Browsing by Author "Ngugi, Mathew P."

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    Acute and Sub-Chronic Oral Toxicity Study of Methanolic Extract of Caesalpinia volkensii (Harms)
    (OMICS International, 2017) Musila, Michael N.; Ngai, David N.; Mbiri, Jane W.; Njagi, Shardrack M.; Mbinda, Wilton M.; Ngugi, Mathew P.
    Medicinal plant Caesalpinia volkensii is used to treat Malaria, conjunctivitis, retinoblastoma, and eyelid swelling as well as gonorrhoea and bilharzia. Animal toxicity information on this plant is limited. This medicinal plant was collected in Embu County in Kenya to evaluate its Acute and sub-chronic toxicity using Wistar rats. The rats were orally administered with different doses of the plants extracts. They were weighed on first day and after every 7 days during treatment with the extract. Signs of toxicity were also observed. After 28 days, the rats were sacrificed and blood samples taken for full hemogram, renal and liver function tests. Weight of internal organs was also recorded. Data was analysed using Minitab statistical software version 17. In acute toxicity studies, C. volkensii extracts did not result to death at extract dose of 2000 mg/kg body weight. In sub-chronic toxicity studies, there was no significance difference in body weight and organ weight among the groups treated with the plant extract (p>0.05). Treatment with extract dose of 1000 mg/kg body weight resulted in significant increase in total bilirubin and aspartate aminotransferase (P˂0.05). In addition, 100 mg/kg body weight resulted in significant decrease in haemoglobin and haematocrit. Qualitative phytochemical screening confirmed the presence of various phytochemicals which have the ability to protect erythrocytes from oxidative damage as well as erythropoietin stimulatory activities. It was therefore concluded that methanolic leaf extract of C. volkensii is safe for acute oral administration. However, care should be exercised in sub-chronic exposure at 1000 mg/kg body weight and above to avoid liver injury.
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    Contribution of Different Frass Fertilizer Products on Enhanced Growth, Yield and Nutrient Quality of Broccoli [Brassica Oleracea]
    (Frontiers in Plant Science, 2025-08) Kagehi, Noella; Beesigamukama,Dennis; Tanga, Chrysantus M.; Ngugi, Mathew P.; Subramanian, Sevgan; Khamis, Fathiya M.
    Vegetables are crucial for food security and income, but in developing countries their production is hindered by low soil fertility. Although the insect frass fertilizer is a potential solution, its use is constrained by limited product choices. Unlike conventional fertilizers, which are available in different forms, the insect frass fertilizer is mostly available in solid form. Here, we evaluated the effects of different black soldier fly frass fertilizer (BSFFF) products on broccoli [Brassica oleracea] growth, yield, and nutritional profiles. Solid, liquid BSFFF, chitin-fortified solid BSFFF, chitin-fortified liquid BSFFF, and commercial organic fertilizer (Safi) were applied at rates equivalent to 250 kg N ha-1 for two cropping seasons. The control treatment consisted of unfertilized soil. Results showed that solid and chitin-fortified solid BSFFF products significantly increased broccoli leaf growth and chlorophyll concentration by 54% and 11%, respectively, compared to the other BSFFF products. Soils amended with BSFFF products produced broccoli with higher number of heads (28 – 158%), fresh yield (26 – 138%), dry yield (17 – 60%), and aboveground biomass (7 – 117%) compared to Safi and control treatments. Broccoli grown in soil amended with BSFFF had higher nitrogen (84%), phosphorus (93%), potassium (51%) uptake, and agronomic use efficiency (4.6-fold) as compared to Safi and the control. Additionally, the application liquid BSFFF produced broccoli heads with higher levels of crude fat (61%), carbohydrates (16%), and calcium (38%) compared to other BSFFF products. Conversely, broccoli grown using chitin-fortified BSFFF exhibited the highest levels of crude protein, potassium, crush ash, and phosphorus. The net income and gross margin achieved with BSFFF treatments were 19 – 26-fold and 29 – 63-fold higher than values obtained Safi, respectively, with higher profitability achieved using chitin-fortified BSFFF formulations. These findings demonstrate the efficacy of different BSFFF formulations in supporting circular economy for safe vegetable production, and improved food and nutrition security
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    Genetic Diversity Studies on Selected Rice (Oryza Sativa) Genotypes Based on Amylose Content and Gelatinization Temperature
    (OMICS International, 2015) Musyoki, Mawia A.; Kioko, Wambua F.; Ngugi, Mathew P.; Agyirifo, Daniel; Muriira, Karau G.; Wavinya, Nyamai D.; Matheri, Felix; Lagat, Chemutai R.; Mwenda, Njagi S.; Kiambi, Mworia J.; Ngithi, Ngari L.
    Improving cooking and eating quality of rice is one of the important objectives of many breeding programs. The aim of the study was to carry out genetic diversity studies on selected rice (Oryza sativa L.) genotypes from Kenya and Tanzania based on amylose content and gelatinization temperature using microsatellite markers. Power marker version 3.25 and GenALEx version 6.5 softwares were used to analyze the data. The number of alleles per locus ranged from 2 to 4 alleles with an average of 2.75 alleles across 8 loci obtained in this study. The polymorphic information content (PIC) values ranged from 0.2920 (RM 202) to 0.6841 (RM 141) in all 8 loci with an average of 0.4697. Pair-wise genetic dissimilarity coefficients ranged from 0.9003 to 0.2251 with an average of 0.5627. Maximum genetic similarity was observed between R 2793 and BS 17, Supa and IR 64, R 2793 and ITA 310, Saro 5 and ITA 310, Saro 5 and R 2794. Minimum similarity of was observed between Wahiwahi and BW 196, IR 64 and BW 196. The dendogram based on cluster analysis by microsatellite polymorphism grouped the rice genotypes into 2 clusters effectively differentiating Kenyan and Tanzanian rice genotypes based on amylose content and gelatinization temperature. The results obtained suggested that use of microsatellite markers linked to Quantitative Trait Loci (QTLs) controlling these two traits could effectively be utilized for diversity analysis among diverse rice genotypes. Keywords: Oryza sativa; Oryza glaberrima; Heterozygosity; Germplasm; Genotypes
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    Phenotypic characterization of selected Kenyan Khat (Catha edulis) cultivars based on morphological traits
    (Academic Journals, 2019-09) Ngari, Loise N.; Njagi, Shadrack N.; Kamau, James K.; Lagat, Rose C.; Musyoki, Amos M.; Akoth, Beryl O.; Kioko, Festus; Okwany, Zedekiah-A; Ngugi, Mathew P.
    Khat (Catha edulis Vahl) is an evergreen shrub habitually ingested for its euphoric and stimulatory effects. The crop is grown in the Middle East, Somalia, East Africa and Ethiopia. It is referred to as Miraa in Kenya, while in Yemen it has several names like Qat, Kat, Kath, Gat, Chat and Tschat. It belongs to the sub-order Rosidae, family Celastraceae and characterized by astringent taste. Despite the daily use and consumption of khat by millions of people in Kenya, little is known about its phenotypic. Phenotypic characterization is an essential approach for assessment of khat diversity; however, it is limited by morphological plasticity and multiple lineage evolution. The study aimed at evaluating the phenotypic diversity of selected khat cultivars grown in Embu and Meru Counties. Ninety samples from 18 cultivars were collected for phenotypic characterization. MINITAB 17 Software was used for description of principal component and construction of dendrogram using the Euclidean distance tool where 58.7% variability was observed among 13 traits studied in 90 samples of khat. Phenotypes grouped into 2 clusters phenotypic diversity showed considerable variability based on 13 khat traits. This will be useful in breeding and characterization programmes of khat cultivars.
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    Phytochemical and Antioxidant Screening of Seed Extracts of Kenyan Custard Apple (Annona squamosa)
    (2017) Mwihia, Stephen K.; Ngugi, Mathew P.; Maingi, John M.
    Medicinal plants have been the mainstay of traditional herbal medicine amongst rural dwellers worldwide since antiquity for their preventive and curative properties. Investigation of plants for phytochemicals and medicinal activities is imperative for the discovery of prospective novel molecules for medicinal use. This current analysis was aimed at screening the seed extracts of Annona squamosa for the presence of phytochemicals and their antioxidant activities. Extraction of the active components was through organic solvents; methanol, dichloromethane and methanol: dichloromethane blend in Soxhlet extractor and concentrated in a rotary evaporator. Investigation of phytochemicals was through standard qualitative screening procedures while antioxidant activities of the extract were evaluated through the radical scavenging effect of DPPH, H2O2 and the FRAP assay. Methanol was the most effective solvent in capturing phytochemicals including tannins, alkaloids, flavonoids, fixed oils and phenols. Dichloromethane captured only alkaloids and fixed oils. The antioxidant data obtained was assayed against that of the standard (Ascorbic acid). The methanolic extract was found to be the most potent extract with highest antioxidant activities followed by methanol: dichloromethane blend while dichloromethane portrayed the least potency. The highest DPPH radical scavenging was at 500mg/ml, while for H2O2 was at 1mg/ml while the highest FRAP activity was at 1mg/ml. Methanolic extracts were the most potent while dichloromethane extracts showed the least DPPH and H2O2 radical scavenging activities. Phenols appear have significantly contributed towards the antioxidant activity of the methanolic extracts and the alkaloids in dichloromethane extracts. Most of the inedible parts of commonly consumed fruits have not been studied for their antioxidant activity but the current assay demonstrates that seeds may be a promising source of antioxidants. This study shows that the seed extracts of Annona squamosa may be utilised therapeutically in the management of oxidative stress related disorders. Keywords:Annona squamosa, Phytochemical, Antioxidant, Radical Scavenging, diphenyl-picrylhydrazyl (DPPH), Hydrogen Peroxide (H2O2) and Ferrous Reducing Antioxidant Power (FRAP)
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    Production of Cellulases by Xylaria Sp. And Nemania Sp. Using Lignocellulose Substrates for Bioethanol Production from Maize Cobs
    (Heliyon, 2024-08) Kamande, Stephen M.; Omwenga, George I.; Ngugi, Mathew P.
    Two species of Xylaria (KM01, KM03) and Nemania sp.KM02 isolated from decaying plant biomass were evaluated for their ability to produce cellulases on maize cob, eucalyptus, and cypress substrates under solid-state fermentation. A total of 10 fungal samples from decaying plant biomass were collected from Karura forest based on morphological variations. The fungi isolated were screened for cellulase activity and positive isolates were selected for the study. ITS4 R and ITS86 F primers were used to identify the fungal isolates with accuracy ranging from 98 % to 100 %. The crude cellulases produced was assayed for FPase, exoglucanase, endoglucanase and β-glucosidase. Cellulases of Xylaria sp. KM01 produced higher FPase and exoglucanase (2.01 ± 0.13 IU/ml and 0.94 ± 0.08 IU/ml) on pretreated maize cobs with 0.1M HCl at 121o C, while that of Xylaria sp.KM03 produced higher β-glucosidase and endoglucanase (588.6 ± 64.2 IU/ml and 3.59 ± 0.02 IU/ml) on maize cobs pretreated with 0.1M NaOH at 121o C. However, cellulases of Xylaria sp. KM01 produced higher β-glucosidase and FPase (629.7 ± 20.2 IU/ml and 1.67 ± 0.03 IU/ml) on untreated maize cobs after the 9th day of incubation, whereas cellulases of Xylaria sp. KM03 and Nemania sp.KM02 produced higher endoglucanase and exoglucanase (2.80 ± 0.21 IU/ ml and 0.83 ± 0.02 IU/ml) on untreated maize cobs after the 3rd and 6th day of incubation. Saccharification of maize cobs by cellulase of Xylaria sp.KM03 produced the highest reducing sugars at 8 % substrate loading (10.17 ± 0.37 mg/ml) after 72 h of incubation. Simultaneous hydrolysis and fermentation of maize cobs by cellulase of Nemania sp.KM02 and Saccharomyces cerevisiae yielded higher bioethanol (28.72 ± 3.82 mg/ml) after 96 h of fermentation. Maize cob is established as a suitable feedstock for cellulases and bioethanol production.
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    Screening of Phytochemicals and Antibacterial Activity of Seed Extracts of Kenyan Sugar Apple (Annona squamosa)
    (2017) Mwihia, Stephen K.; Ngugi, Mathew P.; Maingi, John M.; Kamau, James K.; Muhuha, Anne W.
    Investigation of plants for phytochemicals and antibacterial effects is essential for discovery of prospective novel complexes for therapeutic use. In the present assay the seed extracts of Annona squamosa were screened for phytochemicals present and antibacterial activities against Salmonella typhi (ATCC 1408), Escherichia coli (ATCC 25922), and Klebsiella pneumonia (ATCC700603) and Shigella flexneri (ATCC 12022). Extraction of the active components was done by the use of organic solvents; methanol, dichloromethane and methanol: dichloromethane blend in soxhlet extractor and concentrated in a rotary evaporator. Phytochemical analysis was done through standard qualitative screening procedures. The antibacterial activities were evaluated through the paper disc diffusion method. Phytochemical analysis exhibited the occurrence of fixed oils, alkaloids, saponins, flavonoids, glycosides, tannins, phenols, steroids and terpenoids which are indicated in antibacterial activity. The methanolic extract was the most efficacious in terms of inhibitory activities, exhibiting a MIC range of 15-31.17mg/ml followed by Methanol: dichloromethane with a MIC range of 16.4-56.57mg/ml while dichloromethane displayed the least bacterial inhibitory activity with a MIC range of 47.50-61.83mg/ml. The antibacterial data obtained was assayed against that of the Ciprofloxacin (reference). Ciprofloxacin activity was significantly higher than all the extracts (p<0.05), though some concentrations exhibited equal activities (p>0.05). The extracts have shown antibacterial effects at their MIC against the microorganisms in the study indicating that with further researches these extracts can be used for treating enteric diseases. Keywords: Annona squamosa, Phytochemical, Antibacterial, Paper disc diffusion method, methanol, dichloromethane extract, enterobacteria.