Screening for antimicrobial and anti inflammatory activities and, formulation studies on the extracts of selected medicinal plants topically applied in Ethiopia
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Date
2014-02
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Addis Ababa University
Abstract
In an attempt to integrate traditionally used herbal products into modern topical formulation,
extracts of the leaves of Maesa lanceolata (Myrsinaceae), Osyris quadripartita Decn.
(Santalaceae), Steganotaenia araliacea Hochst ExA. Rich (Apiaceae), Cadaba farinosa
(Capparidaceae) and; the aerial parts of Plantago lanceolata (Plantagonaceae) and Alachemilla
pedata A. Rich (Rasaceae) have been screened for their antibacterial and antifungal activities.
All hydroalcoholic extracts, except C. farinosa and S. araliacea were active against E. coli. And,
all extracts had activities against S. aureus and P. aeroginosa. Similarly, screeneing of the total
extracts against Candida albicans and Trichophyton mentagrophytes indicated that all extracts,
except P. lanceolata on both strains and C. farinosa on T. mentagrophytes, were active. But none
of the extracts tested displayed activity against Aspergillus niger.
The antimicrobial activities of A. pedata and M. lanceolata were higher than those plants tested
and hence, further works have been undertaken on these plants. In an attempt to localize the
active ingredients, successive fractionation with petroleum ether, chloroform, acetone and
methanol have been carried out. The antimicrobial activity study of the various fractions revealed
that the antimicrobial effect of A. pedata was because of the non-polar components (petroleum
ether fraction) and that of M. lanceolata, the activities were distributed among the various
fractions. The action against T. mentagrophytes of the latter was entirely because of the polar
compounds present in the methanol extract.
To assess the clinical utility of these plants, MICs were determined. Accordingly, the results for
A. pedata were 5 mg/ml against S. aureus and E. coli and, 10 mg/ml for C. albicans using agarwell
diffusion technique. The MIC of this plant extract using agar dilution technique on the same
bacteria was 0.125 mg/ml. Similarly; the MIC of M. lanceolata was 1.25 mg/ml against the
abovementioned bacteria and, 0.625 mg/ml against fungi using agar-well diffusion technique.
And, using dilution technique, the result was 1.25 mg/ml for bacteria and 0.0625 mg/ml for fungi.
Anti-inflammatory activities and semi-quantitative standardization works were also conducted
and it was found that M. lanceolata has significant anti-inflammatory activity at 100 mg/kg and
750mg/kg with better activity at 100 mg/kg. Similarly, A. pedata has also displayed antiinflammatory
activity, even though the effect was less than M. lanceolata. The water extractive
values were 4.66 and 5.24% (W/W) for A. pedata and M. lanceolata, respectively. Successive
extractive values using petroleum ether, chloroform, acetone, methanol and water were (3.20,
4.56), (3.38, 4.36), 1.28, 0.56), (5.38, 6.52), (4.60, 6.64) for A. pedata and M. lanceolata,
respectively. Ash value determination and TLC-fingerprinting were also conducted as part of the
standardization work.
Ointments and creams were formulated using the hadroalcoholic extracts of A. pedata and M.
lanceolata. Study on the in vitro performances of the proposed formulations indicated that
releases from hydrophilic bases were better and polyethylene glycol-based preparations were
superior in activity than formulations prepared with hydrophobic bases. Furthermore, the in vitro
performances of the formulated topical dosage forms were comparable to the activity of locally
available marketed antimicrobial products.
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Keywords
Antimicrobial ; Anti inflammatory