Antioxidant Activity, Phytochemical Content and Antibacterial Activity of Extracts of Aloiampelos ciliaris
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Date
2025-11
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Kenyatta University
Abstract
Extensive research on medicinal plants has revealed their antibacterial, antifungal, and
antioxidant properties. However, the increasing prevalence of bacterial resistance to
conventional antibiotics highlights the need to identify new bioactive compounds from
medicinal plants. Currently, natural products account for over 50 % of drugs used in the
treatment of different infections. Within this context, the Aloe genus (family Asphodelaceae),
comprising approximately 500 Aloe species globally and about 50 species in Kenya, has a
long-standing history of medicinal use. Notably, Aloe arborescence, Aloe ferox, and Aloe
perryli have been extensively documented for their therapeutic potential. Traditionally, Aloe
extracts have been employed for anti-malarial, anti-diabetic, anti-inflammatory, ornamental,
and green manure purposes. Despite this established knowledge, inadequate information
exists regarding the phytochemical composition, therapeutic evaluation, antioxidant activity,
and antibacterial properties of Aloiampelos ciliaris (A. ciliaris). The present study, therefore,
aimed to screen for phytochemicals (tannins, phenols, flavonoids, cardiac glycosides),
evaluate antioxidant and antibacterial activities, and determine the total phenolic and
flavonoid content of A. ciliaris. Plant samples were collected from Meru County and
macerated in 80 % methanol for 48 hours, followed by solvent partitioning (n-hexane,
dichloromethane, EtOAc and water). Antioxidant activity was assessed using the 2,2-
diphenyl-1-picrylhydrazyl radical (DPPH) radical scavenging assay, with results ranging
from 15.67 % (IC50 > 0.0300) to 74.74 % (IC50 > 0.0300) at 0.3mg/mL, using ascorbic acid as
a standard reference. Total phenolic content ranged from 105.89 ± 0.07 mg GAE/g in the
flower crude extract to 1.46 ± 0.04 mg GAE/g in flower DCM extract, with gallic acid as a
reference standard. Similarly, total flavonoid content ranged from 182.69 ± 1.64 mg QE/g in
root crude extract to 3.59 ± 0.41 mg QE/g in the flower n-hexane extract, with quercetin as
the reference standard. The antibacterial potential of the extracts was tested against
pathogenic Gram-positive (E. faecalis, B. subtilis) and Gram-negative bacteria (E. coli, S.
typhi) using gentamicin and ciprofloxacin as positive controls and 10 % dimethyl sulfoxide
(DMSO) as the negative control. Activity ranged from inhibition of E. coli by the EtOAc
extract (12.0 ± 0.500) to inhibition of B. subtilis by the root DCM extract (7.0 ± 0.000).
Phytochemical screening revealed the presence of flavonoids, tannins, alkaloids, terpenoids,
cardiac glycosides, phenols, and saponins. Furthermore, GC-MS analysis facilitated the
separation, identification, and quantification of compounds such as methyl-cyclohexane and
dodecane. Overall, the findings demonstrate that A. ciliaris possesses considerable
therapeutic potential, attributable to its diverse secondary metabolites, antioxidant activity,
antibacterial effects, and total phenolic and flavonoid contents.
Description
A Thesis Submitted in Partial Fulfillment of the Requirements for the Award of the Degree of Master of Science (Chemistry) in the School of Pure and Applied Sciences of Kenyatta University, November, 2025
Supervisor:
1.Wilson Njue
2.Henry Mwangi
3.John Maingi