The antimicrobial activity and chemical profile of traditional medicinal plants indigenous to Southern Africa used to treat respiratory tract infections
Date
2010-10-26
Authors
Suliman, Anisa
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Abstract
Fifteen traditional medicinal plants, indigenous to southern Africa, that are used to treat
various respiratory ailments were screened for their antimicrobial activity and their chemical
profiles were documented. Acetone:methanol (1:1) extracts were prepared from the leaves,
stems, roots, barks and thorns of the investigated plant species.
The antimicrobial activity was determined against pathogens associated with respiratory
conditions i.e. Moraxella catarrhalis, Bacillus cereus, Enterococcus faecalis, Klebsiella
pneumoniae, Staphylococcus aureus, Candida albicans and Cryptococcus neoformans. The
MIC values ranged from 0.08 mg/ml to 12 mg/ml. The two pathogens against which the most
number of extracts obtained MIC values that were ≤ 1 mg/ml were Moraxella catarrhalis
(68% of the extracts) and Bacillus cereus (56% of the extracts). The plant extracts that
obtained the five lowest average MIC values against the respiratory pathogens were the root
extracts of Terminalia sericea (0.69 mg/ml), leaf and stem extract of Chenopodium
ambrosioides (1.04 mg/ml), leaf, stem and flower extract of Leucas martinicensis (1.10
mg/ml), leaf extract of Zanthoxylum davyi (1.29 mg/ml) and the leaf and stem extracts of
Lantana rugosa (1.32 mg/ml).
For the bioautographic assays, clear zones of inhibition were recorded for Lantana rugosa
(leaves and stems) and Vitex rehmannii (leaves) against Staphylococcus aureus and Moraxella
catarrhalis. The root extract of Ziziphus mucronata had a clear zone of inhibition against
Staphylococcus aureus. The leaf and stem extracts of Chenopodium ambrosioides had a clear
zone of inhibition against Moraxella catarrhalis.
The chemical profiles that were recorded for the plant extracts comprised of HPLC and TLC
chromatograms. The HPLC and TLC profiles resulted in the separation of the chemical
constituents thus providing a chemical fingerprint for the plant extracts. Flavonoids were
tentatively identified for Acacia sieberiana (leaves), Alepidea amatymbica (roots), Clematis
oweniae (leaves), Clerodendrum glabrum (leaves), Heteromorpha arborescens (bark),
Peucedanum caffrum (roots B), Vitex rehmannii (leaves) and Ziziphus mucronata (leaves).
The TLC chromatograms qualitatively displayed good separation of the compounds present in
the plant extracts.
The antimicrobial activity recorded for the plant extracts validates their traditional uses to treat
various respiratory infections and the chemical profiles provide a reference of the chemical
profiles of the plant extracts that can be used in future investigations
Description
MSc (Med) (Pharmaceutical Affairs), Faculty of Health Sciences, University of the Witwatersrand
Keywords
medicinal plants, respiratory diseases, plant extracts