In Vitro Antibacterial, In Vivo Immunomodulatory and Safety Properties of Ethyl Acetate Leaf Extract of Ocimum Basilicum
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Date
2021
Authors
Rapando, Wambani Japheth
Journal Title
Journal ISSN
Volume Title
Publisher
Kenyatta University
Abstract
Staphylococcus aureus (S. aureus), Methicillin resistant S. aureus (MRSA), Pseudomonas aeruginosa (P. aeruginosa) and Escherichia coli (E. coli) are common bacterial pathogens. Multi-drug resistant strains of these pathogens have led to a demand for new treatment options. O. basilicum is an important medicinal plant and has traditionally been shown to have antimcrobial values. However, there was need to validate its safety and immune modulation potential. The aim of this study was to determine the in vivo immunomodulatory, safety and in vitro antibacterial effects of O. basilicum. This was a laboratory-based experimental study. Ocimum basilicum was obtained from Siakago, Embu County. Different concentrations of the ethyl acetate leaf extract were used for testing antibacterial efficacies by the disc diffusion method followed by determination of MIC and MBC by broth dilution. Phytochemical and elemental properties of the extract were assayed by GC-MS and atomic absorbance spectrophotometry. For immune modulation, 300, 200 and 100 mg/kgbw extract concentrations were used while RRBC‘s were used as the antigen. Administration of mice with 300, 548 and 1000 mg/kgbw for 28 days was done to determine their body weight, organ weight, biochemical and hematological profiles for safety evaluation. Ethical approval for the use of mice was sought from the Kenyatta University animal care and use committee. Phytochemical composition of the extract included terpenoids, alkaloids, essential oils, fatty acids, flavonoids and aldehydes. Of the mineral elements detected in the extract, Mg had the highest concentration (1241.6±0.42 mg/100g) while cobalt had the lowest concentration (0.08±0.02 mg/100g). Heavy metals were not detected. A broad spectrum antibacterial activity was exhibited on the tested bacterial strains. The highest activity was on P. aeruginosa (27.00±2.00mm) while the lowest activity was on the isolate of S. aureus (17.33+0.58mm). The extract reversed the effects of cyclophosphamide on the myeloid stem cells by restoring the counts of Hb, WBC and RBC‘s in the blood. There was a dose dependent effect on the humoral antibody responses with the 300 mg/kgbw concentration of the extract exhibiting statisticaslly significant (12.4±0.894) antibody responses on the RRBC‘s. The extract exhibited an effect on neutrophil adhesion and a dose dependent effect on phagocytic index which wasn‘t significantly different among the extract concentrations. In DTH models, the different extract concentrations had dose dependent effects on TLC‘s and PLT counts. In vivo safety tests revealed that the 1000 mg/kgbw concentration significantly lowered PLT counts (556.00±76.00 10^3/μl) while having no effect on other blood indices. The extract was also proven safe on the liver and kidney. The ethyl acetate leaf extract of O. basilicum had antibacterial, immune modulation effects and was safe for in vivo use, therefore, this plant could be harnessed in efforts to come up with alternative and complementary therapies.
Description
A Thesis Submitted in Fulfillment of the Requirements for the Award of the Degree of Doctor of Philosophy (Medical Microbiology) in the School of Medicine of Kenyatta University, November, 2021
Keywords
In Vitro Antibacterial,, In Vivo Immunomodulatory, Safety Properties, Ethyl Acetate, Leaf Extract, Ocimum Basilicum