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Eleven medicinal plants used by traditional healers in Machakos and Kitui District were screened, namely: Ajuga remota Benth, Aloe secundiflora Engl, Amaranthus hybridus L, Cassia didymobotrya Fes, Croton macrostachyus Del, Entada leptostachya Harms, Erythrina abyssinica DC, Harrisonia abyssinica Oliv, Schkuhria pinnata O. Ktze, Terminalia kilimandscharica Engl and Ziziphus abyssinica Hochst for potential antibacterial activity against four medically important bacterial strains, namely: Bacillus cereus ATCC 11778, Escherichia coli ATCC 25922, Micrococcus lutea ATCC 9341 and Pseudomonas aeruginosa ATCC 27853. The antibacterial activity of methanol extracts was determined as the minimum inhibitory concentration (MIC). The plant extracts were more active against Gram-positive (G+) than Gram-negative (G-) bacteria. The positive controls were streptomycin and benzylpenicillin for G- and G+ bacteria, respectively, both had a significant MIC at <1 mg/mL. The most susceptible bacteria were B. cereus, followed by M. lutea, while the most resistant bacteria were Ps. aeruginosa, followed by E. coli. The present study supports the use of these plants by the herbalists in the management of bacterial ailments. H. abyssinica and T. kilimandscharica showed the best antibacterial activity; hence these plants can be further subjected to phytochemical and pharmacological evaluation.

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Direct detection of saponins in medicinal plants using Fourier Transform Infrared (FTIR) spectroscopy is reported in this paper. Crude dry plant powders were mixed with potassium bromide (KBr) powder and compressed to a thin pellet for infrared examination. FTIR spectra of the test samples showed -OH, -C=O, C-H, and C=C absorptions characteristic of oleanane triterpenoid saponins. The C-O-C absorptions indicated glycoside linkages to the sapogenins. Phytochemical analysis confirmed the presence of saponins in the tested specimens. Entada leptostachya was used as a reference sample. Dry plant powder was extracted sequentially with hexane, dichloromethane, ethyl acetate and methanol. FTIR spectra of the reference sample powder and its organic solvent extracts showed characteristic saponin absorption peaks. These results indicated that direct detection of saponins in medicinal plants was possible by infrared analysis. Lengthy exhaustive chemical analyses necessary for detection of saponins could be avoided.

In this study, Tithonia diversifolia Helms. (A Gray), Aloe secundiflora (Miller) and Azadirachta indica (A. Juss) plant extracts were used to make herbal soaps while Thevetia peruviana (Schum) seed oil was used to make a herbal lotion for skincare. The soaps were tested for the growth inhibition of Escherichia coli, and Candida albicans. The lotion was evaluated against Staphylococcus aureus and E.coli. Although Tithonia diversifolia soap exhibited the highest inhibitory effect on the test bacterial strains, it had the least inhibition against C. albicans. Results from this study indicated that the 'Tithonia diversifolia' soap would have superior skin protection against the tested bacteria but would offer the least skin protection against C. albicans. The herbal lotion inhibited S. aureus and E. coli in a concentration dependent manner, however, the inhibitory effect was more pronounced on S. aureus.

Metallic nanoparticles synthesized using aqueous plant extracts are environment-friendly, biocompatible, and highly stable. The aim of this study was to synthesize iron nanoparticles using aqueous Ageratum conyzoides extracts and evaluating their antimicrobial and photocatalytic properties. The particles were analysed using UV-Vis spectrophotometer, FT-IR Spectrophotometer, X-ray diffractometer and Scanning electron microscope. GC-MS profile of the extracts revealed presence of secondary metabolites which were further quantified to determine the total phenolic and total flavonoids content of the extracts. The antibacterial activity of the plant extract and the synthesized iron oxide nanoparticles was evaluated against five microorganisms using agar well diffusion method. Iron nanoparticles synthesized in a one step process observed using visible spectra and the functional groups present such as C=O were identified from IR spectrum. SEM-EDX profile identified presence of iron, oxygen, chlorine, calcium in the particles while XRD data revealed the particles synthesized were composed oxides of iron which had moderate activity against the selected microorganisms as compared to the antibiotic ciprofloxacin. The particles were able to photocatalytic degrade methylene blue with a degradation efficiency of 92%. The results obtained in this study confirms that Ageratum conyzoides can play an important role in the bioreduction of Fe ions to FeNPs which have moderate activity against microorganisms and can act as photocatalyst to degrade methylene blue.

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