Aquatic ecosystems receive waste water which invariably contain different bacteria, chemicals and antibiotic residues that induces bacterial resistance to antibiotics, resulting into several treatments failures and deaths. Plasmid-mediated antibiotic resistance of bacteria through horizontal gene transfer has been reported to significantly cause resistance in susceptible bacteria. The current study identified antibiotic resistance genes present in gram-negative bacterial plasmids, isolated from River Sosiani and wastewater systems in Uasin Gishu County, Kenya. The sampling sites included Outspan-Nairobi bridge, Pioneer bridge, Moi Teaching and Referral Hospital, Eldoret prison, Kipkaren bridge, Huruma quarry influent, Huruma quarry effluent, Kipkenyo boundary influent and Kipkenyo boundary effluent. The study entailed bacteria isolation, identification, antibiotic susceptibility testing, plasmid DNA extraction and polymerase chain reaction of the antibiotic-resistant genes. Mean and standard deviations were analyzed using Microsoft Excel while Chi square was used to determine significant relationship existing between the phenotypic and genotypic resistance in bacteria. Most of the bacteria coliforms obtained were too numerous to count. A total of 10 gram-negative pathogenic bacteria species were detected, including Escherichia coli, Enterobacter aerogenes, Citrobacter freundii, Klebsiella pneumoniae, Klebsiella oxytoca, Proteus vulgaris, Proteus mirabilis, Pseudomonas aeruginosa, Salmonella enteriditis and Yersinia enterocolitica. All the 10 bacteria conferred resistance to penicillin, ampicillin, amoxicillin-clavulanic acid, ceftazidime, tetracycline, streptomycin and sulfamethoxazole-trimethoprim. Multi antibiotic resistance index was higher in E. aerogenes (0.83) but lower in Y. enterocolitica (0.58). Out of the nine antibiotic-resistant genes investigated, qepA and qnrA genes were present in the plasmids of all the 10 bacteria species, 70% of the total bacteria species had dfrA5, 70% had aadA1, 50% had blaKPC, 40% had mphA, 30% of the bacteria species had blaSHV and sul 1 genes (P≥1) while none of the bacterial plasmid DNA had AmpC gene. The study findings suggested that River Sosiani and the sampled wastewater systems contained different pathogenic bacteria and their plasmid-mediated antibiotic resistance genes which confer resistance to commonly used antibiotics. Therefore, effective waste disposal, continuous monitoring and proper pretreatments of water from River Sosiani and the sampled wastewater systems may reduce bacteria contamination and antibiotic resistance inducers, addressing challenges associated with antibiotic resistance in bacteria.

Antibacterial Activity of the Tender Leaf, Stem Bark and Root Extracts of Guizotia Scabra against Streptococci Bacteria Using Bioassay

Mon, 01 Sep 2025 00:00:00 GMT

Antibacterial Activity of the Tender Leaf, Stem Bark and Root Extracts of Guizotia Scabra against Streptococci Bacteria Using Bioassay Paul, Anjeline Jepchumba; Lagat, Grace; Lutta, Samuel Dental caries remains a major public health concern globally, largely attributed to bacterial pathogens such as Streptococcus mutans and Streptococcus sobrinus. The search for plant-based alternatives to synthetic oral care products has intensified in recent years. This study evaluated the antibacterial activity of ethanol and acetone extracts of Guizotia scabra leaf, stem bark and root against these key oral pathogens in comparison with commercial toothpastes. The ethanol leaf extract exhibited the highest activity against Streptococcus mutans with an inhibition zone of 5.0 mm (62.5%), followed by the root extract (3.0 mm, 37.5%) and stem extract (2.0 mm, 25.0%). Against Streptococcus sobrinus., the ethanol leaf extract recorded 4.0 mm (50.0%), root extract 2.5 mm (31.25%), and stem extract 1.5 mm (18.75%). Similarly, the acetone leaf extract demonstrated the highest inhibition against Streptococcus mutans (4.6 mm, 57.5%) and Streptococcus sobrinus. (4.3 mm, 53.75%), compared to the root extract (2.8 mm, 35.0%; 2.3 mm, 28.75%) and stem extract (1.9 mm, 23.75%; 1.7 mm, 21.25%). In contrast, commercial toothpaste brand 1 produced inhibition zones of 6.0 mm (75.0%) against both pathogens, while brand 2 showed 7.0 mm (87.5%) against Streptococcus mutans and 6.0mm (75.0%) against Streptococcus sobrinus. These findings demonstrate that Guizotia scabra extracts possess significant antibacterial activity, with leaf extracts showing the greatest potential. Although commercial toothpastes were more effective likely due to fluoride and other active ingredients. The results highlight the potential of Guizotia scabra as a natural complementary agent for dental caries prevention. Future research should explore its integration with fluoride or other natural antibacterials to enhance its efficacy. Keywords: Antibacterial Activity, Guizotia scabra, Streptococcus mutans & Streptococcus sobrinus bacteria, Bioassay.

ANTIOXIDANT AND ANTIDIABETIC PROPERTIES OF Mondia whitei ROOT EXTRACT IN STREPTOZOTOCIN-INDUCED DIABETIC WISTAR RATS

Wed, 01 Jan 2025 00:00:00 GMT

ANTIOXIDANT AND ANTIDIABETIC PROPERTIES OF Mondia whitei ROOT EXTRACT IN STREPTOZOTOCIN-INDUCED DIABETIC WISTAR RATS GITAU, KENNEDY KAMAU The rising global prevalence of diabetes mellitus (DM) and its complications presents a major health challenge and is exacerbated by the lack of a definitive cure and the side effects of existing treatments, thus, highlighting the need for safer and more sustainable anti-diabetic agents. This study investigated Mondia whitei root extract as an alternative therapeutic option for DM. While traditional medicine suggests that M. whitei possesses antioxidant and anti-diabetic properties, scientific validation is limited. This research aimed to address this gap. Qualitative phytochemicals analysis of crude root extract of M. whitei was done and it’s in vitro antioxidant properties evaluated through 2,2- diphenyl-1-picrylhydrazyl (DPPH) scavenging activity and ferric reducing antioxidant power (FRAP) assays. DM was induced in twenty-four male Wistar rats by a single intraperitoneal injection of 65 mg/Kg body weight (bwt) of streptozotocin (STZ). Animals were randomly assigned to five groups each containing six subjects; Group I (normal control, saline), Group II (diabetic control, saline), Group III (diabetic rats 200 mg/Kg bwt extract treatment), Group IV (diabetic rats 400 mg/Kg bwt extract treatment), and Group V (diabetic rats 100 mg/Kg bwt metformin treatment). Treatments were orally administered for 21 days. Fasting body weights and blood sugar levels were measured weekly. After 21 days, animals were sacrificed and their blood and liver tissue samples collected followed by serum lipid profile, liver and kidney function indices analysis. Liver malondialdehyde (MDA) levels were measured, and liver and plasma’s ferric-reducing capacity were evaluated. Statistical analysis was performed using R software, with paired Student’s t-test and ANOVA determining statistical significance at 95% confidence level. The qualitative phytochemical analysis of the crude M. whitei root extract revealed the presence of saponins, phenols, tannins, alkaloids, flavonoids, glycosides, coumarins, steroids, and terpenoids, while anthraquinones were not detected. The extract significantly scavenged DPPH radical and reduced ferric ions in vitro. M. whitei also showed significant hypoglycemic, hypolipidemic and significantly reduced serum gamma-glutamyl transferase (GGT), alanine aminotransferase (ALT) and alkaline phosphatase (ALP). M. whitei treatment also significantly increased liver and blood plasma capacity to reduce ferric ions as well as protected liver tissues from lipid peroxidation as indicated by significantly reduced levels of MDA. However, M. whitei showed no significant serum urea and creatinine levels decrease. In conclusion, the phytochemical-rich M. whitei root extract demonstrated anti-diabetic, antioxidant, hypolipidemic and hepatoprotective effects in STZ-induced diabetic rats, highlighting its potential as a natural candidate for the management of DM and its complications.

Fluoride distribution in selected foodstuffs from Nakuru County, Kenya, and the risk factors for its human overexposure

Sun, 01 Jan 2023 00:00:00 GMT

Fluoride distribution in selected foodstuffs from Nakuru County, Kenya, and the risk factors for its human overexposure Nelima, Delphine; Wambu, Enos W.; Kituyi, John L. Critical data on the impacts of fluoride (F) in food systems along the Eastern Africa Rift Valley System (EARS) is needed for public health risk assessment and for the development of strategies for ameliorating its deleterious effects among the affected communities. Long-term F overexposure causes dental and skeletal fluorosis, and leads to neurotoxicity, which impacts several important body functions. Investigating F exposure pathways is of essence to inform and safeguard public health of the affected communities. The current study assessed the F levels in potatoes (Solanum tuberosum L.), beans (Phaseolus vulgaris L.) and garden peas (Possum sativa) from Nakuru County, Kenya, by potentiometric analysis using F ion-selective electrodes. It then evaluated the risk factors for excessive human exposure to F through contaminated foodstuffs. The mean F levels in the potatoes (8.50 ± 4.70 mg/kg), beans (8.02 ± 4.12 mg/kg) and peas (4.99 ± 1.25 mg/kg) exceeded recommended dietary allowances (RDA) level of 4 mg/kg endorsed by US Institute of Medicine for the different categories of people. The F distribution trends in beans and potatoes reflected the environmental patterns of F contamination of the study area but the spatial extent Fin the peas indicated existence of partial resistance of the pea plants to environmental F uptake. The results indicated that both the beans and the potatoes were more liable to accumulating greater amounts of F from the environment than garden peas and that all the three foodstuffs contained high F levels that posed greater risk of F overexposure and its deleterious impacts among the young children, male populations, and in people of greater body weight and high physical activity levels.

Antioxidant and Antidiabetic Effects of Mondia whitei Root Extract in Streptozotocin-Induced Diabetic Wistar Rats

Wed, 01 Jan 2025 00:00:00 GMT

Antioxidant and Antidiabetic Effects of Mondia whitei Root Extract in Streptozotocin-Induced Diabetic Wistar Rats Gitau, Kennedy K.; et. al... Diabetes mellitus (DM) is a chronic metabolic disorder characterized by persistent hyperglycemia and is a major contributor to global morbidity and mortality. Although Mondia whitei has been traditionally used for its antidiabetic and antioxidant effects, scientific evidence supporting these claims remains limited. This study aimed to evaluate the therapeutic potential of Mondia whitei root extract in a streptozotocin (STZ)-induced diabetic Wistar rat model. Phytochemical screening of M. whitei root extract revealed the presence of saponins, phenols, flavonoids, tannins, alkaloids, glycosides, coumarins, steroids, and terpenoids. Antioxidant activity was assessed using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and ferric reducing antioxidant power (FRAP) assays. DM was induced with 65 mg/kg body weight STZ. Rats were grouped into normal control, diabetic control, 200 mg/kg extract, 400 mg/kg extract, and 100 mg/kg metformin treated groups. Treatments were administered orally for 21 days. Fasting blood sugar (FBS) and body weight were measured weekly. At termination, blood and liver tissues were collected for analysis. M. whitei extract exhibited strong antioxidant activity in vitro. The 400 mg/kg dose significantly reduced FBS levels, nearing metformin’s hypoglycemic effect when compared to diabetic control. The extract also significantly lowered serum gamma-glutamyl transferase (GGT), alanine aminotransferase (ALT), alkaline phosphatase (ALP), lipids, and malondialdehyde (MDA), while increasing FRAP values in liver and plasma while serum creatinine and urea levels were reduced, though not significantly. The phytochemical-rich M. whitei root extract showed significant antidiabetic, antioxidant, hypolipidemic, and hepatoprotective activities, supporting its potential as a natural alternative for managing DM and its complications.

ENVIRONMENTAL OCCURRENCE AND ECOTOXICOLOGICAL RISKS OF CONTAMINANTS OF EMERGING CONCERN IN THE RIVER ATHI BASIN, KENYA: ANALYTICAL AND KINETIC ADSORPTION STUDIES USING AGRICULTURAL WASTE BIOCHARS

Mon, 01 Jan 2024 00:00:00 GMT

ENVIRONMENTAL OCCURRENCE AND ECOTOXICOLOGICAL RISKS OF CONTAMINANTS OF EMERGING CONCERN IN THE RIVER ATHI BASIN, KENYA: ANALYTICAL AND KINETIC ADSORPTION STUDIES USING AGRICULTURAL WASTE BIOCHARS CHEBII, FAITH JELAGAT Globally, the environmental occurrence of Contaminants of Emerging Concern (CECs) including Active Pharmaceutical Ingredients (APIs), Personal Care Products (PCPs) and pesticides has raised ecological and human health concerns. However, as the developed world make efforts to establish regulatory measures to mitigate their effects, developing nations including Kenya are lagging, partly due to unavailability of adequate data. Remediation of CECs in water can be achieved via photodegradation, advanced oxidation process, bioremediation, chemical degradation and activated carbon utilization. Adsorption, a cheaper and convenient alternative using the available agricultural wastes products, as biosorbent materials have not been fully explored. The objectives of this study were to determine multi-class CECs load and concentrations, determine ecotoxicological risks towards algae, Daphnia magna and fish, and potential point-of-use technologies via adsorption using Rice Husk Biochar (RHB), Avocado Seed Biochar (ASB)and Banana Peel Biochar (BPB). Water samples were collected from 24 sites across the River Athi basin area, Kenya. Extraction of water samples was done using Solid-Phase Extraction (SPE) and the CECs were analyzed using Ultra-High-Performance Liquid Chromatography coupled to High Resolution Orbitrap Mass Spectrometry (UHPLC-HRMS). The equilibrium adsorption isotherm studies were conducted for 86 CECs using ASB, BPB and RHB and the data was correlated using the non-linear curves of Langmuir and Freundlich rate equations. RHB was used in the adsorption kinetic studies for 86 CECs and the kinetic data acquired were correlated with the non-linear curves of Pseudo-First Order (PFO), Pseudo Second Order (PSO), Elovich and the Weber-Morris intraparticle diffusion models. The fitting performance of each model onto the kinetic data was guaranteed using adjusted R2 and the chi square values. The results of this analysis indicated that 57 CECs comprising 31APIs (0.4 ng L-1 – 142 µg L-1), 6 PCPs (0.7 – 570 ng L-1) and 20 pesticides (0.3 ng L-1 – 8.3 µg L-1) were detected. The maximum loads varied from 217 g day-1 (APIs) to 46 g day-1 (PCPs). Individually, Carbamazepine, Nevirapine, Sulfamethoxazole and DEET were the most ubiquitous CECs, with detection frequencies (DF) higher than 80%. The highest concentrations were observed at river sites that are heavily impacted by informal settlements, highlighting the critical role of slums in pollution of urban rivers. At least 8 CECs including Acetamiprid, Alachlor, Atrazine, Diuron, Nevirapine and Paracetamol showed potential risk to algae, Daphnia magna and fish, as exemplified by Risk Quotients (RQ) up to 174. Similarly, potential risk of antibiotic resistant bacteria development is evident due to exposure to Metronidazole, Sulfamethoxazole and Trimethoprim (RQ up to 64). Comparison of removal efficiencies of the CECs using the ASB, BPB and RHB showed that ASB and RHB had impressive % Removal efficiencies (94.0% - 98% and 87% - 99%) respectively compared to BPB (87% -93%). The lower %RE (% Removal Efficiencies) at lower concentrations for all the selected biochars is attributed to formation of bulky water clusters which may not be accommodated in the micropores on the surfaces of the biochars. The adsorption mechanism may be attributed to π-π electron donor- acceptor interaction, pore filling, ionic interactions and hydrogen bonding between the CECs molecules and the surfaces of the biochars. The kinetic adsorption analysis revealed that the kinetic data acquired for virtually 80% of the compounds were best described by the Elovich kinetic model, indicating that chemisorption was more pronounced on a heterogenous adsorbent surface as to physisorption and the intra – particle diffusion mechanisms. The R2 values approached unity and low Chi-square values approached zero. The equilibrium isotherm data fitted well both with Langmuir and Freundlich models with R2 approaching unity in most instances. However, Freundlich model had higher rate constants as to Langmuir models, an indicator that adsorption process was best described with a multilayer structure than the monolayer. There is a need to sensitize communities in informal settlements on proper waste disposal methods and the government agencies should include CECs in their monitoring schedule. ASB and RHB should be considered in the development of point-of-u

Removal of Selected Heavy Metals from the Water of the River Sosiani in Uasin Gishu County Using Cynodon dactylon (Couch Grass)

Sun, 01 Sep 2024 00:00:00 GMT

Removal of Selected Heavy Metals from the Water of the River Sosiani in Uasin Gishu County Using Cynodon dactylon (Couch Grass) Lelei, Kiptoo Richard; Kipkemboi, Pius; Lutta, Samuel The management of heavy metal pollution in rivers is a growing concern due to the rapid pace of industrialization and urbanization. Rivers are especially susceptible to heavy metal contamination due to various human activities, such as industrial processes, agricultural runoff, mining operations and improper waste disposal. Several studies in Kenya have documented the alarming presence of elevated heavy metal levels in various rivers, raising concerns about environmental and public health impacts. A variety of methods and techniques have been developed and implemented to remove heavy metals from contaminated water however, several of these techniques are expensive. The potential of plants to serve as a bio adsorbent offers a sustainable solution for addressing heavy metal pollution in rivers. This research therefore investigated the efficacy of modified Cynodon dactylon grass as an adsorbent for removing lead (Pb²⁺), manganese (Mn²⁺), cadmium (Cd²⁺) and chromium (Cr⁶⁺) ions from Sosiani River water. Water samples were collected from three purposively selected sites along the Sosiani River in Uasin Gishu County, Kenya and the mean heavy metal concentrations were analysed using Atomic Absorption Spectroscopy (AAS). The batch adsorption experiments were conducted in triplicates for untreated and treated grass. The study also examined the impact of pH levels on adsorption by testing at pH levels of 5, 7 and 9. Data was coded into SPSS software version 20 and analysed using descriptive and inferential statistics. The results indicate that the mean concentration of Cr⁶⁺ and Pb²⁺ in the water samples were 1.49 mg/L and 1.61 mg/L respectively. Both metals ions exceeding the NEMA guideline. However, the concentration of Cd²⁺ and Mn²⁺ was found to be 0.002 mg/L and 0.05 mg/L which is below the NEMA recommended level. Further, the heavy metal concentrations in Sosiani River water samples varied significantly (p<0.05) across different locations. Also, the chemically treated Cyanodon dactylon grass exhibited a higher percentage of adsorption across all tested heavy metals compared to the untreated Cyanodonat pH 5 compared to pH 9. These findings demonstrate the potential of Cynodon dactylon grass as an effective and more accessible alternative for river water purification. Further research is needed to optimize the conditions and modifications for enhanced adsorption performance. dactylon grass. Lastly, there was a higher adsorption efficiency for treated adsorbent

Occurrence and environmental risks of contaminants of emerging concern across the River Athi Basin, Kenya, in dry and wet seasons

Mon, 01 Jan 2024 00:00:00 GMT

Occurrence and environmental risks of contaminants of emerging concern across the River Athi Basin, Kenya, in dry and wet seasons Chebii, Faith; et. al... Globally, the environmental occurrence of Contaminants of Emerging Concern (CECs) including pharmaceuticals (PhACs), personal care products (PCPs) and modern polar pesticides has raised ecological and human health awareness. However, as the developed world races against time to establish regulatory measures to mitigate their effects, developing nations including Kenya are lagging behind, partly due to unavailability of adequate data. In this work, a multi-residue analysis of 86 CECs was carried out on 198 surface water and 18 effluent samples collected at 24 sites across the River Athi basin area, Kenya, in both dry and rainy seasons. Overall, 57 CECs comprising 31 PhACs (0.4 ng L− 1 –142 μg L− 1 ), 6 PCPs (0.7–570 ng L− 1 ) and 20 pesticides (0.3 ng L− 1 –8.3 μg L− 1 ) were detected. The maximum loads varied from 217 g day− 1 (PCPs) to 46 kg day− 1 (PhACs). Individually, carbamazepine, nevirapine, sulfamethoxazole and DEET were the most ubiquitous CECs, with detection frequencies (DF) higher than 80 %. The highest concentrations were observed at river sites that are heavily impacted by informal settlements, highlighting the critical role of slums in urban rivers pollution. At least 8 CECs including acetamiprid, alachlor, atrazine, diuron, nevirapine and paracetamol show potential risk to algae, Daphnia magna and fish, as exemplified by Risk Quotients (RQ) up to 174. Similarly, potential risk of antibiotic resistant bacteria development is evident (RQ up to 64), being driven by metronidazole, sulfamethoxazole and trimethoprim. Ultimately, further studies on the occurrence and distribution of antibiotic resistant bacteria within the basin and among the communities consuming untreated river water for drinking is merited.

HEAVY METALS IN WATER, SOIL AND PUMPKIN (Cucurbita maxima) LEAVES FROM SHIYALU-LURAMBI AREA KAKAMEGA COUNTY KENYA: CONTAMINATION LEVELS AND SPECIATION ANALYSIS

Mon, 01 Jan 2024 00:00:00 GMT

HEAVY METALS IN WATER, SOIL AND PUMPKIN (Cucurbita maxima) LEAVES FROM SHIYALU-LURAMBI AREA KAKAMEGA COUNTY KENYA: CONTAMINATION LEVELS AND SPECIATION ANALYSIS NEKESA, DOREEN MESO Pollution of the environment by heavy metals is a major global concern. Arsenic (As), cadmium (Cd), lead (Pb), nickel (Ni), copper (Cu), and zinc (Zn) present the greatest environmental threat because of their widest distribution and known toxic effects in humans, plants, animals and lower biota. The study was designed to assess the level of selected heavy metals in potable water, soils and Pumpkin leaves (Cucurbita maxima) samples to determine their availability and potential accumulation along the food chain. Samples for the field investigation were collected from randomly selected sites, transported to the research laboratory where they were treated and analyzed for Cd, Pb, Ni, Cu, and Zn using Atomic Absorption Spectroscopy (AAS). Arsenic was determined calorimetrically using Arsenic Test Kit (ATK). Inductive coupled plasma atomic emission spectroscopy (ICP-AES) was used to perform speciation studies for Cd and Pb in soil samples. It was found that whereas the As, Ni, Cu, and Zn concentrations in water, soil and plants were well within the respective World Health Organization (WHO) limits, both the Pb and Cd levels water (Pb -0.0925-0.5680 Cd -0.3911-0.5541); soil (Pb -1.2252-1.9279; Cd -0.6153- 0.7674-) and plants (Pb -1.0482-1.3892); Cd 0.1070-0.11833) respectively exceeded the permissible WHO standards for studied media, respectively. The Soil Pb and Cd were present in the bioavailable exchangeable fractions (0.42 mg/kg, 0.21 mg/kg) and reducible fraction (0.99 mg/kg, 0.28 mg/kg), respectively. Lead (Pb) and Cd in the soils posed significant risk of overexposure because of their high levels and speciation resulting in bioaccumulation and magnification in the plant tissues investigated. Because the overall toxic consequences of excessive exposure to these metals, it is recommended that the levels of heavy metals in plants, water, and soil in the affected areas need to be routinely assessed and measures taken to avert potential environmental and public health damage.