A Survey of Medicinal Plants Used in Kieni Forest, Kiambu County, Kenya

Medicinal plants are affordable and accessible, but documentation and evidence of their effectiveness is limited. A study was conducted in Kieni forest, Kiambu County with the aim of documenting the therapeutic plants, exploring their phytochemical properties and potential antimicrobial properties. Semi-structured questionnaires administered via the snowball technique was used in the survey. Phytochemical investigations was carried out using standard methods while disc diffusion method was used to evaluate antimicrobial properties. The study identified 28 medicinal plants from 25 families. The most common conditions treated by the plants were noted to be skin infections (31 %). The primary sources of medicinal plant knowledge were from parents and grandparents (63%). Plant parts that were most utilized were the leaves (27%), while only 2% of the seeds were used. Qualitative analysis of methanol extracts from Croton macrostachyus, Cordia africana, Elaeodendron buchananii, Senna didymobotrya, and Coleus barbatus identified phytochemicals such as terpenoids, flavonoids and tannins. The microbial sensitivity assay showed that the plant extracts displayed efficacy against Gram-positive bacteria, such as Bacillus subtilis, Streptococcus pyogenes and Staphylococcus aureus. However, limited efficacy was observed against isolates of Salmonella typhi and Escherichia coli although the former exhibited susceptibility to E. buchananii leaves extracts. All the tested plant extracts were unable to inhibit the growth of Candida albicans. E. buchananii emerged as the most effective species against tested microorganisms with a mean zone of inhibition of 9.90 (SD 0.391), while C. macrostachyus and C. africana were relatively less effective. Minimum Inhibitory Concentration (MIC) revealed S. pyogenes as the most susceptible microorganism, with an average MIC of 65.63 mg/ml. S. aureus and B. subtilis had a MIC of 81.25 mg/ml and 125.00 mg/ml respectively. Conducting further research on isolated phytochemical compounds and properties could potentially lead to the development of cost-effective and less toxic drugs for managing microbial infections.