Browsing by Author "Kiboi, Nathan"

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    In Vitro Antioxidant Activity of Haloalkaliphilic Fungal Extracts from Lake Magadi, Kenya
    (Science Mundi, 2025) Kiboi, Nathan; Abonyo, Collins; Ouko, Nahashon; Kimani, James; Juma, Kelvin; Ngugi, Mathew Piero; Marera, Domnic; Were, Tom
    The wide-ranging saline-alkaline ecological setting is steadily acquiring appreciation as a rich source harbouring a repertoire of extremophilic fungal diversity exerting exclusive biological activities ranging from anti-inflammatory, antipyretic, analgesic among other varied medicinal capacities. However, studies characterizing biochemical functionalities from structurally unique haloalkaliphilic fungal biota remain scanty and undocumented. Importantly, saline emitting hot-springs situated in Rift valley soda lakes are gaining recognition as natural reservoirs with enormous fungal microbial community bearing potential for antioxidation capacity. Therefore, we conducted a cross-sectional laboratory based experimental study through random sampling aimed at characterizing in vitro antioxidant activity from haloalkaliphilic fungal strains of Lake Magadi in Kenya. Sample types comprising wet sediments, soils and surface water were cultured in sabouraud’s dextrose agar (SDA), potato dextrose agar (PDA) and malt extract agar (MEA) plates at temperatures of 250c and 410c respectively, for 1-3 weeks. Resulting pure isolates underwent molecular identification. PCR proceeded using ITS-1 & 4 universal primers followed by Sanger sequencing. NCBI’s nBLAST supported molecular identification with ≥90% identity cut-off values. Fermentation and extracts production progressed for 28 days at 250c accompanied by lyophilisation. Yielded freeze-dried extracts were profiled for antioxidant activity through hydroxyl, superoxide, DPPH, hydrogen peroxide, FRAP and lipid peroxidation inhibition assays. Extracts’ total phenolics and flavonoids content were also estimated. IC50 was tabulated based on dose-response curves against standards through linear regression. One-way ANOVA compared means across treatments and Tukey’s post hoc used for pairwise group comparisons. Statistical significance was considered at P≤0.05. Genera Cladosporium exhibited dominance (n=4) among sampled fungal biota. Samples P1, P6, P9 and P5 extracts exhibited maximal scavenging activity at higher concentrations against hydroxyl (76.53% ± 1.27), superoxide (78.90% ± 1.29), H202 (76.19% ± 0.40) and DPPH (80.19% ± 0.94) radicals, respectively. Ferric reductive (0.583 ± 0.005) and lipid peroxidation inhibitive (80.95% ± 1.07) activities for isolate P5 was statistically higher relative to other profiled extracts. Radical scavenging capacity of respective antioxidant standards was substantially higher against assayed extracts. Profound IC50 scavenging effect occurred at extract concentrations between 2.5 - 3.5 mg/ml. P7 extracts revealed peak total phenolic content of 3.61 ± 0.05 mg gallic acid equivalents/mg crude extract at 4mg/ml, while P6 expressed comparable total flavonoid content of 3.32 ± 0.04 mg quercetin equivalents/mg crude extract. Overally, fungi extracts showcased free radicals scavenging ability against reactive species in assorted antioxidant assays. Besides safety profile validation, our extracts demonstrate applicability for antioxidative potential that may further be discerned via comparative in vivo and ex vivo murine experimentation models.
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    Plasma interferon-gamma, interleukin-10 and adiponectin levels in HIV-1 and tuberculosis coinfected injection drug users at Bomu Hospital, Mombasa, Kenya
    (Kenyatta University, 2016-06) Kiboi, Nathan; Were, Tom; Juma, Gerald
    Sub-Saharan Africa accounts for high tuberculosis cases that result from widespread HIV infections, which is exacerbated by injection substance use. Immunologically, HIV critically impairs cell-mediated host responses to Mycobacterium tuberculosis. IFN-γ, IL-10 and Acrp30 are key mediators of systemic inflammation. Although circulating IFN- and IL-10 levels are increased, Acrp30 levels are lowered and associated with disease severity among HIV and TB co-infected non-susbstance users. In contrast, circulating IFN- and Acrp30 levels are decreased while IL-10 levels are upregulated among injecting heroin addicts. However, no studies to date have reported on these cytokine profiles among Kenyan HIV-1 and TB co-infected injection drug users. This study, therefore, investigated plasma IFN-γ, IL-10 and Acrp30 levels among IDUs, and their association with CD4+ T cell counts, HIV-1 viral load and BMI. A cross-sectional study was conducted from August, 2012-November, 2013 using 138 participants recruited at Bomu hospital; a major centre for rehabilitation of drug and substance users in Mombasa County. Following informed consent, IDUs were enrolled through respondent driven sampling, snowball and makeshift methods while convenience and purposive sampling were used for recruiting the control group. IDUs and controls were screened for HIV and TB respectively through Determine™ and Bioline™ rapid tests, and Ziehl Neelsen stained sputum smears. Subsequently, the study participants were categorised into: HIV-1/TB coinfected ART-naive (n=9) and -experienced (n=27); HIV-1 mono-infected ARTnaive (n=26) and -experienced (n=13); TB mono-infected (n=21), HIV-1 negative and TB uninfected (n=25) IDUs and controls (n=17). Demographic, drug use information and physical measurements were recorded using assisted interviews. EDTA venous blood samples were collected and used for preparing plasma and enumerating CD4+ T cell counts. Frozen plasma samples were used for determining cytokine concentrations, and HIV-1 viral load. CD4+ T cell counts were enumerated using flow cytometry; cytokine levels were measured using a sandwich ELISA technique, while HIV-1 viral load was determined by RT-PCR, respectively. Across-group comparisons in continuous data were performed using Kruskal Wallis followed by post-hoc Dunn’s tests. Plasma IFN-γ (P<0.0001), IL- 10 (P<0.0001) and Acrp30 (P=0.006) levels differed significantly across groups. IFN-γ levels were high in co-infected ART-naive (P<0.001) and -experienced (P<0.001), and HIV-1 mono-infected ART-experienced (P<0.001) IDUs relative to healthy controls. IL-10 levels were elevated in uninfected IDUs (P<0.001) compared to healthy controls. Acrp30 levels were lower in TB mono-infected (P<0.01) relative to controls. IFN-γ/IL-10 ratio varied across-groups (P<0.0001) and higher in co-infected ART-naive (P<0.001) and -experienced (P<0.001), and HIV-1 mono-infected ART-experienced (P<0.001) compared to uninfected IDUs. The IFN-γ/Acrp30 ratio also differed across groups (P<0.0001) with HIV-1 mono-infected ART-experienced (P<0.001), and co-infected ART-naive xii (P<0.001) and -experienced (P<0.001) IDUs exhibiting higher ratio relative to uninfected IDUs. CD4+ T cells correlated inversely with Acrp30 (=-0.717, P=0.030) levels in TB mono-infected IDUs whereas BMI correlated positively with Acrp30 (=0.523, P=0.022) among co-infected ART-naive IDUs, respectively. Altogether, circulating IFN-, IL-10 and Acrp30 production is altered in ART-naive and -experienced HIV-1 and TB co-infected IDUs, suggesting a role as disease markers in HIV and TB co-infection among IDUs.